Roots Universal rai series Owner's manual

ROOTS

BLOWERS EXHAUSTERS COMPRESSORS

™™

INSTALLATION OPERATION MAINTENANCE

❏In event of trouble during installation or operation,

do not attempt repairs of ROOTS furnished

equipment. Notify ROOTS, giving all nameplate

information plus an outline of operating conditions

and a description of the trouble. Unauthorized

attempts at equipment repair may void ROOTS

warranty.

❏Units out of warranty may be repaired or adjusted

by the owner. It is recommended that such work be

limited to the operations described in this manual,

using ROOTS™parts. Good inspection and

maintenance practices should reduce the need

for repairs.

NOTE:Information in this manual is correct as of the

date of publication. ROOTS reserves the right to make

design or material changes without notice, and without

obligation to make similar changes on equipment of

prior manufacture.

For your nearest ROOTS Office, dial our Customer

Service Hot Line toll free; 1 877 363 ROOT(S) (7668)

or direct 281-966-4700.

DOTHESE THINGS TOGET THE MOST FROM YOUR ROOTS™BLOWER

CONTENTS

INFORMATION SUMMARY . . . . . . . . . . . 1

SAFETY PRECAUTIONS . . . . . . . . . . . . 2

OPERATING LIMITATIONS . . . . . . . . . . . 2

INSTALLATION . . . . . . . . . . . . . . . . . . . 3

LUBRICATION . . . . . . . . . . . . . . . . . . . 6

OPERATION . . . . . . . . . . . . . . . . . . . . 7

OPERATING CHARACTERISTICS ..............8

❏Check shipment for damage. If found, file claim

with carrier and notify ROOTS.

❏Unpack shipment carefully, and check contents

against Packing List. Notify ROOTS if a

shortage appears.

❏Store in a clean, dry location until ready for

installation. Lift by methods discussed under

INSTALLATION to avoid straining or distorting the

equipment. Keep covers on all openings. Protect

against weather and corrosion if outdoor storage

is necessary.

❏Read OPERATING LIMITATIONS and

INSTALLATION sections in this manual and plan

the complete installation.

❏Provide for adequate safeguards against accidents

to persons working on or near the equipment during

both installation and operation. See SAFETY

PRECAUTIONS.

❏Install all equipment correctly. Foundation design

must be adequate and piping carefully done. Use

recommended accessories for operating protection.

❏Make sure both driving and driven equipment is

correctly lubricated before start-up.

See LUBRICATION.

❏Read starting check points under OPERATION. Run

equipment briefly to check for installation errors and

make corrections. Follow with a trial run under

normal operating conditions.

TROUBLESHOOTING . . . . . . . . . . . . . . 9

MAINTENANCE/REPLACEMENTS

UNIVERSAL RAI®SERIES BLOWERS ...........10

RAM™SERIES BLOWERS .........................14

FIGURES ...........................................18

TABLES .............................................22

ASSEMBLY DRAWINGS .........................26

PARTS LIST .......................................31

US $3.00, Canada $4.50

IRB-180-102

Rev. 12/02

UNIVERSAL RAI®& RAM™SERIES

ROOTS™products are sold subject

to the current General terms of

Sale, GTS-5001 and Warranty

Policy WP-5020. Copies are

available upon request.

Contact your local ROOTS Office

or ROOTS Customer Service

Hot Line 1.877.363.ROOT(S) (7668).

2For your nearest ROOTS Office, dial our Customer Service Hot Line 1 877 363 ROOTS (7668).

SAFETY PRECAUTIONS

It is important that all personnel observe safety

precautions to minimize the chances of injury.

Among many considerations, the following should

be particularly noted:

•Blower casing and associated piping or accessories

may become hot enough to cause major skin burns

on contact.

•Internal and external rotating parts of the blower

and driving equipment can produce serious physical

injuries. Do not reach into any opening in the

blower while it is operating, or while subject to

accidental starting. Protect external moving parts

with adequate guards.

•Disconnect power before doing any work, and avoid

bypassing or rendering inoperative any safety or

protective devices.

•If blower is operated with piping disconnected,

place a strong coarse screen over the inlet and

avoid standing in the discharge air stream.

CAUTION: Never cover the blower inlet with

your hand or other part of body.

•Stay clear of open inlet piping (suction area) of

pressure blowers, and the open discharge blast

from vacuum blowers.

•Stay clear of the blast from pressure relief valves

and the suction area of vacuum relief valves.

•Use proper care and good procedures in handling,

lifting, installing, operating and maintaining the

equipment.

•Casing pressure must not exceed 25 PSI

(1725 mbar) gauge. Do not pressurize vented

cavities from an external source, nor restrict the

vents without first consulting ROOTS.

•Do not use air blowers on explosive or

hazardous gases.

•Other potential hazards to safety may also be

associated with operation of this equipment. All

personnel working in or passing through the area

should be trained to exercise adequate general

safety precautions.

OPERATING LIMITATIONS

A ROOTS™blower or exhauster must be operated

within certain approved limiting conditions to enable

continued satisfactory performance.Warranty is

contingent on such operation.

Maximum limits for pressure, temperature and speed

are specified in TABLE 1 for various models & sizes

of blowers & exhausters.These limits apply to all units

of normal construction, when operated under

standard atmospheric conditions. Be sure to arrange

connections or taps for thermometers and pressure

or vacuum gauges at or near the inlet and discharge

connections of the unit.These, along with a good

tachometer, will enable periodic checks of

operating conditions.

PRESSURE – The pressure rise, between inlet and

discharge, must not exceed the figure listed for the

specific unit frame size concerned. Also, in any system

where the unit inlet is at a positive pressure above

atmosphere a maximum case rating of 25 PSI gauge

(1725 mbar) should not be exceeded without first

consulting the ROOTS. Never should the maximum

allowable differential pressure be exceeded.

On vacuum service, with the discharge to atmospheric

pressure, the inlet suction or vacuum must not be

greater than values listed for the specific frame size.

TEMPERATURE – Blower & exhauster frame sizes are

approved only for installations where the following

temperature limitations can be maintained in service:

•Measured temperature rise must not exceed listed

values when the inlet is at ambient temperature.

Ambient is considered as the general temperature

of the space around the unit.This is not outdoor

temperature unless the unit is installed outdoors.

•If inlet temperature is higher than ambient, the

listed allowable temperature rise values must be

reduced by 2/3 of the difference between the

actual measured inlet temperature and the

ambient temperature.

•The average of the inlet and discharge temperature

must not exceed 250°F. (121°C).

SPEED – These blowers & exhausters may

be operated at speeds up to the maximum listed for

the various frame sizes.They may be direct coupled

to suitable constant speed drivers if pressure/tempera-

ture conditions are also within limits. At low speeds,

excessive temperature rise may be a limiting factor.

Special Note: The listed maximum allowable tempera-

ture rise for any particular blower & exhauster may

occur well before its maximum pressure or vacuum

rating is reached.This may occur at high altitude, low

vacuum or at very low speed.The units’ operating limit

is always determined by the maximum rating reached

first. It can be any one of the three: Pressure,

Temperature or Speed.

ROOTS, RAM, URAI and WHISPAIR are trademarks of Dresser, Inc.

Dresser Design and Universal RAI are registered trademarks of Dresser, Inc.

ROOTS™blowers & exhausters are treated after factory

assembly to protect against normal atmospheric

corrosion.The maximum period of internal protection

is considered to be one year under average conditions,

if shipping plugs & seals are not removed. Protection

against chemical or salt water atmosphere is not

provided. Avoid opening the unit until ready to start

installation, as corrosion protection will be quickly lost

due to evaporation.

If there is to be an extended period between installa-

tion and start up, the following steps should be taken

to ensure corrosion protection.

❏Coat internals of cylinder, gearbox and drive end

bearing reservoir with Nox-Rust VCI-10 or

equivalent.Repeat once a year or as conditions

may require. Nox-Rust VCI-10 is petroleum

soluble and does not have to be removed before

lubricating. It may be obtained from Daubert

Chemical Co., 2000 Spring Rd., Oak Brook, Ill.

60521.

❏Paint shaft extension, inlet and discharge flanges,

and all other exposed surfaces with Nox-Rust

X-110 or equivalent.

❏Seal inlet, discharge, and vent openings. It is not

recommended that the unit be set in place, piped

to the system, and allowed to remain idle for

extended periods. If any part is left open to the

atmosphere, the Nox-Rust VCI-10 vapor will

escape and lose its effectiveness.

❏Protect units from excessive vibration

during storage.

❏Rotate shaft three or four revolutions every

two weeks.

❏Prior to start up, remove flange covers on both

inlet and discharge and inspect internals to insure

absence of rust. Check all internal clearances.

Also, at this time, remove gearbox and drive end

bearing cover and inspect gear teeth and bearings

for rust.

Because of the completely enclosed unit design,

location of the installation is generally not a critical

matter. A clean, dry and protected indoor location is

preferred. However, an outdoor location will normally

give satisfactory service. Important requirements are

that the correct grade of lubricating oil be provided for

expected operating temperatures, and that the unit be

located so that routine checking and servicing can be

performed conveniently. Proper care in locating driver

and accessory equipment must also be considered.

INSTALLATION

Supervision of the installation by a ROOTS Service

Engineer is not usually required for these units.

Workmen with experience in installing light to

medium weight machinery should be able to produce

satisfactory results. Handling of the equipment needs

to be accomplished with care, and in compliance with

safe practices.Unit mounting must be solid, without

strain or twist, and air piping must be clean, accurately

aligned and properly connected.

Bare-shaft Units: Two methods are used to handle

a unit without base. One is to use lifting lugs bolted

into the top of the unit headplates.Test them first for

tightness and fractures by tapping with a hammer.

In lifting, keep the direction of cable pull on these

bolts as nearly vertical as possible. If lifting lugs are

not available, lifting slings may be passed under the

cylinder adjacent to the headplates. Either method

prevents strain on the extended drive shaft.

Packaged Units: When the unit is furnished mounted

on a baseplate, with or without a driver, use of lifting

slings passing under the base flanges is required.

Arrange these slings so that no strains are placed on

the unit casing or mounting feet, or on any mounted

accessory equipment. DO NOT use the lifting lugs in

the top of the unit headplates.

Before starting the installation, remove plugs, covers

or seals from unit inlet and discharge connections

and inspect the interior completely for foreign material.

If cleaning is required, finish by washing the cylinder,

headplates and impeller thoroughly with a petroleum

solvent.Turn the drive shaft by hand to make sure

that the impellers turn freely at all points. Anti-rust

compound on the connection flanges and drive

shaft extension may also be removed at this time

with the same solvent.Cover the flanges until ready

to connect piping.

Mounting

Care will pay dividends when arranging the unit

mounting.This is especially true when the unit is

a “bare-shaft” unit furnished without a baseplate.

The convenient procedure may be to mount such a

unit directly on a floor or small concrete pad, but

this generally produces the least satisfactory results.

It definitely causes the most problems in leveling and

alignment and may result in a “Soft Foot” condition.

Correct soft foot before operation to avoid unnecessary

loading on the casing and bearings. Direct use of building

structural framing members is not recommended.

For blowers without a base, it is recommended that a

well anchored and carefully leveled steel or cast iron

mounting plate be provided.The plate should be at

4For your nearest Roots Office, dial our Customer Service Hot Line 1 877 363 ROOTS (7668).

least 1 inch (25 mm) thick, with its top surface

machined flat, and large enough to provide leveling

areas at one side and one end after the unit is mount-

ed. It should have properly sized studs or tapped holes

located to match the unit foot drilling. Proper use of a

high quality machinist’s level is necessary for adequate

installation.

With the mounting plate in place and leveled, set the

unit on it without bolting and check for rocking. If it is

not solid, determine the total thickness of shims

required under one foot to stop rocking. Place half of

this under each of the diagonally-opposite short feet,

and tighten the mounting studs or screws. Rotate the

drive shaft to make sure the impellers turn freely. If the

unit is to be direct coupled to a driving motor, consider

the height of the motor shaft and the necessity for it to

be aligned very accurately with the unit shaft. Best unit

arrangement is directly bolted to the mounting plate

while the driver is on shims of at least 1/8 inch (3mm)

thickness.This allows adjustment of motor position in

final shaft alignment by varying the shim thickness.

Aligning

When unit and driver are factory mounted on a

common baseplate, the assembly will have been

properly aligned and is to be treated as a unit for

leveling purposes. Satisfactory installation can be

obtained by setting the baseplate on a concrete slab

that is rigid and free of vibration, and leveling the top

of the base carefully in two directions so that it is free

of twist.The slab must be provided with suitable anchor

bolts.The use of grouting under and partly inside the

leveled and shimmed base is recommended.

It is possible for a base-mounted assembly to become

twisted during shipment, thus disturbing the original

alignment. For this reason, make the following checks

after the base has been leveled and bolted down.

Disconnect the drive and rotate the unit shaft by hand.

It should turn freely at all points. Loosen the unit foot

hold-down screws and determine whether all feet are

evenly in contact with the base. If not, insert shims as

required and again check for free impeller rotation.

Finally, if unit is direct coupled to the driver, check

shaft and coupling alignment carefully and make any

necessary corrections.

In planning the installation, and before setting the unit,

consider how piping arrangements are dictated by the

unit design and assembly. Drive shaft rotation must be

established accordingly and is indicated by an arrow

near the shaft.

Typical arrangement on vertical units has the drive

shaft at the top with counterclockwise rotation and

discharge to the left. Horizontal units are typically

arranged with the drive shaft at the left with counter-

clockwise rotation and discharge down. See Figure 3

and 4 for other various unit arrangements and

possible conversions.

When a unit is DIRECT COUPLED to its driver, the

driver RPM must be selected or governed so as not to

exceed the maximum speed rating of the unit. Refer to

Table 1 for allowable speeds of various unit sizes.

A flexible type coupling should always be used to

connect the driver and unit shafts.

Coupling halves must be accurately aligned, and a

sufficient gap between shaft ends provided so that side

strains and end thrust on either shaft are avoided or

minimized.This will require considerable care in the

mounting of the driver.The two shafts must be in as

near perfect alignment in all directions as possible, and

the gap must be established with the motor armature

on its electrical center if end-play exists.

The following requirements of a good installation are

recommended. Coupling halves must be fitted to the

two shafts with a line to line thru .001” interference fit.

Coupling halves must be warmed up, so that only light

tapping is required to install them. Maximum deviation

in offset alignment of the shafts should not exceed

.005” (.13 mm) total indicator reading, taken

on the two coupling hubs.Maximum deviation from

parallel of the inside coupling faces should not exceed

.001” (.03 mm) when checked at six points around

the coupling.

When a unit is BELT DRIVEN, the proper selection of

sheave diameters will result in the required unit speed.

This flexibility can lead to operating temperature prob-

lems caused by unit speed being too low. Make sure

the drive speed selected is within the allowable range

for the specific unit size, as specified under Table 1.

Belt drive arrangements usually employ two or more

V-belts running in grooved sheaves. Installation of the

driver is less critical than for direct coupling, but its

shaft must be level and parallel with the unit shaft.

The driver should be mounted on the inlet side of

a vertical unit (horizontal piping) and on the side

nearest to the shaft on a horizontal unit. The driver

must also be mounted on an adjustable base to permit

installing, adjusting and removing the V-belts.To

position the driver correctly, both sheaves need to be

mounted on their shafts and the nominal shaft center

distance known for the belt lengths to be used.

Install the unit sheave so that its inner hub face is not

more than 1/8 inch (3mm) from the drive end cover.

See page 18 for minimum sheave diameter and

maximum sheave width.The shaft fit should be such

that the sheave can be worked into place by hand or

by very light tapping. A tight or driving fit can damage

a bearing, and may cause internal unit damage by

forcing the impeller out of its normal operating position.

A loose fit or wobbly sheave will cause vibration, and

may result in shaft breakage.

CAUTION: Couplings as well as sheave bushings

must have a slight slide fit with the unit shaft such

that they can be installed in place by hand. Any force

used to install them could change unit end clearance

resulting in unit damage. If interference fit is desired for

the coupling, the coupling hub should be heated and

shrunk on the shaft. For engine drives, use “locktite”

between the coupling hubs and the shafts and on the

threads of the coupling set screws.

ROOTS, RAM, URAI and WHISPAIR are trademarks of Dresser, Inc.

Dresser Design and Universal RAI are registered trademarks of Dresser, Inc.

The driver sheave should also be mounted as close to

its bearing as possible, and again should fit the shaft

correctly. Position the driver on its adjustable base so

that 2/3 of the total movement is available in the

direction away from the unit, and mount the assembly

so that the face of the sheave is accurately in line with

the unit sheave.This position minimizes belt wear, and

allows sufficient adjustment for both installing and

tightening the belts. After belts are installed, adjust

their tension in accordance with the manufacturer’s

instructions. However, only enough tension should be

applied to prevent slippage when the unit is operating

under load. Excessive tightening can lead to early

bearing failures or shaft breakage.

Before operating the drive under power to check initial

belt tension, first remove covers from the unit

connections. Make sure the interior is still clean, then

rotate the shaft by hand. Place a coarse screen over

the inlet connection to prevent anything being drawn

into the unit while it is operating, and avoid standing

in line with the discharge opening. Put oil in the sumps

per instructions under LUBRICATION.

Piping

Before connecting piping, remove any remaining

anti-rust compound from Unit connections. Clean pipe

should be no smaller than unit connections. In addition,

make sure it is free of scale, cuttings, weld beads, or

foreign material of any kind.To further guard against

damage to the unit, especially when an inlet filter is not

used, install a substantial screen of 16 mesh backed

with hardware cloth at or near the inlet connections.

Make provisions to clean this screen of collected

debris after a few hours of operation. It should be

removed when its usefulness has ended, as the wire

will eventually deteriorate and small pieces going into

the unit may cause serious damage.

Pipe flanges or male threads must meet the unit

connections accurately and squarely. DO NOT attempt

to correct misalignment by springing or cramping the

pipe. In most cases this will distort the unit casing and

cause impeller rubbing. In severe cases it can prevent

operation or result in a broken drive shaft. For similar

reasons, piping should be supported near the unit to

eliminate dead weight strains. Also, if pipe expansion is

likely to occur from temperature change, installation of

flexible connectors or expansion joints is advisable.

Figure 2 represents an installation with all accessory

items that might be required under various operating

conditions. Inlet piping should be completely free of

valves or other restrictions.When a shut-off valve can

not be avoided, make sure a full size vacuum relief is

installed nearest the unit inlet.This will protect against

unit overload caused by accidental closing of the

shut-off valve.

Need for an inlet silencer will depend on unit speed and

pressure, as well as sound-level requirements in the

general surroundings.An inlet filter is recommended,

especially in dusty or sandy locations. A discharge

silencer is also normally suggested, even though

Whispair units operate at generally lower noise levels

than conventional rotary blowers. Specific recommen-

dations on silencing can be obtained from ROOTS.

Discharge piping requires a pressure relief valve, and

should include a manual unloading valve to permit

starting the unit under no-load conditions. Reliable

pressure/vacuum gauges and good thermometers at

both inlet and discharge are recommended to allow

making the important checks on unit operating condi-

tions.The back-pressure regulator shown in Figure 2

is useful mainly when volume demands vary while the

unit operates at constant output. If demand is constant,

but somewhat lower than the unit output, excess may

be blown off through the manual unloading valve.

In multiple unit installations where two or more units

operate with a common header, use of check valves

is mandatory.These should be of a direct acting or free

swinging type, with one valve located in each line

between the unit and header. Properly installed, they

will protect against damage from reverse rotation

caused by air and material back-flow through an

idle unit.

After piping is completed, and before applying power,

rotate the drive shaft by hand again. If it does not move

with uniform freedom, look for uneven mounting, piping

strain, excessive belt tension or coupling misalignment.

DO NOT operate the unit at this time unless it has

been lubricated per instructions.

6For your nearest ROOTS Office, dial our Customer Service Hot Line 1 877 363 ROOTS (7668).

LUBRICATION: For Units with a Grease Lubricated

Drive End

A simple but very effective lubrication system is

employed on the drive shaft end bearings. Hydraulic

pressure relief fittings are provided to vent any excess

grease, preventing pressure build-up on the seals.

A restriction plug and metering orifice prevent loss of

lubricant from initial surges in lubricant pressure but

permit venting excess lubricant under steadily rising

pressures.

When servicing drive end bearings, use a NLGI #2

premium grade grease with 300°F (149°C) service

temperature and moisture resistance and good

mechanical stability. Using a pressure gun, slowly

force new lubricant into each drive end bearing

housing until traces of clean grease comes out of

the relief fitting.

After a long shutdown, it is recommended that the

grease fittings be removed, the old grease flushed out

with kerosene or #10 lubricating oil, drained thoroughly,

and bearings refilled with new grease. Be sure grease

relief fittings are reinstalled. Grease should be added

using a hand operated grease gun to the drive end

bearings at varying time intervals depending on duty

cycle and RPM.Table 4 has been prepared as a

general greasing schedule guide based on average

operating conditions.More frequent intervals may be

necessary depending on the grease operating

temperature and unusual circumstances. ROOTS™

synthetic grease (ROOTS P/N T20019-) is highly

recommended.

LUBRICATION: For Units with Splash Lubrication

on Both Ends

Bearings and oil seals are lubricated by the action of

the timing gears or oil slingers which dip into the main

oil sumps causing oil to splash directly on gears and

into bearings and seals. A drain port is provided below

each bearing to prevent an excessive amount of oil in

the bearings. Seals located inboard of the bearings in

each headplate effectively retain oil within the sumps.

Any small leakage that may occur should the seals

wear passes into a cavity in each vented headplate

and is drained downward.

LUBRICATION

Oil sumps on each end of the blower are filled by

removing top vent plugs, Item (21), and filling until oil

reaches the middle of the oil level sight gauge, Item

(37), or the overflow plug.

Initial filling of the sumps should be accomplished with

the blower not operating, in order to obtain the correct

oil level.Approximate oil quantities required for blowers

of the various models and configurations are listed in

Table 3. Use a good grade of industrial type non-deter-

gent, rust inhibiting, anti-foaming oil and of correct

viscosity per Table 2. ROOTS™synthetic oil (ROOTS

P/N 813-106-) is highly recommended.

The oil level should not fall below the middle of the

site gauge when the blower is idle. It may rise

on the gauge during operation, to an extent depending

somewhat on oil temperature and blower speed.

Proper lubrication is usually the most important single

consideration in obtaining maximum service life and

satisfactory operation from the unit. Unless operating

conditions are quite severe, a weekly check of oil level

and necessary addition of lubricant should be suffi-

cient. During the first week of operation, check the oil

levels in the oil sumps about once a day, and watch

for leaks. Replenish as necessary.Thereafter, an

occasional check should be sufficient.It is recommended

that the oil be changed after initial 100 hours of opera-

tion. Frequent oil changing is not necessary unless the-

blower is operated in a very dusty location. Normal life

expectancy of petroleum based oils is about 2000

hours with an oil temperature of about 200°F (93°C).

As the oil temperature increases by increments of

15-18°F (8°C - 10°C), the life is reduced by half.

Example: Oil temperatures of 230-236°F (110°C -

113°C) will produce life expectancy of 1/4 or 500 hours.

Therefore, it is considered normal to have oil change

periods of 500 hours with petroleum based oils.

ROOTS, RAM, URAI and WHISPAIR are trademarks of Dresser, Inc.

Dresser Design and Universal RAI are registered trademarks of Dresser, Inc.

Before operating a blower under power for the first

time, recheck the unit and the installation thoroughly

to reduce the likelihood of avoidable troubles. Use the

following procedure check list as a guide, but consider

any other special conditions in the installation.

❏Be certain that no bolts, tools, rags, or debris have

been left in the blower air chamber or piping.

❏If an outdoor intake without filter is used, be sure

the opening is located so it cannot pick up dirt and

is protected by a strong screen or grille. Use of the

temporary protective screen as described under

INSTALLATION is strongly recommended.

❏Recheck blower leveling, drive alignment and

tightness of all mounting bolts if installation is not

recent. If belt drive is used, adjust belt tension

correctly.

❏Turn drive shaft by hand to make sure impellers

still rotate without bumping or rubbing at any point.

❏Make sure oil levels in the main oil sumps are

correct.

❏Check lubrication of driver. If it is an electric motor,

be sure that power is available and that electrical

overload devices are installed and workable.

❏Open the manual unloading valve in the discharge

air line. If a valve is in the inlet piping, be sure

it is open.

❏Bump blower a few revolutions with driver to check

that direction of rotation agrees with arrow near

blower shaft, and that both coast freely to a stop.

After the preceding points are cleared, blower is

ready for trial operation under “no-load” conditions.

The following procedure is suggested to cover this

initial operation test period.

a. Start blower, let it accelerate to full speed, then

shut off. Listen for knocking sounds, both with

power on and as speed slows down.

b. Repeat above, but let blower run 2 or 3 minutes.

Check for noises, such as knocking sounds.

c. Operate blower for about 10 minutes unloaded.

Check oil levels. Observe cylinder and headplate

surfaces for development of hot spots such as

burned paint, indicating impeller rubs. Be aware

of any noticeable increase in vibration.

Assuming that all trials have been satisfactory, or that

necessary corrections have been made, the blower

should now have a final check run of at least one hour

under normal operating conditions.After blower is

restarted, gradually close the discharge unloading

valve to apply working pressure. At this point it is

recommended that a good pressure gauge or

manometer be connected into the discharge line if

not already provided, and that thermometers be in

both inlet and discharge lines. Readings from these

instruments will show whether pressure or temperature

ratings of the blower are being exceeded.

During the final run, check operating conditions

frequently and observe the oil levels at reasonable

intervals. If excessive noise or local heating develops,

shut down immediately and determine the cause. If

either pressure rise or temperature rise across the

blower exceeds the limit specified in this manual, shut

down and investigate conditions in the piping system.

Refer to the TROUBLESHOOTING CHECKLIST for

suggestions on various problems that may appear.

The blower should now be ready for continuous duty

operation at full load. During the first few days make

periodic checks to determine whether all conditions

remain steady, or at least acceptable.This may be

particularly important if the blower is supplying air to a

process system where conditions can vary. At the first

opportunity, stop the blower and clean the temporary

inlet protective screen.If no appreciable amount of

debris has collected, the screen may be removed.

See comments under INSTALLATION.At this same

time, verify leveling, coupling alignment or belt tension,

and mounting bolt tightness.

Should operating experience prove that blower capacity

is a little too high for the actual air requirements, a

small excess may be blown off continuously through

the manual unloading or vent valve. Never rely on the

pressure relief valve as an automatic vent. Such use

may cause the discharge pressure to become

excessive, and can also result in failure of the valve

itself. If blower capacity appears to be too low, refer to

the TROUBLESHOOTING CHECKLIST.

Vibration Assessment Criteria

With measurements taken at the bearing locations

on the housings, see chart below for an appropriate

assessment guide for rotary lobe blowers rigidly

mounted on stiff foundations.

In general, blower vibration levels should be monitored

on a regular basis and the vibration trend observed for

progressive or sudden change in level. If such a

change occurs, the cause should be determined

through spectral analysis.

As shown on the chart below, the level of all pass

vibration will determine the need to measure discrete

frequency vibration levels and the action required.

OPERATION

All Pass Vibration Discrete Frequency Action

(in/sec) Vibration (in/sec)

0.45 or less N/R Approved

Greater than 0.45 0.45 or less @ Approved

but 1.0 or less any frequency

Greater than 0.45 @ ROOTS™Approval

any frequency Required

Greater than 1.0 Less than 1.0 ROOTS™Approval

Required

Greater than 1.0 ROOTS™Approval

Required

8For your nearest ROOTS Office, dial our Customer Service Hot Line 1 877 363 ROOTS (7668).

OPERATING CHARACTERISTICS

ROOTS™rotary blowers and exhausters, as covered in

this manual, are available in basic frame sizes ranging

from 2 inch to 7 inch gear diameter.Various models,

within this gear diameter range, are available with dif-

ferent case lengths to produce reasonable steps in flow

capacity.The shorter case lengths have lower

volumetric capacities, but are capable of operating

against higher pressures. All models are available for

air service and there are specifically designed models

for gas service.

The basic ROOTS™rotary lobe blower is a positive

displacement type unit. Flow capacity is determined by

frame size, operating speed and pressure conditions.

It employs two impellers mounted on parallel shafts

rotating in opposite directions within a cylinder closed

at the ends by head-plates. As the impellers rotate,

gas is drawn into one side of the cylinder and forced

out the opposite side.The pressure or vacuum

developed depends on the resistance of the piping

and process system.

The unit is a precision engineered product with very

fine clearances between the rotating impellers and

stationary case. Since there is no actual contact

between these surfaces, internal lubrication is not

required. Clearances are maintained by a pair of

accurately machined timing gears, mounted on the

two shafts extended outside the blower casing.

Operation of the familiar basic rotary lobe blower is

illustrated in FIGURE 1, where air flow is left to right

from inlet to discharge with the top impeller rotating

clockwise. In Position 1 it is delivering a known volume

(B) to the discharge, while space (A) between the

lower impeller and cylinder wall is being filled.

Counterclockwise rotation of this impeller then traps

equal volume (A) in Position 2, and further rotation

delivers it to the discharge in Position 3.

One complete revolution of the driving shaft alternately

traps four fixed and equal volumes of air (two by each

impeller) and pushes them through to the discharge.

The volume capacity of a lobe blower operating at a

constant speed therefore remains relatively independ-

ent of reasonable inlet of discharge pressure variations.

To change capacity, it is necessary either to change

speed of rotation or blow off some of the discharge air.

No attempt should ever be made to control capacity

by means of a throttle valve in the intake or discharge

piping.This will not only increase the power load on the

driver, but can also overload and seriously damage the

blower.If a possibility does exist that flow to the blower

inlet may be cut off during normal operation of a

process, then an adequate vacuum relief valve must

be installed near the blower. A pressure type relief

valve in the discharge line near the blower is required

for protection against cut-off or blocking in this line.

Refer to FIGURE 3 for a complete piping schematic.

When a belt drive is installed, blower speed can usually

be adjusted to obtain desired capacity by changing the

diameter of one or both sheaves. In a direct coupled

arrangement a variable speed motor or transmission

is required, or excess air may be blown off through

a manually controlled unloading valve and silencer.

If returned to the blower inlet, the air must be cooled

to 100°F (38°C) through a by-pass arrangement to

maintain acceptable blower temperatures.

Before making any change in blower capacity, or

operating conditions, contact ROOTS for specific

information applying to your particular blower. In all

cases, operating conditions must be maintained within

the approved range of pressures, temperatures and

speeds as stated under LIMITATIONS. The air blower

must not be used to handle liquids or solids as serious

damage to the rotating parts may result.

FIGURE 1 – FLOW THROUGH A BASIC ROTARY LOBE BLOWER

ROOTS, RAM, URAI and WHISPAIR are trademarks of Dresser, Inc.

Dresser Design and Universal RAI are registered trademarks of Dresser, Inc.

TROUBLESHOOTING

Trouble Item Possible Cause Remedy

No flow 1 Speed too low Check by tachometer and compare with published

performance

2Wrong rotation Compare actual rotation with Figure 1 or 2

Change driver if wrong

3Obstruction in piping Check piping, valves, silencer to assure open flow path

Low capacity 4 Speed too low See item 1, If belt drive, check for slippage and readjust

tension

5Excessive pressure rise Check inlet vacuum and discharge pressure and compare

with Published performance

6Obstruction in piping See item 3

7Excessive slip Check inside of casing for worn or eroded surfaces causing

excessive clearances

Excessive power 8 Speed too high Check speed and compare with published performance

9Excessive pressure rise See Item 5

10 Impeller rubbing Inspect outside of cylinder for high temperature areas, then

check for impeller contact at these points. Correct blower

mounting, drive alignment

11 Scale, sludge, rust Clean blower appropriately

or product build up

Overheating of 12 Inadequate lubrication Check oil sump levels in gear and drive end headplates

bearing or gears 13 Excessive lubrication Check oil levels. If correct, drain and refill with clean oil of

recommended grade

14 Excessive pressure rise See Item 5

15 Coupling misalignment Check carefully. Realign if questionable

16 Excessive belt tension Readjust for correct tension

Vibration 17 Misalignment See Item 15

18 Impellers rubbing See Item 10

19 Worn bearings/gears Check gear backlash and condition of bearings, and replace

as indicated

20 Unbalanced or rubbing Scale or process material may build up on casing and

impeller impellers, or inside impellers. Remove build-up to restore

original clearances and impeller balance

21 Driver or blower loose Tighten mounting bolts securely

22 Piping resonances Determine whether standing wave pressure pulsations are

present in the piping

23 Scale/sludge build-ups Clean out interior of impeller lobes to restore dynamic

balance

24 Casing strain re-work piping alignment to remove excess strain

Driver stops, or 25 Impeller stuck Check for excessive hot spot on headplate or cylinder.

will not start See item 10. Look for defective shaft bearing and/or

gear teeth

26 Scale, sludge, rust or Clean blower appropriately

product build-up

Excessive breather 27 Broken seal Replace seals

Blow-by or excessive 28 Defective O-ring Replace seals and O-ring

oil leakage to vent area

10For your nearest ROOTS Office, dial our Customer Service Hot Line 1 877 363 ROOTS (7668).

MAINTENANCE & REPLACEMENTS:UNIVERSAL RAI®SERIES BLOWERS

A good program of consistent inspection and mainte-

nance is the most reliable method of minimizing repairs

to a blower. A simple record of services and dates will

help keep this work on a regular schedule. Basic

service needs are:

•Lubrication

•Checking for hot spots

•Checking for increases or changes in vibration

and noise

•Recording of operating pressures and temperatures

Above all, a blower must be operated within its

specified rating limits, to obtain satisfactory service life.

A newly installed blower should be checked often

during the first month of full-time operation. Attention

thereafter may be less frequent assuming satisfactory

performance. Lubrication is normally the most impor-

tant consideration and weekly checks of lubricant

levels in the gearbox and bearing reservoirs should

be customary. Complete oil change schedules are

discussed under LUBRICATION.

Driver lubrication practices should be in accordance

with the manufacturer’s instructions. If direct connected

to the blower through a lubricated type coupling, the

coupling should be checked and greased each time

blower oil is changed.This will help reduce wear and

prevent unnecessary vibration. In a belted drive

system, check belt tension periodically and inspect

for frayed or cracked belts.

In a new, and properly installed, unit there is no contact

between the two impellers, or between the impellers

and cylinder or headplates.Wear is confined to the

bearings (which support and locate the shafts) the oil

seals, and the timing gears. All are lubricated and wear

should be minimal if clean oil of the correct grade is

always used. Seals are subject to deterioration as well

as wear, and may require replacement at varying periods.

Shaft bearings are designed for optimum life under

average conditions with proper lubrication and are

critical to the service life of the blower. Gradual

bearing wear may allow a shaft position to change

slightly, until rubbing develops between impeller and

casing.This will cause spot heating, which can be

detected by observing these surfaces. Sudden bearing

failure is usually more serious. Since the shaft and

impeller are no longer supported and properly located,

extensive general damage to the blower casing and

gears is likely to occur.

Oil seals should be considered expendable items, to

be replaced whenever drainage from the headplate

vent cavity becomes excessive or when the blower is

disassembled for any reason. Sealing effectiveness

can vary considerably from seal to seal and is also

affected to surprising degree by shaft finish under the

seal lip. Because of these normal variables, minor seal

leakage should not be considered as indicating

seal replacement.

Timing gear wear, when correct lubrication is main-

tained, should be negligible over a period of years.

Gear teeth are cut to provide the correct amount of

backlash, and gears correctly mounted on the shafts

will accommodate a normal amount of tooth wear

without permitting contact between lobes of the two

impellers. However, too high an oil level will cause

churning and excessive heating.This is indicated by

unusually high temperature at the bottom of the gear

housing. Consequent heating of the gears will result

in loss of tooth-clearance , backlash and rapid wear of

the gear teeth usually will develop. Continuation of this

tooth wear will eventually produce impeller contacts

(knocking), and from this point serious damage will be

unavoidable if blower operation is continued. A similar

situation can be produced suddenly by gear tooth

fracture, which is usually brought on by sustained

overloading or momentary shock loads.

Problems may also develop from causes other than

internal parts failure. Operating clearances within a

blower are only a few thousandths of an inch.This

makes it possible for impeller interference or casing

rubs to result from shifts in the blower mounting, or

from changes in piping support. If this type of trouble

is experienced, and the blower is found to be clean, try

removing mounting strains. Loosen blower mounting

bolts and reset the leveling and drive alignment.Then

tighten mounting again, and make sure that all piping

meets blower connections accurately and squarely

Foreign materials in the blower will also cause trouble,

which can only be cured by disconnecting the piping

and thoroughly cleaning the blower interior.

A wide range of causes & solutions for operating

troubles are covered in theTROUBLE SHOOTING

CHECKLIST.The remedies suggested should be

performed by qualified mechanics with a good

background, using procedures detailed in this manual.

Major repairs generally are to be considered beyond

the scope of maintenance, and should be referred

to ROOTS.

Warranty failures should not be repaired at all, unless

specific approval has been obtained through ROOTS

before starting work. Unauthorized disassembly within

the warranty period will void the warranty.

ROOTS, RAM, URAI and WHISPAIR are trademarks of Dresser, Inc.

Dresser Design and Universal RAI are registered trademarks of Dresser, Inc.

It is recommended that major repairs be performed

at an authorized ROOTS facility. However, it is

recognized that this may not always be practical. If a

blower is out of warranty, mechanical adjustments and

parts replacement may be undertaken locally at the

owner’s option and risk. It is recommended that

ROOTS™parts be used to insure fit and suitability.The

maintenance of a small stock of on-hand spare parts

can eliminate possible delays.When ordering parts

give item numbers and their word descriptions from the

appropriate sectional drawings. Also specify quantities

required and the blower model and serial number from

the nameplate.

Repairs or adjustments are best performed by person-

nel with good mechanical experience and the ability to

follow the instructions in this manual. Some operations

involve extra care, patience, and a degree of precision

work.This is especially true in timing impellers and in

handling bearings. Experience indicates that high

percentages of bearing failures are caused by dirt

contamination before or during assembly.Therefore,

the work area should be cleaned before starting

disassembly, and new or re-usable parts protected

during progress of the work.

In the following repair procedures, numbers shown in

brackets ( ) correspond to the item numbers used

in sectional drawings. It is recommended that the

procedures be studied carefully and completely, with

frequent reference to the drawings, before starting

work.This will produce better efficiency through an

understanding of what work is to be done, and the

order of doing it. Before disassembly, mark all parts

so that they may be returned to original locations or

relative positions.

Requirements for special tools will depend on the work

to be done. If impeller clearances and float are to be

checked or re-set, a dial indicator and a set of long

feeler gauges will be needed. Work involving removal

of the timing gears cannot be accomplished without a

suitable puller.

Design of ROOTS™blower is simple, and most repair

operations are straightforward. For this reason, the

following procedures are intended mainly to indicate

a preferred work order and to call out points to be

observed.Where special operations are required,

detailed coverage is given.

A – Replacing Timing Gears

1. Drain all oil from the gearhouse by removing drain

plug (21) in the bottom. Remove gearhouse by

taking out all cap screws (23) in its flange. It may

be necessary to bump the sides with a wood block

or mallet to break the flange joint.

2. Reach through one of the blower pipe connections

and place a chalk mark on the strip of one impeller

and the mating waist of the other, so that they

may easily be returned to their original relative

positions.

3. GEAR REMOVAL: CAUTION: Do not remove gear

nuts (17) completely before the gears are unseated

from the taper fits or damage/injury may result.

For this operation, the impellers should be wedged,

as shown in Table 5. Back off gear clamping nuts

(17) about 1/4”. Use a suitable puller or wedge. As

the puller set screw is torqued, the puller will have

a tendency to turn and contact teeth of the other

gear.To prevent this contact, hold the puller corner

nut with a wrench while torquing the set screw.

Once the gear is unseated, remove the puller.

Remove gear nuts (17) and the gear.

4. GEAR INSTALLATION: Place impellers in correct

position as previously marked. Be sure shafts and

gear bores are clean, oil free and free of scratches.

Clean the shaft tapered fits. Place hardwood

wedges as shown in Table 5. Install drive gear

(4) and gear nut (17).Tighten the drive gear nut

to the torque given below. Blower assembly

must be fastened down for torquing operation.

5. Installing driven gear (4) – Insert a long, metal

feeler gauge between the impellers’ lobes at the

fronts or backs as shown below. Feeler

gauge thickness to be a middle value from Table 5

for fronts and backs. Install nut (17).Tighten lightly

with a small wrench, then check front and back

clearances against Table 5 for each 45° position.

Both fronts and backs should be about the same

and within the specified range in Table 5. Adjust

gear position, if necessary, then insert the

corrected feeler gauge and wedges and use a

torque wrench to tighten the gear nut to the torque

specified in below. Remove wedges and rotate

the drive shaft by hand to make sure there are no

gear tight spots or impeller contacts. CAUTION!

Keep fingers away from impellers and gears.

UNIVERAL RAI®SERIES BLOWER GEAR NUT TORQUE

Frame Size Torque

lb.-ft. (kg-m)

22, 24, 60 (8.3)

32, 33, 36 110 (15.2)

42, 45, 47 190 (26.3)

53, 56, 59 250 (34.6)

65, 68, 615 400 (55.3)

76, 711, 718 550 (76.1)

12For your nearest ROOTS Office, dial our Customer Service Hot Line 1 877 363 ROOTS (7668).

bar with recessed end that will bear on the outer

metal edge of seal enclosure. Seal lip should

point toward the driving tool. Seals to be flush

without board bore face. Apply a light coat of oil or

grease to the seal lips. In a similar fashion, install

lip seals into the drive end headplate.

8. Place cylinder on a flat surface. Assemble gear

end headplate to cylinder after checking flange

punch marks. Drive in the two locating dowel pins

before tightening flange screws. Also install gear

end foot using the same longer cap screws (32)

and washers (41). (On 6” & 7” UNIVERSAL RAI®

blower install both gear end feet.)

9. Place the assembly horizontally on steel blocks

with gear end headplate on bottom.The height

of the blocks should be sufficient to clear gear

end shaft extensions. Assemble impellers into

the cylinder with the drive shaft (longer shaft)

in same location as in original assembly. Before

starting the shafts through the headplate holes,

make sure shaft ends have no sharp or rough

edges to damage seal lips. Position impellers at

90° to each other in the cylinder, using lobe-and-

waist match marks if original impellers are being

re-installed. Install drive end headplate and feet in

same manner as gear end.

10. It is recommended that new bearings be used for

rebuild. Apply thin film of machine oil on the shaft

bearing fit, bearing I.D., and headplate bearing

bore. Install drive end bearings into headplate.

Use a tube with flanged end that will contact both

bearing faces simultaneously. Refer to Assembly

Drawing for proper bearing depths.

NOTE: Cylindrical drive bearing should be

installed with inner race large shoulder

facing outboard.

11. Place blower on its feet on a flat surface.

Loosen feet capscrews (32) and square up unit.

Re-tighten capscrews (32). Clamp unit down to

a solid base for further assembly.

12. Oil the gear end bearing fits as described

previously. Install 2-1/2” thru 5” blower gear end

bearings flush with the headplate bearing

shoulders using proper drivers.On 6” & 7”

gear diameter units, install thrust washer

(29) in bearing bores then install gear end

bearings so they protrude 1/16” (1.6mm) above

headplate surface.

13. Install bearing clamp plates (34). On 6” & 7”

gear diameter units, blower impeller end

clearances are also to be set during this step.

Install clamp plates (34) with capscrews (31)

making sure that the gap between the clamp plates

and the headplate is even all around.At the same

time, set end clearances per Table 5.

14. Install gears and time impellers as in (A).

6. Check the end clearances between impellers and

headplates. Adjust clearances per B-15 below.

7. When clearances are correct, clean and re-install

the gearhouse. Check condition of flange gasket

(7) and replace if questionable. Fill gearhouse to

correct level with proper grade oil.

B – Replacing Shaft Bearings and Impellers

Remove coupling or sheave from the drive shaft.

Drain and remove gearhouse, and pull the timing

gears. If gears are to be re-used, mark them so

they may be returned to the same shafts.

1. Break corners and deburr the keyway. Remove

bearing end cover at the drive end. Remove

bearing clamp plates (34).

2. Make single and double identifying punch marks

on the mating edges of headplate and cylinder

flanges at the two ends of the blower.

3. At the drive end, drive out the two dowel pins and

remove all capscrews holding headplate to

cylinder. By inserting jacking screws into the two

threaded flange holed, and turning them in evenly,

the headplate will be separated from the cylinder.

As the headplate comes off the shafts it will bring

bearings with it. 2-1/2” and 3-1/2” gear diameter

units do not have tapped holes for jack screws in

the drive end headplates.Remove dowel pins and

all capscrews holding headplate to cylinder and

foot on the drive end. Support unit under gear end

cylinder flange with the shafts vertical. Using soft

metal block against gear end shafts, push them

out of gear end headplate.

4. For 2-1/2” and 3-1/2” gear diameter units, support

the drive end headplate on the underside, and

using soft metal block against drive end shafts,

push them out of drive end headplate.

For 4”, 6” & 7” gear diameter units, from the gear

end, using a wood or soft metal block against the

ends of the shafts, drive them out of the head

plate. If they are to be reused, protect them from

damage in this operation.

5. If blower interior surfaces need cleaning, it may be

advisable to separate the gear end headplate from

the cylinder. Use the same general procedure as

employed at the drive end.

6. Working from the back (flat) face of each head

plate, push or tap out the bearings and seals. Use

a round bar or tube that will pass through the shaft

clearance holes in the headplates.All lip seals will

be damaged during removal and must be

replaced.

7. Clean bearing and seal pockets in headplates and

remove burrs or rough edges. (Apply a thin coating

of sealant on seal O.D.) Press new seals (27) into

gear end headplate using a round tube or

ROOTS, RAM, URAI and WHISPAIR are trademarks of Dresser, Inc.

Dresser Design and Universal RAI are registered trademarks of Dresser, Inc.

15. For setting end clearances on 2-1/2” thru 5” gear

diameter units, special tools, thrust adjuster fork

and thrust adjuster saddle are required. Refer to

Table 5 for installation of tools.The flat side of the

saddle rests against the bearing inner race and the

flat side of the fork rests against the back side of

the gear. Install a shim, with thickness equal to

gear end clearance (Table 5), between the impeller

and the gear end headplates.Tap on top of the fork

until the shim becomes snug. Remove the shim

and check end clearances.To increase gear end

clearance, tap on the end of the gear end shaft

with a soft metal mallet. Set end clearances for

6” & 7” by turning capscrews (31) evenly in or out.

16. Install drive end cover (5) after packing bearing

cavities with suitable grease. Replace drive shaft

seal. Lip must point toward (33) the bearing.

Exercise care not to damage the lip as it passes

over shaft keyway.

17. Install gasket item (7). Install the gear house after

cleaning out the inside.Tighten gear box cap

screws (23) evenly. Fill with correct grade of oil

until oil flows out through oil level hole.Grease

drive and bearings. (See Lubrication.)

18. Reinstall coupling or belt sheave making sure that

they have a slight slide fit with the shaft and could

be installed by hand.

discharge gas pressure. Also, there exists a

possibility of gear end oil and drive end grease

leakage into the gas stream.

The lubricants selected must be compatible with the

gas. Mechanical Seal Replacement: Disassemble the

blower.During disassembly, damage to mechanical

seals is very likely. During rebuild, always use new

mechanical seals. Prior to any assembly, make sure

that all parts are completely clean and free from nicks

and scratches.

(1) Place head plate on an assembly table with seal

bores pointing up. Coat the OD of the stationary

seal element and install it with carbon facing up in

the seal bore with a seal driver that is guided by the

bearing bore. Drive the seal flush with front face of

the seal bore. Repeat this procedure for all four

seals. Apply a light coating of lubricating oil on the

sealing surface. Protect sealing faces during

assembly from any damage.

(2) Apply teflon based sealant on the cylinder flanges

before installing head plates. Continue the assembly

procedure as outlined up to bearing installation.

Before installation of the bearings, the seal mating

rings need to be installed. Apply light film of

lubricating oil on mating ring o-rings and sealing

faces. Slide mating rings on the shaft and up to

carbon faces making sure that no damage to the

o-rings occur during installation (break sharp

shaft corners to avoid damage to the o-rings during

initial preparation). Install bearings all the way

against the back bearing bore shoulders.

(3) Complete the rest of the assembly.Make sure all

plugged holes are sealed with teflon thread

liquid sealant.

Note: On 6” gear diameter units, shims (44) are used

between the bearing clamp plates and the head plate

on the gear end.

Also, on size 32 and 42, washers with embedded

o-rings are used on the center head plate to

cylinder bolts.

After the assembly is completed, plug the blower

inlet and discharge connections and run static

soap bubble.Leak test to assure leak

free assembly.

For satisfactory operation of mechanical seals,

synthetic lubricants are recommended (Check

suitability to gases before using.)

Oils:

(1)ROOTS™GT Synthetic Lubricant ROOTS

P/N 13-106-001 (1) one quart ISO-220

(2) Mobil SHC 600 Series Lubricating Oils

Grease:

ROOTS™Synthetic Grease – NLGI # 2

ROOTS P/N T20-019-001 (1) one 14 oz tube

TECHNICAL SUPPLEMENT

for 32, 33, 36, 42, 45, 47, 53, 56, 59, 65, 68, 615

UNIVERAL RAI®-G BLOWERS

ROOTS™Universal RAI™-G rotary positive gas blowers

are a design extension of the basic Universal RAI™

blower model. URAI™-G blower uses (4) mechanical

seals in place of the standard in board lip seals to

minimize gas leakage into the atmosphere.The seal

vent chambers are plugged.These units are intended

for gases which are compatible with cast iron case

material, steel shafts, 300/400 series stainless steel

and carbon seal components, viton o-rings and the

oil/grease lubricants. If there are any questions

regarding application or operation of this gas blower,

please contact factory.

Precaution: URAI™-G blowers: Care must be used

when opening the head plate seal vent chamber

plugs ( 43) as some gas will escape–if it is a pres-

sure system, or the atmospheric air will leak in-if

the system is under vacuum.There is a possibility

of some gas leakage through the mechanical seals.

This leakage on the gear end will escape through

the gear box vent, and on the drive end, through

the grease release fittings. If the gas leakage is

undesirable, each seal chamber must be purged

with an inert gas through one purge gas hole

(43 ) per seal .There are two plugged purge gas

holes(1/8 NPT) provided per seal.The purge gas

pressure must be maintained one psi above the

14For your nearest ROOTS Office, dial our Customer Service Hot Line 1 877 363 ROOTS (7668).

MAINTENANCE & REPLACEMENTS:RAM™SERIES BLOWERS

A good program of consistent inspection and mainte-

nance is the most reliable method of minimizing repairs

to a blower. A simple record of services and dates will

help keep this work on a regular schedule. Basic

service needs are:

•Lubrication

•Checking for hot spots

•Checking for increases or changes in vibration

and noise

•Recording of operating pressures and temperatures

Above all, a blower must be operated within its

specified rating limits, to obtain satisfactory service life.

A newly installed blower should be checked often

during the first month of full-time operation. Attention

thereafter may be less frequent assuming satisfactory

performance. Lubrication is normally the most impor-

tant consideration and weekly checks of lubricant

levels in the gearbox and bearing reservoirs should

be customary. Complete oil change schedules are

discussed under LUBRICATION.

Driver lubrication practices should be in accordance

with the manufacturer’s instructions. If direct connected

to the blower through a lubricated type coupling, the

coupling should be checked and greased each time

blower oil is changed.This will help reduce wear and

prevent unnecessary vibration. In a belted drive sys-

tem, check belt tension periodically and inspect for

frayed or cracked belts.

In a new, and properly installed, unit there is no contact

between the two impellers, or between the impellers

and cylinder or headplates.Wear is confined to the

bearings (which support and locate the shafts) the oil

seals, and the timing gears. All are lubricated and wear

should be minimal if clean oil of the correct grade is

always used. Seals are subject to deterioration and

wear, and may require replacement at varying periods.

Piston ring seals (28) are designed to operate without

rubbing contact, once temperature and thermal growth

have stabilized.The stationary rings will rub the rotating

sleeve (38) briefly as a result of temperature cycles

that occur during the startup and shutdown of the unit.

The sleeves are hardened and the rings are coated

with dry lubricant that provides for temporary break in

wear. Replace piston ring seals if they become exces-

sively worn or inspection shows more than .010”

(.25mm) axial clearance between ring and groove.

Shaft bearings are designed for optimum life under

average conditions with proper lubrication and are

critical to the service life of the blower. Gradual bearing

wear may allow a shaft position to change slightly, until

rubbing develops between impeller and casing.This

will cause spot heating, which can be detected by

observing these surfaces. Sudden bearing failure is

usually more serious. Since the shaft and impeller are

no longer supported and properly located, extensive

general damage to the blower casing and gears is

likely to occur.

Oil seals should be considered expendable items, to

be replaced whenever drainage from the headplate

vent cavity becomes excessive or when the blower is

disassembled for any reason. Sealing effectiveness

can vary considerably from seal to seal and is also

affected to surprising degree by shaft finish under the

seal lip. Because of these normal variables, minor

seal leakage should not be considered as indicating

seal replacement.

Timing gear wear, when correct lubrication is main-

tained, should be negligible over a period of years.

Gear teeth are cut to provide the correct amount of

backlash, and gears correctly mounted on the shafts

will accommodate a normal amount of tooth wear

without permitting contact between lobes of the two

impellers. However, too high an oil level will cause

churning and excessive heating.This is indicated by

unusually high temperature at the bottom of the gear

housing. Consequent heating of the gears will result in

loss of tooth-clearance , backlash and rapid wear of the

gear teeth usually will develop. Continuation of this

tooth wear will eventually produce impeller contacts

(knocking), and from this point serious damage will be

unavoidable if blower operation is continued. A similar

situation can be produced suddenly by gear tooth

fracture, which is usually brought on by sustained

overloading or momentary shock loads.

Problems may also develop from causes other than

internal parts failure. Operating clearances within a

blower are only a few thousandths of an inch.This

makes it possible for impeller interferences or casing

rubs to result from shifts in the blower mounting, or

from changes in piping support. If this type of trouble

is experienced, and the blower is found to be clean, try

removing mounting strains. Loosen blower mounting

bolts and reset the leveling and drive alignment.Then

tighten mounting again, and make sure that all piping

meets blower connections accurately and squarely

Foreign materials sucked into the blower will also

cause trouble, which can only be cured by disconnect-

ing the piping and thoroughly cleaning the blower interior.

A wide range of causes & solutions for operating

troubles are covered in the TROUBLE SHOOTING

CHECKLIST.The remedies suggested should be

performed by qualified mechanics with a good

background, using procedures detailed in this manual.

Major repairs generally are to be considered beyond

the scope of maintenance, and should be referred

to ROOTS.

Warranty failures should not be repaired at all, unless

specific approval has been obtained through a Sales

Office or the factory before starting work. Unauthorized

disassembly within the warranty period will void the

warranty.

ROOTS, RAM, URAI and WHISPAIR are trademarks of Dresser, Inc.

Dresser Design and Universal RAI are registered trademarks of Dresser, Inc.

It is recommended that major repairs be performed at

an authorized ROOTS facility. However, it is recognized

that this may not always be practical. If a blower is

out of warranty, mechanical adjustments and parts

replacement may be undertaken locally at the owner’s

option and risk. It is recommended that ROOTS™parts

be used to insure fit and suitability.The maintenance

of a small stock of on-hand spare parts can eliminate

possible delays.When ordering parts give Item

numbers and their word descriptions from sectional

drawings and parts lists. Also specify quantities

wanted and the blower size and serial number from

the nameplate.

Repairs or adjustments are best performed by

personnel with good mechanical experience and the

ability to follow the instructions in this manual. Some

operations involve extra care, patience, and a degree

of precision work.This is especially true in timing

impellers and in handling bearings. Experience

indicates that high percentages of bearing failures

are caused by dirt contamination before or during

assembly.Therefore, the work area should be cleaned

before starting disassembly, and new or re-usable

parts protected during progress of the work.

In the following repair procedures, numbers shown

in brackets ( ) correspond to the Item numbers

used in assembly drawings, and parts lists. It is

recommended that the procedures be studied carefully

and completely, with frequent reference to the draw-

ings, before starting work.This will produce better

efficiency through an understanding of what work is to

be done, and the order of doing it. Before disassembly,

mark all parts so that they may be returned to original

locations or relative positions.

Requirements for special tools will depend on the work

to be done. If impeller clearances and float are to be

checked or re-set, a dial indicator and a set of long

feeler gauges will be needed. Work involving removal

of the timing gears cannot be accomplished without a

puller suitable. Heat must be used during bearing and

sleeve installation.

Design of ROOTS™blower is simple, and most repair

operations are straightforward. For this reason, the

following procedures are intended mainly to indicate

a preferred work order and to call out points to be

observed.Where special operations are required,

detailed coverage is given.

DISASSEMBLY OF DRIVE END

1. Remove the sheave or coupling and key from the

drive shaft. File off any burrs or sharp edges along

the keyway.

2. Drain oil by removing drain plug (22).

3. Remove the flange screws (75).Tap the drive end

cover to loosen it, then slide it along the shaft care

fully to avoid damaging the lip seal (33) on the

drive shaft keyway. Remove the gasket (7).

Remove oil slinger (40) and cap screw (60).

4. Remove bearing clamp plates (34) by unscrewing

capscrews (32) and removing lock washers (35).

Keep shim halves (10) together exactly as removed

by tagging them with each clamping plate.

5. Remove the headplate – remove all capscrews

(23) holding headplate to the cylinder. Insert

jacking screws into the four threaded flange

holes and turn them in evenly.The headplate will

separate from the cylinder.The lip seals (27), and

bearing outer race and rollers, are removed with

the headplate and can be pressed out later.

6. Remove the bearing inner race and sleeve (38)

from the shaft with aid of a bearing puller by

inserting the puller jaws in the groove in the sleeve

and applying the jacking screw against the end of

the shaft. Protect the threaded hole and the end

of the shaft with a small, flat spacer between the

shaft and the puller.

DISASSEMBLY OF GEAR END

1. Drain oil completely from the gearbox sump by

removing plugs (22) in bottom of the headplate (1).

2. Loosen all flange screws (75) in the gearbox and

remove all but two upper screws. Bump the gear

box to break the joint if it cannot be pulled free by

hand, then remove the last two screws and lift off

the gearbox. Remove gasket (7).

3. Removing gears: CAUTION:Do not remove gear

nuts (31) completely before the gears are unseated

from the taper fits or damage/injury may result.

Be sure that each gear is marked for return to the

same shaft in the same angular position and that

the gears have match marks for the teeth.For this

operation, the impellers should be wedged as

shown in Figure 8. Back off nuts (31) and slinger

(46).The timing gears (4) have two 1/2” – 13 holes

for pulling purposes. Use a suitable puller.

4. Remove bearing clamp plates (54) by unscrewing

capscrews (32) and removing lock washers.

Group the shims (10), the wavy spring washers

(29) with each clamp plate and tag for ease of

reassembly.

5. Remove the headplate – remove all capscrews

23) holding the headplate to the cylinder. Insert

jacking screws into the four (4) threaded flange

holes and turn them in evenly.They headplate will

separate from the cylinder.The lip seals (27), and

bearing outer race and rollers, are removed with

the headplate and can be pressed out later.

For RAM™-J WHISPAIR™gas pump units:

The gear end headplate which is removed next

requires a different approach from the drive end.

On this end, the shafts are forced from the bearing

bore by using a bar across the end of the shaft

with threaded rods to the headplate. Once the

headplates are removed from the assembly, the

seal housings can be pressed or driven from

16For your nearest ROOTS Office, dial our Customer Service Hot Line 1 877 363 ROOTS (7668).

the headplate bores. Generally, new seals will be

required prior to reassembly.

6. Remove the bearing inner race and sleeve (38)

from the shaft with the aid of a bearing puller by

inserting the puller jaws in the groove in the sleeve

and applying the jacking screw against the end of

the shaft. Protect the threaded hole and the end

of the shaft with a small, flat spacer between the

shaft and the puller.

ASSEMBLY

Prior to any assembly operation, it is essential that all

parts are completely clean and free from nicks and

scratches.

Prior to assembly, lightly coat the groove in the sleave

with slip plate. ROOTS P/N813-314-000.

1. Assembly of Piston ring seals (28) – To avoid

scratching the lip seal surface, install the Piston

ring seals (28) in the sleeves (38) from the end

nearest the groove before assembling the sleeve

on the shaft.

Unhook the gap joint and expand the ring while

sliding it to the groove, then compress it so one

end of the hook joint slides over the other. Move

the ring in the groove to be sure it is free.

NOTE: Care must be taken not to scratch or dent

the sleeve surface since it is the sealing surface

for the lip seal.

2. Installation of sleeves (38) – heat the sleeve to

300° F. (149°C) then quickly slide it on the shaft

tightly against the impeller. If the sleeve hangs up

during assembly, it can be pressed into place

using a tubular pressing tool with square,

clean ends.

3. Assembly of seals (27) in headplate (1) – Place

headplate flat with seal bores up. Be sure the

pressing tool face is clean and square and there is

a smooth, clean entering bevel in the headplate.

Lubricate the seal lips. Place seal over the bore

with lip facing up, then press the seal evenly until it

is flush with bore face.

For Gas Sealed Units: Assemble mechanical

seals (27) in headplate – (CAUTION: Care must

be used to avoid damaging the carbon face.

Before proceeding with this step, you should have

a piloted seal driver which is designed to clear

the carbon face.) with headplate positioned

horizontally with seal bores up. Be sure the

pressing tool face is clean and square and there is

a smooth, clean entering bevel in the headplate.

Place the seal over the bore with carbon facing up.

Then press the seal evenly on its steel shell using

the piloted seal driver until the driver seats against

the stop.

4. Assembly of impellers (12 and 13) to headplate

(1) – Place gear end headplate flat on 3 in.

(76 mm) blocks with the smallest bores facing up.

Inspect entering bevels to be sure they are smooth

and clean. Locate the drive impeller correctly

(top for vertical units and toward the driver for

horizontal units). Place the seal ring gaps toward

the inlet for pressure applications and towards dis

charge for vacuum applications. Insert the impeller

shafts in the headplate so the impellers rest on

the headplate. Use care to avoid damaging the

lip seals.

5. Assembly of cylinder (11) to gear end headplate

(1) – Install dowel pins (16) and secure cylinder to

headplate with capscrews (23).Torque to 35 ft.-lbs

(4.5 Kg-m).Then, install drive end headplate (1)

and dowel pins (16) and secure with capscrews

(23). Install feet (76) & 77) to both headplates and

secure with capscrews (66).Torque to 35 ft.-lbs.

(4.5 kg-m).

For Gas Sealed Units: Use a Teflon sealant

between headplate and cylinder joint. Assemble

rotating seal – apply a light coating of oil to the

O-ring and seal face.Then with flute side out

install the rotating seat tight to the shaft sleeve.

Check and record seal compression – With the

seal body in place and the impeller against the

opposite headplate, check that seal compression

is adequate.This can be checked using a depth

gauge or dial indicator from the face of the head

plate to the face of the mating ring. First, measure

this distance while the carbon is out at its full

length.Then, push the mating ring back against its

stop and measure it again.The difference

between these measurements is the compression.

This can be done easily with finger pressure as the

spring force is only 10 lbs.The correct travel is

given below (record actual compression on

clearance sheets).

SEAL COMPRESSION

Frame Minimum Maximum

400 .047” .097”

600 .108” .151”

* Prior to to assembly, lightly coat the groove in the sleave(38) with slip plate.

ROOTS™P/N 813-314-000

6. Installation of bearings (14) – Heat bearing inner

race to 300°F (149°C) in an oven or hot oil; then

slide it onto the shaft so the bearing shoulder is

snugly against the sleeve. Note: Be sure to install

the shaft shim (70) behind the shaft sleeve before

installing the drive end drive bearing inner race.

This is required to compensate for the oil leader for

shimming. Insert the bearing outer race and rollers

in each bore and tap lightly in place. Spray

bearings with lubricant.

7. Measure and record the end clearances between

the impellers and drive headplate using long feeler

gauges.Then, subtract the allowed average drive

end clearance.See Table 6.The result is the

space required between clamping plates (34) and

bearing outer race. Place shims (10) as required

to get this clearance.Then, fasten the clamping

ROOTS, RAM, URAI and WHISPAIR are trademarks of Dresser, Inc.

Dresser Design and Universal RAI are registered trademarks of Dresser, Inc.

plates to the headplate with capscrews (32) and

lock washers (35).

8. Installation of gear end bearings (14) – Turn the

blower so that the gear end headplates is up. Heat

bearing inner race to 300°F (149°C) in an oven or

hot oil; then slide it onto the shaft so that the

bearing shoulder is snugly against the sleeve.

Insert the bearing outer race and rollers in each

bore and tap lightly into place.

9. Measure and record the end clearance between

the impellers and gear end headplate, then sub-

tract the allowed average gear end clearance.See

Table 6.The result is the space required between

clamping plate (54) and bearing outer race. Place

shims (10) as required to get this clearance.Then

fasten the clamping plates (54) to the headplate

using capscrews (32) and lock washers (35). Do

not install wavy-spring washers (29) at this time,

as a final check of clearances is required first.

10. Final check of end clearances and float – Using

long feeler gauges, check the clearance between

the impellers and drive end headplate.See Table

6. Place the blower assembly on its feet and

correct shimming as required.Then, force the

impellers as close to the gear end headplate as

possible, and check the clearance between

impellers and gear end headplate for agreement

with Table 6. Adjust shimming on the gear end as

required.With unit securely fastened down, use a

dial indicator to measure the impeller float. Again

push the impeller to one end of the cylinder.With

indicator firmly mounted, place contact point on the

end of the shaft just pushed and set dial on zero.

Force the impeller to the opposite end (toward

indicator). Indicator reading will be a measurement

of the impeller float. Repeat process on second

impeller and compare float to Table 6. Adjust

shimming at bearing clamp plates to obtain both

float and end clearances specified in Table 6.

Finally, after clearances and float have been

corrected and checked, remove the gear end

clamping places (54) and install wavy-spring

washers (29) and reinstall shims (10) and clamping

plates (54). Be sure oil feed grooves are up and

toward bearings.

11. Installing drive gear (4) – Be sure shafts and gear

bores are clean and free of scratches.Oil gear nut

threads lightly. Place hardwood wedges as shown

in Figure 8. Install gear (4) and nut (31) so match

mark at the tooth is at the line of engagement.

Tighten the drive gear to the torque given below.

Blower assembly must be fastened down for

torquing operation.

12. Left side discharge machine

Installing driven gear (14) – Insert a long metal

feeler gauge between the impellers’ lobes at the

fronts as shown in Table 6. Feeler gauge thickness

to be a middle value from Table 6 for fronts.

13. Right side discharge machine

Installing driven gear (4) – Insert a long metal

feeler gauge between the impellers’ lobes at the

backs. Feeler gauge thickness to be minimum

value from Table 6 for backs.

RAM™SERIES BLOWER GEAR NUT TORQUE

Frame Size Torque

lb.-ft. (kg-m)

404, 406, 409, 412, 418 400 (56)

616, 624 630 (88)

RAM™SERIES BLOWER OIL SLINGER SCREW TORQUE

Frame Size Torque

lb.-ft. (kg-m)

404, 406, 409, 412, 418 75 (10)

616, 624 140 (19)

Align the gear so the tooth match marks agree with

the drive gear, then install slinger (46) and nuts (31).

Tighten lightly with a small wrench, then check front

and back clearances against Table 6 for each 45°

position. Both fronts should be about the same and

backs should about equal and be within the specified

range in Table 6. Adjust gear position if necessary, then

insert the corrected feeler gauge and wedges and use

a torque wrench to tighten the gear nut to the torque

specified above. Remove wedges and rotate the drive

shaft by hand to make sure there are no gear tight

spots or impeller contacts. CAUTION: Keep

fingers away from impeller end gears.

Install gearbox (3) with gasket (7) and tighten the

capscrews (75) evenly to 10 ft.-lbs. (1.3 kg-m).

Install drive end oil slinger (40) and capscrew

(60), apply Locktite to threads and torque to value

specified above.

Install drive end cover (5) and gasket (7) with drive lock

pins (17) in place, being careful not to dent or scratch

drive shaft lip seal surface.Tighten capscrews (75)

evenly. Check seal bore for concentricity with shaft

using an indicator; reposition drive lock pins, if neces-

sary. Install seal (33) with lip facing inward, using care

to avoid tearing or scratching seal on shaft keyway. Use

a pressing tool with clean, square ends to insure cor-

rect positioning of the seal. For hydrodynamic style

seals, the shaft rotation is critical for correct installation

and proper sealing. Match the directional arrow shown

on the seal faces with the required shaft rotation. An

installation protective sleeve is required to protect seal

lip during installation.

Install vent plug (21) in each headplate.

Replace oil drain plugs (22) and refill drive end and

gear sumps with proper grade of oil as discussed

under LUBRICATION.

Install drive sheave or coupling half and install blower,

refer to INSTALLATION instructions.

18For your nearest ROOTS Office, dial our Customer Service Hot Line 1 877 363 ROOTS (7668).

ALLOWABLE OVERHUNG LOADS FOR V-BELT DRIVES UNIVERSAL RAI®/URAI™-JUNITS

Belt Pull lbs = 252100 • Motor HP

Blower RPM • Sheave Diameter

B = (1/8” + )

Sheave Width

Frame Dimension Max Allowable

Size “A” Shaft Load (lb-in.)

22, 24 0.61 80

32, 33, 36 0.80 300

42, 45, 47 1.02 640

53, 56, 59 1.13 1,110

65, 68, 615 1.36 1,550

76, 711, 718 1.16 2,300

NOTE: Arc of sheave belt contact on the smaller sheave not to be less than 170°

Driver to be installed on the inlet side for vertical units, and on the drive shaft side

for horizontal units.

ALLOWABLE OVERHUNG LOADS FOR V-BELT DRIVES 400 - 600 RAM™UNITS

A1/8" Max

Belt Pull lbs = 27500 • Motor HP

Blower RPM • Sheave Diameter

Shaft Load (lb.in) = Belt Pull • (A + 1/8” + )

Sheve Width

Max Allowable

Frame Standard Bottom Drive or Shaft Load

Size Unit Double Shaft Seal (lb-in.)

404, 406 1.90 2.11 3,200

409, 412, 418 1.90 2.11 3,200

616, 624 2.11 2.67 7,975

Dimension “A”

NOTE: Arc of sheave belt contact on the smaller sheave not to be less than 170°

Driver to be installed on the inlet side for vertical units, and on the drive shaft side for

horizontal units.

C = Distance between drive bearing center line and

sheave center line (A+B)

Shaft Load (lb.in) = Belt Pull • C

FIGURE 2

ROOTS, RAM, URAI and WHISPAIR are trademarks of Dresser, Inc.

Dresser Design and Universal RAI are registered trademarks of Dresser, Inc.

AIR BLOWER INSTALLATION WITH ACCESSORIES

Manual Discharge Unloading Valve

Inlet Air FIlter

Vacuum Relief Valve

Temperature Gauge

Manometers

Inlet

Silencer

Temporary Screen

Expansion Joint

Expansion Joint with Control Unit

AIR BLOWER

Back Pressure

Regulator (optional)

Pressure Relief Valve

Check Valve

Isolation Valve

with Limit Switch

Temperature Gauge

Discharge Silencer

*Differential Pressure &

Temperature Switches

Above are suggested locations for available accessories.

GAS BLOWER INSTALLATION WITH ACCESSORIES

Inlet

Silencer

Temperature

Gauge

Temperature

Gauge

Expansion Joint with Control Unit

Differrential Pressure &

Temperature Switches

GAS BLOWER

Check

Valve

Discharge

Silencer

Temporary

Starting Valve

Back-Pressure

Regulator By-Pass Cooler

Pressure Relief Valve

Pressure

Gauge Vacuum

Relief

Valve

Normal Starting Valve

Temporary Screen

Expansion Joint

Above are suggested locations for available accessories.

FIGURE 3

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