Hydraulic Pump Contaminant Wear

The contaminant wear of any pump depends on the operational and the contaminant severity as well as the inherent contaminant sensitivity of the pump. In order to evaluate the contaminant sensitivity of a pump it is necessary to conduct a carefully controlled test. The primary result obtained from this test is a lumped parameter called the contaminant wear sensitivity coefficient, which represents the degree of contaminant tolerance. A contaminant sensitivity theory has been developed which states that for every contaminant particle that passes through a pumping chamber, the pump looses a finite portion of its flow delivery potential. The degraded flow rate equals the sum of the product obtained by using both the wear sensitivity coefficient and the particle exposure rate for all particles sizes to which the pump has been exposed. The wear sensitivity coefficient is simply the volume of the pumping potential that the pump looses per particle exposed. The particle exposure rate equals the product of the flow rate and the particle concentration in the fluid. An analytical treatment of the contaminant sensitivity concept is called the Omega Theory. This paper first reviews the contaminant sensitivity test and discusses the various test parameters. In addition, the paper presents the analytical model that permits computer techniques to be applied in deriving and manipulating contaminant sensitivity coefficients obtained from testing in order to construct the contaminant tolerance profile (Omega Life) and calculate the service life for a specific pump. Furthermore, the paper provides a means by which the field service life can be estimated based upon the standard test.