Spirax Sarco KBV21i/KBV40i Key-Operated Boiler Blowdown Ball Valves

There are essentially two valve versions: the standard-pressure version and the high-pressure version. KBV21 and KBV21i are different designations for the same product, with i being the official international model designation. The same applies to KBV40 and KBV40i. KBV21i is suitable for PN40 conventional industrial boilers, while KBV40i is suitable for ASME Class 300 high-pressure systems.

Both are key-operated blowdown ball valves with the same safety mechanism. However, KBV40i has a heavier body and flanges for high-pressure flanged piping. The cold hydraulic test pressure is 60 barg for KBV21i and 76.5 barg for KBV40i. For larger nominal sizes, an extended T-handle operating key is generally recommended for KBV40i.

There is no permanently fixed handle on top of the valve. A standard key or extended T-handle key must be inserted to operate the valve. The operating key can be removed from the socket only when the valve is fully closed. When the valve is open for blowdown, the key is mechanically locked in place to prevent incorrect operation that could leave the blowdown valve continuously open.

Available nominal sizes are DN25, DN32, DN40, DN50, and DN65. KBV21i is available with BS4504 PN40 or BS1560 Class 300 flanges; DN32 is available only in PN40. KBV40i is primarily suitable for ASME Class 300 high-pressure flanged connections.

For the same nominal size, the internal spare parts kits for KBV21i and KBV40i are interchangeable. They include the stainless steel ball, carbon/graphite-reinforced PTFE seats, stem seals, and gasket assemblies. When ordering, specify the model, nominal size, and application.