On Mon, 25 Jul 2016 09:54:31 +1200
RussellMc <apptechnz@gmail.com> wrote:

> What are the common features in a compressor on/off switch?
> And, are they common enough to allow substitution with ease or wit due ca=
re?
> What do you need to look for?

>From what I read, there are basically two large families - one which
has only one high-pressure port which sits directly on the reservoir,
and one kind which also distributes the air - Inport: reservoir,
Output: Pressure sensor, manometer, and one aux port, which isn't
used very often.

In the latter category, there is also a venting port which unloads
the remanent pressur in the tubing.
=20
> Does it seem likely that the pressure from the compressor is now 'working
> backwards' and causing the switch to return to the on position?

I don't think so. The back (=3D unload) pressure, was quite weak, but the
retaining force of the circular spring was almost non-existent.

> Or is it more likely to be a breakage of a detent or similar with a swrin=
g
> performing the return action. (John probably has a better understanding f=
or
> this as he can see & feel what is happening).

These 'economic' compressors, are not really designed to be repaired and
use really cheap materials. Some years ago, the pressure regulator valve
broke down, and I repaired that one too - changed the membrane with an
improvised one... Still works. Thing is, the spring was oxidising because
of the condensation.

> Is there liable to be a similar range of pressures and pipe sizes and
> fittings at the switch which allow easy substitution. Or are there
> mechanical or pneumatic aspects which make this likely to be infeasible?

As far as I can see all these compressors work in the same range (90-120 ps=
i),
though some (very few) advertise 'extended range' switches. Again, from=20
the adds I've seen all use 6mm tubing, same diameter as the hose.

This one is very similar to mine:
http://unfilterednewsnetwork.com/wp-content/uploads/2016/01/c.jpg
=20
> What would happen if a simple inline switch was added?

Switching off only the motor has the disadvantage that the (air) line
from the pump to the reservoir retains the full pressure. It can present
a high load to the motor when switching on again (this pressure is
also present in normal operation, but inertia of a fly wheel - in case
of larger compressors - or motor's rotor takes care of it then)


Anyways, much of this is guesswork. I do love this thingie... Used it
for many tasks...

John

--=20
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