Hey Gary, it's basically still a gate valve, but without the fine adjustment capabilities.

Thanks Tony.

I wasn't sure because I've never heard of a knife valve before.

Yeah, don't waste your time with knife/gate valves that are slide in / out - very hard to truly fine tune... Unfortunately I haven't seen any pvc gates with a threaded adjuster in calgary - anyone seen em?

Here...they are referred to as "Knife Gate Valves". So they are basically a type of gate valve.

http://www.usplastic.com/catalog/pro...uct%5Fid=19532

Internally they are both the same as they rely on a "gate" vertical flat disk LIKE A GATE that raises and lowers by means of either a screw mechanism (gate valve with hand wheel) or sliding action (knife Gate).

A Globe valve is a valve with a linear motion, push-pull stem, whose one or more ports and body are distinguished by a globular shaped cavity around the port region. This type of valve is characterized by a torturous flow path and is also referred to as a LOW RECOVERY VALVE because some of the energy in the flow stream is dissipated; and the inlet pressure will not recover to the extent that it would in a more streamlined HIGH RECOVERY VALVE.

Just posting links to the place you got this info from for others who might be interested. :)

http://www.maintenanceresources.com/...inologyPg1.htm

http://vaveco.be/Valves%20Concepts/T...nologyPg1.html