Why would a pressure relief valve fail like this ?

[Zkittlez]

Hello im a new member and hoping for some experienced advise

Im a plumber with 12 years experianced and have recently started working in a super luxury 35 story tower block in london all very expensive

Anyway a prv on the hot water exploded the other day inside a riser cupboard and flooded the entire building. 12 bar of pressure was behind this leak.

By looking at the photos you can see the plastic head of the prv has blown off causing £££££ of damage.

Why would this happen ?

Will it happen again ?

Can anything be done to prevent it ?

Should this valve be serviced in any sort of way ?

Thanks alot

 

[snowhead]

The obvious answer is that the 12 bar or maybe actually higher at the time of failure exceeded the maximum pressure of the valve.
Is it on the HOT, ?
Have you checked to see the max working pressure AND TEMPERATURE for the valve, what make is it?

And untill a positive answer is found I'd say all similar PRVs in the building are at risk of failure.

 

[adonis]

Are there any expansion vessels that have lost their air?

 

[ShaunCorbs]

Could of been knocked on install and had a crack in it ?

 

[Chuck]

Is the 12 bar supply from a pump? Faulty pump controller perhaps?

What make is the PRV? Is it genuine or counterfeit? If it's a decent brand contact the manufacturer and ask their technical dept for advice.

 

[Zkittlez]

The obvious answer is that the 12 bar or maybe actually higher at the time of failure exceeded the maximum pressure of the valve.
Is it on the HOT, ?
Have you checked to see the max working pressure AND TEMPERATURE for the valve, what make is it?

And untill a positive answer is found I'd say all similar PRVs in the building are at risk of failure.

Yes its the Hot , was fitted by contractors a while back and we have zero information on the valves , not even a make let alone any specifications , i will upload a photo of an unbroken prv incase anyone is able to ID it thanks again

 

[Zkittlez]

Is the 12 bar supply from a pump? Faulty pump controller perhaps?

What make is the PRV? Is it genuine or counterfeit? If it's a decent brand contact the manufacturer and ask their technical dept for advice.

Yes 12. Bar from the pumps. Currently trying to identify the valve manufacturer

 

[Zkittlez]

Could of been knocked on install and had a crack in it ?

Is a possibility but has been there for 7 years.

 

[John.g]

Slightly shocked to see a plastic safety valve but I suppose its OK if I call it a PRV.

 

[Todd Springer]

Water pressure pushes up on the diaphragm that is captured within the bell (missing part). The spring pushes back on the diaphragm, allowing pressure to be adjusted/balanced. More pressure on the spring means more pressure pushing the bell away from the housing. This could cause the connection to fail. HOWEVER, these things are usually rated for high incoming pressure, although the ones I'm used to seeing are brass. For example Watts 3/4" PRV's typically come with a 300 psi (20.6 bar) ax inlet rating.

 

[Knappers]

12bar?
Plastic prv?
I'd be checking spec on those.

Maybe it's just modernisation but I didn't really see this style of PRV untill I moved over to domestic, give me a proper brass valve pls

 

[SimonG]

Pressure reducing valve not pressure relief. Majority are plastic nowadays.