Was: Shaping rubber and rubber balls: Update
 

Hi all,

I just thought I let anyone who offered help re my previous post know
where we as of just now. ;-)

Recap. Bambi 75/150 Silent compressor, not been used for a few years,
now slightly leaking (back into the pump) and the pump not starting
back up when under pressure.

I removed the one_way_valve between the pump and the tank/pressure
switch and found it was a simple spring loaded rubber 'bullet' that
was gently pushed into it's conical seat by a reasonably light spring,
opened simply by the pump pressure.

When the pump stopped the valve leaked air back from tank to pump 1)
loosing tank air pressure and 2) stopping the pump from re-starting
(till the pressure dropped to about 40 psi).

The cause seemed to be an indentation across the sealing face of the
rubber 'valve' (probably caused by some long-term trapped debris).

I had been considering different ways to gently and symmetrically
re-face the valve but being only 10mm diameter and 10mm long (and
rubber) it wasn't that easy, till just now. ;-)

I was doing something else and dug out a hex drive socket set and
found said rubber valve fitted quite nicely inside the 9mm hex driver.
I put that in the variable speed drill and after a bit of manual
re-centering, used various grades of paper (down to 240) to do the
re-facing.

I put the valve back together (using an O ring as designed, not the
PTFE tape as I found it) but it was still leaking back *slightly*.
Partially releasing the pipe from the pump to the valve, bleeding off
the pressure in the hose seemed to stop it leaking completely
(probably the increased pressure on the back of the valve). The pump
would also restart after this procedure (there is no dump valve on
this design because it would be too noisy).

I stripped the valve again and slightly stretched the compression
spring to apply a bit more pressure to the valve [1] and that has
fingers crossed seemed to have done it! ;-)

When the pump switches off you can still hear some air leaking back
into the pump but that is simply the pressurized air trapped between
the pump and valve relieving itself (ready for the next re-start).

I'm glad I seem to have sorted it as a new valve was 19 quid but the
postage another £19 (it could have been £30 as there was a minimum
order of £50)! :-(

Anyway, all the best and thanks again. ;-)

T i m

[1] If it starts to leak again I'll probably look for a replacement
spring.