Products
Vacuum Pumps
Belt Driven PumpsDuoSeal 1374DuoSeal 1376 DuoSeal 1376B-46DuoSeal 1380DuoSeal 1397 DuoSeal 1397B-46DuoSeal 1399DuoSeal 1400DuoSeal 1402DuoSeal 1402B-46 DuoSeal 1405DuoSeal 1400W-01DuoSeal 1402W-01DuoSeal 1405W-01ChemStar 1400N-90ChemStar 1402N-90ChemStar 1376NChemStar 1400NChemStar 1402NCapture CRRBelt Kit 1397ABelt Kit 1399ABelt Kit 1400ABelt Kit 1405AMajor Repair Kit 1373K-06Major Repair Kit 1376K-06Major Repair Kit 1376K-10Major Repair Kit 1380K-04Major Repair Kit 1397K-08Major Repair Kit 1399K-04Major Repair Kit 1400K-04Major Repair Kit 1400K-10Major Repair Kit 1402K-06Major Repair Kit 1402K-10Major Repair Kit 1402K-47Minor Repair Kit 1373K-05Minor Repair Kit 1376K-05Minor Repair Kit 1376K-09Minor Repair Kit 1376K-46Minor Repair Kit 1397K-07Minor Repair Kit 1380K-03Minor Repair Kit 1399K-03Minor Repair Kit 1400K-03Minor Repair Kit 1400K-09Minor Repair Kit 1402K-05Minor Repair Kit 1402K-09Minor Repair Kit 1402K-46Seal Kit 1401EDuoSeal Oil
Vacuum Gauges and Controllers
Vacuum Pump Oils
Applications
Mass Spectrometry
Botanicals Processing
HVAC Pumps
Rotary Evaporator
Vacuum Concentrator
Vacuum Manifold
Freeze Dryer
Vacuum Oven
Vacuum Filtration
Vacuum Distillation
Aspiration (Cell Culture)
Glove Box
Gel Dryer
Vacuum Measurement & Control
Pick & Place
Vacuum Workhholding
Degassing / Dessicator
Vacuum Leak Detection: Methods, Tools & Tips
Service
Maintenance Kits
FAQ
About Us
News
Careers
History
Our Values
Downloads
Knowledge Base
Discover & Learn
Install & Setup
Operate & Maintain

Built for Demanding Lab and Industrial Applications

If you're running vacuum processes that require consistent performance, low maintenance, and oil-free operation, the WOB-L Piston Pump Model 2581B-50 from Welch Vacuum is designed to meet those needs. This pump delivers up to 74 L/min (2.6 CFM) and reaches an ultimate vacuum of 60 Torr, making it suitable for filtration, aspiration, degassing, and other mid-range vacuum tasks.

Its compact footprint and quiet operation make it a fit for benchtop use, while the rugged design supports continuous duty cycles. The pump is oil-free, reducing contamination risk and simplifying upkeep—ideal for labs that prioritize clean environments and low operating costs.

Full Product Manual

The official product manual includes installation instructions, performance specs, maintenance schedules, troubleshooting guidance, and part diagrams

Key Specifications

Feature

Value

Model

2581B-50

Flow Rate

74 L/min (2.6 CFM)

Ultimate Vacuum

60 Torr

Motor

1/3 HP, 115V, 60Hz

Noise Level

~50 dB (A)

Weight

18.6 kg (41 lbs

Port Size

3/8" NPT

Pump Type

Oil-free WOB-L piston

 

Common Use Cases

 

  • Filtration and aspiration in biological and chemical labs
  • Degassing liquids in analytical workflows
  • Vacuum drying of small samples
  • Vacuum ovens and desiccators
  • Environmental testing setups

FAQs

Minimal. Replace inlet filters periodically and inspect diaphragm and piston seals annually. The pump is oil-free, so no fluid changes are needed.