The Importance of Oil Filtration on your Hydraulic Tank Unit

Elevator Oil Filtration

One of the main causes of failures and service interruptions on a hydraulic elevator comes from particle contamination within the hydraulic oil.  All oil contains some level of contaminants, but unlike your automobile, an elevator’s hydraulic system does not have an oil filter located within the system.  As such, manual filtration and cleaning of the contaminants is one of the most important maintenance assignments that can be applied within the hydraulic system.

Contaminants can come in many forms such as chemical residuals, dirt, sand, water, dust, and metal shavings from worn out parts within the elevator itself.  The contaminants must be cleaned from the oil through filtration.

The presence of contaminants, if left untreated, can cause a catastrophic failure, which takes place when a component suddenly fails to function, such as the jamming of a check valve or when a fiber of a critical size goes between the seat and the plug, causing excessive leaking or malfunctioning of the system (1).

A more slow and progressive failure can happen when a wear process produces a slow deterioration of components over time.

Consequences of Particle Contamination Include:

  • Cylinders
    • Quick wearing of seals and scratches on the piston
  • Hydraulic Control Valves
    • Destruction of orifices within the valve’s interior
    • Quick wearing of seals causing frequent re-leveling
    • Larger contaminants can interfere with the closing of internal valve rods potentially interfering with starting, stopping, leveling, and uncontrolled descent (1).

Filtration of the oil is the only practical method to prevent contaminants flowing into the hydraulic components. The objective of filtration is to maintain a predetermined cleanliness level that will provide sufficient service life (1).

If you are interested in having this particular maintenance performed on your elevator, do not hesitate to contact our offices for an estimate and to schedule a visit.


  1. Celik,F, (2010), Hydraulic Elevators:  Importance of Oil Cleanliness, Elevator World 9/2010