Hydraulic Reservoir Sizing & Selection                     

By Jeff Bready, CFPHS

Hydraulic reservoirs provide a centralized source for the hydraulic fluid used throughout a normal industrial hydraulic system. They provide both the inlet fluid for the pump(s) and retain the return flow from the system. Additionally, the hydraulic reservoir with its appropriate accessories can function to improve the fluid in the system by providing a place for cooling the fluid, by allowing certain contaminants to settle out and be removed, and by allowing air and water vapor entrained in the fluid to be eliminated.


Reservoirs are offered in wide varieties of styles. The selection of a particular style or configuration is dependent upon a customer’s required specifications, such as conformity to JIC or DIN standards. The reservoir and its associated hydraulic circuit can assist in fulfilling certain application requirements such as flooded suction, spatial limitations, noise control, vibration control, and contamination elimination. The most common reservoir designs are horizontal and overhead, but many custom designs are also available. Custom materials such as stainless steel or aluminum can be utilized for special applications. A drip pan for containing accidental spillage and removable cleanout covers for easy access are two of the most common accessories for the hydraulic reservoir.


The most important consideration when selecting a hydraulic reservoir is proper sizing. In general, for most industrial applications, the minimum reservoir size should be approximately 2.5 times the pump(s) flow. Additionally, consideration must be given to a return flow which may be greater than the original pump flow. Accessories such as filler/breather, magnet, and heater should be considered in order to make the hydraulic reservoir as versatile and useful as it can be.