100# Low Vapor Pressure Anti Foam Rotary Vane Vacuum Pump Oil Sealing Lubricant

100# Low Vapor Pressure Anti Foam Rotary Vane Vacuum Pump Oil

In a rotary vane pump the oil is the working seal. It fills the clearance between vane, rotor and cylinder wall, holds the pressure difference across each vane and carries heat away from the vane tips. When the fluid is wrong the pump still turns and still sounds normal, but pull-down time lengthens and vane wear accelerates. This 100# vacuum pump oil is a mineral base stock blended with sealing, anti foam and oxidation inhibitors against the SH/T 0528-92 specification.

For buyers comparing sealing fluids, three properties decide whether a pump holds its ultimate vacuum over a full service interval: how little gas the oil itself releases, how fast it sheds foam, and how well it seals a rotary vane clearance at operating temperature.

The three properties that matter on a rotary vane pump

• Low vapor pressure. Saturated vapor pressure of 7.5 x 10-5 Pa at 60 °C means the fluid contributes almost no gas load inside the chamber, so the pump reaches its rated ultimate pressure instead of hovering above it.
• Anti foam behaviour. Foam carries oil out of the exhaust and breaks the sealing film. Inhibited foam tendency keeps the reservoir free of a persistent foam layer during high throughput duty.
• Rotary vane sealing. Kinematic viscosity of 101.5 mm²/s at 40 °C is thick enough to seal vane clearances hot, while a -15 °C pour point still allows a clean cold start.

Typical properties

Where this grade is used

• Rotary vane vacuum pumps on packaging and thermoforming lines, where the pump runs continuously and foam control decides the oil change interval.
• Central vacuum systems serving several stations, where a stable ultimate pressure matters more than peak speed.
• Pumps handling slightly humid gas, where water separation keeps the fluid from turning into an emulsion.
• Reciprocating mechanical pumps that need a low vapor pressure sealing fluid at moderate ambient temperature.

Supply and packaging

Field practice that protects the vacuum

Keep the drum sealed and store it indoors, away from water and dirt, because a low vapor pressure fluid loses that advantage the moment it absorbs moisture. Change oil on the pump maker's interval, then shorten it when the sight glass darkens, when a milky layer appears, or when pull-down time stretches. Never top up with another viscosity grade: mixed grades shift both the sealing behaviour and the vapor pressure of the batch. When switching to this grade after long service, drain and flush the reservoir so residual old oil does not dilute the anti foam package.

An honest limit worth stating: if a pump cannot reach its rated vacuum after an oil change, the cause is usually worn vanes, a scored cylinder or an intake leak, not the fluid. Such a fluid cannot compensate for mechanical clearance that has already opened up.

Questions buyers ask about this grade

Why does vapor pressure matter more than viscosity here?
Viscosity controls the sealing film; vapor pressure controls how much gas the oil adds to the chamber. A fluid that seals well but releases vapor holds a stable but poor ultimate pressure.

How do I check whether the foam package still works?
Look at the reservoir during pull-down. A short-lived foam band that collapses within seconds is normal; a foam layer that persists or climbs the sight glass means the oil needs changing.

Can this grade run in a pump handling humid gas?
Yes, water separation and foam control are formulated for that duty, but shorten the drain interval and check for free water in the reservoir. Gas ballast practice matters as much as the oil.

Is 100# the right grade for a small bench pump?
Not always. Smaller, faster pumps often run a lighter grade. Share the pump model and rated ultimate pressure and the grade can be confirmed before you order.

Send the pump model, required ultimate pressure and monthly consumption, and the grade match will be confirmed with typical data before shipment.