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Old 15 June 2014, 07:30   #1
DGR
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Pressure Release Valves

Quick question - when a pressure relief valve operates, I've always assumed that it vents excess air to relieve pressure, and then reseals/stops venting - is that right?

When I went to the RIB today in the club compound - one tube compartment is flat, with the entire centre of the pressure relief valve missing.

Current thinking is that it's either:

1) malfunctioned and blown itself out completely, or

2) somebody's nicked it...

I suspect 2 - as I can't find it in the boat (or anywhere around it).

D...
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Old 15 June 2014, 08:45   #2
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Do you mean the whole valve has gone? Is the white threaded screw on part showing through the hole? If so then someone definitely unscrewed it as it would never blow out.
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Old 15 June 2014, 11:16   #3
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No - the main outside black bit is still there - it's the actual valve bit in the middle (i.e. ~10mm diameter bit in the very centre) that's gone. The outside black bit is still firmly attached to the tube and inside (white?) bit, but where the middle bit was, there's now just a hole, which I can just about stick my finger through.

It feels like there's a lip or ridge around the inside which would hold the working bit of the valve - but nothing there.

Looking at the clips on how to clean them etc on youtube, it's the sprung bit that's missing - but it doesn't look like a part that you'd be able to take out or swap - but it also doesn't look like it should be able to blow out completely and vanish. Really odd.

D...
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Old 16 June 2014, 05:37   #4
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I had one fail in the way you describe a few years ago, it was a Leafield A6 pressure release valve. It was a very hot day and I was working on the engine in the drive. I can only assume the valve had stuck, because it suddenly let go with an almighty bang and the tube section went flat. The valve must have come un-stuck with enough force to break the plastic retaining piece, the valve is angled down towards the deck but it came out with enough force to hit the deck and ricochet up onto next doors roof. Fitting a new insert is very straight forward and I always carry a spare and a blanking cap now just in case.

Keith
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Old 18 June 2014, 08:12   #5
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Hi Kwil,

I think that must be what's happened - although I didn't think that the tubes were inflated that hard, but it was a hot day - and it would explain why I can't find the bits!!

It was an A6 valve as well - I've ordered a new one, so hopefully I'll be back in business by the weekend...

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Old 18 June 2014, 11:07   #6
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Pressure release Valve question.

Hope i can ask my question as it's connected to the same subject.

My SR4 is now installed in the Lakes with a breathable reflective cover.

I'm sure that the valves installed are for blowing up only.

I've left the tubes slightly soft but still fairly firm. The air temp was around 20 when i did this on a sunny day.

If the tubes get too hot, do they just burst i assume?

How easy is it too fit a pressure relief valve?

THanks
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Old 18 June 2014, 11:35   #7
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Just drain the tubes until they are floppy, there's no reason to keep the firm or sorta full or anything like that. Adding relief valves is not that easy a job (at least given what's available over here)

And yes the tubes can pop/rip. Its not pretty and they might require replacement so can be very expensive.
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Old 18 June 2014, 11:38   #8
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Thanks Capnjack, i'd better get up there sharpish and let some pressure out then!

Sheesh, with hindsight i may have left them too firm.
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Old 18 June 2014, 12:07   #9
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If you have them they will look like this....one with cap for pumping up and one next to it without is release valve.
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Old 18 June 2014, 12:09   #10
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Deff not got those.....

How hot does it need to get before the tubes pop..................

PS, what does S.A.B.S stand for please?
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