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FE nut keeps coming loose


15 Mar 2011
Been using a FE for quite a while now, every time I refill it, I replace the fibre washer with a new one (all from the same batch).

The previous refill, it was on the tank for about a month, when I heard a hissing sound, and had to tighten the main regulator nut onto the FE.

I thought it was a fluke that it came loose and I couldn't have tightened it as good as I thought I had.

I refilled the FE, replaced the washer, made sure it was very tight, and was surprised how quick the FE ran out. I went to remove the FE and the reg was loose on the FE.

I was advised to use the fibre washers in around 2011 by someone on this forum and up until the last two refills, they have worked fine. I wouldn't have thought unused fibre washers deteriorate, they look fine?

Are there better washers I could try please?

It's a D-D thread converter going onto a normal FE




Global Moderator
25 Jan 2012
Wouldn't use fibre washers, they will certainly leak with pressurised gas, the plastic/rubber in the washer will be attacked by the CO2. Probably fine for a normal use ie 30seconds putting out a fire, but not for prolonged used at 800psi.

For CO2 must be plastic type washer, usually Teflon based. My current regulator came with a Teflon washer and when I got my last two FE's I was given a spare Teflon washer just in case my next regulator didn't have one.

I don't check for FE leaks with soap and water, just open the FE with regulator solenoid off, then lock FE handle closed and leave over night. In the morning if the pressure gauge is not 800psi (or at the permanent marker pen mark on the dial I have) then there is a leak.

What you need is something like this (22m diameter)
Buy Sealing Washers ISO metric nylon 6.6 sealing washer,M10 RS 6110771 online from RS for next day delivery.
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