Valve "Closeoff Pressure" Definition

[2Evil4U]

Hi! I working on an emergency water shutoff system for my home and have settled on either a Johnson Controls JT2323G23B020 or JT2323H23B020 Normally Open, 120V, actuated valve.

The unit's lit, see

http://www.johnsoncontrols.com/cg-valves/selection_guide/publ3510.pdf)

states that the valves have a working pressure of up to 300psi which is more than adequate for what I need. I'm confused by the "Closeoff Pressure" rating. The G series is only rated at 25psi closeoff and the H series is rated at only 30psi closeoff.

I've Googled everything possible and searched all over this site and have found nothing to define exactly what Closeoff Pressure is.

Can anyone shed some light as to what the "closeoff" rating means to the actual operation of the valve?

Thanks!

 

[DRWeig]

Hiya 2Evil,

Closeoff is how much differential pressure the valve / actuator combination can overcome in order to seat the valve and stop flow completely. The valve you're looking at is meant for small differential pressures -- a circulating system for heat or cooling. Its spring (or motor) can only apply so much force against the water pressure difference across itself.

If you have typical domestic pressure (100 PSI maybe) and you're wanting to shut off in case of a major leak (near zero pressure), you'll have almost the full system pressure to close off against.

Since you're in the Johnson Controls book, look at their ball valves. You should be able to find a non-characterized, full-port ball valve in the appropriate size that will handle 100PSI plus.

Let us know what you come up with!

Old Dave

 

[2Evil4U]

Aahhh. So effectively, if the system is not flowing any volume, there is no differential pressure across the valve and the unit will be able to cycle normally.

I think it will work for what I need. My house is below sewer-grade and it has a 60 gallon effluent ejector pit in a corner of my finished basement. Twice in the last few months people have flushed things that jammed the pump impeller. The last time, the audible alarm failed at the same time. So, since we don't use the basement all that often, we went for about 24 hours fat dumb and happy and ended up ruining the carpets downstairs.

What I'm going to use this for is not so much leak stop, but when the emergency float in the ejector pit activates, it will turn on power to the valve and shut down the water supply to the house. Then not only will it not be able to overflow, you'll know immediately when you try to run water that there is something amiss.

Thanks!

Aaron

 

[DRWeig]

Say 2Evil,

If you're closing your valve during a no-flow condition, you are correct. It will shut. However, during flow, or if pressure is allowed to drop on the downstream side (someone opens a faucet) it won't be able to deal with the difference in pressure and will not close all the way.

It may work for you anyway, you might be able to notice a substantially reduced flow rate when you open a faucet, etc...

Good luck!

Test it out and tell us how it performs!

Old Dave

 

[2Evil4U]

Well, the Aquapex connectors arrived and they look good. The valve arrived today and it is not so good. The Johnson Controls people butchered their own part number when they transcribed it from middle-man to JC and I ended up with a normally closed 1/2" NPT, 24V, low close-off valve instead of the normally open, 3/4" NPT, 120V high close-off model I actually ordered. They apologized and will be Fedexing the correct valve with a prepaid return box for the other one.

Hopefully, second time's a charm.

 

[jsummerfield]

For a control valve, shutoff pressure is the differential pressure accross the valve when closed. The shutoff pressure is used to calculate the seat loading for actuator sizing.

Seat load, (pounds per lineal inch of port circumference)
is determined by shutoff requirements. Charts and tables for certain valves accommodate various leakage classes per ANSI/FCI 70-2-1991.


John

 

[NGiLuzzu]

Just for information: the latest valid revision of the standard mentioned by jsummerfield is FCI 70-2-2003 (see also Thread408-76110 and other leakage class related discussions).
The equivalent European standard is IEC 60534-4 (1999).

Bye, 'NGL

 

[2Evil4U]

Well the correct valve arrived last Monday. HVA products, where I purchased the valve from was a bit pushy about shipping the other unit back, but otherwise they've been OK.

I installed the unit this morning and it looks like it's going to work perfectly. I had to buy some thread sealing goo because the plastic fittings would not quite seal their threads to the brass valve body.

After installation I turned on a tub faucet, a sink faucet, and flushed two toilets. The valve was able to completely shut off in about 10 seconds after I put power to it.

Now I just have to wire it into the emergency float system in the septic ejector pit and I'm good to go.

Thanks to all for the help!

Aaron