Outside screw and yoke

OS Y Valve A type of outside screw and yoke valve used on piping or in pits connected to sprinkler systems. The position of the stem shows the valve to be eidier open or closed. Osteroporosis a condition in which bones become very fragile. 

Gate valves (rising-stem, outside-screw-and-yoke). 

Most process gate valves are specified with an Outside Screw and Yoke because of the corrosive and high temperature service encountered in process streams. For noncorrosive service, the thread can be inside the valve body, screwing into the body like nonrising stem gate valves and small globe, angle, Y and needle valves. 

Valves in pipelines supplying fire-protection water are generally required to be indicating valves. These include underground gate valves with indicator post, underground butterfly valves with indicator post, and outside screw and yoke (OS Y) gate valves. 

Screwed or flanged joints should be kept to a minimum, and cast iron or malleable iron fittings and valves should not be used nonar-mored porcelain valves must not be used, regardless of the pressure with either liquid or gaseous phosgene. Only outside yoke or rising... 

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