US VACUUM DURAVAC RP Series User manual

DURAVAC “RP” SERIES
Oil Lubricated, Rotary Piston Vacuum Pumps
Models RP-35C & RP-50C
INSTALLATION
OPERATION
MANUAL
US VACUUM PUMPS LLC
P.O. BOX 909
CANTON, TX USA 75103
TEL: [phone] FX: 877-416-7599
EMAIL: [email protected]
WWW.USVACUUMPUMPS.COM
WARNING
DO NOT OPERATE BEFORE
READING MANUAL

This manual contains installation, operation, maintenance and troubleshooting information for the Model
RP-35C & RP-50C Rotary Piston Vacuum Pumps. Please read it in its entirety before operating the pump.
Our Rotary Piston Vacuum Pumps are designed to ensure safety when used properly. It is the responsibility of
the user to follow safety-related warnings, cautions, notes and other requirements described in this manual.
Returned equipment will not be accepted by our company without prior authorization. Prior to shipping please
call for a returned goods authorization number (RGA).
Our company reserves the right to cancel the warranty if the pump is disassembled without authorization, if
pump fluids are used that are not compatible with the design and materials used in the manufacturer of the
pump, and if unauthorized spare parts are used.
FORWARD
WARNING
The pumps associated with this manual use industrial systems including heavy Current/Voltage installations.
Depending on the operating conditions, particularly where dangerous conditions may be present, improper
handling could lead to severe personal injury or property damage.
Those responsible for safety of the installation must therefore insure that:
 ONLY QUALIFIED PERSONNEL ARE ALLOWED TO WORK ON THE MACHINE(S).
 THESE PERSONS ALWAYS HAVE AT THEIR DISPOSAL THE SUPPLIED OPERATING INSTRUCTIONS
AND OTHER PRODUCT DOCUMENTATION WHEN DOING SUCH WORK, AND THEY UNDERTAKE TO
FOLLOW ANY SUCH INSTRUCTIONS CONSTANTLY.
 NONQUALIFIED PERSONNEL ARE NOT PERMITTED TO WORK ON OR NEAR THE MACHINE(S).
 ALL WORK DONE ON ANY ELECTRICAL DEVICES AND ASSOCIATED EQUIPMENT ( including motors,
control panels, circuit panels, etc) MUST PERFORMED BY A PROPERLY TRAINED AND CERTIFIED
ELECTRICAN.
 THE WARNINGS, CAUTIONS, AND INSTRUCTIONS DISCUSSES IN THIS MANUAL CANNOT COVER ALL
POSSIBLE CONDITIONS AND SITUATIONS THAT MAY OCCUR. IT MUST BE UNDERSTOOD BY THE
OPERATOR THAT COMMON SENSE AND CAUTION ARE FACTORS THAT CANNOT BE BUILT INTO
THIS PRODUCT, BUT MUST BE SUPPLIED BY THE OPERATOR.

SAFETY PRECAUTIONS
CAUTION: When using PVC pipe or any static enhancing material for exhaust
piping, make provisions to safeguard against arcing from static electricity.
Arcing can ignite oil vapor that may be present.
CAUTION: Do not operate the pump without the belt guard properly attached.
Operating the pump without the belt guard secured in place exposes people in
the vicinity of the pump to risk from rotating drive parts.
CAUTION: Do not operate this pump in oxygen service. Oxygen service is
defined as any application which has a process gas concentration that exceeds
20%. Pumping oxygen enriched gases with mineral oil or other non-inert fluids
can cause an explosion in the pump, resulting in damage or injury.
CAUTION: Take precautions to avoid prolonged or excessive exposure to oil
mist or process materials from the discharge of the pump. Do not discharge the
pump into a closed room or a room without adequate ventilation. Always use a
discharge oil mist eliminator unless the pump discharge is vented to the open
air. Venting the outlet to open air is highly recommended
CAUTION: Disconnect the pump from the electrical supply at the main
disconnect before dismantling or servicing the pump.
CAUTION: Lift only with the lifting eyebolts supplied with the pump. Do not lift
equipment attached to the pump with the eyebolts supplied.
CAUTION: Do not restrict the pump discharge line in any way, or place any
valves in the discharge line. Excessive pressure build-up could cause damage
or injury.
CAUTION: Do not touch hot surfaces on the pump. In normal operation at
low pressures surface temperatures will not normally exceed 160 Degree F.
Prolonged operation at 200 torr may cause surface temperatures up to 200
Degree F.

TABLE OF CONTENTS
SAFETY PRECAUTIONS…………………Page 2
INTRODUCTION…………………...………Page 4
PERFORMANCE SPECIFICATIONS…….Page 6
DESCRIPTIONS…………………………….Page 7
GENERAL INFORMATION……….………..Page 8
START-UP……………………………………Page 10
TROUBLESHOOTING………………...……Page 11
PARTS LIST & EXPLODED VIEWS………Page 15
WARRANTY STATEMENT…………….......Page 21

CONGRATULATIONS on your purchase of a new Duravac “RP” Series OIL LUBRICATED, Rotary Piston Vacuum
Pump from US VACUUM. Please examine the pump for shipping damage, and if any damage is found, report it
immediately to the carrier. If the pump is to be installed at a later date make sure it is stored in a Clean, dry location
and rotated regularly. Make sure covers are kept on all openings. If pump is stored outdoors be sure to protect it
from weather and corrosion.
DURAVAC vacuum pumps are built to exacting standards and if properly installed and maintained will provide many
years of reliable service. We urge you to take time to read and follow every step of these instructions when installing
& maintaining your pump.
WARNING: Serious injury can result from operating or repairing this machine without first reading the
service manual and taking adequate safety precautions.
IMPORTANT: Record the pump model and serial number in the OPERATING DATA form below. You
will save time and expense by including this reference information on any replacement parts orders.
INTRODUCTION
OPERATING DATA
It is to the user’s advantage to have the requested data filled in below and available in the event a problem
should develop in the vacuum pump. This information is also helpful when ordering spare parts.
Model No____________________________ Oil Type________________________________
Serial No.____________________________ Operating Vacuum________________________
Startup Date__________________________ Inlet Gas Composition_____________________
Motor Hp_____________ RPM____________ Accessories supplied______________________
NOTES:____________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________

PRINCIPLE OF DESIGN
The Duravac RP-35/50 series of pumps are of the cam (eccentric) and piston (Slide) type and are Duplex in design. Within the pump,
the piston is driven by the cam. The cams are mounted 180 degrees apart on a single shaft so that centrifugal forces of the moving
pistons will oppose one another. The shaft passes through the center wall separating the two pump sections and is supported by
bearings in the heads at each end of the cylinder. The open head which the shaft extends, has a shaft seal set-up to prevent air
leakage into the pump and an outboard bearing to handle the belt pull force. The driven pump pulley is weighted to provide for final
pump balancing
Each piston has an integral hollow extension (called a slide) which extends through the slide pin (hinge bar). One side of the slide
contains diagonal slots; as the slide passes back and forth through the slide pin, these slots are covered and uncovered to form an
inlet valve. Outlet valves are over the discharge port on top of the cylinder. All working parts are precisely machined to suitable
clearances for high vacuum requirements.
The covering and uncovering of the slots in the piston slide by the slide pin constitutes a mechanical inlet valve. Air of gas is admitted
Through these slots from the high vacuum side of the slide pin into the space between the piston and cylinder at certain parts of the
cycle. As there is no spring loading, no pressure difference is required to operate this valve. The outlet (discharge) valve is opened
automatically by the compression of the air or gas in the pump against atmospheric pressure, plus a slight spring pressure.
Since the success of the pump depends on its being sealed and lubricated, an oil reservoir is mounted above the pump. The sealing
oil needs to be free from gases or moisture. Otherwise, the vapors will be pulled out of the oil (outgassing) and will prevent obtaining
low absolute pressures.
In view A from the figures below, the piston is moving in the direction of the arrow and is rapidly creating more space into which some
of the gas is admitted through the inlet port; at the same time, view B is compressing the gas previously trapped and is taking place on
the opposite side of the piston. As the piston reaches the end of it’s compression cycle in view B, it expels all the air or gas and sur-
plus sealing oil through the outlet valve and into the oil reservoir tank. The reservoir tank is where the oil is retained for recirculation
and the air or gas being pumped is expelled out the discharge port of the reservoir.
Fig-1
OIL
OIL SEPARATOR
EXHAUST
INLET
SLIDE PIN
DISCHARGE
VALVE
CAM
PISTON

INTRODUCTION
PERFORMANCE SPECIFICATIONS
SPECIFICATIONS
Pump Model RP-35C RP-50C
Displacement CFM 35 52
Ultimate Vacuum (Partial pressure) Torr 10 microns (0.010 mm Hg)
Motor Hp 2 3
Pump Speed RPM 424 612
Oil Capacity Gal 4 4
Inlet connection in. 2" Flg 2" Flg
Exhaust connection in. 2" NPT 2" Flg
Cooling Media AIR AIR
Pump Weight Lbs. 485 495

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US VACUUM PUMPS, LLC
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GENERAL
UNPACKING
Inspect the box and pump carefully for any signs of damage incurred in transit and report with-in 7 days of receipt. Since all our
pumps are shipped F.O.B. our factory, such damage is the responsibility of the carrier and reported to them. The inlet & exhaust of
the pumps are covered with plastic caps to prevent dirt and other foreign substances from entering the pump. Leave the caps in place
until you are ready to pipe the pump to your equipment.
LOCATION
Locate the pump as near as possible to the equipment being evacuated so that the vacuum, water and exhaust connections can be
conveniently made. Leave 12-18” of access around the pump to allow proper access for routine maintenance. Allow access to the oil
sight glass in order to inspect the oil level and for easy access to change the lubricating oil and exhaust
filter.
INSTALLATION
The pump should be mounted on a rigid foundation, such as a concrete floor. The pumps come with four (4) rubber vibration
dampening supports to be mounted (bolted) onto each corner of the pump. The pumps can operate without foundation securing.
Remove cap from exhaust and intake openings only when ready to make pipe connection. When the pump is to be subjected to tem-
peratures below freezing, drain water jacket through the housing drain plug to prevent cracking the housing, then blow out water jack-
et with compressed air. Follow this same procedure for storage
Cooling water:
The pumps are AIR COOLED and do not require cooling water for operation. The pumps are designed to operate up to a maximum
ambient temperature of 110 Deg F.
VACUUM CONNECTION
All pipe lines should be as short as possible and should be no smaller in diameter than the inlet to the pump….if it is absolutely
necessary to run a long line, the suction pipe should be increased 50% in diameter. Conductance of long lengths of suction piping
must be checked and the line sized large enough so the pumping speed of the system will not be seriously affected.
Pumps operating in parallel on a common main line should have a manual or automatic shut-off valve or positive acting check valve
installed in the suction line of the pump.
Should the process gas contain dust of other foreign material, a suitable inline particulate filter should be connected to the inlet
port…..contact US Vacuum for recommendations.
When connecting the pump to the system, provide proper piping geometry to prevent dirt from the system from entering the pump and
to prevent back siphoning of pump oil in the system chamber.
The vacuum piping should be designed to insure that no liquids such as condensate or liquid carryover from the process can reach
the pump. If this possibility exists, a knock-out liquid separator should be installed…..contact US Vacuum for recommendations.
The best piping for the vacuum side of the pump is made up with flanges using neoprene/fiber gaskets or O-rings. Flanges may be
welded or threaded to pipe. If threaded connections are used, use a heavy sealing compound to insure no leaks are present.
CAUTION: Make sure the system to be evacuated and connecting lines are clean and free of weld splatter, dirt, or grit.
Foreign matter entering the pump can cause failure and possibly damage the internal parts,

Typical piping arrangement for pump mounted below system (Fig-2) and for the pump mounted above the system (Fig-3)
VACUUM CONNECTION (cont.)
TYPE OF PIPE JOINTS
A) Standard steel piping with welded joints makes the best vacuum piping system.
B) Copper piping with sweated fittings and joints can also made vacuum tight and has the advantage
of providing a neat, clean vacuum installation.
C) Standard threaded piping, however, is satisfactory and more readily installed. The piping should be
Carefully cleaned to remove any scales or chips. Blow out any loose material with compressed air prior
to installation. All male threaded joints should be carefully doped, screwed up tight and NEVER “backed-off”
to make parts align-this is apt to cause a leak.
Paint the joints while the system is under vacuum with a vacuum grade sealant until the sealant is no longer
drawn into the piping threads. U.S. Vacuum Sealant should be used..

DISCHARGE PIPING
It is recommended that the exhaust be piped horizontally a short distance and tied into a vertical exhaust pipe. The vertical exhaust
pipe must be at least 1 ft. long and the bottom end of the vertical exhaust pipe be terminated with a plug or drain valve to allow
removal of moisture and contaminated oil before it can accumulate sufficiently to drain back into the pump oil reservoir.
The exhaust pipe should be no smaller than the pump exhaust outlet and as short as possible. Run the pipe outside the building
or into a coalescing Oil mist filter. When pumping noxious or toxic gases, the exhaust must be vented outside the building even if a
discharge oil mist filter is installed.
The pump exhaust should have a horizontal run to a drop-out Tee, and then go up if necessary. Equip the Tee with a drain valve to
drain off condensate from time to time as needed. Oil mist eliminator filters are available to replace the piping.
When starting the pump or handling large amounts of air, oil vapor in the form of smoke will exit the pump exhaust port. This is no
indication of trouble, as the volume of smoke will decrease as the volume of air reduces and the vacuum in the system improves.
OIL EXHAUST FILTERS are available to alleviate exhaust smoke.
Oil Mist exhaust Filter
Used to eliminate (99%) of the oil mist from the
pump discharge. High efficiency coalescing
technology
Pump Model Cat. No
RP-35 VFSG850200
RP-50 VFSG850200

ELECTRICAL CONNECTIONS
A schematic diagram for the electric motor terminal box is located either inside the junction box cover or on the side of the motor itself.
The motor must be connected according to applicable electrical codes Through a fused switch in order to protect the motor against
electrical or mechanical overload conditions. The overload of the motor starter must be set at a level equal to the full load motor
current listed on the nameplate.
Wire the solenoid valve to allow oil flow from the pump oil reservoir to the pump bearings & internals. Insure proper voltage
is used to power the solenoid or the valve will not open and cause a pump failure.
AFTER ELECRICAL CONNECTIONS HAVE BEEN MADE, BUT PRIOR TO FILLING THE PUMP WITH OIL, THE ROTATION OF
THE MOTOR SHOULD BE CHECKED. IF BACKWARD, REVERSE ANY TWO LEADS OF THE THREE AT THE POWER
CONNECTION.
COOLING
The pumps are AIR COOLED and do not require cooling water for operation. The pumps are designed to operate up to a maximum
ambient temperature of 110 Deg F.
CAUTION: Do not start the pump when oil temperature is below 55 Deg F. Excessive wear and galling damage
to the moving parts may occur
OIL FILLING
The successful operation of this pump depends largely on the type of oil used. An initial charge of oil is included with each pump. This
standard oil is US550-SS which is recommended for general operating in a relatively clean environment.
After level installation and correct rotation of the pump has been established, fill the pump with recommended oil through the oil fill
port. Oil level should be at the 3/4 position on the sight glass window.
Oil capacity: 4 Gallons
CHANGE OIL EVERY 500-750 OPERATING HOURS
Check the oil for contamination on a weekly basis by shutting the pump off and draining some of the oil into a small glass
or container through the oil drain port.
Oil life is dependent upon the condition to which it is exposed. The oil must be changes after the first 100 hours of initial
operation. After the initial oil change, and when using US350-SS, it is recommended that the oil changes are made every
three (3) or four (4) months or 500-750 hours of operation, or as necessary if high heat is contaminating the oil.
To change the pump oil, the pump must be switched off and ventilated to reach atmospheric pressure. Open the oil drain
valve and drain the oil. Dispose of the oil in compliance with local or national regulations. When oil stops draining,
replace the oil drain plug.
Start the pump again for a few seconds. Stop the pump once again, and then reopen the oil drain valve and discharge
any remaining oil. Refill with new oil. Optimum pump oil temp. should be between 140-160 Def F.
EXCESSIVE HEAT:
When the pump is subjected to operating conditions that will cause the oil to be heated above 200 Deg F, the oil will
carbonize and become contaminated after a relatively low number of operating hours if standard hydrocarbon oil is used.
The higher the temperature, the quicker the oil becomes contaminated and thermally breaks down. In these type of high
heat applications, US550SLR oil is recommended.
CONTAMINATED AIR STREAM
When the air stream contains solids and/or liquids that may contaminate the oil, the oil must be changed more often. If
the air stream contains a small percentage of particulate matter, the solution is to install a pre-filter or knock-out pot to
keep the contaminates out of the pump.

START-UP
1) Be sure the suctions lines are free of foreign matter and perfectly tight. Use inlet protection screens or drop-out traps
on new installations where large welded piping is employed.
2) Make sure the pump discharge is not obstructed
3) Check that the cooling water is connected to the pump and available (If required)
4) Check belt tension. Deflection should be 1/2” at the center (midway) span of the belt
5) Check the oil level and adjust if necessary
6) Ensure that the oil line solenoid is wired correctly and oil is flowing
Check for correct rotation of the pump (counter-clockwise looking at pump drive shaft)
7) Ensure the suction line is not under vacuum (at atmospheric pressure)
8) Close the vent valve if one is used
9) Start the pump
10) Turn on cooling water and adjust flow according to previous instructions
11) Adjust gas ballast as required
.
STOPPING THE PUMP
To stop the pump:
1) Close the isolation valve in the suction line
2) Vent the pump to atmosphere thru vent valve or gas ballast valve
3) Stop the pump
4) Turn off cooling water
NOTE: Venting the pump prior to shutdown returns the lubricating oil in the pumping chamber back to the oil reservoir
and prevents the pump from rotating backwards. Failure to follow proper shutdown
Procedures can result in both hydraulic and vacuum locking the pump and possibly causing pump
damage.
GAS BALLAST
The gas ballast valve is a manual valve located on the endplate. The valve introduces atmospheric air into the pumping
chamber to aid in removing condensable vapor contaminates from the vacuum pump oil. Vapor contaminates in the
pump oil can dramatically impair the pump performance by vaporizing during the low pressure section of the pumping
cycle thereby preventing gas from being drawn into the pump.
Isolate the pump from the system and fully open the gas ballast valve and run the pump overnight.
If this is not possible, partially open the valve during operation and run until oil is clean.
CAUTION: Gas ballast should NEVER be used if vapors being pumped are explosive, (ie: methane gas, hydrogen and certain solvent vapors)
When gases of an explosive nature are being handled, the safest procedure is to remove the gas ballast valve entirely
and plug or cap the pipe to which the gas ballast valve is attached.
Opening the gas ballast valve slightly will quite valve noise when pump is blanked-off.
SOLENOID VALVE
The solenoid valve feeds oil from the upper oil reservoir to the pumping cylinder via an oil line feeding each endplate.
The solenoid is N.C. (normally closed) and is used to keep oil in the upper reservoir from draining into the pump cylinder
when the pump is not in operation, thereby preventing oil from filling up the cylinder. Restarting the pump with the
cylinder filed with oil can cause hydraulic lock and damage to the pump.
Make sure to check the voltage requirements on the solenoid and that it is wired accordingly. Low or incorrect voltage
will cause the valve not to open and lead to a loss of oil lubrication to the pump causing severe damage to the pump. Hot
smell or smoke from the solenoid is cause for investigation. Do not energize the coil when it is removed from the valve
body, this will cause the coil to fail.
Oil Line Solenoid Valve
wiring diagram

SOLENOID VALVE (CON”T)
Foreign matter will cause the valve to stick, jam or leak. Any solenoid valve should be cleaned periodically. Solenoid
valves should be cleaned when the oil is changed due to contamination by foreign matter. Solenoids are designed for
use in relatively dry locations and in temperatures up to 115 Degree F. Weather-proof and special purpose solenoids
are available. There is always a slight hum when the solenoid is working; a slight click will be heard when the solenoid
opens properly as the core hits the plug at the tope of the core tube.
MAINTENANCE
Periodic Maintenance
 DAILY: Visually check oil level in sight glass & color, oil flow through the solenoid & oil lines
 Weekly: Check inlet filter
 Every 3 Months/ 500-750 hours– Change oil
 3000 Hours– Change exhaust filter.
 Replace V-belt and Discharge valves
 10,000– Replace bearings and seals. This is to be done by specially trained service personnel.
Change oil every 500-700 hours or as needed. Clean oil reservoir housing every 1000 hours to increase the life of the lubricating oil.
Darkening of the pump oil indicates pump wear or chemical reaction between the oil and the gases being pumped. White milky oil is
an indication of water contamination...use gas ballast to clear oil or change oil. Water can also be removed by draining water from the
pump (oil drain valve) before starting the pump.
DISCHARGE VALVES
Discharge valves are located inside the oil reservoir, under the oil baffle & valve plate. After draining oil from the pump, remove valve
assembly by removing the six (6) cap screws and valve gasket….inspect valve discs and springs for wear. Change if required.
Repair kits
RP-35: Pt#RKIT-RP35-RKIT
RP-50: Pt#RKIT-RP50-RKIT
Repair Kit includes bearings, shaft seals, gaskets, o-rings, discharge valves & misc. hardware .
NOTE:
US Vacuum Pumps LLC is not liable for operational failure due to mistakes made by non-US Vacuum
personnel during the installation/operation or the utilization of non-US Vacuum parts
Direct Drive Units
The RP35C & RP-50C pumps are available in Direct Drive configuration for specialty applications where a V-belt drive would be
objectionable. The direct drive system utilizes an inline gear reducer to reduce output rpm to the desired value depending on the
vacuum pump model selected. The gear box is sealed (non-vented) and uses an ISO 220 EP mineral oil. The initial oil fill is good for
10,000 hours , no initial oil change required after break-in. Ambient temperature limits 10F-105F for the gearbox, but the vacuum
pump itself is limited from 55F-105F...cold starts on the vacuum pump can lead to high motor running current and/or stalling.
The gearbox is a single reduction unit, therefore the motor/gearbox input shaft rotation is opposite the vacuum pump. Motor rotation
(fan end) is clockwise.

EXCESSIVE HEAT:
When the pump is subjected to operating conditions that will cause the oil to be heated above 200 Deg F, the oil will
carbonize and become contaminated after a relatively low number of operating hours if standard hydrocarbon oil is
used. The higher the temperature, the quicker the oil becomes contaminated and thermally breaks down. In these
type of high heat applications, US550SLR oil is recommended.
CONTAMINATED AIR STREAM
When the air stream contains solids and/or liquids that may contaminate the oil, the oil must be changed more often. If
the air stream contains a small percentage of particulate matter, the solution is to install a pre-filter or knock-out pot to
keep the
contaminates out of the pump.
Seal Oil Vacuum Pump (Power Generation)
On seal oil vacuum applications, large amounts of water vapor is often distilled out of the seal oil from the degassifiac-
tion tank with the water vapor entering the seal oil vacuum pump. The mixture of water and the vacuum pump lube oil
inside the seal oil vacuum pump will result in the formation of an oil/water emulsion that will reduce the viscosity of the
vacuum pump lube oil. Also, VARNISH can form inside the vacuum pump from the oil/water emulsion when the pump
operates at elevated temperatuers. The varnish will cause frictional drag on the motor and eventually cause the pump
to stall. Using a lube oil with detergent additive or performing a kerosene flush will help in the formation of the varnish.
VARNISH build-up on vacuum pump cylinder (above)
High temp operation from loss of lubrication (Right). Oil
line solenoid valve clogged, reducing oil flow to the pump.
Use detergent lube oil or synthetic oil for the vacuum
pump. VG68/VG100

TROUBLESHOOTING
TROUBLE
The pump does not reach “blank-off” pressure
or takes too long to evacuate the system.
Possible cause: Contaminated oil is the most
common cause of not reaching ultimate pressure.
Remedy: Shut off the pump, after the operating
temperature has been reached, drain the warm oil
from the pump. Flush and fill the pump with new oil
and take a new “blank off” measurement after oper-
ating temperature is reached (20-30 minutes).
Possible cause: Solenoid valve not opening
properly or inoperative..
Remedy: Check and clean valve or replace coil.
Possible cause: Loose intake flange or head bolts
Remedy: Tighten bolts
Possible cause: No oil or not enough oil in the oil
reservoir.
Remedy: Shut off the pump, add the necessary oil,
or if oil seems contaminated, drain the balance of
the oil from the pump, exchange oil filter and refill
with fresh oil. Flush if necessary.
Possible cause: Oil line connection leaking
Remedy: Tighten if necessary
Possible cause: Exhaust valve not sealing.
Remedy: Disassemble and clean if necessary.
Possible cause: Threaded connections leaking
Remedy: Paint with vacuum sealant
Possible cause: Shaft seal leaking
Remedy: Inspect and replace if necessary
Possible cause: The internal parts are worn or
damaged.
Remedy: Contact U.S. Vacuum for instructions.
TROUBLE
The pump is excessively noisy
Possible cause: Typical noise at high vacuum
Remedy: Open gas ballast valve
Possible cause: Poor or no oil lubrication
Remedy: Check solenoid valve/coil, replace if
required. Check oil lines for blockage, clean or
replace.
TROUBLE
The pump will not start
Possible cause: Motor overloads tripping out
Remedy: Check overload settings Vs motor
nameplate value. If necessary use 1 size larger
thermal overload
Possible cause: Possible internal seizure
Remedy: Disassemble and correct
TROUBLE
The pump will not turn over when motor
starts
Possible cause: Belts too loose
Remedy: Tighten V-belts
 Before attempting to locate the cause of the of poor ultimate pressure,
check the accuracy of the vacuum gauges on the system.

Possible cause: Cylinder may be flooded with
excessive oil due to defective solenoid valve (stuck
in open position).
Remedy: Turn pump over by hand to remove ex-
cessive oil. Check solenoid valve, clean or replace
Possible cause: Oil temperature too low, or
viscosity too high.
Remedy: Warm up oil, use ISO100 oil.
TROUBLE
Possible cause: Pump turns backwards for
several revolutions when motor turned off.
Remedy: Close gas ballast valve before shutting
off pump. This prevents atmospheric air from
reversing direction of pump piston when power is
off.
TROUBLE
Pump smokes at the exhaust side or expels oil
droplets from the exhaust
Possible cause: No exhaust filter in place
Remedy: Install exhaust filter
Possible cause: The exhaust filter is not
properly seated with the o-ring in filter base or filter
material is cracked.
Remedy: Exhaust filter not properly seated with o-
ring, replace if necessary. Check element and se-
cure
Possible cause: The exhaust filter is clogged with
foreign particles.
Remedy: Replace the exhaust filter.
TROUBLE
Pump runs hot
Possible cause: Water temperature or flow
inadequate
Remedy: Check water flow to pump. Increase
flow is necessary. Check that the water jacket is
not clogged with mineral deposits or scale. Clean
is necessary
Possible cause: No oil flow to pump.
Remedy: Check solenoid valve-clean or replace
as necessary.

RP35/50 VACUUM PUMP
61
57 56
55  0
58 · .
59
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25
27
28
51
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49
12
 
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34 7
5
48

RP 35/50 ROTARY PISTON VACUUM PUMP
NO.
PARTS NAME
QTY
MATERIAL
1
NUT
1
STEEL
2
WASHER
1
STEEL
3
PUMP SHEAVE
1
IRON
4
MECHANICAL SHAFT SEAL
1
STEEL, VITON, ETC.
5
BOLT
4X2
STEEL
6
BEARING COVER A
1
IRON
7
O-RING
2
VITON
8
LONG SHAFT SLEEVE
1
STEEL
9
O-RING
3
VITON
10
BEARING
2
STEEL
11
BOLT
13
STEEL
12
PIN
4
STEEL
13
PUMP COVER A
1
IRON
14
SHORT SHAFT SLEEVE A
1
STEEL
15
LONG HINGE BAR
1
IRON, STEEL, ETC.
16
LONG PISTON
1
IRON
17
LONG ECCENTRIC
1
IRON
18
KEY A
1
STEEL
19
SHAFT
1
STEEL
20
KEY B
1
STEEL
21
KEY C
1
STEEL
22
OIL DRAIN VALVE
1
COPPER
23
SOLENOID VALVE
2
STEEL
24
PUMP BODY
1
IRON
25
MIDDEL PLATE A
1
IRON
26
MIDDEL PLATE B
1
IRON
27
SHORT ECCENTRIC
1
IRON
28
SHORT PISTON
1
IRON
29
SHORT HINGE BAR
1
IRON, STEEL, ETC.
30
SHORT SHAFT SLEEVE B
1
STEEL
31
O-RING
2
VITON
32
GAS BALLAST VALVE
2
ALUMINUM, STEEL, COPPER, VITON
33
PUMP COVER B
1
IRON
34
BOLT
13
STEEL