VHS-250 Diffusion Pump

Available in 4-inch, 6-inch, 250-mm, 10-inch, and 400-mm sizes, the VHS series pumps are the fastest and cleanest diffusion pumps of their size available today. The VHS series patented Bulge Contour doubles gas capture and maintains lower pressure. All VHS series pumps have sight glass/fill and drain assemblies for continuous monitoring and easy maintenance of pump fluid. Finned boilers increase surface area, prolonging pumping fluid life. Full thermal protection and quick-cool coils are also standard. The 4-inch, 6-inch, and 10-inch pumps can be ordered with ASA or ISO flanges, standard or extended cold caps, and a variety of voltages.

Product details Related Product


  • Highest pumping speed available
  • Fluid-level sight glass provides a quick indication of pump fluid status at all times
  • Fill and drain assembly for pump oil
  • Fractionating jet purifies pumping fluid
  • High tolerable forepressure
  • Full thermal protection
  • Stainless steel pump body and jet
  • Finned boiler increases surface area, prolonging fluid life


Pumping Speed, Operating Range Pumping Speed, AVS 4.1 (1963) 2,125 l/s Air, 2,660 l/s He/H2 3,700 l/s Air
Maximum Throughput 2.6 T-l/s (3.5 mbar-l/s) in operating range, 3.5 T-l/s (4.5 mbar l/s) @ 0.01 torr
Operating Range 1.2 x 10-3 to <5 x 10-9 torr (1.6 x 10-3 to <6.5 x 10-9 mbar)
Maximum Forepressure No Load: 0.65 torr (0.85 mbar) Full Load: 0.55 torr (0.72 mbar)
Recommended Backing Pump ≥17 cfm (29 m3/hr)
Backstreaming Rate, Standard Cold Cap < 5.0 x 10-4 mg/cm2/min
Warmup Time 10 minutes
Cooldown Time 10 minutes (with quick cool coil)
Fluid Charge 500 cc – exact fluid charge available
Electrical Requirements 1 ph, 50/60 Hz, 120/208/240 VAC
Pump Power 2200 watts
Cooling Water Requirements 0.25 gpm (50 l/hr)
Water Connections 1⁄8 in. FPT Tee



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