In a valve data sheet I found ZCMS 66 specified as seat and spring material. I didn't any International standard referring to it. Does anybody know if this is a specific manufacturer standard or what it is? Thanks. I found that "ZCM" may stand for Zinc Composite or Zinc Containing Material; nothing meaningful for "ZCMS"... Is there the possibility of a mispelling, parhaps?ZCM is a solenoid valve series .Zinc Material Safety CAS number 7440-66-6. I would believe they are stating the material coating is Zinc or has Zinc in it, and the safety date sheet Cas Number is 66, Making it ZCMS-66. If I remember right, 66 stand for Molecular weight for ZINC. The ultimate test is to introduce a disturbance to the compressor such as cutting back the suction throttle valve slightly or changing the turbine speed if it