... "2) Working Medium: air, water, oil, gas, LPG, natural gas,coal gas,firedamp3) Action Type: direct action4) Valve Body: 2W: Brass or 2S:Stainless Steel5 ... ) Valve Control Style: NC(normal close), NO ... (normal open)6)Orifice Size:2.5,4,,16,20,25,35,40,507 ...