[OMNI Valve] 1

[gguliye]

Dear All,
My question will be to those who have been using CROSBY OMNI valves for quite some time.
While reading its maintenance manual i have noticed the following things:
1) we dont have any soft kit between cap and base. what it means, the valve is prone to leak through the cap and cylinder when the valve open. Am I right?
2) I dont understand how guide is inserted to the base. is it threaded connection?
3) The disk insert is neither threaded, nor hold by circlip in the holder. How it stays there, by fluid pressure only?
4) Do we have any seals between the cylinder and guide?
5) how spindle is attached to holder? is it loose connection? the holder is in contact with the spindle with the help of fluid pressure?

 

[The Obturator]

Here are your answers;-
1) No gaskets are used in the OMNI design. It has been designed to keep those joints tight through greater machining tolerances on the surface areas f the joints. The valves joints are tested for integity at the factory. Testing is covered in the maintenance manual.
2) The guide is dropped into the body cylinder at assembly stage. It is not threaded. Having a flange on the end, the guide is held in place by the base (nozzle).
3) The Disc Insert is not held by anything. It cannot drop out as its thickness is greater than any lift. You will see that the lift of the valve is restricted by means of the internal "lip" on the inside diameter of the guide at its top. During assembly the disc (in the holder), is placed first into the guide, then the whole of this onto the base.
4) No seals.
5) No spindle to disc holder attachment - cannot fall out.

The OMNI valve was designed to be a low maintenance PRV with very few components. It has been in use sucessfully for some 28 years (replaced the JR/l, JMB/L valve types).

Hope that helps.

Per ISO, only the term Safety Valve is used regardless of application or design.

 

[gguliye]

avalveman,
thanks for ur broad explanation.
Most of the parts are clear, however, still it is not clear why disk doesnt fall down. suppose the thickness of the disk is 10 mm, and the valve lift is 3 mm. in this case the disk will move up 3 mm, and may fall down onto the base due to the gravity. I think the pressure of the fluid is the things which pushes the disk to the holder. Am I right?

 

[The Obturator]

Yes, you're correct. The disc will be held closed against the seat by the spring in all non-overpressure cases.

Per ISO, only the term Safety Valve is used regardless of application or design.

 

[gguliye]

thank u very much