In the GRP (glass-reinforced plastic) fire water piping system for seawater service, GRP pipe manufacturer recommended to install automatic air release valve at each high pipe in the system. I understand that Ni-Al bronze is suitable body material for seawater application. However, I'm in doubt whether we can use other material for competitive price with the equivalent corrosion resistance or not? Are there any manufacturers of ARV who can supply GRP body material? Please comment.

Be carefull about this. High points in a fire water system can be really dangerous with regards to water hammer.

Assuming that its a wet system heres what can happen:

U have deluge valves (and downstream dry deluge arrays and you have some fire water monitors at fairly high elevations with standpipes (wet).

The pressure in the ring main is maintained using jockey pumps with bleeds and the fire water pumps start on low pressure alarms.

When the deluge valves open then the pressure will drop and you may get collumn separation in the risers. When the pressure starts to increase when the fire water pumps gets up and running - bang!

You may argue that this is just what the air release valves will avoid - because the air that sucked into the system will not collaps when the pressure goes up - and this is correct. But then somy opens the monitor (while the system is pressurized) - and a valve has a very high capacity for air compared to water and you will get the same effect!

I have resently done surge studies just into this problem.

Air valve supplies sell valves. Of course they will agree with a higher quantity than you need. ARV software always over predicts the needs of a system.

Check out Haestad Methods Advanced Water Distribution Modelling and Management. The book is worthwhile. Haestad were giving away CDs of the book at recent exhibitions.

Prof ARD Thorley councils engineers that air valves can cause more problems than they solve. refer Fluid transients in Pipeline Systems. Check out www.ventomat.com for some article son their deployment.

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