Thomas Industries Welch DUOSEAL 1400 User manual

OWNER’S MANUAL
FOR
DUOSEAL® VACUUM PUMPS
MODELS:
1400, 1405, 1402,
1376, 1397, 1374,
1399, 1380, 1392
Contents: Installation
Operation
Maintenance
Specification
Dimensional Drawings
Parts List
Accessories
MSDS Sheet for DUOSEAL® OIL
WARNING
Never Block the Exhaust Port.
If the exhaust is blocked, pressure will build-up in the pump
with the potential of the pump body bursting and causing
possible injury to personnel in the area.
Welch Rietschle Thomas
7301 North Central Ave.
Skokie, IL 60077
Phone: [phone]
Fax: [phone] (Technical Support)
Fax: [phone] (Ordering)
Web Page: www.welchvacuum.com Part No. 67-0777R2.9
E-mail: [email protected] Printed in the U.S.A.

CONTENTS
SECTION PAGE
1. Installation 3-5
2. Operation 6-8
3. Maintenance 9-11
4. Trouble Shooting Guide 12
5. Quick Reference Charts 13-14
6. Pumping Speed Curves 15
7. Dimensional Drawings (with rotation) 16-17
8. Exploded Parts Listings 18-31
9. Accessory Section 32-33
10. MSDS Sheet For DUOSEAL® OIL 34
PLEASE READ BEFORE OPERATION
While reading your manual, please pay close attention to areas labeled WARNINGAND CAUTIONS.
The description of each is found below.
WARNING
Warnings are given where failure to observe instruction
could result in injury or death to people
CAUTION
Cautions are found where failure to observe the instruction should
result in damage to the equipment, associated equipment and process.
These units conform to the SI International system of units of measurement.
The following symbols (with recommendations of IEC1010) of warning will be found on the pump.
Caution- refer to accompanying documents
Caution- risk of electrical shock
Caution- hot surface
WARNING
Motor includes a self resetting thermal cutout and the pump could restart
without actuation under fault condition.
2

Section 1: INSTALLATION
1.1 Introduction
This manual has been complied not only for the care and maintenance of the DUOSEAL pump now in your
possession but as a helpful reference and guide for many problems which are usually associated with mechani-
cal vacuum pumps. Take time to read these instructions carefully and preserve this manual for future refer-
ence; we think it will be useful to you.
1.2 Unpacking
Carefully remove the pump from the shipping case and unfasten and remove the wooden skid. Preserve all
paper work and inspection tags for future reference. If damage has occurred from shipment a claim must be
filed with the carrier immediately; preserve the shipping container for inspection by the carrier. If you are
required to communicate with your dealer or with Welch Vacuum be sure to include your order numbers for
quick identification. Do not return the pump to the factory with out first calling for a returned goods number.
1.3 Pump Mounting
1.3a Mounted Pumps
Rubber bumpers are supplied with most of our mounted pumps, either loosely or attached. Bumpers are
excellent for applications involving a semi-flexible surface such as a bench top; they help to isolate noise and
eliminate creeping. For more rigid requirements, the pump base may be bolted directly to a firm foundation
with or without the bumpers. All DUOSEAL pumps should be mounted in a horizontal plane.
1.3b Unmounted Pumps
If you have purchased an unmounted pump, refer to parts list for information concerning the motor, motor
pulley and belt necessary to drive your particular pump at the recommended speed.
1.4 Pump Location
The pump should be located preferably in a clean and well ventilated area and adequate space should be
provided wherever possible for routine maintenance such as changes of oil and belt adjustments and replace-
ments. Above all, the pump should be located as closely as possible to its system in order to utilize it most
efficiently. Its location should include such determining factors as the length and size of connections, the
number of bends and the type of exhaust connections.
1.5 Exhaust Provisions (See Accessory section in back of this manual.)
Exhaust connections will be determined by the type of system to be exhausted and the desired cleanliness of
the atmosphere surrounding the pump. Under normal conditions of mild evacuation nothing more than the dust
cap will be necessary to cover the port. Where relatively high gas flows are involved or where the presence
of oil vapor is objectionable an exhaust filter may be fastened to the exhaust port in place of the dust cap. The
exhaust filters used on our pumps are capable of absorbing and restricting any vapor particle larger than 0.1
micron.
WARNING
Never block the exhaust port. If the exhaust port is blocked, pressure
will built-up in the pump with the potential of the pump body bursting
and causing possible injury to personnel in the area.
Where extreme exhaust conditions are encountered it is best to pipe the exhaust direct out of the building.
Welch recommended wire reinforced PVC, metal pipe or thick walled rubber hose be used as exhaust lines to
avoid potential of line becoming crimped or collapsing resulting in the exhaust port being clocked. Be sure to
call Welch technical service prior to start-up at 847-676-8800 if you have any questions.
3

1.6 Electrical Power
1.6a Power source Review
Review the power source and the motor rating to be sure they agree in voltage, phase and frequency. On three-phase
applications the direction of rotation of the motor must be considered. Make a momentary check rotation at the time of
power installation and wiring. Momentary backward rotation of the pump is not harmful. Check the layout drawings for
proper direction of rotation.
CAUTION
Make certain the power settings on the pump match your power
source before attempting to operate the pump
1.6b Overload Protection
Motor thermal overload protection is made available by the motor manufacturer as an aid to minimizing motor failure.
Overload protection is a standard feature on all single-phase 60Hz motors. Single-phase motors will normally have
automatic overload protection. Motors of 1-1/2 horsepower or larger supplied with DUOSEAL pumps contain no
overload protection. Installations of such equipment must comply with local electrical codes which dictate appropriate
starter and protection devices. It is strongly suggested that you familiarize yourself with the protection supplied with
your motor so that you may react accordingly in the event of an emergency. Automatic reset protection is designed to
reset itself after a predetermined cooling period. If the fault to the drive remains unaltered, the motor will cycle on and off
until the fault is corrected. The motor data plate will indicate the presence of thermal protection.
1.7 Vacuum Connections (See Accessory Section in back of this manual.)
1.7a Choice of Connections
The choice of connections and fitting can have a very marked effect on the pumping speed at the vacuum chamber. Any
connection placed between the pump and the chamber creates an impedance to the flow of gas. This is particularly true at
low pressures in the millitorr range where the gas flow is substantially molecular in character. The gas flow is then
dependent upon the kinetic activity of the molecules to bring it to the intake of the pump.
1.7b The Effects of Condutance
It has been shown that the conductance of a tube is proportional to the cube of its radius and inversely propor-
tional to its length. Therefore it is imperative that the connecting lines be as large in diameter and as short in
length as practical. For best results the diameter of the connecting tube should be at least as large as the
diameter of the pump intake. To avoid a large reduction in pumping speed at the vacuum chamber, it is clear
that the conductance of the line must be considerably greater than the speed of the pump.
1.7c Metal Joints
If metal piping or tubing is used, it is preferable to solder or braze all of the connections. Where threaded joints must be
used, coat the threads with LocTite® Thread Sealant with Teflon®, or Leak Lock and screw together tightly. Flanged
connections with elastomer gaskets make excellent demountable joints. Modular vacuum piping and fittings are now
extensively used.
1.7d Rubber Tubing Joints
Where metal tubing is used between the system and the pump intake, joints can be make by butting the ends of the two
sections together in a short section of vacuum hose.Worm-screw band clamps are useful for securing the hose to the
tubing.Whatever the joint you choose to use, cleanliness should be of utmost importance.
1.7e Valves and Stopcocks
Metal valves or stopcocks may be used in the connecting line between the system and the pump to provide a means of
isolating the pump from the system. To minimize the impedance of flow, the valve openings should be as large as possible.
Lubricate the rotating plug of the stopcock with a film of vacuum grease sufficiently thick enough to prevent seizure.
4

1.8 Vacuum Gauges (See Accessory section in the back of this manual.)
The type of vacuum gauge to be used is determined largely by the pressure range to be measured. Pressures
in the ranges produced by DUOSEAL pumps can be covered by McLeod, Pirani or Thermocouple gauges.
The McLeod gauge is used where high accuracy of measurement is required. The Pirani and Thermocouple
gauges are electrical and give continuous readings of the total pressure. There are preferred where rapid
pressure changes occur. The McLeod gauge does not measure condensable vapors; therefore, if vapors are
present it will generally read lower in pressure than electrical gauges. For higher vacuums in systems employ-
ing diffusion, turbo-molecular or ion pumps, a hot or cold cathode gauge is used.
1.9 Traps (See Accessory section in the back of this manual.)
1.9a The need for a Trap
Where corrosive vapors or large quantities of condensable vapors are evolved from vacuum processing, a cold
trap may be used in the connecting line to the pump. It will help prevent damage to the pump mechanism and
reduce oil contamination. The cold trap, immersed in a suitable Dewar flask, is installed to that the vapors may
come in contact with the surfaces of the trap and condense. Commonly used refrigerants are liquid nitrogen
or dry ice and acetone. The refrigerant to be used depends upon the freezing point of the contaminations. A
variety of cold traps are available from Welch Vacuum, Thomas Industries, inc.
1.9b The care of a Trap
When using a cold trap the refrigerant should be maintained at a high level in the flask to keep the trap at a
uniformly low temperature. If the trap is re-warmed it may allow re-evaporation of the condensate. The
refrigerant add tube on the liquid nitrogen trap should not be obstructed as the refrigerant boil-off can produce
dangerously high pressures. If the trap becomes saturated it should be disconnected from the system, drained
and cleaned. An increase in pressure in the vacuum system will normally indicate that the trap has become
saturated. To clean the trap, remove the trap from the system, allow the trap to warm up and rinse off the
condensate with a suitable solvent in a fume hood. Thoroughly clean and dry the trap before reinstalling in the
system.
1.10 Types of Lubricants (See Accessory section in the back of this manual.)
All DUOSEAL mechanical vacuum pumps are normally tested with DUOSEAL® oil and shipped with a full
charge to prevent unnecessary contamination. An additional supply of oil is furnished with each pump with
instruction to drain and discard the oil contaminated in the pump and replace with the fresh oil. DUOSEAL oil
has been especially prepared and is ideally suited for use in mechanical vacuum pumps because of its desirable
viscosity, low vapor pressure and chemical stability.
The vacuum guarantee on all DUOSEAL pumps applies only when DUOSEAL oil is used. Other lubricants
for special applications are available including various lubricants compatibility, lubricants for use with diffusion
pumps as well as other special requirements.
5

Section 2: OPERATION
2.1 Starting Procedures
2.1a Starting a DUOSEAL Pump
Before attaching the pump to a system it is well to familiarize yourself with the function and action of the
pump which you have now required.Remove the intake and exhaust port plugs and temporarily provide a
stopper for the intake and a dust cap for the exhaustReview the power requirements as described in Section
1.6.
CAUTION
Do not run this pump with the intake open directly to the atmosphere.
The pump will overheat, excessive oil mist will be emitted from the
exhaust and the pump will eventually seize.
2.1b Starting of the Model 1392 with Diffusion Pump.
1. Turn on Mechanical pump ONLY until a pressure of 100 millitorr or less has been reached.
WARNING
Do NOT operate diffusion pump until a pressure of 100 millitorr
has been reached.Turning on the diffusion pump before a pressure
of 100 millitorr has been reached will damage your diffusion pump
and may cause serious damage to surroundingequipment and personnel.
2. After a pressure of 100 millitorr had been reached by the mechanical pump, plug in the diffusion pump.
Make sure diffusion pump has oil in it at an appropriate level before turning it on. Check the oil indicator sight
glass to confirm oil level. Also, make sure that fan is on when operating diffusion pump. Note that it will take
the diffusion pump a few minutes to warm up.
Refer to the Varian diffusion pump manual for more information.
2.1c Cleanliness
Take every precaution to prevent foreign from entering the pump. A fine mesh screen is provided for this
purpose in the intake passage of all DUOSEAL pumps.
2.1d Oil Level Determination
The amount of oil suitable for efficient and satisfactory performance should be determined after the pump has
reached its operating temperature. Initially, however, the pump should be filled with fresh oil while the pump is
idle. Fill the pump until the oil level falls half way of the oil level window. If after a short period of operation
the level should fall, it is likely the result of oil entering some of the interior pockets of the pump. If the oil level
rises, this signifies oil has drained into the pump cavity while pump was idle. Shut off pump, then drain oil
down to proper level.
If a gurgling sound occurs, additional oil must be added. Mechanical pumps will gurgle in varying degrees
under four conditions of performance: [a] when operating at high pressure as in the beginning cycles of
evacuation of a chamber; [b] when the oil level in the pump reservoir is lower than required; [c] when a large
leak is present in the system; and [d] when the gas ballast is open. Awareness of the possibilities will save
time in setting up a system. Best performance of a mechanical pump is generally obtained after sufficient time
has been allowed for the pump to come to operating temperature.
6

2.2 Leak Detection
2.2a Large Leaks
The importance of eliminating all leaks in a vacuum system is obvious when it is realized that a leak into the
system, at atmospheric pressure, expands in volume by a factor of 750,000 to 10,000,000 or more. The pump
must remove this added volume to maintain the desired vacuum. Fortunately a number of effective techniques
for leak detection have been developed. Large leaks can be located by pressurizing the system and painting
the suspected area with a thick soap solution. Escaping air will produce soap bubbles.
2.2b Small Leaks
Small leaks may also be detected by spraying a suspected area with acetone or gases rich in hydrogen, and
observing a sudden change in pressure on an electrical gauge. The difference in calibration of these gauges,
for air and other gases, will produce a distinct change in the pressure reading. To use this method of detection,
the system must be under vacuum and the gauge sensing tube must be located between the pump and the area
to be probed. Use extreme caution, as these materials are highly flammable!
2.2c Fine Leaks
Locating very fine leaks requires a helium-sensitive, mass-spectrometer leak detector. This instrument will
locate leaks which cannot be detected by any other method. Numerous fine leaks can have the total effect of
a large leak.
2.3 High Pressure Operation
DOUSEAL two-stage pumps are designed to be most efficient when operated at or near their ultimate
blankoff pressure. The pump is designed to remove air from a vacuum system at atmospheric pressure to a
deep vacuum. When the pump is operated at elevated pressures up to about 10 Torr for long periods of time,
the pump will run hotter. At elevated ambient temperatures under these conditions, the thermal protection
switch on single phase motors may cute out. Use of an exhaust filter with coalescing element is required.
CAUTION
Do not run this pump for prolonged periods of time at or above
10 Torr. The pump will overheat, excessive oil mist will be emitted
from the exhaust and the pump will eventually seize.
Leaky vacuum systems, too large a vacuum chamber for pump size or high gas loads to the vacuum systems
are causes for extended runs of the pump at elevated pressure. If you need additional information, please
contact Welch Vacuum at 847-676-8800, extension 1, for further information and precautions.
2.4 Shutdown Procedures
2.4a DuoSeal Shutdown
A few simple precautions are all that is necessary when shutdown is in order. If a gauge is connected to the
system, first isolate the gauge, then turn off the power and open the system to atmosphere. If the pump is
removed from the system, cover the intake port with a rubber stopper or suitable cover to protect the pump
against contamination and loose particles. If the pump has been contaminated in service and is going to be
shelved for a prolonged period it is best to drain the oil refill with a fresh charge.
7

2.5 the Principle of Gas Ballast
2.5a the Effects of Unwanted Vapor
systems which contain undesirable vapors cause difficulty both from the standpoint of attaining desirable ultimate
pressures as well as contamination of the lubricating medium. A vapor is defined as the gaseous form of any substance
which is usually a liquid or a solid. Water, oil and a mercury vapors are three of the more common vapors encountered in
typical vacuum systems. When such vapors exist in a system, the vapors or mixtures of gas and vapor are subject to
condensation within the pump; the precipitated liquid may thus ultimately dissolve or become emulsified with the
lubricating medium. This emulsion is recirculated to the chambers of the pump where it is again volatilized causing
increased pressure within the system.
2.5b the Presence and Removal of Condensate
Condensation takes place particularly in the compression stroke of the backing or second stage of a two-stage pump.
The compression stroke is that portion of the cycle during which the gas drawn from the intake port is compresses to the
pressure necessary to expel it past the exhaust valve. Condensation takes place when the ratio between the initial
pressure and the end pressure of the compression is high, that is, when the mixture of vapor and gas drawn from the
intake port is compressed from a low pressure to high pressure. By adding air though the gas ballast valve to the mixture
of vapor and gas being compressed, the pressure required for delivery past the exhaust valve is reached with a consider-
ably smaller reduction of the volume of the mixture; this, depending upon the amount of air added, condensation of the
vapor is wither entirely avoided or substantial reduced.
2.5c Pump function With Gas Ballast
In a pump functioning on a contaminated system and operating without the gas ballast, compression within the stage
takes place in the normal manner until the saturation pressure of the contaminating vapor contained within the mixture of
gas and vapor is reached. The saturation pressure of water vapor is that pressure and corresponding temperature at
which the dew point of the vapor is reached and condensation occurs. The saturation pressure of water vapor at an
ambient temperature of 20°C is 17.5 Torr, while at 60°C, the approximate operating temperature of a pump, the saturation
pressure is 149 Torr. The external side of the exhaust valve is subjected to atmospheric pressure. Consequently a
compressive force somewhat greater than atmospheric pressure is required to open the valve and permit expulsion of the
gas. Sometime during increased compression of the mixture of gas and vapors, the saturation pressure of 149 Torr for the
water vapor is reached and the vapor condenses. The condensate is then allowed to emulsify with the oil which is
recirculated within the pump stages this providing continued contamination of the system.
2.5d Pump function with Gas Ballast
On the other hand, when ballast air at atmospheric pressure is supplied to the compression stroke by means of the gas
ballast, the partial pressure of the unwanted vapor becomes a very small part of the total pressure of the mixture of gas,
vapor and newly supplied air. The vapor is thus prevented from reaching its saturation pressure corresponding to the
temperature of the pump and is finally expelled form the pump as a vapor.
2.5e Controlled Ballast Flow
Some degree of variation in ballast flow may be obtained by the amount of opening applied tot he gas ballast. Two or
more turns of the gas ballast are sufficient to open it wide. With the gas ballast open, the sound of the exhaust is similar
to that of a pump operating against a large leak. Because of the increased pressure introduced into the compression
stroke, the pump must work a little hard to function, thus resulting in an increased operating temperature of approximately
8°C over a prolonged period of time. Tests have shown that continuous and prolonged operation for several weeks under
these conditions is not injurious tot he pump.
2.5f Other Forms of contamination control
The application of the gas ballast is a moderate and very successful method for the removal of condensable vapors. For
very heavily laden systems, other means of removal such as oil separators may be required. For mild cases of contamina-
tion the simple expedient of a cold trap or a change of oil serve the purpose.
8

Section 3: MAINTENANCE
3.1 Vacuum Problems
3.1a Pressure Determinations
Leakage, contamination and unusual outgassing are the genera causes of problems associated with poor
vacuum. To operate a maximum efficiency a system must be thoroughly clean. If the system is completely
clean and free from leaks, and unwarranted vacuum problems still exist, the pump should be checked. A
simple criterion for the condition of a mechanical pump is a determination of its ultimate pressure capability.
This can be accomplished by attaching a gauge directly to the pump. The gauge may be any suitable type
provided consideration if given tot e limitations of the gauge being used. Refer to Paragraph 1-8 for further
suggestions. If the pressure is unusually high, the pump may be badly contaminated, low on oil or malfunction-
ing. On the other hand, if the pressure is only slightly higher than the guaranteed pressure of the pump, an oil
change may be all that is required.
3.1b Oil Contamination
the most common cause of a loss in efficiency in a mechanical pump is contamination of oil. It is caused by
condensation of vapors and by foreign particles. The undesirable condensate emulsifies with the oil which is
recirculated and subject to re-evaporation during the normal cycle of pump activity this reducing the ultimate
vacuum attainable. Some foreign particles and vapors may form a sludge with the oil, impair sealing and
lubrication and cause eventual seizure. A gas ballast calve is helpful in removing vapors, especially water, but
it is not equally effective on all foreign substances; therefore, periodic oil changes are necessary to maintain
efficient operation of the system. The required frequency of changes will vary with the particular system,.
Experiences with the process will help you determine the normal period of operation before an oil change
required.
3.1c Oil Overheating
This pump is designed to operate continuously below 10 Torr. Continuous operation of this pump above 10
Torr will lead to overheating and eventual pump failure. See Section 2.3. High Pressure Operation.
3.2 Maintenance of the Model 1392 with Diffusion Pump
3.2a Determination of an Oil Change
The Model 1400 pump of the diffusion-mechanical pump combination may be repaired and maintained as
outlined in the preceding paragraphs, The pump fluid of the diffusion pump should be inspected periodically for
color change and odor. If the fluid is slightly darkened and had no odor, a simple change of fluid is normally all
that is needed. If the fluid had developed a noticeable odor, the pump should be cleaned. Follow the instruc-
tions in the Owner’s Manual for the Diffusion Pump.
3.2b Diffusion Pump Cleaning Procedures
To clean the diffusion pump, first turn off the power. Turn off the cooling fan and disconnect the power plug
after the diffusion pump has cooled. Disconnect the inlet and foreline connections. Do not scratch or damage
sealing surfaces. Remove the cold cap and jet assembly and all O-rings and gaskets. Drain oil from the
diffusion pump. Thoroughly clean the diffusion pump body interior and the jet assembly with acetone followed
by an isopropyl alcohol rinse. The inside of the pump can be dried using dry nitrogen. Install jet assembly with
he cold cap inside of the pump body. Fill the pump with 30ml of fresh diffusion pump fluid. Reinstall the pump
in the system. For more detailed information and how to replace a burned heater red instructions on the AX-
65 Diffusion Pump Instruction Manual supplied with this pump.
WARNING
Solvents, such as acetone, used to clean different pumps are extremely hazard
ous. Inhalation may be fatal or harmful. Acetone is also extremely flammable.
Never use acetone near heat or open flame. Use only in a well ventilated area.
9

3.3 Oil Changes and Oil Level
3.3a Developing a Maintenance Schedule
After studying many examples of pump failure, Welch has found the most common reason is poor condition of
the oil. This is why a regular maintenance schedule for the oil is critical to obtain the longest service life out of
your DUOSEAL pump. Welch recommends that you examine the condition of the oil on a daily basis in the
early days of a new process or experiment. You want to look for discoloration of the oil and whether the oil
level is rising. The discoloration can indicate deterioration of the oil and a rising oil level can indicate conden-
sation of vapors is occurring in the pump. When changes occur, the oil needs to be change. If no changes in
the oil level or color are observed, extended pump service life is obtained if the oil is changed every three to
four months.
3.3b Forced Oil Flushing
When you drain oil through the drain valve, you are not removing the oil and contaminants that are inside the
pumping mechanism. You are removing oil only from the oil case. Welch recommends a forced oil flush of
DUOSEAL pumps be performed at the regular maintenance oil change. The procedure for the forced oil
flush is given below.
1. Check the oil level.
If the oil level is well above the fill mark, (This may indicate either the pump has been overfilled with oil or has
ingested a liquid or a large amount of vapor water or organic solvents.) Please go to step 2.
If the oil level is even with the fill mark and you do NOT suspect corrosive gases or particulates (hence
forth called contaminants) ingested have damaged the mechanism, run the pump for 15 minutes to allow the
pump oil to warm up before going to step 2.
2. Turn off motor for the vacuum pump. Drain the oil into a clear plastic container (may need pliers to open
drain valve). Look for contaminations settling to the bottom of container. If you see contaminants, you will
need to repeat step 3 through 5 several times until the oil comes out clear. The oil you drained from the
pump came from the oil case only. There may be contaminants in the pumping mechanism. To be sure all
contaminants have been removed, the pump mechanism needs to be flushed.
3. Make sure the belt guard is installed before proceeding further. Attach a short hose to the drain valve
which runs into a clear plastic container.
4. Flushing the pump is carried out by adding a cup of DUOSEAL vacuum pump oil through the intake port
(IN) while the pump is turned on for 15 to 20 seconds. While adding the pump oil, the palm of your hand is
placed lightly over the exhaust port (OUT). Look for water coming out of the drain. Turn off the pump.
5. Repeat step 4 until clean oil comes out of the drain hose.
6. Fill the pump with the amount of DUOSEAL vacuum pump oil your pump needs.
7. Plug the intake (IN) port with a rubber stopper. Turn the pump on and run the pump for 10 minutes. Close
the gas ballast.
8. Check the vacuum reading of the pump by connecting a thermocouple gauge tube to the pump’s intake. If
the pump is running nearly as good as when it was new, the total pressure reading you will read on wither
of these two gauges will be at least 10 micron.
A simple way to connect the gauge tube to the pump is to run the threaded tip of tube through a hole in a
rubber stopper. Use pump oil as a lubricant for inserting the tube. The stopper chosen should be bigger than
the outer diameter of the intake flange.
10

3.3c Refilling The Pump
After you are satisfied that the pump has been thoroughly flushed, refill the pump by pouring new DUOSEAL
oil into the exhaust port. Fill to the indicated level and start the pump with the intake closed. A gurgling noise
is characteristic when high pressure air is drawn through the pump. It should disappear quickly as the pres-
sure within the pump is reduced. If gurgling continues, add sufficient additional oil through the exhaust port
until gurgling ceases.
3.4 Shaft Seal Replacement
To replace the shaft seal of a pump, drain the oil and remove the pump pulley and key. Remove the screws
securing the old seal and pry it loose with a screwdriver or similar wedge, being careful not to mar the surface
of the pump body against which the seal fits. Discard the seal and its gasket, inspect all surfaces and repair
any damages with a fine abrasive stone. Wipe all sealing areas clean and place a film of DUOSEAL oil on
both the shaft and the inside bore of the new shaft seal. Using a new gasket, carefully slide the new seal into
position and center it on the shaft. It is not necessary to apply any sealant to the gasket. Tighten the mounting
screws uniformly and refill the pump with DUOSEAL oil. Follow instructions included in repair kit.
3.5 Repairing Vacuum Leaks
3.5a Location, Cause and Effect
Oil leaks may develop wherever two mating faces are sealed with a gasket. Such seams may fail as the result
of deterioration of the gasket material, loosening of the screws caused by temperature variations, or improper
care as the result of previous reassembly. Typical gaskets seams in a mechanical pump are located at the oil
level window, the shaft seal, the oil drain, and the mating faces of such mechanical surfaces as the intake
chamber cover, the oil case, and the exhaust chamber cover. The importance of a gasketed seam is deter-
mined principally by its function. If it is a vacuum seal, the ultimate performance of the pump is dependent
upon it. If it is an oil seal, the pump may be operated satisfactorily for some time without loss of function.
Eventually, of course, a great loss of oil may cause harmful damage.
3.5b Repairing Techniques
An oil seam may be sealed by any of several methods. When an O-ring is employed, the surfaces of the O-
ring and its groove should be wiped clean. If the O-ring is not badly deformed or scratched it may be reused
by sealing with a slight film of vacuum oil or vacuum grease. Thin composition gaskets are generally used for
large irregularly shaped areas. A replacement joint of this type should be thoroughly cleaned of all previous
gasket material and the mating surfaces cleaned of any nicks.
3.6 Repairing Vacuum Leaks
3.6a Surface Preparation
Good Vacuum seals are an essential and important attribute of a good mechanical pump. A good seal is
dependent upon the quality of the mating surfaces as well as the sealant and its preparation. The mating faces
should be carefully inspected for any projections or foreign particles which might interfere with proper mating.
Slight projections such as nicks and burrs are most easily removed by rubbing with a fine abrasive stone. The
surface of the mating parts may be washed with a solvent or alcohol after which they must be thoroughly
dried.
3.6b Temporary Repair
Temporary vacuum repairs are often made by covering the known leak with an industrial sealant such as
Loctite with Teflon. Such a practice, however, is not recommended for seals of a permanent nature.
3.7 Drive Problems
If for any reason the pump will not operate, turn off the power and check the fuse and electrical connections.
Then try the power to the motor only by removing the belt. If the motor operates properly try hand-rotating
the pump in the proper direction with the pump intake port open. If both turn freely then replace the belt and
check the belt tension. The tension should be sufficient to drive the pump without visible slippage. Any
greater tension will cause noise and possible damage to the bearings of both the motor and pump. Make
certain that both pulley grooves are clean and free from oil. The pulleys must be fastened securely on their
respective shafts, and in parallel alignment.
11

Section 4: TROUBLE-SHOOTING GUIDE
4.1 Poor Vacuum Reading
1. Disconnect vacuum pump from your vacuum system.
2. Obtain 1 gallon of DUOSEAL oil, 1 gallon or larger clear plastic container, clear drain hose (1/4
inch ID by at least 2.5 feet long), rubber gloves, goggles, apron and pliers.
3. Carry out a forced oil flush (See Section 3.3b) if motor can turn pumping mechanism without
excessive noise. If pumping mechanism cannot be turned by motor, have pump sent into factory
repair center.
4. Check ultimate vacuum with thermocouple gauge. If reading is still unsatisfactory, consult with
Welch Technical Service after checking for leaks in your connections.
4.2 Noisy Pump
1. Locate noise source on your vacuum pump (motor, belt, pump).
2. If motor makes noise:
. Check for loose bolts on motor mount.
. Motor may need to be replaced
3. If belt makes noise:
. Pulley may be bent. If so, replace.
. Loose belt, tighten by loosening bolts on motor and moving motor away from pump until belt
exhibits a 1/2 inch deflection.
4. If pump makes noise: vanes may be sticking, carry out a forced oil flush.
5. If noise level is still unsatisfactory, consult with WELCH Technical Service at [phone],
Extension 1.
4.3 Excessive Oil Mist
1. Check oil level. Maintain the level between the two lines on the oil window during operation. Too
high a level will cause excess oil mist.
2. Determine the vacuum level in your system with a thermocouple gauge or manometer. Be sure
the pump is operating at a pressure of 10 Torr or lower for continuous operation.
CAUTION: if not, discuss application with Welch Technical service before proceeding
to prevent oil from overheating and breaking down resulting in the pump failing.
3. A system leak(s) or degassing can cause excessive oil mist. Locate and seal the vacuum leaks.
High vapor loads may require a larger pump to compensate.
4. An oil eliminator can be installed for coalescing the oil mist from the exhaust gases. If an oil mist
eliminator is already installed, the element may need to be replaced if saturated with oil. Open up
oil mist eliminator and examine the element; replace if needed.
5. Check the oil condition for any visible change in color or consistency. contaminants in the oil can
add to the amount of oil exhausted. Carry out a forced oil flush if contamination is discovered.
(See Section 3.3b.)
12

Section 5: QUICK REFERENCE CHART
13

14

Section 6: PUMPING SPEED CURVES
HIGH EFFICIENCY PUMPING
CHARACTERISTIC OF DUOSEAL®
PUMPS
The low RPM design of DuoSeal vacuum
pumps makes it possible to maintain high
pumping efficiencies into the low micron range.
High RPM direct drive vacuum pumps, on the
other hand, experience a rapid fall off of
pumping speed below 100 microns.
A comparison of the DuoSeal pumping speed
curves shown below, versus high RPM pump
speed curves conclusively illustrates the
superior performance of the DuoSeal pump.
What does that mean for the vacuum pump user?
DuoSeal pumps provide considerable faster
pumpdown in the low micron range.
15

Section 7: DIMENSIONAL DRAWINGS
Mounted Pumps
1374B-01 1376B-01
1380B-01 1392B-01
16

1397B-01 1399B-01
1400B-01 1402B-01
1405B-01
17

ITEM QUAN PC. NO. A* B* DESCRIPTION
01 1 41-2074 Pulley incl. item 2 02 1 2-01-9306 Socket Head Set Screw 5/16-18x3/8 03 1 61-8378A Shaft Lip Seal Assy 04 1 41-0643 Seal Gasket 05 3 2-00-2706 Fil. Head Screw 10-32x3/8 06 1 61-8685 Large End Plate 07 1 61-8671 Intake Cover 08 1 41-0234 1 1 Intake Cover Gasket 09 4 2-01-6112 Socket Head Screw 1/4-20x3/4 10 1 41-1692 1 1 Intake Screen 11 1 61-8329A Intake Screen Bracket 12 6 41-2363 Washer 13 3 2-01-6316 Socket Head Screw 5/16-18x1 14 1 41-0612 Dust Cap 15 1 61-8468A Adapter Hose 16 1 61-9284A 1 1 O-Ring, Fluoroelast. #214 17 2 41-0403 2 2 Oil Case Gasket 18 10 62-0015 Socket Head Screw 1/4-20x3-1/8 19 1 41-0508 1 1 Thrust Washer 20 1 41-1683 Shaft 21 1 41-0624 1 1 Pulley Key 22 1 41-1688 Large Ring 23 1 41-1682 Large Rotor 24 2 41-1684 2 Large Vane 25 3 41-0696 3 3 Spring Holder 26 6 41-1304 6 6 Vane Spring 27 1 61-8250C Center Plate 28 2 2-36-9900 Lock Nut 1/4-20 29 2 2-01-6320 Socket Head Screw 5/16-18x1-1/4 30 1 41-1518 Exhaust Rotor 31 2 41-1487 2 Small Vane 32 2 41-0613 2 2 Woodruff Key 33 1 61-8108D Exhaust Ring 34 1 41-2045 Small End Plate 35 1 41-0672 End Cap 36 1 61-8310A Pressure Release Tube Part 2 37 1 4-40-1200 1 1 Steel Ball
ITEM QUAN PC. NO. A* B* DESCRIPTION
38 1 41-0992 1 1 Pressure Release Valve 39 1 61-8309B Pressure Release Tube Part 1 40 3 62-0259 Self Tap Screw #6x1/4 Type ‘A’ 41 6 2-01-0356 Hex Head Screw 5/16-18x3-1/2 42 1 41-2154 1 1 Lower Exhaust Valve 43 7 2-61-0000 Steel Washer 1/4 44 2 2-01-8128 Set Screw 1/4-20x1-3/4 45 6 2-31-0112 Hex Nut 1/4-20x3/16x7/16 46 4 61-8314A 4 4 Block Valve 47 4 41-2158 4 4 Valve Spring 48 2 41-2156 Valve Block 49 2 41-2159 2 2 Valve Block Spacer 50 1 61-8102A Flange for Gas Ballast Valve 51 3 2-00-6712 Socket Head Screw 10-32x3/4 52 1 41-1686 Baffle Plate 53 2 41-2175 Set Screw (Special) 54 1 61-8687 Oil Case Spacer 55 1 61-8101 Oil Case Assy incl.items 63,67,72,74,75 56 2 61-8362 Socket Head Screw 8-32x1 57 1 61-8100A Gas Ballast Valve Adapter 58 1 61-8103 1 1 O-Ring, Fluoroelast. #905-75 59 1 41-1736 Gas Ballast Valve incl. item 64 60 6 61-8456A Washer Copper 5/16 61 2 41-1056 Washer 62 10 2-63-0193 Split Lock Washer 1/4 63 2 61-2229A Glass Window 64 1 41-1742 1 1 O-Ring, Fluoroelast. #011 65 3 41-1766 Thrust Disk 66 1 61-8101A Gas Ballast Connector 67 1 61-2278 Drain Valve 68 1 41-2757 Lock Nut 70 1 2-01-5106 Round Head Screw 1/4-20x3/8 71 1 41-2153 1 1 Upper Exhaust Valve 72 2 61-2370 Cover, Window 73 3 2-01-0316 Hex Head Screw 5/16-18x1 74 2 61-2231 2 2 O-Ring, Fluoroelast. #127 75 4 62-1037 Flat Hd Screw 8-32x7/16
1-99-5282 1 1 Sealant, 6 cc 1401D 1 1 Mechanical Seal option**
A*: MAJOR REPAIR KIT CAT # 1376K-06 B*: MINOR REPAIR KIT CAT # 1376K-05 ** 1401D is mechanical seal kit includes mechanical seal, gasket and 3 screws *** MANOR REPAIR KIT CAT # 1376K-11 FOR REFRIGEATION SERVICE PUMPS USES NEOPRENE SEALS
67-0894 Sheet 1 of 2 Rev. 6 01/04
PARTS LIST MODEL 1376 VACUUM PUMP
18
Section 8: PARTS LISTS & EXPLODED VIEWS

19

ITEM QUAN PC. NO. A* B* DESCRIPTION 1 1 41-2074 Pulley incl. item 2 2 1 2-01-9306 Soc, Hd. Setscrew 5/16-18x3/8 3 1 61-8671 Intake Cover Chamber 4 4 2-01-6112 Soc Hd Screw 1/4-20x3/4 5 1 41-0234 1 1 Intake Cover Gasket 6 1 41-0660 1 1 Air Filter 7 6 2-01-0316 Hex Hd Screw 5/16-18x1 8 12 41-2363 Steel Washer 9 1 41-0663 Air Filter Bracket 10 3 2-00-2706 Fil Hd Screw 10-32x3/8 11 1 61-8378A Shaft Lip Seal Assy. 12 1 41-0643 Seal Gasket 13 10 2-01-0114 Hex Hd. Screw 1/4-20x7/8 14 10 2-63-0193 Split Lock Washer 1/4 15 1 61-8505D Large End Plate 16 1 41-0403 1 1 Oil Case Gasket 18 1 61-8468A Intake Nipple 19 1 61-9284A 1 1 O-ring #214 20 1 41-0508 1 1 Thrust Washer 21 1 4-06-0754 Retaining Ring 22 2 41-0624 2 2 Woodruff Key 23 1 41-1773 Shaft 24 1 41-1766 1 1 Thrust Disk 25 1 61-8101 Oil Case incl. items 56, 59, 60, 61, 62 26 1 41-1736 1 1 Gas Ballast Valve incl. item 27 27 1 41-1742 O-ring #011 28 2 61-8362 Soc Hd Screw 8-32x1 29 2 41-1056 Aluminum Washer 30 3 2-00-6712 Soc Hd Screw 10-32x3/4 31 1 61-8102A Flange For Gas Ballast 34 1 41-1772 Ring
ITEM QUAN PC. NO. A* B* DESCRIPTION 35 3 41-1775 3 3 Lower Exhaust Valve 36 3 41-0695 3 3 Upper Exhaust Valve 37 4 2-61-0000 Steel Washer 3/16 38 2 2-01-5106 Rd Hd Screw 1/4-20x3/8 39 1 61-8507B Buffle 40 3 2-31-0112 Hex Nut 1/4-20 41 1 41-2175 Special Set Screw 1/4-20x2-1/4 42 2 41-0959 2 Vane 4 3 4 41-1304 4 4 Vane Spring 44 1 41-1771 Rotor 45 2 41-1685 2 2 Vane Spring Holder 46 1 41-2045 Small End Plate 47 1 41-1005 Pressure Release Tube No.2 4 8 1 4-40-1200 1 1 Steel Ball 3/8 49 1 41-0992 1 1 Pressure Release Valve 50 6 2-01-0318 Hex Hd Screw 5/16-18x1-1/8 51 3 62-0259 Bind Hd Sheet Met Screw #6x1/4 52 1 41-0986 Pressure Release Tube No.1 53 1 41-0672 End Cap 54 1 41-2757 Lock Nut 55 1 61-8103 1 1 O-ring #905 56 2 41-3753 Oil Level Sight 57 1 61-8100A Gas Ballast Valve Adapter 58 1 61-8101A Gas Ballast Connector 59 1 61-2278 Drain Valve 60 2 61-2231 1 1 O-Ring Tetr. #127 61 2 61-2228A Cover, Oil Window 62 4 61-2232 Flat Hd Screw #8-32x1/2
1-99-5282 1 1 Sealant, 6 cc 1401D 1 1 Mechanical Seal Option**
A*: MAJOR REPAIR KIT CAT # 1380K-04 B*: MINOR REPAIR KIT CAT # 1380K-03 . ** 1401D is mechanical seal kit includes mechanical seal, gasket and 3 screws
67-0896 sheet 1 of 2
Rev. 7-1998
PARTS LIST MODEL 1380 VACUUM PUMP
20