This ARP describes a gravimetric method for the determination of particulate contaminant in hydraulic fluids by the control filter technique.NOTE: With this method, detectable contamination levels down to 0.2 mg (7.0 ¿¿ 10-6ounces) per sample can be obtained with a standard deviation of ¿¿0.1 mg (¿¿3.5 ¿¿ 10-6ounces).