Spring Return Valves 1

[vacuumdesigner]

Has anybody heard of a vendor that deals in manually operated, spring return open, 6" and 4" NPT valves for a low mass flow application?

 

[dcasto]

Whats going to hold the spring in compression.

Bettis actuators and others like them can be set up that way to work on lots of different valve bodies.

 

[vacuumdesigner]

I'm not trying to hold the valve closed, I want it to "fail" open. What I'm trying to do is set something up to meet the follow terms:

There is a flow meter setup in parallel with the main discharge of a vacuum pump. My client wants to, about once a month, walk up to the discharge, pull this valve closed, redirecting the discharge through the flow meter, take a measurement, and let the valve go, returning the system to normal operation.

My current vendors keep trying to get me to go with some type of actuator, but my client wants a manual valve.

 

[nonic]

It appears what you are looking for is a "dead-man handle" and generally used on ball valves, tho' typically they are normally closed. I don't see why it couldn't be configured as normally open. Often you will see this type of spring return handle assembly in conjuction with a fusible link for a "fire safe" application.

I know of a few mfg'rs/distributors who should handle this product. What area are you in and maybe I can steer you in the right direction if that is allowed here.

 

[vacuumdesigner]

I'm in the industrial vacuum industry in NW indiana. I've spoken with quite a few vendors on this subject, and they say that nobody makes anything like that in a size larger than .5" NPT. So any help in that direction would be greatly appreciated.

 

[nonic]

The sizes of your valves could produce a challenge. What type of valves were looking to use? Service conditions?

Depending on the size and type of valves used the "spring mechanism" could be quite large to overcome valve opening/closing torque. Unless your client is a very big gorilla, more than likely a gear operator in conjuction with the spring would be specified.

Be warned that this type of mechanism has been known to break fingers/arms etc. if mis-handled.

 

[dcasto]

The answer to my question about what is going to compess the spring is your clients arm. If you specify a 6" ball valve, the torque required will be fairly high (to assur proper return and sealing) and so the spring will require a lot of force to overcome so your client should start lifting weights. I'm being slightly sarcastic. What I fail to see why spring return, if your client could open the valve manually, it'll take less effort to close the valve manually versus the effort to overcome the spring. A manual butterfly valve or an actuated one if your client is not in shape.

 

[vacuumdesigner]

You guys are shouting the same litany that I have presented to my boss and that every vendor I've spoken to has presented to me. If they can close it, why can't they open it? Nevermind that whole torque issue. But I was asked to research a way to do what they want to do and see if it's possible, so that's what I'm doing. I do appreciate the help though guys, I really do.

 

[dcasto]

Put a long handle on the valve, weld an piece of steel to the line, go to the hardware store and get a whole bunch of door springs and connect them to the handle and the supports. The problem is just like your old screen dor, the pounding of the valve will cause a failure, get an acctuator designed to control the closing and increase the life of the valve. (hint another talking point)

PS I am not judging you as the messanger and I understand. Fisher valve makes a 3" snappy Joe valve that could be changed (i'd bet) to a fail open spring valve.

 

[danw2]

Is there some reason they can't plumb the flow meter directly in the discharge line so it runs cotinuously and then look at the meter reading only once a month?

 

[vacuumdesigner]

Primary discahrge for the pump is 6" NPt, the flow meter is only 1" NPT. At the time of the test mass flow will be very limited (no more than 30 cfm) but during normal operation the mass flow could become much higher, the pump itself is 950 cfm under normal operating conditions. The 1" NPT is just too small for normal operating.

 

[nonic]

Check out the links below...

http://www.bitorq.com/fusible_ht.html

http://www.bitorq.com/deadman_handles.html

 

[vacuumdesigner]

Thanks nonic. The first link doesn't quite look up my alley, but the second one looks pretty dead on!

 

[nonic]

The only situation is their deadman handles are limited to the size of valve you can use.

The fusible link assemblies use the same concept, difference is they have the "link" retaining the handle in position (against the spring). You could possibly use this style, just disconnect the fusible link.

Good luck.