Rising stem VS OS&Y valves

[hyari]

Hi ,

is there any difference between the Non rising stem valve & OS&Y valves ? i see some time some ppl used rising stem description and others use OS&Y valve description

Thx
Ahmad

 

[hydrae]

In a Rising Stem (RS) the thrust bearing is inside the valve and the operating wheel rises as the valve opens, the bearing is lubricated by the fluid inside the valve.

Open Yoke and Stem (OS&Y) has the thrust bearing outside the valve so may require external lubrication, but it is very easy to see the valve position. This valve also takes more room to operate. The operating wheel does not change vertical position at the valve is operated.

Non rising stem (NRS) does not indicate the position of the valve and is typically buried, this valve remains the same size no mater what the position is nor does the operator wheel or nut move vertically. The thrust bearing is lubricated by the fluid.

Hydrae

 

[LittleInch]

http://www.eng-tips.com/viewthread.cfm?qid=381825

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[bimr]

Yes, depends on the application.

Non-rising stem valves are primarily used on gate and globe valves with cast-iron materials used in water applications with low pressure/temperature requirements. Non-rising stem valves cannot be lubricated externally and require a higher torque.

http://www.eng-tips.com/viewthread.cfm?qid=16760