Caliber Valves Pvt. Ltd. Offers FS Non Return Valves. Caliber Valves Pvt. Ltd. Is an ISO 9001-2000 certified company. The FS Non Return Valves are used in different industries. Specifications of FS Non Return Valves are: Complies BS 5352 Sizes 15mm to 50mm Material Forged Steel - ASTM A105 Trim 13 percent Cr Steel / AISI 410 Type Lift Type, Bolted Cover, Horizontal Rating Class 800 Ends Screwed / Socket Weld / Butt Weld - Class 800