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Choosing the best vacuum pump fluid for your industry

Oil Sampling Pump

As a rule, the best way to select a vacuum pump oil for your industry is to follow your original equipment manufacturer (OEM) recommendations while adhering to any regulations and legislation that is sector specific.

For example, if you’re operating a vacuum pump in an environment where consumable products are manufactured, you’ll likely need a fluid with Incidental Food Contact Approval.

Reducing friction, cooling, forming fluid seals and controlling contamination are just some of the roles a pump oil must fulfil effectively to promote healthy operations and prolong equipment lifespan.

In vacuum pump applications, the relationship between the pump oil’s volatility and vapour pressure is key. A more volatile pump oil is more likely to turn from a liquid state into a vapour when temperatures rise.

As vacuum pumps work within tight pressure tolerances, any change can be detrimental to operations. As a result, picking a low vapour pressure fluid is desirable to ensure the system efficiency.

How viscosity impacts vacuum pump performance

Viscosity is a prime consideration when choosing pump fluid.

When the lubricant isn’t viscous enough, it can’t create the correct lubrication seal required. This leads to efficiency loss of due to flow reversal and leakage. The lubricant must provide enough coverage to prevent metal-on-metal contact that results in excessive wear and equipment failure prematurely. However, fluid that is too viscous can restrict flow, leaving critical pump areas starved of lubrication.

Various pump designs will have specific lubrication needs. For instance, liquid ring vacuum pumps usually need fluids with an ISO 32 or ISO 22 viscosity, while rotary vane-type vacuum pumps use an ISO 68 or ISO 100 fluid.

Process vacuum pumps and those gearbox-driven will need a more viscous lubricant, like an ISO 220.

Vacuum pump oils for industry

There are a wide range of vacuum pump oils available on the market from lubricant experts like CPI fluid Engineering, Shell and Petronas, and terms used to describe them can be baffling to the uninitiated.

Options involve mineral and petroleum oils, hydrocracked paraffinic fluids, POEs, PAOs and diesters, among many others.

Put simply, petroleum and mineral oils refer to the same products and hydrocracked oils, and are refined versions with more impurities extracted.

PAO is an abbreviation of polyalphaolefin, a popular synthetic option that offers excellent low and high temperature performance, compatibility with most synthetic and mineral oils and good thermal and oxidative stability.

Esters, like diesters and polyol esters (POEs), are also synthetic oils that typically have improved thermal stability, and are suitable for higher temperature applications where sludge build up is an issue. They are also excellent cleaners, acting as a detergent.

Finally, semi-synthetics are formulated with synthetic base oil and a mineral or petroleum oil, and offer a balance of performance and affordability.

Understanding Additives

Beyond the base oils are the additive packages used to enhance them.

Various additives are included that either improve upon qualities of the base oil or suppress them entirely. Select the best vacuum pump oil for your industry by choosing a product that has additives that answer the unique operating and environmental conditions present on-site.

Other considerations for vacuum pump fluid selection

While our guide is designed to act as a shorter summary of considerations for selecting a suitable vacuum pump oil and the different lubricants used commonly in industrial applications, it’s key to remember that other variables can have an influence on fluid choice.

For example, demanding or severe conditions, compatibility with process materials, unique applications and harmful contaminants present may need accounting for. Extreme temperatures often place additional stress and strain on pump fluids.

Many lubricant manufacturers will supply guidelines that indicate how long fluids should last, but assume they are seeing use in normal or ideal conditions. A temperature variation of just 20 or 30 degrees can cut oil lifespan by half, while in under other circumstances, an oil can develop a damaging sludge when run for too long at higher temperatures.

Once you have selected a vacuum pump fluid, establishing an oil analysis programme can be valuable when analysing a lubricant’s condition and its expected active service life in different operating environments and applications.

While an OEM recommendation can be an ideal starting point, some industry applications will require operators to deviate from advice. In such cases, an expert fluid engineer, supplier or technician can help.

OEMs work to select lubricants that work with equipment and applications, but today’s fluid manufacturers are constantly formulating new solutions that exceed OEM performance requirements to help users enhance their operations.

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