King Valve

JM_2

I am having a new Boiler installed and I want the installer to put a king valve like I have sen on some of Mad dog's photos. Does this valve need to be a Gate valve or can it also be a full bore ball valve. I know that the ball valve has some type of plastic bearing inside, will this breakdown with the steam heat?

Thanks
John Mahoney

Ken_8

That depends...

On the pipe size and the rationale for installing one in the first place.

Typically they are required only to allow isolation of each boiler (of two or more) from the system. In those sorts of applications (which are almost always commercial/industrial) we use OS&Y types. That style of valve (as well as gate valves) are arguably NOT a "positive stop" valve and depending on what you are trying to achieve, may be innapropriate and a rather expensive "option" at that.

Why do you want one?

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Mad Dog

I wouldn't use a ball valve as the teflon seals

will eventually deteriorate. I like an OS & Y or a gate valve. I put them only where people want the best and will be doing serious maintenance on the system. Ken, you cannot beat the complete blowdown of the boiler and all the mud legs and ports that the King valve affords. You can truly steam clean the whole pup. A gate valve will hold the steam back sufficiently to do a blow down. They don't go on every boiler we put in either - just the special ones. Mad Dog

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Ken_8

MD

"King" valves are not a style of valve. The name king valve implies a location on the near boiler piping. That location is the point at which all the risers off the boiler vessel (steam chest) finally join into a manifold (header) and anywhere from that collected single pipe we put a valve - THAT becomes the "king" valve. If one closes the "king" valve, no steam can enter the system resulting in complete isolation of that boiler's output; effectively "dead-heading" that boiler.

The term king is used because of the absolute hierarchy of valve functions. The valve that prevents or allows steam into the system is king! That's the basis of that name. There can only be one king valve on a boiler, and it is the highest "ranking", most sigificant one for each boiler - the one that lets the boiler energy to pass into the system.

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