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Articles, guides, and SOP's for Goldleaf Scientific Equipment. Learn to select, operate, and maintain your purchase by reading our informational blog only found here.

VHS-4 Oil Diffusion Pump, Water Cooled, 750L/s (air)

Delivery time: 2-8 days

$6,025.00 USD Excl. tax
$6,025.00 USD Incl. tax

The Agilent Varian VHS-4 has been designed to fill a special need in applications where high pumping speeds are required and space limitations demand a compact pump. This VHS-4 is the smallest of the VHS series pumps being well suited for laboratory and research use. The VHS-4 pump is a rugged, general-purpose unit with an operating range of 2 x 10-3 to <5 x 10-9 Torr. The Agilent Varian VHS-4 is ideal for applications requiring fast cycling because of its high pumping speed (maximum rated at 950 l/s) air combined with high forepressure tolerance (0.65 Torr with no-load and 0.55 Torr when at full gas load). Backstreaming rate of the unit is 1x10-4 mg/cm2/ min, without the use of any cooled cold cap.

Diffusion pumps use a high-speed jet of vapor to direct gas molecules in the pump throat down into the bottom of the pump and out the outlet. The oil diffusion pump is operated with an oil that has low vapor pressure (Santovac 5 oil)). Its purpose is to achieve higher vacuum (lower pressure) than possible by use of positive displacement pumps alone. The Agilent Varian VHS-4 can pump down to pressures of <5x10-9 Torr. Diffusion pumps cannot discharge directly into the atmosphere, so a mechanical forepump, roughing pump is typically used to maintain an outlet pressure around 1 mTorr.

These Agilent Varian Diffusion Pumps are very reliable, simple in design and operate with no noise or vibration. Diffusion pumps are still the most economical means for creating high-vacuum pressures. Diffusion pumps also tolerate operating conditions such as excess particles and reactive gases that would destroy other types of high-vacuum pumps. They can be ordered with a 1-phase 115, 208, 240 VAC heater harness and with standard or extended cold cap. We stock and sell Santovac 5 diffusion pump fluids for this pump. Please see below in our “Related” section for additional accessories that may benefit your vacuum applications and maintenance needs. We offer a large variety of vacuum greases, oils, vacuum fittings, hoses, vacuum gauges, sensors/transducers, parts and accessories sold separately on this website.

These Agilent Varian VHS-4 diffusion pumps have ISO 160K inlet flange, operate on 1-phase 240 VAC, extended cold cap and has Agilent Varian part number L6256312. The Agilent Varian VHS-4 diffusion pump user's instruction manuals can be downloaded in PDF format below. 

Technical Specifications


Pumping Speed, Operating Range Pumping Speed, AVS 4.1 (1963) 750 l/s air, 940 l/s He/H2 1,200 l/s Air
Maximum Throughput 1.5 T-l/s (2.0 mbar-l/s) in operating range, 2.5 T-l/s (3.2 mbar-l/s) @ 0.01 torr
Operating Range 2 x 10-3 to <5 x 10-9 torr (2.7 x 10-3 to <6.5 x 10-9 mbar)
Maximum Forepressure No Load: 0.65 torr (0.86 mbar) Full Load: 0.55 torr (0.73 mbar)
Recommended Backing Pump ≥10 cfm (17 m3/hr)
Backstreaming Rate, Standard Cold Cap <5 x 10-4 mg/cm2/min
Warmup Time 10 minutes
Cooldown Time 10 minutes (with quick cool coil)
Fluid Charge 300 cc
Electrical Requirements 1 ph, 50/60 Hz, 120/208/240 VAC
Pump Power 1450 watts
Cooling Water Requirements 0.15 gpm (30 l/hr) at 60-80°F (15-26°C)
Water Connections 1⁄8 in. FPT Tee
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