Icing under pressure? 1

[cctdiag]

Gents

I have a watermist fire extinguishing system which states 'Protect from freezing'. It has a water filled sensing line charged at about 50 psi, this in turn fires a bank of water filled cylinders at 200 psi.

The installation is in an unheated generator room, so what I would like to know is, will the increase in pressure of the sensing line & water stored bottles affect the freezing temp of the system water.

thanks

 

[BobPE]

cctdiag:

In short the answer to your question is no, pressure will not affect the freezing of water in that system. Water, however is a very strange liquid so your thoughts are not too far off. Unfortunately it takes far greater pressures to alter the fundumental characteristics of water we are used to seeing in our every day experiences. Water at extremely high pressures in a lab environment will actually support the ignition of a match and sustain the flame....and it gets stranger. Unfortunately, your pressures are quite common in water engineering and will allow whatever is exposed to freezing temperatures to freeze solid.

BobPE

 

[Mistmaker]

Besides, I would not fiddle around with the pressure in a water mist system without consulting the manufacturer first. Increasing the system pressure most likely leads to a decrease in the water discharge (=protection) time offered by the system. If you have an approved water mist system which is altered from how it was originally designed, in case there is a fire resulting in severe damages you might end up in trouble with your insurance company. Working for a water mist company I know even a small change in a system can have a huge effect on how the system accomplishes its task of extinguishing or suppressing a fire.

 

[saxon]

Mistmaker, As Bob has said, "no". Above critical pressures fluids can do strange things out of the ordinary, but in fire suppression systems, this elevated pressure is never reached and if you did try to reach this pressure the system would have failed long before you reached it. So, if the system is exposed to any tempratures below freezing, for any length of time, heat tracing and insulation will be required, but only on those portions exposed to the freezing temps..

saxon

 

[Mistmaker]

Saxon, I understand changing the pressure would not help. What I just tried to say was that you should never alter the design of a fire suppression system in any way without consulting the manufacturer first. Sorry if the answer was a little confusing.

By the way, there might be suitable anti-freezing agents available to lower the operating temperature below freezing point. Again, consultation with the manufacturer prior to making any such modifications is strongly advisable.