Welch WOB-L 2561B-50 User manual

OWNER’S MANUAL
FOR
WOB•L®PISTON VACUUM PUMP
MODELS:
2561B-50 2563B-24
2561C-50 2563C-24
2561C-56 2563C-25
For outside of U.S. and Canada, contact your local
Gardner Denver sales office.
WELCH-ILMVAC
Warning
Not recommended for pumping acid, base or organic vapors or gases.
Warning
Be sure to properly identify intake and discharge before using pump.
See section 2.5
Part No. 642826
Printed in USA
Welch-Ilmvac
5621 W. Howard Street
Niles, IL 60714
Phone: [phone] (Technical Support)
Fax: [phone]
E-Mail: [e-mail]
Web-Page: www.welchvacuum.com

INSTRUCTION
WARNING AND CAUTION
PLEASE READ BEFORE OPERATION
While reading your manual, please pay close attention to areas labeled:
WARNING AND CAUTION.
The description of each is found below.
WARNING
Warnings are given where failure to observe instruction could result in
injury or death to people.
CAUTION
Cautions are found where failure to observe the instruction could result
in damage to the equipment, associated equipment and process.
These units conform to the SI International system of units of measurement.
The following symbols (with recommendation of IEC1010 ) of warning will be found on the pump.
Caution - Refer to accompanying documents
Caution - Risk of electrical shock
Caution - Hot surface
WARNING
Motor includes a self resetting thermal cutout and the pump could restart
without actuation under fault condition.
2

TABLE OF CONTENTS
Section 01 - Safety Information
1.10 Warning to prevent injury
1.20 Warning to reduce risk of electrical shock
1.30 Warning to reduce risk of electrocution
1.40 Warning to reduce risk of explosion or fire
Section 02 - Installation
2.10 Introduction
2.20 Unpacking
2.30 Pump mounting
2.40 Pump location / Environmental conditions
2.50 Intake and discharge provisions
2.60 Electrical power
2.70 Vacuum connections
2.80 Vacuum and gauges
2.90 Traps
Section 03 - Operation
3.10 Starting procedures
3.20 Leak detection
3.30 Pressure range
3.40 Shutdown procedures
Section 04 - Maintenance
4.10 General Maintenance
Section 05 - Troubleshooting
5.10 Vacuum problems
5.20 Troubleshooting table
Section 06 - Specifications
6.10 Specification chart
6.20 Pumping speed curve
Section 07 - Warranty
Section 08 - Exploded views and parts list
8.10 Dimensional Drawing
8.20 Exploded view and parts list
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Section 1: SAFETY INFORMATION
1.10 WARNING: TO PREVENT INJURY...
1.11 Never operate this product if it has a damaged cord or plug. If it is not working properly, has
been dropped, damaged or has fallen into water, please return the product to a Welch service
center for examination and repair.
1.12 Keep the cord away from heated surfaces. All electrical products generate heat. To avoid
serious burns never touch unit during or immediately after operation.
1.13 Never block any air openings or place it on a soft surface where the openings may be blocked.
The air openings are for ventilation of the motor inside the housing. Keep all air openings free
of lint, dirt and other foreign objects.
1.14 Never drop or insert fingers or any other object into any openings.
1.15 Do not operate this product where oxygen is being administered.
1.16 This pump is thermally protected and can automatically restart when the protector resets.
Always disconnect power source before servicing.
1.17 Wear safety glasses and goggles when operating this product. Never point any air nozzle or air
sprayer toward another person or any part of the body.
1.18 Use only in well ventilated areas. The motor on all pumps are totally enclosed fan cooled
1.19 Do not use any tools or attachments without first determining maximum air pressure for that
tool or attachment. Be sure to properly identify intake and discharge before using pump. See
Section 2.50
1.20 WARNING: TO REDUCE RISK OF ELECTRICAL SHOCK…
1.21 Do not disassemble. Disassembly or attempted repairs if accomplished incorrectly can create
electrical shock hazard. Refer servicing to qualified service agencies only.
1.22 Unit is supplied with a three pronged plug. Be sure to connect pump to a properly grounded
outlet only.
1.30 WARNING: TO REDUCE RISK OF ELECTROCUTION…
1.31 Do not use this product in or near area where it can fall or be pulled into water or other liquids.
1.32 Do not reach for this product if it has fallen into liquid.
1.33 Never operate this product outdoors in the rain or in a wet area.
1.40 WARNING: TO REDUCE RISK OF EXPLOSION OR FIRE…
1.41 Do not use this pump in or near explosive atmospheres or where aerosol (spray) products are
being used.
1.42 Do not pump anything other than atmospheric air.
1.43 Do not pump combustible liquids or vapors with this product or use in or near an area where
flammable or explosive liquids or vapors may exist.
1.44 Do not use this product near flames.
WARNING
Failure to observe the above safety precautions could result in severe
bodily injury, including death in extreme cases.

Section 2: INSTALLATION
2.10 INTRODUCTION
2.11 This manual has been compiled not only for the care and maintenance of the Welch Dry
Vacuum Pump now in your possession, but as a helpful reference and guide to prevent many
problems which occur if used improperly
2.20 UNPACKING
2.21 Carefully remove the Vacuum Pump from the shipping case and unfasten and remove the
wooden skid. Preserve all paperwork for future reference. If damage has occurred from
shipment, a claim must be filed with the carrier immediately; preserve the shipping carton for
inspection by the carrier. If you are required to communicate with your dealer or Welch Vacuum
Technology, be sure to include your order numbers for quick identification. Do not return the
pump to the factory without first calling for a return goods number.
2.30 PUMP MOUNTING
2.31 Rubber feet are attached to the pump. Rubber feet are excellent for applications involving a
semi-flexible surface such as a bench top; they help to isolate noise and eliminate creeping.
All Vacuum Pumps should be mounted on a horizontal plane.
2.40 PUMP LOCATION / ENVIRONMENTAL CONDITIONS
2.41 Pump Location:
The Vacuum Pump should be located preferably in a clean, dry, and well ventilated area.
Please be sure not to block the ventilation holes located on the motor housing. The pump
should be placed where the surrounding temperature remains between 10°C and 40°C (50°F
and 104°F). Always check to insure the location chosen is protected from direct or indirect
moisture contact. Welch recommends that the pump be installed at the highest point within the
system to prevent possible water condensate from entering the pump. The pump should be
located as closely to its system in order to utilize it most efficiently.
2.42 Pump Environmental Conditions:
The pump is rated for indoor use only. Maximum altitude 2000 meters. Operating temperature
range 5°C to 40°C. Maximum relative humidity of 80% for temperatures up to 31°C decreasing
to 50% at 40°C. Rated for +/-10% of supply voltage. Pollution Degree 2, Installation Category
II.
WARNING
Don’t pump flammable or explosive gases or vapors or operate this
pump in an atmosphere containing flammable or explosive gases or
vapors.
2.50 INTAKE AND DISCHARGE PROVISIONS
2.51 The intake fitting is a NW25-flange / 1/4”NPT. A muffler is supplied for the exhaust.
WARNING
Bursting Hazard- use on exhaust port the silencer or air handling
parts suitable for pressures not less than 100 PSIG
Be sure to call Welch technical service prior to start-up at [phone] if you have any questions.
5

6
2.60 ELECTRICAL POWER
2.61 Power Source Review
Review the power source and the motor rating to be sure they agree in voltage, phase, and
frequency. Serious damage may occur to the motor if it is connected to an improper voltage.
All Welch pumps must be grounded. Grounding reduces the risk of electric shock in the event
of an electrical short circuit. The plug must be plugged into a properly grounded outlet. Consult
your local electrical codes if you have doubts.
2.62 Overload Protection
Motor thermal overload protection is made available by the motor manufacturer as an aid to
minimize motor failure. Overload protection is a standard feature on both 50 and 60 Hz single-
phase-motors. The motors have automatic overload protection.Automatic reset protection is
designed to reset itself after a predetermined cooling period. If the fault to the drive remains
unaltered, the motor will cycle on and off until the fault is corrected.
WARNING
The motor is thermally protected and will automatically restart
unexpectedly when the overload device resets. Don’t pump flammable
or explosive gases or vapors or operate this pump in an atmosphere
containing flammable or explosive gases or vapors.
2.63 Identification Symbols:
Power Off Power On
2.64 Grounding Instructions
This product should be grounded. In the event of an electrical short circuit, grounding reduces
the risk of electric shock by providing an escape wire for the electric current. This product is
equipped with a cord having a grounding wire with a grounding plug. The plug must be plugged
into an outlet that is properly installed and grounded in accordance with all local codes and
ordinances.
DANGER
Improper installation of the grounding plug can result in risk of electrical
shock
- If repair or replacement of the cord or plug is necessary, do not connect the grounding wire to
either flat blade terminal. The wire with insulation having an outer surface that is green with or
without yellow stripes is the grounding wire.
- Check with a qualified electrician or serviceman if the grounding instructions are not
completely understood, or if in doubt as to whether the product is properly grounded. Do not
modify the plug provided; if it will not fit the outlet, have the proper outlet installed by a qualified
electrician.
- This product is for use on a nominal 120V circuit, and has a grounding plug that looks like
the plug illustrated in Sketch A in Figure #1. A temporary adapter, which looks like the adapter
illustrated in sketches Band C, may be used to connect this plug to a 2-pole receptacle as
shown in sketch B if a properly grounded outlet is not available.
- The temporary adapter should be used only until a properly grounded outlet (SketchA) can
be installed by a qualified electrician. The green colored rigid ear, lug, etc. extending from the
adapter must be connected to a permanent ground such as a properly grounded outlet box
cover. Whenever the adapter is used, it must be held in place by a metal screw.

The adapter shown in Figure #1 B and C is not acceptable in Canada.
2.65 Extension Cords
Motor thermal overload protection is made available by the motor manufacturer as an aid to
minimize motor failure. Overload protection is a standard feature on both 50 and 60 Hz single
phase-motors. The motors have automatic overload protection.Automatic reset protection is
designed to reset itself after a predetermined cooling period. If the fault to the drive remains
unaltered, the motor will cycle on and off until the fault is corrected.
2.70 VACUUM CONNECTIONS
2.71 All Dry Vacuum Pumps come with intake and discharge hose barbs which accept 3/8” ID
rubber pressure/vacuum hose. Hose clamps should be used to hold the hose in place. Since
all four models operate in the viscous flow regime, the small diameter of the hose will generate
minimal conductance loss. For best results, Welch recommends the length of the tubing
between the pump and the chamber be kept as small as possible.
2.80 VACUUM GAUGES
2.81 Typical in the rough vacuum range, a dial vacuum gauge is used to measure pressure in mm
Hg or Inches of Hg. The dial vacuum gauge gives negative pressure – that is pressure below
atmospheric. The reference point for the vacuum gauge is atmospheric pressure. Please keep
in mind that atmospheric pressure tends to vary from day to day. As a result of variability, the
dial vacuum gauge will indicate slightly different maximum vacuum readings from day to day.
2.90 TRAPS
2.91 The need of a Trap
The pumps will handle humid air. All wetted aluminum parts are treated for corrosion protection
from moisture. All other wetted parts are stainless steel. If there is a chance liquid may be
drawn from the process under evacuation, Welch recommends a liquid trap be placed between
the process and the pump. A simple liquid trap is a filtering flask.
When a heavy load of water vapor is evolved from the vacuum process, a cold trap is
recommended to help prevent damage to the pump mechanism. The cold trap, immersed in a
suitable Dewar flask, is installed so that the water vapor may come in contact with the surfaces
of the trap and condense. Commonly used refrigerants are liquid nitrogen or dry ice and
acetone or alcohol. Dry ice provides sufficient cooling to freeze out most heavy water vapor
loads. A variety of cold traps are available from Welch.
7

8
The symptom of a high water vapor load is if you have droplets coming out of the exhaust
port. If you see droplets of water, Welch recommends you use a cold trap to capture the water
before entering the pump or dilute the water vapor stream by adding dry nitrogen to the gas
flow. Please call our customer service department for additional information at [phone].
2.92 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 rewarmed it may allow re-evaporation of
the condensate. The refrigerant add tube on the liquid nitrogen trap should not be obstructed
as the refrigerant boil-off can produce dangerously high pressures. If the trap becomes
saturated it should be disconnected from the system, drained, and cleaned. An increase in
pressure in the vacuum system will normally indicate that the trap has become saturated. To
clean the trap, remove the trap from the system and allow the trap to warm up and rinse off the
condensate with a suitable solvent in a fume hood. Thoroughly clean and dry the trap before
reinstalling into the system.

Section 3: OPERATION
3.10 STARTING PROCEDURES
3.11 Starting A Welch Pressure/Vacuum Pump
Before attaching the pump to a system, familiarize yourself with the function and action of the
pressure/vacuum pump that you have acquired. Review the power requirements as described
in Section 2.60. Welch recommends running the pump for a few minutes to warm it up, before
use. The warm-up improves the pumps ability to handle humid air.
3.12 Cleanliness
Take every precaution to prevent foreign particulates from entering the pump. Particulates
will damage the pump’s performance. If you find that particulates come off the process during
evacuation, a particulate trap in the fore line will work. A simple, inexpensive trap may be
made by placing glass wool in a glass or plastic tube. Screens must be inserted to hold the
glass wool in place.
WARNING
The pump is not recommended for pumping acid, base or organic vapors
or gases. Serious damage to the pump will shorten the pump’s service
life. In addition, pumping flammable vapors or gases can lead to serious
safety hazard leading to fire or explosion.
3.20 LEAK DETECTION
The importance of eliminating all leaks in a vacuum system is obvious. The pump must remove
this added volume of leaked gas to maintain the desired vacuum. Leaks for these pump can
be located by slightly pressuring the system and painting the suspected area with a thick soap
solution. Escaping air will produce soap bubbles.
3.30 PRESSURE RANGE
Vacuum pumps are designed to be run from slightly below atmospheric to their maximum
vacuum level on the intake side. The pumps also may be run from atmospheric to their
maximum rated pressure rating. Consult the Specification Table (See Section 6, Specifications)
for the ratings of your specific model.
3.40 SHUTDOWN PROCEDURES
After use, Welch recommends the pump be run for about 2 minutes disconnected from the
vacuum process. The air pumped through the mechanism will purge out water vapor or
droplets of water condensate that may have formed on the inside of the pump. This purge of
the pump mechanism helps prevent corrosion.
Section 4: MAINTENANCE
4.10 GENERAL MAINTENANCE
Welch dry vacuum pumps are 100% oil-free. The pump employs a non-lube piston and
cylinder. No maintenance is necessary for the bearings. All bearings are sealed and
permanently lubricated. Lubrication should not be attempted. The units are built for continuous
duty operation with the quietness and durability of a diaphragm, but with piston performance.
9

Section 5: TROUBLESHOOTING
5.10 VACUUM PROBLEMS
Welch dry vacuum pumps are 100% oil-free. The pump employs a non-lube piston and
cylinder. Leakage, contamination and unusual outgassing are the general causes of problems
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 the pump is the
determination of its maximum vacuum capability. This can be accomplished by blocking of the
intake and reading the vacuum level on the gauge (See Section 2.8).
5.20 TROUBLESHOOTING TABLE
Poor
Pumping
Speed
Poor
Vacuum Loud Unit Possible Cause Corrective Action
X X X Damaged valves Replace flapper valves
X X X Debris in valves Remove debris and check for valve damage
X X X Damaged gasket Replace gasket
X X X Loose head screw Tighten head screw
X X X Loose fitting Tighten fitting
10

Section 6: SPECIFICATION
6.10 SPECIFICATION CHART
Welch Model 2563
Free Air Displacement
CFM (L/min.) @ 60Hz
CFM (L/min.) @ 50Hz 2.12 (60) 1.77 (50)
Ultimate Pressure
Torr (mbar) 5 (7)
Motor Horsepower
Horsepower 1/3
Tubing needed
I.D. in Inches (mm) 1/4 (7)
Shipping Weight
Weight lbs (Kg) 16.5 (7.5)
Catalog Number
Catalog Number Wired for 115V, 60Hz, 1Ph with
North American Plug 2563B-24
Catalog Number Wired for 220V, 50Hz, 1Ph with
European Schuko Plug 2563C-24
Catalog Number Wired for 100V, 50/60Hz, 1Ph with
North American Plug 2563C-25
6.20 PUMPING SPEED CURVE
11

Section 7: WARRANTY
UNPACKING
Inspect the pump carefully. If any damage has occurred, file claim with the carrier immediately.
Save the shipping container for carrier to inspect.
OPERATING PUMP
Refer to the enclosed Instruction/Operation Manual for all information to properly operate and
maintain the pump.
WARRANTY
This Welch-Ilmvac Inc. product is warranted to be free from defects in material and
workmanship. The liability of Welch-Ilmvac Inc. under this warranty is limited to servicing,
adjusting, repairing or replacing any unit or component part which in the judgment of Welch-
Ilmvac Inc. has not been misused, abused or altered in any way causing impaired performance
or rendering it inoperative. No other warranties are expressed or implied. The method of
executing this warranty: servicing, adjusting, repairing or replacing shall be at the discretion of
Welch-Ilmvac Inc. Vacuum pumps that have been used for any period, however short, will be
repaired under this warranty rather than replaced.
The warranty is effective for one year from the date of original purchase when:
1. The warranty card has been completed and returned.
2. The product is returned to the factory or other designated service centers, freight prepaid.
3. The product in our judgment is defective through no action or fault of the user.
If the product has become defective through misuse, abuse, or alteration, repairs will be billed
regardless of the age of the product. In this event, an estimate of the repair costs will be
submitted and authorization of these charges will be required before the product is repaired
and returned.
To reduce additional charges and delays either within or outside of the warranty period, contact
Welch-Ilmvac Inc. @847-676-8800 for a return authorization number. Products without a return
authorization number will be refused by our receiving department. Before shipping, properly
pack the pump, insure it against loss or damage, and on the outside of the pump packaging
and the packing slip write in the return authorization number. Pumps damaged due to improper
packaging are the customer’s responsibility.
12

Section 8: PARTS LISTAND EXPLODED VIEWS
8.10 MODEL 2563 DIMENSIONAL
13

8.20 MODEL 2563 PARTS LISTAND EXPLODED VIEW
14
Item No. Part No. Description Service Kit
2563K-03 Gasket Kit 2567K-04 Foot Kit 2500K-04
1 2563K-01** Connecting Rod Assembly - - -
2 2567K-02 Valve Plate Assembly 2 - -
3 * Cylinder O-Ring 2 2 -
4 * Valve Plate Head Gasket 2 2 -
5 * Cylinder Sleeve 2 - -
6 * Piston Cup - XL9650 2 2 -
7 * Suction Cup Feet - 4
8 * Retainer Hold Down Screw 2 2 -
* These parts are only available in kits.
** These parts should be repaired by qualified service personnel only.

15
Section 9: APPLICATION INFORMATION
9.10 VACUUM SYSTEM FOR VACUUM CHAMBER, GLOVE BOX, ANNULAR SPACE &
TRANSFER LINE
-2561B-50
-2561C-50
-2561C-56
9.20 SYSTEM COMPONENTS* Item
No. Catalog No. Description
1 - PTFE Coated Aluminum Lid
2 - Vacuum Regulator
3 - PTFE Encapsulated Gasket
4 - Metal Intake Hose Barb for 3/8” ID Hose
5 - Kynar Hose Barb
6 1415B Glass Jar, Inlet Trap
1415C Plastic Jar, Inlet Trap
7 726021 Vacuum Gauge, in. Hg, cm Hg
726024 Vacuum Gauge - mbar/kPa
726025 Pressure Gauge - psi/kgcm
8 2561B-50 Vacuum System 115V 60Hz 1Ph
2561C-50 Vacuum System 230V 50/60Hz 1 Ph
2561C-56 Vacuum System 100V 50/60Hz 1 Ph
9.30 SYSTEM OPERATION
Welch’s new portable oil-free general utility roughing pumps provide continuous, reliable
vacuum that your vacuum chamber, glove box, annular space and transfer line applications
require. The pumping mechanism is an economical twin head oil-free Wob-L® known for
reliability and durability. These rugged pumps handle 20,000 plus roughing cycles – from
atmospheric to 5 Torr – before needing seal maintenance. The pumps come completely
equipped and ready to use. An inlet trap to help prevent ingestion of fluids into the pump, a
dial gauge for continuous vacuum level monitoring, and a vacuum regulator to adjust vacuum
levels. Just plug it in and you’ re up and running.
Models 2561B-50, 2561C-50 & 2561C-56 are suited for 1.5 cubic foot ovens or smaller.
The pumping speed of the 2561 at rough vacuum levels is equal to oil-seal rotary vane pumps
of similar size. This makes the 2561 an economical, oil-free solution for replacing oil-seal rotary
vane pumps. These pumps are therefore highly recommended for standard duty laboratory
applications, general vacuum work and where quick roughing of a chamber is needed. The
2561 Pump Models are for use in standard duty applications. This means that they are not
recommended for pumping acidic, basics or organic vapors or gasses. If you are looking for
a pump to handles these types of conditions, contact a Welch representative and they will be
able to assist you in selecting the correct pump for your application.
* System components available as kit Cat. No. 2565K-50

Welch-Ilmvac
5621 W. Howard Street
Niles, IL 60714
Phone: [phone] (Technical Support)
Fax: [phone]
E-Mail: [e-mail]
Web-Page: www.welchvacuum.com
Copyright© 1997-2007 Gardner Denver Welch Vacuum Technology, Inc.
Welch is registered trademarks of Gardner Denver