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WOB-L pumps

A piston-driven vacuum pump is a type of pump that uses a special piston mechanism to create a vacuum. WOB-L® pumps are robust, oil-free piston pumps with complete accessories, developed for standard applications where corrosion resistance is not required – such as filtration, gas sampling, vacuum drying, and automation.

With flow rates ranging from 0.66 to 12.06 m³/h and an ultimate vacuum between 292 and 6 mbar, WOB-L® pumps stand out for their high performance, reliability, and ease of use. They are known for efficiency, speed, and long service life.

Welch offers a wide range of piston pumps – both single- and twin-head models, built-in and OEM versions – as well as an extensive selection of vacuum pump accessories.

See all our Welch vacuum pumps.

Order information about WOB-L pumps
Order information about WOB-L pumps

Single-Head Pumps

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Welch WOB-L 2522 oljefri stempelpumpe

Wob L 2522

Pumping speed 60Hz (m3h):  1.29

Ultimate Pressure (mbar): 133

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Welch WOB-L 2534 oljefri stempelpumpe

Wob L 2534

Pumping speed 60Hz (m3h):  2.04

Ultimate Pressure (mbar): 93

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Welch WOB-L 2546 oljefri stempelpumpe

Wob L 2546

Pumping speed 60Hz (m3h):  2.72

Ultimate Pressure (mbar): 80

Dual-Head Pumps

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Welch WOB-L 2561 oljefri stempelpumpe

Wob L 2561

Pumping speed 60Hz (m3h):  3.91

Ultimate Pressure (mbar): 6.7

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Welch WOB-L 2567 oljefri stempelpumpe

Wob L 2567

Pumping speed 60Hz (m3h):  5.95

Ultimate Pressure (mbar): 80

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Welch WOB-L 2581 oljefri stempelpumpe

Wob L 2581

Pumping speed 60Hz (m3h):  5.95

Ultimate Pressure (mbar): 6.7

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Welch WOB-L 2585 oljefri stempelpumpe

Wob L 2585

Pumping speed 60Hz (m3h):  12.6

Ultimate Pressure (mbar): 80

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Contact us

Frode Rangset

Frode Rangset

+47 948 26 016
on.tesuhbal@edorf

We would like to hear from you if you have any questions or inquiries about our services and products!

Get an offer

Send melding - Frode eng (#10)

Contact us

Frode Rangset

We would like to hear from you if you have any questions or inquiries about our services and products!

Frode Rangset

+47 948 26 016
on.tesuhbal@edorf

Product Specifications

Areas of Use

WOB-L® pumps are designed for general vacuum and pressure applications in physical and chemical laboratories, industry and field use. They are not recommended for pumping acidic, basic or organic vapours — for such applications, Welch MPC chemical diaphragm pumps are recommended.

Typical areas of use include:

  • Vacuum filtration of water-based solutions and buffers (1–2 filter funnels)
  • Pressure filtration
  • Vacuum drying and desiccators
  • Glove boxes
  • Vacuum ovens
  • Environmental monitoring and air sampling
  • Gas sampling
  • Automation and process control in industry

Advantages

Completely oil-free operation
Piston and cylinder are maintenance-free lubricated. All bearings are sealed and permanently lubricated — no oil changes, no oil filters and no risk of oil contamination of samples.

Complete factory equipment
The pumps are supplied with vacuum regulator with gauge, glass separator (suction side), silencer and carrying handle — ready to use straight out of the box.

Vacuum and pressure in one unit
Built-in regulators for both vacuum and pressure provide precise and instant control over both functions. The pump can be used as a vacuum pump and compressor without modification.

Liquid stop on the suction side
The glass separator with ball stop valve on the suction side prevents condensates or liquids from being inadvertently drawn into the pump and causing damage.

Wide model coverage
From compact single-piston models (2522, 5.3 kg, 133 mbar) to powerful dual-piston pumps (2585, 12.1 m³/h) — WOB-L® covers everything from simple filtration setups to demanding industrial applications.

Long service life with low maintenance cost
Oil-free piston technology with PTFE piston rings and stainless steel valves provides long-lasting operation. Service kits with all wear parts are available for all models.

Functions

  • Oil-free piston technology — no oil contamination, no oil changes
  • PTFE piston rings and EPDM gaskets
  • Stainless steel valves and hose connections — long service life
  • Glass separator with ball stop valve (suction side) — protects against condensates and accidental liquid ingestion
  • Vacuum regulator with gauge — precise control of vacuum level
  • Pressure regulator with gauge — precise control of delivery pressure
  • Silencer on exhaust side — reduced noise level
  • Carrying handle — easy transport and flexible placement
  • Suction cup feet — stabilises pump during operation
  • Thermal motor protection with automatic reset
  • CE certified, RoHS II and WEEE compliant

Documentation

Individual datasheets and user manuals are available for models 2522, 2534, 2546, 2581 and 2585 via the product page.

Key technical data — overview:

  • Ultimate pressure: 6.7–133 mbar
  • Max. pumping speed: up to 12.1 m³/h (50Hz)
  • Noise level: ≤ 56 dB(A)
  • Operation: Completely oil-free
  • Voltage: 230V/50Hz or 115V/60Hz
  • Certification: CE, RoHS II, WEEE

Who are WOB-L pumps suited for?

WOB-L® pumps are suited for laboratories and businesses that need reliable, oil-free vacuum power for standard applications with non-corrosive media. They are particularly well suited for:

  • Laboratories with vacuum filtration of water-based solutions and buffers
  • Environmental laboratories with air sampling and gas sampling
  • Clinical and analytical laboratories with desiccators and vacuum drying
  • Laboratories that need one pump for both vacuum and pressure
  • Industrial automation and process control
  • Glove boxes and vacuum ovens where a moderate vacuum level is sufficient

Note: For aggressive solvents, acids or basic vapours, Welch MPC chemical diaphragm pumps are recommended. For deeper vacuum down to 0.016 mbar, the Welch SCSpro scroll pump or CRVpro rotary vane pump is recommended.

About the Manufacturer – Welch

Welch is part of Gardner Denver Thomas GmbH and is one of the world’s leading suppliers of vacuum pumps and systems for laboratories and industry. The company has extensive experience in the development of pump technology and serves customers globally in research, pharmaceuticals, chemistry and industry.

  • EMEA office: Am Vogelherd 20, 98693 Ilmenau, Germany
  • Gardner Denver Thomas GmbH: Livry-Gargan-Str. 10, 82256 Fürstenfeldbruck, Germany
  • Website: www.welchvacuum.com
  • Certifications: CE and cUL

At Labhuset you will find a selection of Welch vacuum pumps adapted to various laboratory purposes.

Order information about WOB-L pumps
Order information about WOB-L pumps

Frequently Asked Questions

Single-piston models (2522, 2534, 2546) have one piston and cylinder, giving lower pumping speeds (1.29–2.72 m³/h) and moderate ultimate pressures (80–133 mbar). They are compact, lightweight and well suited for simple filtration, desiccators and light vacuum applications. Dual-piston models (2561, 2567, 2581, 2585) have two pistons operating in parallel or in series, giving higher pumping speeds (3.91–12.6 m³/h) and in some models much deeper ultimate pressures (down to 6.7 mbar). The dual-piston models are suited for more demanding applications such as glove boxes, vacuum ovens and industrial automation.

Yes. All WOB-L® pumps are equipped with built-in regulators for both vacuum and pressure, with individual gauges for each function. This means the same pump can be used as a vacuum source and as a low-pressure compressor without any modification or additional equipment. This makes WOB-L® particularly cost-effective for laboratories that need both functions.

No. WOB-L® pumps are designed for non-corrosive media only and are not recommended for pumping acidic, basic or organic solvent vapours. For applications involving aggressive chemicals, Welch MPC chemical diaphragm pumps with PTFE diaphragms and carbon fibre reinforced heads are the correct choice. Using WOB-L® pumps with corrosive media will damage the piston rings, valves and internal components.

The glass separator with ball stop valve on the suction side serves two functions: it acts as a visible indicator showing whether any liquid is being carried over from the application, and it provides an automatic safety stop via the ball valve that prevents liquid from reaching the pump if the separator fills up. This protects the pump from damage caused by accidental liquid ingestion — a common failure mode in filtration applications when filter funnels overflow.

When large amounts of water vapour are involved, Welch recommends using a cold trap, or a liquid trap (filter flask), between the process and the pump to prevent condensate from damaging the pump mechanism. With humid air, it also helps to run the pump for a few minutes to warm it up before use, as this improves its ability to handle moisture. If you see water droplets at the exhaust port, the vapour load is too high and you should use a cold trap or add dry nitrogen to the gas stream.

Yes. Labhuset offers service and spare parts for Welch WOB-L® vacuum pumps in Norway, including complete service kits with all wear parts for each model. Contact Frode Rangset at frode@labhuset.no or +47 948 26 016 for more information.

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