How to Select the Pump Ratio

When use the pneumatic or air-operated pump, selecting the correct pump ratio is important for smooth and safe transfer of lubricants, oils, and greases. Otherwise, it can cause slow delivery and wasted energy, or even damage of the system. To match the right pump, we need to first understand what pump ratio means.

What Does Pump Ratio Mean

A pump ratio is defined by comparing the piston area of the air side to the piston area of the fluid side. Or more simply, a pump ratio means the relationship between the air pressure supplied at the inlet and the fluid pressure delivered at the outlet.

Think of it this way, a 1:1 pump with 1 bar(14.5 psi) air input pressure will generate 1 bar(14.5 psi) of fluid pressure. For a pump ratio of 50:1, the same 1 bar(14.5 psi) of air input pressure will generate 50 bar(725 psi) of fluid pressure.

How to Select the Pump Ratio

When selecting the pump ratio, consider the following:

• Fluid type and viscosity

    • Thin oil: 1:1 or 3:1 pumps

    • Medium oil: 3:1 or 5:1 pumps

    • Heavy grease: 50:1 or 60:1 pumps

• Drum size and distance

    • Shorter distance transfer often using lower ratio pump

    • Larger the drum often using higher ratio pump

Common Pump Ratio and Their Uses

• 1:1 Pump- For low-viscosity fluids and short-distance transfer. The JINLIN 1:1 pump is suitable for oils up to 120SAE maximum viscosity.

• 3:1 Pump or 5:1 pump- For medium-viscosity fluids and regular-distance transfer. The JINLIN 3:1 pump is suitable for oils up to 150SAE maximum viscosity. The JINLIN 5:1 pump is suitable for oils up to 250SAE maximum viscosity.

• 50:1 Pump or 60:1 pump- For high-viscosity grease and long distance distribution system.

Conclusion

Selecting the right pump ratio is very important for smooth fluid transfer and improves safety. At JINLIN, we design and produce a series of pneumatic oil and grease pumps, from 1:1 oil transfer pump to 60:1 high-pressure grease pump, to meet different applications. Partner with us if you are a distributor looking for reliable lubrication equipment.