Self-Regulating Freeze Protection Valves - expected life of valves

[hondashadow1100vt]

This posting is intended to request feedback on self-regulating thermally actuated freeze protection valves for non-heat traced, non-insulated water systems that are exposed to ambient temperature conditions.

I am a PE working on a construction project. My project includes an outdoor, non-potable, small water distribution system (total gallons <= 50 gal). Our local ambient climate is cold (i.e., down to -5 Degrees F). By client request this system is not heat traced nor is it insulated - instead the system was designed with a low point manual valve that will need to be opened in order to drain the system after each use. We recently received a request to add a level of reliable freeze protection (but not a manual drain valve approach nor heat tracing and insulating). This has led us to consider installation of a self-actuating thermally actuated freeze protection valve (i.e., a drain valve) that automatically opens to drain the system when the temperature reaches 38-degrees F +/-. This valve's integral actuator contains a wax that expands and contracts against a counterforce spring in response to changes in fluid temperature. This seems like a pretty nice mousetrap.

I have asked the valve manufacturer to indicate the expected life of the valve. The response is that many clients change these valves out every three (3) years although the valves have been observed in service for 8 to 10 years. The expected lift of the facility that we are constructing is 30-years. The difference in expected life of the valve and the facility presents an issue.

My questions to the group are:
1. What observed life of thermally actuated freeze protection valves have others observed?
2. What causes this type of valve to fail? Is there a way to engineer around the cause of failure (e.g., materials selection)?
3. Apart from heat tracing and insulating, or manual drainage, or freeze protection valves, is there another approach to freeze protection that I have overlooked?
4. I have identified only one manufacturer of this type of valve. Without asking for endorsement of any brand, what other manufacturers are out there?

I thank you very much for any/all feedback that you are willing to provide!

 

[MikeHalloran]

1. No info; never heard of the proposed valve, though it sounds like a good idea.
2. Wax-actuated engine thermostats are usually dependable for three years or so. ... they _often_ last much longer, but not _always_. Float operated automatic drain valves don't usually last even a year. Silt and other particulate contaminants cause problems by holding frequently operated valves open, and by gumming up infrequently operated valves so they won't open.
3. One other freeze protection strategy is an always-open drain orifice, small enough to be overpowered by whatever fills the system, say 1/8" diameter or so. But it will need a screen if mud daubers have access.
4. None known. It wouldn't be a violation of forum rules for you to reveal the identity of the one manufacturer you found, since I am, hereby, asking.

Mike Halloran
Pembroke Pines, FL, USA

 

[Ehzin]

An industry that would have quite a bit of experience on self draining valves for low temp is actually industrial safety. Safety showers and eye wash stations often come with these valves installed to establish a minimum flow to prevent an ice blockage. I'd recommend starting your search there to see what they use and then research the valves from there.

-Ehzin

 

[hondashadow1100vt]

MikeHalloran: Thank you for the suggestion to use an always-open orifice. I had not previously thought of the idea of using an always-open orifice -- For this application the end result would basically the same as using a self-contained thermostatically actuated freeze protection valve (i.e., both valves would probably split off a small portion of the city water flow during operation and then also self drain the system during non-operation periods). I will give that concept further consideration. In response to your question, the currently identified freeze protection valve manufacturer is Ogontz (

http://www.ogontz.com/)

-- their products seem pretty cool although I have not personally previously used them.

Ehzin: Thank you for your suggestion to give consideration to normal practices of emergency shower/eyewashes. I will look for precedent freeze protection practices from that industry sector. I appreciate the suggestion.