Welch CHEMSTAR 1374N User manual

OWNER’S MANUAL
FOR
CHEMSTAR®VACUUM PUMPS
MODELS:
1374N
1376N
1400N
1402N
Contents: Installation
Operation
Maintenance
Warranty
MSDS Sheet For Pump Oil
Specifications
Parts List and Expl. Views
Applications Booklet
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 Avenue
Skokie, IL 60077
Phone: [phone]
Fax: [phone] (Technical Support)
Fax: [phone] (Ordering)
E-Mail: [email protected] Part No. 67-0544R3.2
Web-Page: www.welchvacuum.com Printed in USA
For outside U.S. and Canada, contact your local
Rietschle Thomas sales office, see back page

CHEMSTAR® OWNERS MANUAL
CONTENTS
Section Page
1. Installation 3
2. Operation 6
3. Maintenance 8
4. Quick Reference Charts 10
5. Pumping Speed Curves 10
6. Dimensional Drawings (with rotation) 11
7 Exploded Parts Listing 12
8. MSDS for Welch 8995G Gold Vacuum Pump Oil 20
9. Accessory Section 22
11. Application Booklet – CHEMSTAR® and Corrosive Gases 23
12. Warranty Information 36
Stainless Steel ISO NW Intake and Exhaust Fittings
The Pumps come with ISO NW fitting on both the intake and exhaust ports. The fittings make it easy to
use Welch modular piping to connect the pump to your system and allow easy disassembly. For users who
prefer to use rubber hose, a rubber hose adapter for the intake fitting is provided.
Be sure prior to start-up, you have properly identified the intake port on the pump (see Schematics Below).
NEVER BLOCK THE EXHAUST PORT. If the exhaust port is blocked, this will lead to a pressure build
up in the pump resulting in the pump body bursting and possible injury to the pump operator. Be sure to call
Welch technical service prior to start-up at (847)-676-8800 if you have any questions.
INTAKE PORT
1400N-01 1402N-01 1376N-01 1374N-01

Section 1: INSTALLATION
1.1 Introduction
This manual has been compiled not only for the care and maintenance of the CHEMSTAR pump now in your
possession but as a helpful reference and guide for many problems which are usually associated with mechanical
vacuum pumps. Take time to read these instructions carefully and preserve this manual for future reference; 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 Technology, Inc. be sure to include your order numbers for
quick identification. Do not return the pump to the factory without 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 CHEMSTAR 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 re-
placements. Above all, the pump should be located as closely as possible to its system in order to utilize it
most efficiently. Its locations 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
Exhaust connections will be determined by the type of system to be exhausted and the desired cleanliness of the
atmosphere surrounding the pump. SEE APPLICATION BOOKLET WITHIN OWNER’S MANUAL
FOR COMPLETE DETAILS ON OIL MIST ELIMINATORS AND EXHAUST SYSTEMS FOR
CORROSIVE GASES.
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 frequently. On
three-phase applications the direction of rotation of the motor must be considered. Make a momentary
check of 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.
Identification Symbols:

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 60 Hz motors. Single-phase
motors will normally have automatic overload protection. Motors of 1-1/2 horsepower or large supplied
with DuoSeal pumps contain no overload protection. Installations of such equipment must comply with
local electrical codes which dictage 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 accord-
ingly in the event of an emergency. Automatic reset protection is designed to rest itself after a predeter-
mined 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
1.7a Choice of Connections
The choice of connections and fittings 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 isthen dependent upon the kinetic activity of the
molecules to bring it to the intake of the pump.
1.7b The Effects of Conductance
It has been show that the conductance of a tube is proportional to the cube of its diameter and inversely proportional 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 the connections. Where threaded
joints must be used, coat the threads with LocTite Thread Sealant with Teflon and screw together tightly.
Flanged connections with elastomer gaskets make excellent demontable 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 made by butting the ends of
the two sections together in a short section of rubber 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 impor-
tance.
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.

1.8 Vacuum Gauges
The type of vacuum gauge to be used is determined largely by the pressure range to be measured. Pressures in the
ranges produced by CHEMSTAR pumps can be covered by McLeod, Thermistor, Pirani or Thermocuple gauges. The
McLeod gauge is used where high accuracy of measurement is required. The Pirani, Thermistor and Thermocouple
gauges are electrical and give continuos readings of the total pressure. They 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 employing diffusion, turbo-
molecular or ion pumps, the hot filament ionization of the Philips gauge is used.
1.9 Traps
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 Dewier flask, is installed so 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 contaminants. A variety
of cold traps are available from Welsh Vacuum Technology, Inc. SEE APPLICATION BOOKLET WITHIN
MANUAL THAT PROVIDES ADDITIONAL DETAILS ON WHEN TO USE TRAPS.
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 rewarded it may allow re-evaporation of the condense. 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 condense with a suitable
solvent in a fume hood. Thoroughly clean and dry the trap before reinstalling in the system.
1.10 Types Of Lubricants
All CHEMSTAR mechanical vacuum pumps are normally tested with DIRECTORR Gold oil and shipped with a
full charge to prevent unnecessary contamination. An additional supply of oil is furnished with each pump with
instructions to drain and discard the oil contaminated in the pump and replace with the fresh oil. DIRECTORR
Gold 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 CHEMSTAR pumps applies only when DIRECTORR gold oil is used. Other
lubricants for special applications are available including various lubricants for oxygen compatibility, lubricants for
use with diffusion pumps as well as other special requirements. SEE APPLICATIONS BOOKLET IN
OWNERS MANUAL FOR OTHER LUBRICANTS USED FOR SPECIAL APPLICATIONS SUCH
AS OXYGEN SERVICE.

Section 2: OPERATION
2.1 Starting Procedures
2.1a Starting a CHEMSTAR 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 acquired. Remove the intake and exhaust port plugs and temporarily provide a stopper for
the intake and a dust cap for the exhaust. Review the power requirements as described in Paragraph 1.6.
2.1b Cleanliness
Take every precaution to prevent foreign particles from entering the pump. A fine mesh screen is provided for
this purpose in the intake passage of all CHEMSTAR pumps.
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 Shutdown Procdures
2.3a CHEMSTAR Pump Shutdown
A few simple precautions are all that is necessary when a 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 pumps removed
from the system, over the intake port with a rubber stopper or suitable cover to protect the pump against contami-
nation 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 and refill with a fresh charge.
2.4 The Principle of Gas Ballast
2.4a 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 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.

2.4b 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
compressed 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 is compressed from a low pressure to a high pressure. By
adding air through 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 considerably smaller reduction of the volume of the mixture;
thus, depending upon the amount of air added, condensation of the vapor is either entirely avoided or substantially
reduced.
2.4c Pump Function Without 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 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 20C is 17.5 torr, while at 60C, 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 conden-
sate is then allowed to emulsify with the oil which is recirculated within the pump stages thus providing continued
contamination of the system.
2.4d 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 from the pump as a vapor.
2.4e Controlled Ballast Flow
Some degree of variation in ballast flow may be obtained by the amount of opening applied to the 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 approxi-
mately 8C over a prolonged period of time. Tests have shown that continuous and prolonged operation for several
weeks under these conditions is not injurious to the pump.
2.4f 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 contamination the simple expedient of a cold trap or a change of oil may serve the purpose.

Section 3: MAINTENANCE
3.1 Vacuum Problems
3.1a Pressure Determinations
Leakage, contamination and unusual outgassing are the general causes of problems associated with poor vacuum.
To operate at 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 is given to
the 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 malfunctioning. 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 subjected to re-evaporation during the normal cycle of pump activity thus reducing the ultimate
vacuum attainable. Some foreign particles and vapors may form sludges with the oil, impair sealing and lubrica-
tion and cause eventual seizure. A gas ballast valve is helpful in removing vapors, especially water, but it is not
equally effective on all foreign substances; therefore, periodic oil changes will vary with the particular system.
Experience with the process will help you determine the normal period of operation before an oil change is
required. SEE APPLICATION BOOKLET WITHIN MANUAL THAT PROVIDES ADDITIONAL
DETAILS ON PREVENTING OIL CONTAMINATION.
3.1c Oil Overheating
This pump designed to operate continuously below 10 Torr. Continuous operation of this pump above 10 Torr will
lead to overheating and eventual pump failure.
3.2 Oil Changes and Oil Level
3.2a Draining the Pump
An oil change is mot easily accomplished when the pump is warm and the oil is less viscous. Use a container
large enough for the oil in the particular pump. Stop the pump, and open the drain valve. A thorough job may be
accomplished by tipping the pump slightly if this is possible. The small residue remaining in the pump may be
forced out by hand-rotating the pump pulley with the exhaust port partially closed and the intake port open.
Closing the exhaust port completely under these conditions will create excessive pressure at the drain valve
which may cause the oil being drained to splatter.
3.2b Flushing the Pump
SEE APPLICATION BOOKLET WITHIN OWNER’S MANUAL THAT DESCRIBES FORCED OIL
FLUSHING PROCEDURES TO REMOVE CONTAMINANTS FROM PUMPING MECHANISM.
3.2c Refilling the Pump
After you are satisfied that the pump has been thoroughly flushed, refill the pump by puring new DIRECTORR
Gold 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 pressure
within the pump is reduced. If gurgling continues, add sufficient additional oil through the exhaust port until
gurgling ceases.

3.3 Repairing Oil Leaks
3.3a 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 gasketed 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 important of a gasketed seam is determined 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.
3.3b Repairing Technique
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.
3.4 Repairing Vacuum Leaks
3.4a 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.
3.4b 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.
3.5 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 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.

Section 4: QUICK REFERENCE CHARTS

Section 5: PUMPING SPEED CURVES
HIGH EFFICIENCY PUMPING CHARACTERISTIC OF DUOSEAL® PUMPS
The low RPM design of DuoSeal vacuum pumps makes it possible to maintain high puming
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.
Vacuum Pump 1400N
Vacuum Pump 1376N/1402N
Vacuum Pump 1374N

Section 6: MOUNTED PUMPS DIMENSIONAL DRAWINGS
All Dimensions are in Inches
Model 1400N-01 Model 1402N-01
Model 1376N-01 Model 1374N-01

PARTS LIST FOR 1400N
ITEM QTY P/N A* B* DESCRIPTION
1 1 2-01-9306 Soc. Hd. Screw 5/16 - 18x3/8
2 1 41-2191 Pulley Including Set Screw Item 1
3 1 41-3696 Shaft Seal
4 1 41-0643 Shaft Seal Gasket
5 1 41-0624 1 1 Pulley Key
6 1 41-1060 Shaft
7 1 41-1150 1 1 Retaining Ring
8 2 41-0613 2 2 Woodruff Key
9 1 2-00-2704 Fil. Hd. SS Screw 10-32x1/4
10 2 61-8682 Leg
11 6 41-1138 Washer, Copper 7/16 OD
12 1 41-3753 Oil Sight
13 1 41-1742 1 1 O-Ring #011
14 1 61-8548C Oil Case Assy. (see note below)
15 2 61-8384 Plug, 1/4 NTP
16 1 61-8355B 1 1 Oil Case Gasket
17 9 2-01-0332 Hex. Hd. Cap Screw 5/16 - 18x1-1/2
18 9 41-2363 Washer
19 1 41-1045 Back Endplate
20 1 41-1040 Exhaust Rotor
21 1 61-1239 1 1 Exhaust Valve
22 2 2-71-0040 2 2 Brass Washer #10
23 8 41-1056 Aluminum Washer
24 1 41-1039 Vented Exhaust Plug
25 1 61-8678 Center Plate
26 1 41-1285 Steel Washer
27 1 41-0890 1 1 Air Filter
28 1 41-0383 1 1 Gasket, Intake Chamber
29 1 61-8676 Intake Chamber
30 2 61-8464A Adapter, NW16
31 2 2-01-0524 Hex. Hd. Cap Screw 3/8 - 16x1-1/2
32 1 61-8701 Back Endplate
33 1 61-8672 End Cap
34 5 2-00-2706 Hex. Hd. Screw 10 - 32x3/8
35 2 2-31-2521 Hex. Nut 3/8x16
Note:Oil Case Assy. Item # 14 Includes Items # 10, 12, 15, 30, 48, 49, 52 , 54,
60, 61, 62, 65 & 66
A*: MAJOR REPAIR KIT CAT# 1400K-10
B*: MINOR REPAIR KIT CAT# 1400K-09
** 1401E-01 is a shaft seal repair kit, it includes a shaft seal, gasket, and 3 screws
ITEM QTY P/N A* B* DESCRIPTION
36 1 61-8674 Intake Ring
37 1 41-1041 Intake Rotor
38 2 41-1063 2 2 Spring Holder
39 4 61-8559A 4 4 Vane Spring
40 4 41-1059 4 Vane, Metal
41 5 2-01-0112 Hex. Hd.. Cap Screw 1/4 - 20x3/4
42 1 41-1042 Exhaust Ring
43 3 2-00-6712 Soc Hd Screw 10-32x3/4
44 1 41-0578 1 1 Lip Seal
45 1 61-8102A Flange For G.B. Valve
46 1 61-8103 1 1 O-Ring Viton
47 2 61-8362 Soc. Hd. Screw 8 - 32x1
48 1 61-8266 Tee 1/4 NTP
49 1 41-1734 Drain Valve
50 1 2-01-0120 Hex. Hd. Cap Screw 1/4 - 20x1-1/4
51 1 41-1736 Gas Ballast Valve incl. item 13
52 4 2-01-0308 Hex. Hd. Screw 5/16 - 18x1/2
53 2 2-61-0571 Steel Washer .071 x 3/8 I.D.
54 2 61-2159A 1 1 O-Ring, Viton #116
55 1 61-8348A 1 1 Baffle Stud
56 1 61-8347B Exhaust Baffle
57 1 61-8100A Valve Adapter
58 1 61-8101A Connector
59 1 41-2757 Locknut
60 2 62-0118 2 2 O-Ring, Tetr., #013
61 1 61-8382 Union
62 1 61-8327B Bubbler Tube
65 1 62-0121 Washer, SS
66 1 62-1141 Plug
67 1 61-8665 1 1 O-Ring, M2 .5x86, Viton
68 1 61-9378 1 1 O-Ring, #152, Viton
69 1 66-0183 1 1 O-Ring, #120, Viton
1401E-01 1 1 Shaft Seal Kit**
1-99-5282 1 1 Sealant, 6cc
67-0903
Sheet 1 of 2
Rev. 2 6/04
Section 7: PARTS LIST AND EXPLODED VIEWS

PARTS LIST FOR 1402N
ITEM QTY P/N A* B* DESCRIPTION
01 1 61-8113C Intake Ring
02 3 2-61-0000 Steel Washer 3/16 size
03 3 2-31-0112 Hex Steel Nut
04 1 61-8315A 1 1 Valve Block Spacer
05 2 61-8314A 2 2 Valve
06 2 41-2158 2 2 Valve Spring
07 1 2-01-8128 Headless Steel Set Screw
08 1 61-8313A Valve Block
09 1 61-2372 Filler Plug
10 1 61-8316A Baffle Plate
11 1 2-36-9900 Nut, Lock 1/4-20
12 3 2-00-2706 Fil. Head Screw 10-32x3/8
13 1 61-2159A 1 1 O-Ring, Fluoroelast. #116
14 1 41-2175 Headless Steel Setscrew
15 1 41-2092 Intake Rotor
16 1 61-8266 Tee 1/4 NPT
17 1 61-8250C Center Plate
18 1 41-1742 1 1 O-ring, Fluoroelast. #011
19 2 2-01-6320 Socket Head Screw 5/16-18x1-1/4
20 1 41-2154 1 1 Lower Exhaust Valve
21 1 61-8310A Pressure Release Duct, Part 2
22 1 41-0992 1 1 Pressure Release Valve
23 6 41-2363 Washer
24 6 2-01-0356 Hex Head Screw 5/16-18x3-1/2
25 3 62-0259 Self Tap Screw #6x1/4 Type ‘A’
26 1 61-8309B Pressure Release Duct Part 1
27 1 41-0672 End Cap
28 1 4-40-1200 1 1 Steel Ball 3/8
29 1 41-2045 Small End Plate
30 1 61-8108D Exhaust Ring
31 1 41-1518 Exhaust Rotor
32 6 61-8559A 6 6 Vane Spring
33 2 41-1487 2 Small Vane
34 1 41-0696 1 1 Vane Spring Holder-Exhaust
35 2 41-0959 2 Large Vane
36 1 41-2074 Pulley inc. set screw, Item 37
37 1 2-01-9306 Socket Head Set Screw
38 1 61-8670 Large End Plate Cover
39 1 41-2153 1 1 Upper Exhaust Valve
40 1 2-01-5106 Round Head Steel Screw 1/4-20x 3/8
41 4 2-01-6112 Socket Screw 1/4-20x3/4
42 1 61-8278A 1 1 Intake Chamber Cover Gasket
ITEM QTY P/N A* B* DESCRIPTION
43 1 61-8329A Air Filter Bracket
44 6 2-01-0316 Hex Head Cap Screw 5/16-18x1
45 1 61-8382 Union
46 2 61-8465A Intake Adapter NW25
47 2 61-9284A 2 2 O-ring, Fluoroelast. #214
48 1 61-8279B 1 1 Oil Case Gasket
49 2 62-0118 2 2 O-Ring, Fluoroelast. #013
50 1 61-8102A Flange for Gas Ballast Valve
51 1 41-1736 Gas Ballast Valve
52 2 61-8362 Socket Head Screw 8-32x1
53 1 61-8319B Oil Case Assy. Incl. Item
16,45,49,56,59,75,76,78,79,80,81
54 1 41-2757 Lock Nut
55 1 61-8103 1 1 O-ring, Fluoroelast. #905-75
56 2 61-2229A Glass Window
57 1 61-8100A Gas Ballast Valve Adapter
58 1 61-8101A Gas Ballast Valve Connector
59 1 41-1734 Drain Valve
60 6 61-8456A 6 6 Washer Copper 5/16
61 2 41-1056 Washer
62 2 41-0613 2 2 Woodruff Key
63 1 41-2093 Shaft
64 2 41-0624 2 2 Woodruff Key
65 1 41-0508 1 1 Thrust washer
66 1 61-8669 Large End Plate
67 10 2-63-0193 Split Lock Washer
68 10 2-01-0114 Hex Head Cap Screw 1/4-20x3/4
69 1 41-0660 1 1 Air Filter
70 1 41-0643 Seal Gasket
71 1 1401D-01 1 1 Shaft Lip Seal Kit include items 70 & 77
72 2 41-1685 2 2 Spring Holder - Intake
73 3 41-1766 3 3 Thrust Disc
74 1 4-06-0754 1 1 Truarc Ring
75 1 61-8321B Bubbler Tube
76 2 61-8384 Plug 1/4 NTP
77 3 2-00-6712 Socket Head Screw 10-32x3/4
78 1 62-0121 SS Washer
79 2 61-2370 Cover, Window
80 2 66-0304 2 2 O-Ring, Fluoroelast. #127
81 4 61-2232 Flat Head Screw 8-32x1/2
82 1 62-1141 Plug
1-99-5282 1 1 Sealant, 6cc
A*: MAJOR REPAIR KIT CAT # 1402K-10
B*: MINOR REPAIR KIT CAT # 1402K-09
** 1401D-01 is a shaft seal kit and includes a shaft seal, gasket, and 3 screws
67-0902
Sheet 1 of 2
Rev. 11 6/04

PARTS LIST FOR 1376N
ITEM QTY P/N 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 1401D-01 1 1 Shaft Lip Seal Kit includes items 4 & 5**
04 1 41-0643 Seal Gasket
05 3 2-00-2706 Fil. Head Screw 10-32x3/8
06 1 61-8684 Large End Plate
07 1 61-8670 Intake Cover
08 1 61-8278A 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 2 61-8465A Adapter NW25
16 1 62-1141 Plug
17 2 61-8279B 2 2 Oil Case Gasket- Fluoroelast.
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 61-8559A 6 6 SS 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 Duct Part 2
37 1 4-40-1200 1 1 Steel Ball
38 1 61-8262A 1 1 SS Pressure Release Valve
39 1 61-8309B Pressure Release Tube Part 1
40 3 62—0259 Bd. Head Sheet Metal Screw #6x1/4
41 6 2-01-0356 Hex Head Screw 5/16-18x3-1/2
42 1 61-8312A 1 1 SS Lower Exhaust Valve
43 3 2-61-0000 Steel Washer 1/4 size
ITEM QTY P/N A* B* DESCRIPTION
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 61-8313A Valve Block
49 2 61-8315A 2 2 SS Valve Block Spacer
50 1 61-8102A Flange For G.B. Valve
51 3 2-00-6712 Socket Head Screw 10-32x3/4
52 1 61-8368B Baffle Plate
53 2 41-2175 Setscrew (Special)
54 1 61-8686 Oil Case Spacer
55 1 61-8319B Oil Case Assy.incl.63,67,76,77,78,79,80
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
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 41-1734 Drain Valve
68 1 41-2757 Lock Nut
69 2 66-0304 2 2 O-Ring, Fluoroelast. #127
70 1 2-01-5106 Round Head Screw 1/4-20x3/8
71 1 61-8311A 1 1 SS Upper Exhaust Valve
72 2 61-2370 Cover, Window
73 3 2-01-0316 Hex Head Screw 5/16-18x1
74 1 61-2372 Filler Plug
75 1 61-2159A 1 1 O-Ring, Fluoroelast. #115
76 1 61-8266 Tee 1/4 NTP
77 2 62-0118 2 2 O-Ring, Fluoroelast. #013
78 1 61-8382 Union
79 2 61-8384 Plug 1/4 NTP
80 1 61-8321B Bubbler Tube
81 1 62-0121 SS Washer
82 4 61-2232 Flat Hd Screw 8-32x1/2
83 2 61-9284A 2 2 O-Ring, Fluoroelast. #214
1-99-5282 1 1 Sealant 6cc
A*: MAJOR REPAIR KIT CAT # 1376K-10
B*: MINOR REPAIR KIT CAT # 1376K-09
** 1401D is mechanical seal kit includes mechanical seal, gasket and 3 screws
67-0901
Sheet 1 of 2
Rev. 13 6/04

PARTS LIST FOR 1374N
ITEM QTY P/N A* B* DESCRIPTION
01 1 2-01-9306 Set Screw 5/16-18x3/8
02 1 41-1492 Pulley incl. Item 1
03 4 2-01-6116 Soc Hd Screw ¼-20x1
04 1 1401F-01 1 1 Shaft Seal incl. (1)Item5&(4)Item3
05 1 61-8601A Seal Gasket
06 2 41-1490 2 2 Woodruff Key
07 1 41-1484 Shaft & Collar
08 2 61-8694 2 2 Leg
09 7 2-01-6324 Soc Hd. Screw 5/16-18x1-1/2
10 38 41-2363 Steel Washer
11 3 41-1137 Plug Washer
12 2 41-1136 Plug
13 1 61-8769 Large End Plate
14 1 41-0055 Spacer
15 2 2-00-2704 Fil Hd Screw 10-32x1/4
16 2 61-8384 Pipe Plug ¼ NTP
17 1 61-8266 Tee ¼ NTP
18 1 61-8321B Bubbler Tube
19 1 61- 8382 Bulkhead Union ¼ Tube
20 1 62-1141 Plug
21 2 62-0118 2 2 O-Ring, Tetra. #013
22 1 62-0121 Washer, SS
23 1 61-8270A Cover
24 1 61-8606A 1 1 Valve Gasket
25 1 41-1736 Gas Balast Valve incl. Item 45
26 1 41-2258 Hardened Sleeve ¼ Size
27 1 61-8538A 1 1 Valve Backer
28 4 2-61-0000 Steel Washer 3/16 Bolt Size
29 4 2-31- 0112 Hex Steel Nut ¼-20x7/16
30 1 61-8604A Discharge Valve Cover
31 1 61-8688 Center Plate
32 1 41-2161 1 1 SS Exhaust Valve
33 2 2-01-0120 Hex Hd Screw ¼-20x1-1/4
34 1 61-8592B Cover
35 1 2-01-8132 Headless Screw ¼-20x2
36 1 61-8310A 1 1 Pressure Release Tube Part 2
37 1 61-8595B Baffle Assy.
38 1 61-8309B 1 1 Pressure Release Tube Part 1
39 3 62-0259 Bd Hd Screw #6x1/4
40 1 61-8603C 1 1 Viton Oil Case Gasket
41 1 2-01-0344 Hex Hd Screw 5/16-18x2-3/4
42 1 61-8539A 1 1 Valve Flapper
43 22 2-01-6316 Soc Hd. Screw 5/16-18x1
45 1 41-1742 1 1 O-ring #011 Viton
46 2 41-3753 Oil Sight
A*: MAJOR REPAIR KIT CAT. # 1374K-12
B*: MINOR REPAIR KIT CAT .# 1374K-11
ITEM QTY P/N A* B* DESCRIPTION
47 2 61-8362 Soc Hd Screw 8-32x1
48 1 61-8101A Connector for GB Valve
50 1 61-8264B Oil Case Assy. Incl. Items 16, 17,18,
. 19, 20, 21, 22, 46, 54, 67 & 68
51 4 62-0213 Soc Hd. Screw 5/16-18x1-3/4
52 1 61-8102A Flange For GB Valve
53 1 61-8103 1 1 O-Ring #3-905 Viton
54 1 41-1734 Drain Valve
55 5 62-0222 Soc Hd Screw 5/16-18x2-3/4
56 3 2-00-2706 Flat Hd Screw 10-32x3/8
57 1 41-0672 Shaft End Cap
58 1 41-0992 1 1 SS Pressure Relief Valve
59 1 4-40-1200 1 1 Steel Ball 3/8 Dia
60 1 41-1500 Small End Plate
61 1 41-1497 Exhaust Ring
62 1 41-1499 Exhaust Rotor
63 1 41-0696 1 1 Small Spring Holder
64 2 61-8559A 2 2 Small Vane Spring
65 2 41-1487 2 Small Vane Metal
66 2 2-01-0316 Hex Hd Screw 5/16-18x1
67 2 61-8466A Adapter NW40
68 2 61-8475 2 2 O-Ring #224 Viton
69 4 2-01-6314 Soc Hd Screw 5/16-18x7/8
70 1 61-8690 Intake Chamber
71 1 61-8602A 1 1 Intake Chamber Gasket
72 1 41-0937 1 1 Screen Filter
73 1 61-8690 Large Ring
74 1 41-1478 Large Rotor
75 2 41-1489 2 2 Large Spring Holder
76 4 61-8609A 4 4 Large Vane Spring
77 2 41-1477 2 Large Vane Metal
79 2 2-01-6320 Soc Hd Screw 5/16-18x1-1/4
81 1 41-1516 1 1 Key for Small Rotor
82 4 41-1056 4 4 Aluminum Washer
83 1 41-1469 1 1 Spacer Disk
84 1 2-63-0193 Split Lock Washer ¼
85 1 61-8607A Coil Spring
86 1 41-2257 Hardened Sleeve 5/16 Size
87 1 61-8605A 1 1 Spacer
89 1 61-8100A GB Valve Adapter
90 1 2-69-7007 SS Washer 11/32x11/16x1/16
91 1 61-8608A 1 1 Coil Spring
92 1 41-2757 Lock Nut
93 1 41-2165 Guard Stud
94 1 61-8712 1 1 O-Ring #372 Viton
1-99-5282 1 1 Sealant, 6 cc
67-0904
Sheet 1 of 2
Rev. 2 6/04

Section 8: MSDS for Welch 8995G Gold Vacuum Pump Oil

Section 9: ACCESSORY SECTION
Coaxial Traps
• Reduces oil backstreaming • Stainless steel construction • Easy replacement of elements
ISO Size Capacity Diameter Height A2Cat. No. 1
NW16 To 4 CFM (140 L/min) 3.75 5.25 8.25 541001
NW 25 To 12 CFM (340 L/min) 5.50 5.25 8.25 541001
NW40 To 25 CFM (710 L/min) 5.50 5.25 8.25 541001
Copper Element for ISO NW 16 Trap 1. 541001
Stainless Steel Element for ISO NW 16 Trap 1. 541001
Copper Element for ISO NW 25 and NW 40 Traps 1. 541001
Stainless Steel Element for ISO NW 25 and NW 40 Traps 1. 541001
1. Element must be ordered with trap.
2. Distance between ISO NW inlet and outlet connections.
Modular Sieve Traps
• Blocks backstreaming by absorbing hydrocarbons. • Regenerates charge using built-in heater.
• Removes trace amounts of water vapor.
ISO Size Capacity Diameter Height A2Cat. No. 1
NW16 To 8 CFM (140 L/min) 4.50 6.38 9.00 543001
NW 25 To 8 CFM (226 L/min) 4.50 6.38 9.00 543002
NW40 To 17 CFM (481 L/min) 4.50 9.00 9.00 543003
Synthetic Zeolite Charge 1. 543950
Activated Alumina Charge 1. 543960
1. Element must be ordered with trap.
2. Distance between ISO NW inlet and outlet connections.
Dry Ice Cold Traps
• Removable 3 quarter center well for dry ice/alcohol slurry (do not use acetone)
• Visible trapping surface
• Cold temperature up to 12 hours depending on vapor load
• Available with straight tube connections
ISO Size Diameter Height A 1. I/O Offset Cat. No. Repl. Seal Cat. No.
NW 16 10 8.25 11.06 3.5 545001 545200
NW 25 10 8.25 11.06 3.5 545002 545200
NW 40 10 8.25 11.06 3.5 545003 545200
Straight Tube
½ O.D. 10 8.25 10.75 3.5 1420H-14 545200
1. Distance between ISO NW inlet and outlet connections.
Liquid Nitrogen Cold Traps
• A highly efficient method of trapping condensible vapors
• Produces a lower mechanical vacuum pump base pressure
• Allows quick clean-up of the trapping surface with the two-piece clamped body design
ISO Size Capacity Diameter Height A 1. Cat. No.
NW 16 0.75 Liter 5.5 11.00 7.0 546001
NW 25 0.75 Liter 5.5 11.00 7.0 546002
NW 40 1.65 Liter 7.5 13.75 9.0 546003
1. Distance between Iso NW inlet and outlet connections.
Dimensions are in inches.