WELCH DUO-SEAL VACUUM PUMPS

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP70B00584R000200270001-3
• Release Decision: RIFPUB
• Original Classification: K
• Document Page Count: 20
• Document Creation Date: December 14, 2016
• Document Release Date: January 16, 2003
• Sequence Number: 1
• Content Type: MISC

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WELCH
2
VACUUM
PUMPS
R,-MDR AVENUE -=KFE,TCCINOIS ooo/o
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 Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
WELCH DUO-SEAL VACUUM PUMPS are me-
chanical, rotary, oil-sealed, vane-type pumps of one-
or two-stage construction. Their superior design and
precision manufacture achieves high volumetric effi-
ciency and low ultimate pressure - qualities which
have made them the leading choice for all applications
of rotary, oil-sealed vacuum pumps.
Welch's exceptionally high standards in manufacture,
continuous testing and assembly by skilled craftsmen
result in long life and extremely low maintenance. All
pumps are thoroughly run-in and frequently tested to
reach a performance level which surpasses their guar-
antee.
The following pages cover the installation, operation
and maintenance of your Duo-Seal Pump. These in-
structions should be read carefully before operating
the pump or attempting repairs. Complete instructions
are included for routine servicing of the pump and
motor.
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PRINCIPLES OF OPERATION 2
Vented Exhaust ................................................................................................... 2
UNPACKING 3
Mounting ......................................................................................................... 3
Electrical ............................................................ . . . . . . . . . . . . . . . . . . . . . ........................ 3
Connection to System ............................................................................................. 3
Oil Level and Type ............................................................................................... 4
Recommended Accessories ....................................................................................... 4
Installation of Nos. 1392 and 1392A Mechanical-Diffusion Pump Combinations ....................................... 4
General Procedures ............................................................................................... 5
Start-up Procedures ............................................................................................... 5
Start-up Procedures of Nos. 1392 and 1392A Mechanical-Diffusion Pump Combinations .............................. 5
Vented Exhaust ................................................................................................... 5
Shut-down Procedures ............................................................................................ 6
Shut-down Procedures of Nos. 1392 and 1392A Mechanical-Diffusion Pump Combinations ........................... 6
Drive Problems ................................................................................................... 6
-Vacuum Problems ................................................................................................ 7
Oil Changes and Level ............................................................................................ 7
Oil Leakage ..................................................................................................... 7-10
Vented Exhaust .................................................................................................... 10
Air Filter Removal and Cleaning ................................................................................... 10
Routine Maintenance of Nos. 1392 and 1392A Mechanical-Diffusion Pump Combinations ............................. 10
Checking Pump Performance ...................................................................................... 11
VACUUM PUMP PERFORMANCE CURVES
Welch Repair Service ............................................................................................. 11
Welch Exchange Service ......................................................................................... 11
Replacement Parts and Ordering Instructions ....................................................................... 11
Replacement Parts and Numbers ................................................................................... 12
Pump Performance ................................................................................................ 13
Motor Specifications ............................................................................................. 13
Vacuum Connections and Fittings ................................................................................. 14
Valves .......14
............................................................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Traps ............................................................................................................. 14
Vacuum Gauges .................................................................................................. 15
Leak Detection .................................................................................................... 15
Repairing Leaks ................................................................................................... 15
BIR IOGRr PIIY 15
{ .1I+ K DISCI TI EC's` OUPLING, ASSEMBLIES 16
E H ST " I eFor Release 2003/01/28 CIA-RDP70B00584R000200270001-3 17
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THE WELCH SCIENTIFIC COMPAN'
PRINCIPLES OF
OPERATION
Each stage of the Welch Duo-Seal Pumps consists of
a rotor, mounted concentrically on the drive shaft and
positioned eccentrically in a cylindrical stator. The
contact area of the rotor and stator is called the SEAL.
It is a cylindrical seat machined into the stator, with
the same radius as the rotor, and located between the
inlet and outlet of the pump. The rotor is fitted with
two spring loaded, diametrically-opposed vanes which
move in and out of their slots, always pressing against
the inner surface of the stator ring. Any wear on the
vanes is reduced to a very insignificant amount because
of a thin oil film which lubricates all parts of the
pump. As a vane leaves the seal, it sweeps the air from
the crescent-shaped space and forces it out the one-
way exhaust valve. This operation is repeated twice
each revolution, reducing the pressure in the vessel
connected to the intake, thereby achieving a higher
and higher vacuum. A patented feature called the Duo-
Seal provides a by-pass at the seal. This by-pass carries
the last increment of gas, which may escape the port,
back to the exhaust stage. It eliminates the possibility
of entraining the gas into the intake stage and re-
pumping it.
The operating combination of stator, rotor and vanes
constitutes the vital part of the pump. One of these
units is used in a single-stage pump. In a two-stage
pump, two of these units are connected in series and
mounted on a common drive shaft for better ultimate
vacuum.
VENTED EXHAl ST
The presence of water or other vapors in the vacuum
system can be very detrimental to the performance of
the pump. They may contaminate the oil, and if cor-
rosive, they will damage the pump parts. One method
of removing such vapors is using cold traps between
the pump and vacuum system. A vented exhaust valve
on the pump will give additional protection.
The vented exhaust minimizes the condensation of
vapors in the compression cycle of the exhaust stage
by introducing an adjustable flow of atmospheric air.
The diluting effect of the admitted air lowers the par-
tial pressure of the vapor below its saturation pressure
at the operating temperature of the pump. This pre-
vents condensation and the vapors are expelled with
the exhaust gases.
The vented exhaust is also helpful in removing con-
densed vapors from previously contaminated oil.
Method of use and adjustment is described on page 5
under "Operation".
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P VACUUM PUMPS
I UNPACKING
J
Remove the pump from the shipping case with care.
If any damage has occurred, file claim with the carrier
immediately. Always save the shipping container for
carrier inspection.
If it is necessary to communicate with your dealer or
C
MOUNTING
The Welch Scientific Company, please include your
order number, pump catalog number and serial number
to expedite replacement. Do not return the pump to
the factory without obtaining shipping instructions.
INSTALLATION
Welch Pump-Motor Sets are furnished mounted on
formed steel bases, supported on rubber bumpers.
These units should be placed on a firm foundation.
See instructions for No. 1392 and No. 1392A Mechan-
ical-Diffusion Pump Combinations at the end of this
section.
All Duo-Seal Pumps have supporting legs drilled for
mounting bolts.
The pump should be located in a clean area with good
ventilation, and as close as. possible to the vacuum
system to which it will be attached. Adequate space
should be allowed around the pump for normal main-
tenance, such as oil changes, belt adjustments, etc.
Before operation, check belt tension and pulley align-
ment.
The pumps are air-cooled, eliminating the need for
cooling water.
ELEC'RICAL
Care should be taken to insure that the electric motor
is connected to the correct voltage, phase and frequency.
Check the motor wiring connection by removing motor
plate and comparing connections with diagram on in-
side of plate. Pump-motor sets (other than explosion
proof and 3 phase motors) are furnished with a switch
and cord. The cord can be plugged directly into the
proper receptacle.
If the electric motor to be used is not furnished by
Welch, be sure that the motor, belt and pulley will
operate the pump at the proper speed.
Check the rotational direction of the motor before
connecting belt to pump pulley.
CONNECTION TO SYSTEM
The connecting line between the pump and the vessel
to be evacuated should be as short as practical and as
free from bends as circumstances permit. The inner
diameter should be at least as large as the inside diam-
eter of the pump intake. (See page 14, "Vacuum
Connections and Fittings.")
A good vacuum-tight joint between the pump intake
and connecting line-can readily be made by sliding the
correct size, heavy-walled rubber tubing (Welch No.
5518B) over the intake nipple. Insert the connecting
line into the tubing so it butts flush against the nipple.
Use of worm-screw band clamps is desirable, and/or
sealing with vacuum wax or "Leak-Lock" (Welch
Catalog No. 1372).
For permanent connections, remove either or both the
intake nipple and exhaust dust cap, and screw the
piping into the connections. See Page 14 for thread
dimensions. Use a sealant such as "Glyptal" or "Leak-
Lock" on the intake threads.
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THE WELCH SCIENTIFIC COMPANN
OIL LEVEL AND TYPE
To insure efficient operation, low maintenance and
freedom from unnecessary noise and oil vapors, it is
extremely important to use the proper type and quan-
tity of oil. Welch Duo-Seal Oil has been specially de-
veloped over a period of years, to have the required
viscosity, low vapor pressure and chemical stability.
The vacuum guarantee on Welch Pumps applies only
when Duo-Seal Oil is used. A sufficient supply of oil
is furnished with each pump. Additional Duo-Seal Oil
(Welch Catalog No. 1407K) is available in quart and
gallon plastic bottles and in five gallon cans.
After pump has been running for at least fifteen min-
utes, check the oil level. It should be maintained be-
tween the oil-level marks, with the pump in operation.
In general, the oil level will be slightly higher while the
pump is running than when it is stopped. If the oil
level gradually rises during prolonged operation, water
or other vapor is condensing in the pump. When this
occurs, the vented exhaust valve, on pumps so equipped,
should be opened to purge the oil, or the oil should
be changed.
The No. 1404 Pump does not have an oil-level window.
In this pump the oil-level mark may be seen by remov-
ing the top plate. This requires the removal of two
screws. In all No. 1404 Pumps, the top plate must be
removed to add oil to the reservoir.
An explanation of the effect of too much or too little
oil and oil contamination is contained on page 7,
under the heading, "Oil Changes and Levels".
2EC(MMENED,_AE0SORIES
Belt guards totally enclose the pulleys and belts, and are
strongly recommended for the protection of personnel
working near the pumps. Belt guards are furnished with
mounted Nos. 1397 and 1398 Pumps and are available
for all others. To service belts or pulleys, the outer half
of the guard can be removed or folded down, depend-
ing on type. This can be done without use of tools. All
pump bases made in the last five years have been pre-
drilled to accept guard brackets. Older bases require
drilling of two holes.
Exhaust filters are available for attachment to the ex-
haust port in place of the dust cap. Their use is
recommended when it is necessary to operate the pump
with relatively high gas flows. Any oil-sealed mechani-
cal vacuum pump tends to discharge oil mist from its
exhaust port when it is operating at high flow. Oil
droplets entrained in the discharge air are removed by
the combined action of a two-stage filter element. One
stage consists of multiple layers of fine wire screen and
the other of a special fiber. Oil is drained from the
element, back through the discharge connection into
the oil reservoir of the pump.
EXHAUST FILTERS:
No. 1417 for Nos. 1399, 1400, 1405, 1406 and
1410 Vacuum Pumps. (2" diameter x 43/4"
high, 3/4 - 20 male thread)
No. 1417A for Nos. 1402 and 1403 Vacuum
Pumps. (6" diameter x 71/2" high, 1 - 20 male
thread)
No. 1417B for No. 1397 Vacuum Pump. (7" diam-
eter x 10" high, 1-3/4 - 20 male thread)
REPLACEMENT FILTERS:
No. 1417F for 1417 Filter; No. 1417G for No.
1417A Filter; No. 1417H for No. 1417B Filter.
BELT GUARDS
No. 41-0791 for No. 1397; No. 41-2496 for No.
1398; No. 1399G for No. 1399; No. 1400G
for Nos. 1400 and 1410; No. 1404G for Nos.
1404 and 1406; No. 1405G for Nos. 1402,
1403 and 1405.
These combinations consist of a No., 1400B Duo-Seal
Pump with motor and a modified, two-stage metal
diffusion pump, mounted on a common base. Installa-
tion is the same as that for other Welch Duo-Seal
Pumps with the following additional requirements.
Connect diffusion pump intake (large diameter) to the
vacuum system, preferably by brazing or silver solder-
ing. Use as short a connection as possible with as large
a diameter as possible.
Connect diffusion pump heater and electric motor to
115 V, 60 cycle power supply, with separate cords and
switches provided.
Connect diffusion pump to coolant supply. No. 1392
uses a water-cooled diffusion pump and requires 0.08
G.P.M. of water at normal temperatures. Connect
water supply to tubing at intake stack. The No. 1392A
uses an air-cooled diffusion pump. For best results a
small blower or fan with a capacity of 20 C.F.M.
should be used to direct air across the cooling fins,
impinging first on the intake stack.
Check system for leaks before filling diffusion pump
with pump fluid.
Fill the diffusion pump with 55 c.c. of No. 1391K
Octoil Pump Fluid supplied. This may be accomplished
by removing the drain plug, starting the mechanical
pump and sucking the pump fluid into the boiler
through a clean length of rubber tubing. Use a new
drain plug gasket and replace drain plug while the
mechanical pump is running. Turn off mechanical
pump. More complete instructions are furnished with
the Nos. 1392 and 1392A pump assemblies.
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UO'SAL VACUUM PUMPS
OPERATION
Nos. 1392 and 1392A
Mechanical-Diffusion Pump Combinations
START-UP
1. Remove intake and exhaust port plugs and
install dust cap in exhaust port.
2. Check the oil level before operating and check
it periodically during operation.
3. Use only clean Duo-Seal Vacuum Pump Oil.
4. All Welch Pumps, except No. 1404, contain an
air filter screen in the intake port to prevent
foreign particles from entering the pump.
Greatest possible care should be exercised to
exclude foreign particles from the intake line.
5. If corrosive vapors or excessive water vapor is
evolved in the vacuum process, a cold trap
should be placed in the vacuum line to pre-
vent damage to the pump mechanism and
contamination of the oil.
6. When the pump is not being used and is dis-
connected from the vacuum system, plug the
intake to keep out dirt.
7. Carefully check connection and vacuum sys-
tem for leaks.
8. Periodically check V-belt tension and pulley
alignment. V-belt should be adjusted so that
a firm downward pressure at the middle of
the span will cause a deflection of 1/2" to 3/4".
TA t !~~' PR~7CE9URES
1. Turn on power, with intake closed (to mini-
mize splashing).
2. Check for proper direction of rotation.
3. Check oil for proper level, with pump running.
4. The gurgling noise, characteristic of mechani-
cal vacuum pumps when operating at high
pressures, should disappear after a few sec-
onds. If it does not, check to see if oil level is
too low, or if there is a leak in the connecting
lines.
5. Open intake to the vacuum system.
1. Turn on mechanical pump and evacuate the
system to less than 500 microns.
2. Turn on diffusion pump coolant and heater
(fresh oil will evolve the gases dissolved in it
and this will tend to increase system pressure
temporarily). The diffusion pump requires 20
to 30 minutes to reach normal operating tem-
perature and full pumping capacity. If system
pressure does not decrease within a few min-
utes after diffusion pump reaches operating
pressure, turn off heater and recheck system
for leaks.
Vented exhaust valves are supplied with No. 1397,
1398, 1399 and 1402 Pumps, and they are available as
optional accessories for the No. 1400 and 1405 Pumps.
Vented exhaust valves can be field-mounted on any
No. 1400 or 1405 Pumps which have serial numbers
higher than 25500-0 and 26157-5 respectively. Single-
stage pumps, other than the No. 1399, are not adapt-
able to the use of the vented exhaust.
The vented exhaust is used to prevent, or minimize,
the condensation of vapors in the pump. Condensed
vapors raise the vapor pressure of the oil, reducing the
vacuum obtainable. These vapors can also form sludges
with the oil, causing corrosion and eventual freeze-up.
The vented exhaust is also used to purge previously
condensed vapors which will generally re-evaporate as
they are exposed to the low pressure of the intake
cycle. Recondensation in the compression cycle is pre-
vented by operating the pump with the vented exhaust
valve open.
A vented exhaust is not equally effective on all vapors
encountered in vacuum processing, so it does not al-
ways entirely eliminate contamination of the oil. It
does, however, reduce the contamination so oil changes
are not needed as frequently.
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THE WELCH SCIENTIFIC COMPAN`
The vented exhaust valve consists of a hollow stem
with a metal ball closure fitting into a conical seat in
the valve port housing.
A fixed passage through the stem includes a ball check
valve which prevents back-flow of air in the final com-
pression stages. Counter-clockwise rotation of the valve.
stem unseats the ball, opening an air passage to the
exhaust opening in the pump. One full turn of the
valve stem fully opens the valve. Any fraction of a
turn will open the valve correspondingly. Newer model
pumps have a needle valve at the top of the valve stem
to control the flow of air into the valve stem. These
needle valves can be finely adjusted to any position
between fully open and fully closed.
To eliminate water and other condensed vapors from
forming in the pump, open the vented exhaust valve.
This is done by loosening the knurled lock-ring and
turning the valve stem one full turn counter-clockwise
. . . tighten lock-ring. The needle valve, included on
new pumps, is opened by turning counter-clockwise
far enough to handle the volume of vapor. Experience
with the system will enable the operator to quickly
determine the proper needle valve position. As the
volume of vapors diminish, the needle valve should be
closed progressively. Older pumps are not equipped
with a needle valve. On these older pumps, turning the
valve stein one full turn counter-clockwise will give
maximum venting - fractions of a full turn will give
a corresponding amount of venting. When valve is
fully closed, the pump will produce the highest possible
vacuum under the existing conditions. If not needed,
the vented exhaust valve should be closed. It is closed
by turning the stem clockwise until fully seated, then
adjust lock-ring seal accordingly. Finger pressure is
sufficient to seat the needle valve and valve stem for a
leak-tight seal.
SHUTDOWN PROCEDURES
1. Close the pump intake.
2. Turn off power.
3. Bleed in air through intake.
4. Cover intake nipple if pump is disconnected
from vacuum system.
5. If pump is going to be out of service for a pro-
longed period, drain the oil and fill with new
Duo-Seal Oil to prevent the possibility of cor-
rosion from contamination.
Nos. 1392 and 1392A
Mechanical-Diffusion Pump Combinations
SHUTDOWN
1. Turn off diffusion pump heater.
2. Continue cooling until diffusion pump boiler
is cool enough to touch.
3. Shut off coolant supply.
4. Turn off mechanical pump.
5. Admit air to diffusion pump intake.
NOTE-To avoid decomposition, do not expose diffu-
sion pump fluid to pressures above I mm
Hg (Tarr), while hot. If pressure rises above
1 mm Hg, turn off pump heater immediately
and maintain cooling of pump.
ROUTINE
MAINTENANCE
The need for routine maintenance of the pump is
usually quite apparent. In most cases the problems can
be solved with very little down time. The following
paragraphs cover the most common of these problems.
Routine maintenance for the Nos. 1392 and 1392A
mechanical-diffusion pump assemblies is at the end of
this section. Major repair, requiring the disassembly
of the pump, is covered later in this manual, starting
on page 11.
If pump will not run, turn off switch. Check the fuse
and electrical connections to be sure power is present
to the motor. If power is present, proceed as follows:
Remove V-belt. Rotate motor pulley and pump pulley
clockwise, by hand. If motor is stuck, it will have to
be replaced or repaired. If pump is jammed, it will
have to be disassembled (see "Major Repairs," page 11).
If the motor turns freely by hand, turn on switch, with
V-belt removed. If the motor does not work, it will
6
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VACUUM PUMPS
have to be replaced or repaired. If the motor operates
normally and the pump pulley turns freely, replace
V-belt and check the belt tension. A firm downward
pressure at the middle of the belt span will cause a
deflection of 1/z" to 3/a" when the tension is correct.
To increase or lessen the tension, loosen motor mount-
ing bolts and slide motor away from or toward the
pump. If the belt is too tight, it will cause excessive wear
on the pump, It it's too loose, it will slip, reducing
the pump's efficiency and cause excessive belt wear.
Lubricate motor as directed on motor plate. The
motors furnished with Welch Pumps are sleeve-bearing
type. With normal use they require lubrication about
every three years.
Periodically check the set screws on the pulleys and
tighten if necessary.
VACuuM ;PF OBLEM$
A decrease in the vacuum system's efficiency will be
apparent by a decrease in the ultimate vacuum attain-
able, and/or an increase in the time required for
evacuation. This failing is usually caused by leakage or
unusual out-gassing. It is rarely the fault of the pump-
ing system.
To operate at maximum efficiency, the system must be
thoroughly clean. Check all connections for leaks, as
outlined on page 15, "Leak. Detection". If the system
is completely clean and free from leaks, and unwar-
ranted vacuum problems still exist, the pump should
be checked.
The most common cause of a mechanical pump's loss
in efficiency is contamination of oil. It is caused by
condensation of vapors and by foreign particles. Con-
densed vapors increase the vapor pressure, reducing the
ultimate vacuum attainable. Foreign particles and some
vapors form sludges with the oil. These sludges impair
sealing and lubrication, and can cause eventual "freeze-
up". A vented exhaust 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 changing oil varies, depend-
ing on the particular system. Experience with the process
will help you determine the normal period of opera-
tion before an oil change is necessary.
OIL CHANGES .AND LEVEL
the intake closed, for approximately 15 minutes. Stop
the pump and remove the oil drain cap. Most of the
oil will drain out freely. USE CAUTION - oil will
be hot! The small residue remaining in the pump can
be forced out by turning the pump pulley by hand,
with the exhaust port closed and intake open. The oil
will spurt out suddenly and should be deflected into
the drain pan. Extensive operation with the exhaust
port sealed should be avoided, as excessive internal
pressure may loosen the shaft seal.
After removing all oil, close the drain and pour 3 or
4 ounces of clean Duo-Seal Oil into the intake port.
Open exhaust port and run pump for a short period to
completely circulate the new oil. Drain the flushing oil
and force out residue, as above. Repeat flushing with
new Duo-Seal Oil until flushing oil remains clean and
free of color and foreign matter.
WARNING-Do not use solvents or light flushing oils.
Their complete removal is difficult and their higher
vapor pressures will prevent the attainment of high
vacuum.
If the oil has thickened or contains sludges, it is ad-
visable to remove the oil reservoir case and thoroughly
clean out the case with clean, lint- free rags. In re-
placing the oil case, varnish a NEW gasket and posi-
tion on the pump case. Tighten all screws uniformly.
Also replace the shaft seal as explained under the
heading, "Oil Leakage".
After the pump is completely flushed, refill by pouring
new Duo-Seal Oil into the exhaust port. Fill to proper
level indicated on the sight glass. Replace dust cap.
A gurgling noise is characteristic when high pressure
air is drawn through the pump. It should disappear
quickly as the intake pressure is reduced. If the pump
continues to gurgle, the oil level may be too low. In-
sufficient oil does not give proper sealing or lubrication.
Add oil through the exhaust port until it reaches the
proper level. The oil level should be maintained
between the marks on the sight glass, with the pump
running. Level will drop when pump is stopped.
Leakage of oil is readily apparent and easily corrected.
The areas affected are:
SHAFT SEAL-To replace shaft seal, drain oil, re-
move the pump pulley and key, and all parts of the
seal. Clean the shaft and inspect it for any burrs or
nicks. Carefully hone any damaged areas with fine
emery paper. Hone the key way to remove sharp
edges. Place new gasket on the pump casing (do not
use cement). Carefully slide the replacement seal over
the shaft and position against the pump housing. Align
To change oil, disconnect the pump from the system, screw holes and tighten screws uniformly. Instructions
if possible. Warm the oil by operating the pump with are included with replacement seals.
7
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THE WELCH SCIENTIFIC COMPANY
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DU -SEA VACUUM PUMPS
'UMP PERFORMANCE CURVES
861
10-1 10-2
PRESSURE IN mm Hg (TORR)
NO
13978
.
NO. 1405H
H
-1
NO. 1402B
NO. 1405
PRESSURE IN mm OF Hg (TORR)
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w
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THE WELCH SCIENTIFIC COMPANY
OIL LEVEL SIGHT GAUGE-Unless the glass disc
is damaged, it is generally only necessary to replace the
inner and outer rubber gaskets. Drain oil and remove
all parts of the oil level gauge. Insert new inner ten-
sion washer into counterbored seat in casing. Place
glass disc in position. Mount new outer rubber washer
over glass disc and into seat. Place oil window cover
into position and tighten the 4 flllister head screws
uniformly. The oil level gauge on the No. 1406
Pumps consist of a glass disc mounted in a metal ring.
This assembly is mounted by pressing it into the open-
ing in the case. A damaged unit can be easily knocked
out.
OIL DRAIN CAP-Should a leak develop at the oil
drain, replace the rubber disc within the drain cap.
The old disc can be pried out with a stiff wire or
pointed tool. Press the new disc firmly into the cap.
OIL CASE-If oil leaks at the oil case seal, drain the
oil from the pump and remove case and gasket. Thor-
oughly clean the sealing surfaces of the case and pump.
Varnish a new gasket and place in position. Mount
case and thoroughly tighten all screws.
VENTED EXHAUST
Should the seat of the needle valve wear so that it will
not seal with hand pressure, the valve stem should be
replaced.
AIR FILTER REMOVAL AND CLEANING
With the exception of No. 1404 Pumps, all Welch
Duo-Seal Pumps are equipped with an air filter screen.
It is located below the pump intake port and functions
as a trap for solids, which could cause damage to the
pump. Such particles are usually the result of an im-
plosion in the vacuum system. Unless the screen has
been damaged, the filter may be removed and cleaned
in the following steps:
1. Turn off the pump.
(Drain oil in No. 1406 Pump)
2. Remove the intake cover.
3. Lift out air filter. (The air filter on the No.
1398 is a two piece screen attached to the in-
take elbow.)
4. Tap filter on clean disposable surface to re-
move solid particles. If further cleaning is re-
quired, rinse thoroughly in clean acetone
followed by a rinse in clean alcohol and then
a rinse in distilled water. Dry in stream of
hot, dry air.
5. Replace the cleaned filter in intake area.
6. Use a new intake cover gasket and coat both
sides with varnish. (The 1398 has a rubber
O-ring rather than a gasket that should be
replaced.)
7. When varnish is tacky, mount gasket in posi-
tion on pump casting.
8. Replace intake cover and tighten screws even-
ly.
9. Fill pump with clean Duo-Seal Oil (Check level
after running pump for a few minutes.)
Nos. 1392 and 1392A
Mechanical-Diffusion Pump Combinations
The No. 1400 mechanical pump should be maintained
and repaired as directed in the preceding instructions.
The following procedures should be followed as routine
maintenance of the diffusion pump.
OIL CHANGE-The pump fluid should be inspected
periodically for color change and odor. If the fluid is
slightly darkened and has no odor, a simple change
of fluid is normally all that is needed. Follow the tech-
nique described under "Installation Procedures". If the
fluid has developed a noticeable odor, it is recom-
mended that the pump be cleaned in the following
method.
CLEANING-Remove diffusion pump from system.
Thoroughly drain ojl through drain outlet (slight warm-
ing is helpful). Rinse pump with acetone and fill with
a 50% solution of Caustic Soda (use care in handling).
By using pump heater, boil Caustic Soda solution in
pump for approximately 30 minutes. Drain caustic
solution and rinse with clean, hot water. Rinse with
acetone and dry with stream of warm, dry air. Replace
drain plug and reinstall pump in system (replace drain
plug gasket each time a plug is removed). Fill pump
with 55 cc. of new "Octoil" pump fluid.
PUMP HEATER-If burn-out occurs, the heater can
easily be removed and replaced. Remove holding nut at
bottom of boiler and lower heater to remove. Addi-
tional instructions are included with the pump.
10
Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
 Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
DUO-SEAL VACUUM PUMPS
C kN" PUM PER1ORMANCE
An excellent criterion of the condition of a mechanical
pump is the ultimate vacuum it will achieve. This can
be easily measured by connecting a suitable gauge to
the intake of the pump and operating the pump until
the highest vacuum reading is obtained.
This procedure can be used as a quick test to deter-
mine the need for maintenance and repair. Also, as a
final test after all the necessary routine maintenance
procedures have been followed. If the pump does not
achieve or closely approach the performance of a new
pump, the need for major repair is clearly established.
Welch Duo-Seal Pumps are fully tested at the factory
with upright, untrapped McLeod gauges. Other gauges,
such as the Pirani or Thermocouple vacuum gauges
can be used if allowance is made for the inherent dif-
ference in readings. See "Vacuum Techniques " in this
manual for the explanation of gauges.
MAJOR REPAIRS
WE"~"CH; REPAIR SERVICE
With proper care, Welch Duo-Seal Vacuum Pumps can
be depended on to give many years of reliable service.
Should major repairs, which require disassembly of the
pump mechanism, become necessary, it is strongly
recommended that the pump be returned to the factory
for reconditioning.
The basic working parts of Duo-Seal Pumps are ma-
chined to,very close tolerances and require assembly on
special fixtures, and with special tools by mechanics
who are highly skilled at this work. It is our experience
that the majority of pumps repaired by others fail to
operate with maximum efficiency. It is usually still
necessary to return them to the factory for proper re-
pair.
The Welch Scientific Company maintains complete
repair departments strategically located at the addresses
shown on the back page. These facilities are well
equipped and staffed with experts to insure prompt
reconditioning of all returned pumps. Broken, worn,
scored or corroded parts are replaced with new parts
and the pump is thoroughly run-in and tested until it
exceeds the performance requirements of the original
guarantee.
PUMP
CAT.
NO.
REPLACEMENT CHARGE
PLUS CUSTOMER'S
REPAIRABLE PUMP
PUMP
CAT.
NO.
REPLACEMENT CHARGE
PLUS CUSTOMER'S
REPAIRABLE PUMP
1397
$225.00
1403
$90.00
1398
500.00
1404
70.00
1399
45.00
1405
95.00
1400
60.00
1406
70.00
1402
135.00
1410
45.00
F. 0. B. Our Plant or Branch
Exchange Service Instructions-Simply order a factory
reconditioned replacement pump of the same catalog
number as the pump you wish to replace. It will be
shipped to you immediately. Your pump may then be
returned to the factory in the same container. You
will be billed the full price of the replacement pump,
at time of shipment. On receipt of your pump at the
factory, a credit memorandum will be issued to you,
covering the difference between the billed charge and
the exchange allowance for your pump.
If your pump is not a standard model, the cost of parts
and labor necessary to convert it to a standard model
will be added to the cost of the replacement pump. If
your pump is not repairable, you will be notified. You
may then purchase a new pump and return the replace-
ment to us when you receive the new unit. Return the
pump only--do not send motor or base.
A rapid pump exchange service is offered by Welch
through all of its offices to save customers the normal
down-time required for factory reconditioning. A pool
of reconditioned pumps is maintained for this service.
Under this plan, a customer's repairable pump will be
replaced by a factory reconditioned pump of the same
catalog number. The prices for this exchange are as
follows (subject to change without notice):
The parts list on the next page includes all of the items
necessary to affect the repairs or replacements de-
scribed in this manual. The numeral in parentheses,
prece.eding the part number, indicates the total quantity
required of the item. When ordering replacement parts,
list the quantity required, the part number and descrip-
tion. Shipment will be made immediately from stock.
ORDERING
INSTRUCTIONS
Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
 Approved For Rel281?VT-tMA#$(W00200270001-3
DESCRIPTION
PUMP C
ATALOG NU
MBERS AN
D PART NU
MBERS
OF PARTS
1397
1398
1399
1400
1402
1403
1404
1405
1406
1410
EXHAUST PORT DUST CAP.
41-1501
41-1345
41-1345
410612
41-0612
41-1345
345
'41-1C
or11151
51
I
INTAKE
Ni
le
41---
41-1493
4
41-0920
41-0920
410993
41.0993
41 0924
41-1274
41-0920
41-0920
pp
Nipple Washe r
41-0961
410491
41-0491
41-0570
41-0409
Cover Gasket
41-1495
41-2375
41-0383
41-0234
41-0234
41-1308
41-1310
41-0258
Air Filter Screen
Ai
41-0937
41-2523
41.2524
41-0306
41-0890
41-0660
41-0660
41-0891
41-0877
41-0306
T
OIL CASE GASKE
41-1496
41.2518
41-1052
41-1052
41-0403
41-0403
41-1308
41-1052
-
----.
OIL DRAIN CAP
41-1151
4f-1 166
_..- - ---
41 1166
41-1166
41-1166
41-1166
41-1166
41-1166
41-1166
OIL DRAIN CAP DISC
41-1172
41-2499
41-1192
41-1192
41-1192
41-1192
41-1192
41-1192
41-1192
41-1192
OIL LEVEL GAUGE
Tension Washer
41-1266
41-1266
41-1266
Glass Disc
41-1268
41-1268
41-1268
Outer Gasket
41-1267
41-1267
41-1267
Window Cover
41-1061
41.1061
41-1061
SHAFT SEAL
1401E
included
Screws
(4)2-01 6120
2-01-0110
included
VALVE EXHAUST
41-1266
41-1266
41-1266
41-1266
41-1266
41-1268
41-1268
41-1268
41-1268
41-0555
41-1268
-
41-1267
41-1267
41-1267
41-1267
41.1267
41-1061
41-1061
41-1061
41-1061
41-1061
1401E
1401D
"'1401A
or 1401E
1401E
1401E
1401E
1401E
included
included
included
included
included
included
included
included
included
included
included
included
included
included--
- - -
41-2161 41-0695 (2)41-1239 41.1281 41-1281 41.1239
~
..-..41 1239 1 41 1239 ~
41-Ml 1-41-1239-
VALVE, EXHAUST STAGE PRESSURE RELIEF
Clock Spring
41 0992
41-2506
Steel Ball
4_40-1200
4
40-2000
VALVE, FIRST STAGE CONVE
RSION
Gasket
41-1508
O-Ring
41-1507
41-1507
Spring Unit
41-1504
41.1504
Bellows
14.1505
41-1505
Valve
Spring
41 2248 41-2398
41 2244 41-2507
4
Tension Strip 41 -K47 41-2485
PRESSURE CROSS
VALVE,
41-0992
4-40-1200
(2)41-2157
(2)41-2158
. 41-0992
4-40-1200
Spn
Spring
1399T
41-1186
Adapter
41-1184
PUMP PULLEY
41-1492
41-2510
41-2192
41-2191
41-2174
41-2194
41-2194
41 2194
41.2194
41-2191
Key
41-1 1490
41-2 2514 4
41 0624
41-06 624
41-0624
41 0624
41-0624
41-0624
41-0624
41-0624
DUO-SEAL OIL
1407K
1407K
1407K
1407K
1407K
1407K
1407K
1407K
1407K
1407K
EXHAUST FILTER
14176
41.2495
1417
1417
1417A
1417A
1417
1417
1417
Repl. Element
1417H
41-2516
1417E
1417F
1417G
1417G
1417E
1417F
1417F
VENTED EXHAUST VALVE
included
included
included
1414
included
1414A
Repl. Stem Assembly
41-2289
41-2497
41-2289
41 2289
41-2348
41-1258
0-Ring
41-2364
41-2364
41-2364
41-2364
BASE
Rubber Feet
(4)41 0588
(4)41 0929
(4)41-0929
Screws
(4)2-01-0312
(4)2.02 5708
(4(2-02-5708
f
Nuts
PUMP
41-071 94
41-0753
41-0788
(4)41 0929
(4)41 0929
(4)41-0929
(4)41-0929
(4)41-0929
(4)41 0929
(4)2-02 5708
(4)2-02 5708
(4)2-02-5708
(4)2-02-5708
(4)2-02-5708
(4)2-02-5708
Bolts
(4)2-01-0516
(8)2-01-0520
(4)2-01-0312
(4)2-01-0312
W2
Washers
(4)2-63-0593
(8)2-63-0593
(4)2-61.3100
(4)2-61-3100
(4)2-
Nuts
(4)2-31-2521
(8)2-31-2521
(4)2-35-3800
(4)2 353800
(4)2-
MOTOR
I H.P.
3 N.P.
' H.P.
Mounting Strips
(2)41-0669
(2)41-0670
(2)41-0670
(2
Bolts
Pulley or Clutch
(4)2 01-0312
41.0995
41-2513
(4(2-01-0312
41-2377
(4)2-01-0312
41-0549
(1)2
V-BELT
(2(1397A
(4)41-2512
1399A
CORD, POWER, 115V
41-2500
41-1058
41-1058
4
230V
51
41-1057
41-1057
4
BELT GUARD
-
41-0791
t
41-2496
13996
14006
00 (2)2 61-3100 (4)2-61-3100 (4)2-61.3100 (4)2-61-3100
613100 (4)2-61 -31
35-3800 (4)2-35-3800 (2)2-35-3800 (4)2-35-3800 (4)2-35-3800 (4)2-35.3800
-1277
1-1058
1058
1057
1-1057
1405G
'Use No. 1151C Dun Cop on all Model 1406 Pumps wah serial number below 3956
"'Use No. 1401A Shall Seal on oll Model 1403 Pumps with serial number below 5132
No. 1392 and 1392A MECHANICAL-DIFFUSION PUMP COMBINATION REPLACEMENT PARTS
DESCRIPTION OF PARTS
DIFFUSION PUMP
Heater-135 Watt, 115 Volt
ac-toll Pump Fluid
150 m1.
Silicone Pump Fluid
DC-702-200 ml
-500 ml
DC-703-200 ml.
DC-704-500 ml.
1391 R
1391 U
1391S
Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
FIRST STAGE PRESSURE RELIEF
No.1400 DUO-SEAL PUMP No. 1392 DIFFUSION PUMP No. 1392A DIFFUSION PUMP
-(SEE LARGE TABLE, THIS PAGE) (Water -Cooled) (Air-Cooled)
1391 1394
-0 1-0312
REPLACEMENT PARTSLIST
-0312
(4)2-01-0312
(2)2-01-0312
(4)2-01-0312
(4)2-01-0312
(4)2-01-0312
(2)41-0669
(2)41.0670
41-0670 41-0669
(2)41-0669
(2)41-0669
(4)2-01-0312
(4)2-01-0312
(4)2-01.0312
(4)2-01-0312
(4)2-01-0312
41-1247
41-0549
41-1181
41-1181 41-127
41-0549
41-0549
1405A
41-1058
1406A
41-1058
1405A
41-1058
1406A
41-1058
1400A
41.1058
41-1057
41-10571
41-1057
41-1057_
41-1057,_
1405G
~ 14046
1405G
1404G
14006
1391 K
1391E
 / A proved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
DUO-SEAL,' VACUUM PUMPS
PUMP SPECIFICATIONS
which it is used. An examination of the speed curves
PUMP ;PERFORMANCE on pages 8 and 9 will show that Welch Duo-Seal
pumps maintain high volumetric efficiency, almost
down to their ultimate vacuums. Another important
feature of a vacuum pump is the ultimate vacuum that
A vacuum pump is best described by its pumping it can obtain.
speed, in volume per unit of time, at various pressures. The above data is necessary to determine the proper
Example: 100 liters/minute at 0.1 micron. This meas- size and type to best obtain the desired results, with a
urement is independent of the vacuum system with specific vacuum system.
WELCH DUO-SEAL VACUUM PUMP SPECIFICATIONS
PUMP
CAT.
NO.
ULT. PRESSURE
mm Hg
(McLeod)
FREE AIR
DISPLACE.
(liters/ min.)
NO. OF
STAGES
APPROX.
PUMP SPEED
(RPM)
VENTED
EXHAUST
OIL
CAPACITY
(milliliters)
PUMP
PULLEY
DIA.
RUBBER
TUBING
BORE
INTAKE
PORT
THREAD
*1392
1 x 10-6
600.(1 x 10-4)
55
1397
1 x 10-4
425.
2
365
Included
1230
12"
1-5/8"
1-3/4"-2
139&
1 x 10-4
1400.
2
245
Included
2500
19"
1399
1.5 x 10-2
35.
1
750
Included
450
7"
7/16"
3/8" IPS
1400
1 x 10--4
21.
2
450
Optional
550
7"
7/16"
3/8" IPS
1402
1 x 10-4
140.
2
525
Included
2200
10"
13/16"
1"-20
1403
5 x 10-3
100.
1
375
1400
10"
13/16"
1"-20
1404
2 x 10-2
33.4
1
300
2300
10"
5/8"
1405B
1405H
1 x 10-4
or
5 x 10-5
58.
33.4
2
2
525
300
Optional
Optional
250
250
10"
10"
5/8"
5/8"
3/4"-20
3/4"-20
1406
5 x 10-3
33.4
1
300
60
10"
5/8"
3/8"-IPS
1410
2 x 10-2
21.
1
450
450
7"
7/ 16"
3/8"-IPS
*No. 1392 Mechanical Pump Specifications are the same as No. 1400 in table. 946 Milliliters= 1 Quart
No. 1392 Diffusion Pump Specifications are listed in table.
MOTOR SPECIFICATIONS FOR WELCH DUO-SEAL VACUUM PUMPS
PUMP CAT
NO
RATING
MOTOR
MOTOR PULLEY
.
.
H.P.
R.P.M.
DIAMETER
BORE
BELT GUARD
1397B
1
1725
2-1/2"
5/8"
Included
1398M
3
1160
4"
1-1/8"
Included
1399B
1/3
1725
3"
1/2"
Optional
1400B
1/3
1725
2"
1/2"
Optional
1402B
1/2
1725
3"
5/8"
Optional
1403B
1/2
1725
2-1/4"
5/8"
Optional
1404H
1/3
1725
2"
1/2"
Optional
1405B
1/2
1725
3"
1/2"
Optional
1405H
1/3
1725
2"
1/2"
Optional
1406H
1/3
1725
2"
1/2"
Optional
1410B
1/3
1725
2"
1/2"
Optional
(to operate pump at proper speed)
Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
 Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
THE WELCH SCIENTIFIC COMPANY
VACUUM TECHNIQUES
VACUUM CONNECTIONS AND FITTINGS
The choice of line sizes and fittings, such as valves,
can have a very marked effect on the pumping speed
at the vacuum vessel. Any connection placed between
the pump and the vessel creates an impedance to the
flow of gas. This is particularly true at low micron
pressure where the gas flow is substantially molecular
in character. It is then dependent on the kinetic ac-
tivity of the molecule, bringing it to the intake of the
pump.
It has been shown that the conductance of a tube is
proportional to the cube of the diameter (D3) and
inversely proportional to its length (L). 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
as large as the diameter of the pump intake. The effect
of line impedance on the net pumping speed (S) can
be seen in the following relationship:
1/S = US, + I/ C
(S1 is speed of pump in liters per second. C is the
conductance of the tubing.)
To avoid a large reduction in pumping speed at the
vacuum vessel, it is clear that the conductance of the
line must be considerably greater than the speed of the
pump. For example, if the conductance is equal to the
speed of the pump, the net speed will be one-half that
of the pump.
If metal piping or tubing is used, it is preferable to
solder or braze all connections. Where threaded joints
must be used, screw the members together several
turns, coat the remaining threads with "Glyptal" or
"Leak-Lock" and screw together tightly. Flanged con-
nections with Elastomer 0-ring gaskets make ex-
cellent demountable joints.
Where glass tubing is used between the system and
pump intake, joints can be made by butting the ends
of the two sections together in a short section of rub-
ber tubing. This type joint can also be used with metal-
to-metal or glass-to-metal tubing. After' assembly, coat
the ends of rubber tubing with vacuum grease, such as
DC Silicone Grease (available from Welch). Perma-
nent glass-to-metal seals can be made by the use of
"Kovar" glass-to-metal seals.
Standard tapered and ball-and-socket joints should be
coated with a thin film of vacuum grease before as-
sembly.
VALVES
Metal valves or glass stopcocks are generally used in
the connecting line between the system and the pump.
They 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. Stopcocks
should be lubricated with vacuum grease.
TRAPS-
Where corrosive vapors or large quantities of condens-
able vapors result from vacuum processing, a cold trap
should be used in 'the connecting line to the pump. It
will help prevent damage to the pump mechanism and
contamination of the oil.
The cold trap is installed so the vapors come in contact
with the surface of the trap and are condensed. Com-
monly used refrigerants are liquid nitrogen or dry ice
and acetone. The refrigerant to be used depends on the
freezing point of the contaminants. A variety of glass
cold traps are available from Welch.
When using a cold trap, the refrigerant should be
maintained at a high level, to prevent warm-up of the
trap. Warm-up of the trap may allow re-evaporation
of the condensed vapors. The refrigerant cavity open-
ing 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 and the condensed vapors removed from the
trap. An increase in pressure in the vacuum system
will normally indicate that the trap has become satu-
rated. When this occurs, the vapors are being evolved
faster than they can be carried away.
To clean the trap, remove the refrigerant and allow the
trap to warm up. Rinse off the condensed vapors with
a suitable solvent. Thoroughly clean and dry the trap
before reinstalling in the system.
Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
 Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
VACUUM PUMPS
V"ACUUM GAUGES
The type vacuum gauge to be used is determined
largely by the pressure range to be measured. Pressures
in the range produced by Welch Duo-Seal Pumps can
be covered by McLeod, Dubrovin, Pirani or Thermo-
couple type gauges.
The McLeod gauge is used where high accuracy of
measurement is required. The Pirani and Thermo-
couple gauges are electrical and give continuous read-
ings 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 than electrical
gauges.
For higher vacuums in systems employing diffusion
turbo-molecular or ion pumps, the hot filament ioniza-
tion or the Philips gauge is used.
LEAK DETECTION
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.
Small leaks in glass systems can be located by probing
with a Tesla Coil (available from Welch). This instru-
ment is a high frequency, ungrounded, high potential
spark coil with a pointed electrode. The discharge from
the coil will pass through any minute opening and
produce a pink glow at the location of the hole. In
using a Tesla Coil, the electrode point should be held
1/4" to 1/z" from the glass. It is not recommended for
use in very thin-walled systems or adjacent to glass-
to-metal seals.
Small leaks can also be detected by spraying a sus-
pected area with acetone or gases rich in hydrogen,
and observing a sudden change in pressure reading on
an electrical gauge. (Pirani or Ionization type 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!
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 a total effect
of a large leak.
REPAIRING .LEAKS
it is preferable that a permanent repair be made when-
ever a leak is located. Rewelding welded joints, refu-
sion of glass or soldered joints, etc., are done by
normal methods. Gasketed joints, which cannot be
sealed by further tightening of bolts, should have the
gasket replaced andior the seal reground. Threaded
joints should be loosened and the threads coated with
"Glyptal" or "Leak-Lock", then retightened.
Temporary repairs can frequently be made by painting
the area with "Glyptal" or "Leak-Lock".
BIBLIOGRAPHY
Scientific Foundation of Vacuum Technique, Saul Dushman, (John Wiley & Sons, Inc.) 1962.
High Vacua, Swami Inanananda, (D. Van Nastrand Do., Inc.) 1947.
Vacuum Equipment and Techniques, Guthrie and Wakerling, (McGraw-Hill) 1949.
Procedures in Experimental Physics, J. Strong, (Prentice Hall) 1938.
High Vacuum Technique, J. P. Yarwood, (Chapman & Hill) 1955.
15
Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
 Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
THE WELCH SCIENTIFIC COMPANY
QUICK DISCONNECT
COUPLING ASSEMBLIES
No. 1393A.
for pumps
1399
1400
1406
1410
No. 1393B.
for pump
1405
FOR EASY CONNECTION OF ANY
METAL OR RUBBER TUBING
OF PROPER DIAMETER
for
pumps
aim
CONNECTING SQUEEZE RUBBER INTAKE COUPLING
RING WASHER O-RING WITH AL. GASKET
ATTACHES TO PUMP
No. 1393C.
for pumps
1402
1403
No. 1393D.
for pump
1397
The Welch Quick Disconnect Cou-
pling, when screwed into a Duo-Seal Pump
instead of the standard intake nipple, permits
direct, rapid attachment of metal or rubber
vacuum tubing. The 0-ring joint provides
a vacuum-tight seal and permits quick dis-
assembly. It is not necessary to dismantle
the vacuum line when the pump must be
removed. Simply unscrewing the threaded
ring releases the connection.
Each coupling includes a short, stain-
less steel intake tube onto which rubber
tubing may be slipped if desired. This intake
tube should be replaced by a terminal tube
of the same O.D. when a metal vacuum
line is used.
c
OU L
QUCKDI Coll 1 1: 9. 1
Cat. No. 1393A. For Model 1399, 1400, 1406 and
1410 Pumps. Intake tube 'h" O.D. Each, $6.00
Cat. No. 1393B. For Model 1405 Pump.
Intake tube 5/e" O.D. .......... Each, $7.50
Cat. No. 1393C. For Model 1402 and 1403
Pumps. Intake tube 78" O.D. ....Each, $8.50
Cat. No. 1393D. For Model 1397 Pump.
Intake tube 13/a" O.D. ........ Each, $26.00
Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
Welch
 Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
DUO-SEAL VACUUM PUMPS
EXHAUST FILTERS
No. 1417.
for pumps
1399
1400
1405
1406
1410
No. 1417A.
for pumps
1402
1403
I ELIMINATE OIL MIST AROUND EXHAUST
L KEEP VACUUM PUMP AREA CLEAN
Welch Duo-Seal Pumps operating at
high pressures emit far less oil vapor from
the exhaust than any other equivalent pump.
Nevertheless, if you operate your Duo-Seal
Pump frequently at the higher pressures, an
Exhaust Filter is desirable.
The Welch Exhaust
Filter simply screws into
the exhaust port in
place of the dust cap
and effectively removes
these oil vapors.
No. 1417B.
for pump
1397
Oil droplets entrained in the discharge
air are removed by the combined action of
a two-stage filter element. One stage con-
sists of multiple layers of fine wire screen
and the other of a special non-organic fiber.
Oil collected by these two components is
drained from the element back through the
discharge connection into the oil reservoir
of the pump.
EXHAUST FILTERS
No. 1417. For Nos. 1399, 1400, 1405, 1406
and 1410 Pumps. 2" Dia. X 43/4" High,
3/4-20 male thread..........Each, $17.50
No. 1417A. For Nos. 1402 and 1403 Pumps.
6" Dia. X 7!is" High,
1-20 male thread ........ Each, $30.00
No. 1417B. For No. 1397 Pump. 7" Dia.
X 10" High, 13/4-20 male thread.
....................... Each, $52.50
REPLACEMENT FILTERS
No. 1417F. For No. 1417 Filter....... Each, $ 6.50
No. 1417G. For No. 1417A Filter..... Each, $12.00
No. 1417H. For No. 1417B Filter...... Each, $17.50
Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
14
 Approved For Release 2003/01/28 : CIA-RDP70B00584R000200270001-3
WELCH DUO-SEAL?
PUMP OIL
For All Duo-Seal Vacuum Pumps
WITH OUTSTANDING
Low Vapor Pressure
Chemical Stability
Ideal Viscosity
MADE UNDER A PATENTED PROCESS
Produced according to the most exacting specifications.
Each batch must pass rigorous tests in our control lab-
oratory before it can be released for use.
DUO - SEAL OIL IS SO DEPENDABLE THAT
The high vacuum performance guarantee of Welch
Duo-Seal Pumps applies ONLY when Duo-Seal Oil is
used. Repeated tests prove that Duo-Seal Pumps per-
form best with Duo-Seal Oil. There can be no substitute
for high quality.
FOR BEST RESULTS --
Whether you operate your Welch Duo-Seal Pump
constantly or intermittently ...
1. Check oil level periodically-
2. Inspect for contamination regularly-
3. Change oil when necessary-and-
4. Always use WelchDuo-Seal Pump Oil.
No. 1407K DUO - SEAL OIL, For Welch Mechanical
Pumps. Best results can be expected when an oil of very
low vapor pressure is used. This is the only oil recom-
mended for use with Welch Duo-Seal Vacuum Pumps.
ORDER LARGER QUANTITIES AT A SAVING
Quart.-$0.90 Gallon.-$2.65 5-Gal. Drum-.$10.85
12-Qt. Case. .8.40 4-Gal. Case. .9.00 55-Gal. Drum. .79.75
MANUFACTURED ESPECIALLY FOR 055E IN
*k CH DUO SEAL*VACUUM PUMPS
Eastern Division: 331 E. 38th Street, New York, New York 10016
Western Divisions: 840 Cherry Street, San Carlos, Calif. 94070
Approved For Release 206 Th l ??t 'Ft*896?oi'F{&db29d6 10001-3
General Offices: 7300 N. Linder Avenue, Skokie, Illinois 60076