Compressors- leaving under pressure?

[Brian Reay]

I have a portable compressor- one of the ones Machine Mart sells (or
sold about 8 years back, I expect the still sell similar models). It has
a storage tank etc and does all I need. (The air pumps on garage
forecourts are limited to (something like) 60psi and I need 80 for our
motorhome.) I use it now and then, just to top up the tyres on our
vehicles, the trailer, and the odd air tool.

My concern is, it is rather loud and, while I don't use it often and I'm
always careful about when I use it etc, it seems wasteful (for want of a
better word) in terms of noise, to bring it up to pressure, top up all
the tyres etc, and then empty it (including the 'drain valve'). I've
noticed, having got to pressure, typically, it will start up once during
use for perhaps a minute, maybe two. While I check my tyres far more
often, they only need topping up perhaps twice a year, three at most.

Would it be safe to leave the compressor pressurised between uses?

[Richard Edwards]

 I have a portable compressor- one of the ones Machine Mart sells (or
sold about 8 years back, I expect the still sell similar models). It has
a storage tank etc and does all I need. (The air pumps on garage
forecourts are limited to (something like) 60psi and I need 80 for our
motorhome.)  I use it now and then, just to top up the tyres on our
vehicles, the trailer, and the odd air tool.
My concern is, it is rather loud and, while I don't use it often and I'm
always careful about when I use it etc, it seems wasteful (for want of a
better word) in terms of noise, to bring it up to pressure, top up all
the tyres etc, and then empty it (including the 'drain valve'). I've
noticed, having got to pressure, typically, it will start up once during
use for perhaps a minute, maybe two. While I check my tyres far more
often, they only need topping up perhaps twice a year, three at most.
Would it be safe to leave the compressor pressurised between uses?

IMHO there is no reason not to leave it on pressure, however it is
always possible that there is a small undetectable leak and it will be
at low pressure when you next use it. BTW do not forget to drain once in
a while.
Changing the subject it is worth checking your axle loadings when loaded
for normal travelling. At a weighbridge check the rears and the fronts
separately. You now have the confidence to know you are not outside your
plated maximum but also can speak to your tyre supplier and determine
the correct pressures. MH suppliers seem to spec 80psi all the time,
probably because they know people overload. My van is specified at 80psi
all round but I run at 50 psi on the front based on axle loading and I
get a better ride and more even tyre wear.
Richard

[Brian Reay]

Post by Richard Edwards

  I have a portable compressor- one of the ones Machine Mart sells (or
sold about 8 years back, I expect the still sell similar models). It
has a storage tank etc and does all I need. (The air pumps on garage
forecourts are limited to (something like) 60psi and I need 80 for our
motorhome.)  I use it now and then, just to top up the tyres on our
vehicles, the trailer, and the odd air tool.
My concern is, it is rather loud and, while I don't use it often and
I'm always careful about when I use it etc, it seems wasteful (for
want of a better word) in terms of noise, to bring it up to pressure,
top up all the tyres etc, and then empty it (including the 'drain
valve'). I've noticed, having got to pressure, typically, it will
start up once during use for perhaps a minute, maybe two. While I
check my tyres far more often, they only need topping up perhaps twice
a year, three at most.
Would it be safe to leave the compressor pressurised between uses?

IMHO there is no reason not to leave it on pressure, however it is
always possible that there is a small undetectable leak and it will be
at low pressure when you next use it. BTW do not forget to drain once in
a while.
Changing the subject it is worth checking your axle loadings when loaded
for normal travelling. At a weighbridge check the rears and the fronts
separately. You now have the confidence to know you are not outside your
plated maximum but also can speak to your tyre supplier and determine
the correct pressures. MH suppliers seem to spec 80psi all the time,
probably because they know people overload. My van is specified at 80psi
all round but I run at 50 psi on the front based on axle loading and I
get a better ride and more even tyre wear.
Richard

Thank you for the response.

I expect there will be some loss of pressure, few things are perfect
seal wise. I'll leave it pressurised next time I use it.

OK re axle loads etc.

80 psi all round is a bit high, 80 / 72 psi seems to be more or less
'standard'- at least for the recommended pressures on the Fiat chassis.
The trade off between pressure/load and 'ride' is a common topic on the
various mh forums. I've tended to follow the recommended pressures and
been happy with the ride, both on our previous and new mh.