This SAE Recommended Practice describes the requirements necessary for four-way subbase mounted, directional air-control valves to be used in automotive manufacturing applications. It includes minimum performance, operation, and physical requirements to qualify the valves for service in automotive manufacturing applications. Included are spool, poppet, and sliding disc types of air valves for pressures in a range of vacuum to 1034 kPa (150 lb/in²) gage, and temperatures from −18 to 60 °C (0 to 140 °F).

Rationale - This revision of SAE J2051 incorporates changes to the contaminant, the original of which was found to cause coagulation in the components tested. The revised contaminant is a mixture of 75% iron filings and 25% ferric(ous) oxide; whereas the previous contaminant was 100% ferric(ous) oxide. In addition, the amount of water injected is increased; and a prescribed schedule of injecting these contaminants is provided.