Drain screw on CAV filter bowl

[MJWB]

My CAV filter has solid bowl not glass. At the bottom is a drain screw. That currently has what appears to be a copper washer which I assumed was supposed to help seal when the screw plug is tightened. I am not mechanically minded but learning.
In the last couple of years when I've changed the filter, refitted the drain screw and tightened it up there hasn't been any leak. I changed the filter and reassembled in December and now find there is a leak. I'm almost certain it is around the drain screw as I can't find deisel anywhere else on the unit. I note that the air bleed screw washer on the top of my unit also appears to be copper coloured.
These were what was in place when I got the boat in 2020 and I've re-used them as there is nothing in the seal kit to use.
Is this the correct washer on the drain screw and should it prevent leaks? It isn't now.
Should I replace it with something else more appropriate?
Many thanks.

 

[peteK]

Fibre washer should be ok as that is what I have.

 

[MJWB]

Would a rubber washer be okay or would the deisel degrade it?

 

[VicS]

My CAV filter has solid bowl not glass. At the bottom is a drain screw. That currently has what appears to be a copper washer which I assumed was supposed to help seal when the screw plug is tightened. I am not mechanically minded but learning.
In the last couple of years when I've changed the filter, refitted the drain screw and tightened it up there hasn't been any leak. I changed the filter and reassembled in December and now find there is a leak. I'm almost certain it is around the drain screw as I can't find deisel anywhere else on the unit. I note that the air bleed screw washer on the top of my unit also appears to be copper coloured.
These were what was in place when I got the boat in 2020 and I've re-used them as there is nothing in the seal kit to use.
Is this the correct washer on the drain screw and should it prevent leaks? It isn't now.
Should I replace it with something else more appropriate?
Many thanks.

Would a rubber washer be okay or would the deisel degrade it?

If they are plain copper washers either replace them or anneal them every time.
They can easily be annealed by heating to a dull red for a few seconds and allowing to cool ( or quenche d in water if you are in a hurry)

Maybe they are what used to be "copper and asbestos" washers ... in which case replace them.
Fibre washers will be OK but they won't last for ever.

O rings for diesel must be nitrile rubber bur really should only be used if the drain/ vent screws are designed for O rings. They would have to be replaced every time

 

[PCUK]

Take the old copper washer off, heat it to cherry red on the boat hob and dunk it into cold water. That will Anneal (soften it) and should then work fine again.

 

[Plum]

My CAV filter has solid bowl not glass. At the bottom is a drain screw. That currently has what appears to be a copper washer which I assumed was supposed to help seal when the screw plug is tightened. I am not mechanically minded but learning.
In the last couple of years when I've changed the filter, refitted the drain screw and tightened it up there hasn't been any leak. I changed the filter and reassembled in December and now find there is a leak. I'm almost certain it is around the drain screw as I can't find deisel anywhere else on the unit. I note that the air bleed screw washer on the top of my unit also appears to be copper coloured.
These were what was in place when I got the boat in 2020 and I've re-used them as there is nothing in the seal kit to use.
Is this the correct washer on the drain screw and should it prevent leaks? It isn't now.
Should I replace it with something else more appropriate?
Many thanks.

Mine has the plastic drain screw with a "rubber" (thermoplastic elastomer) sealing washer. CAV Spares, CAV Fuel Filter Drain Bung

www.solocoastalsailing.co.uk

 

[Porthandbuoy]

I drilled and tapped the bowl then fitted a small ball valve. No mess draining of the bowl

 

[jdc]

A tip when annealing a copper washer; don't drop it in water to quench it, but in meths. And, no, it doesn't catch fire but comes out untarnished.

I was taught this trick when working on High Vacuum systems (< 10^-9 torr), building a particle accelerator when leaks, even tiny ones, would be a disaster.

 

[Boater Sam]

A tip when annealing a copper washer; don't drop it in water to quench it, but in meths. And, no, it doesn't catch fire but comes out untarnished.

I was taught this trick when working on High Vacuum systems (< 10^-9 torr), building a particle accelerator when leaks, even tiny ones, would be a disaster.

Getter ion pumps to get below 10-9 torr ?

 

[jdc]

Yes, roughing pump first, turbo-molecular 2nd and getter last. Folded tandem accelerator, as used to date the Turin shroud among others...

 

[smithy]

Use dowty seals or bonded washers, far easier to seal than copper washers.

 

[ean_p]

A tip when annealing a copper washer; don't drop it in water to quench it, but in meths. And, no, it doesn't catch fire but comes out untarnished.

I was taught this trick when working on High Vacuum systems (< 10^-9 torr), building a particle accelerator when leaks, even tiny ones, would be a disaster.

Is the tarnishing ( or lack of) the only difference?