Compressor Workings

The unloading valve does not vent the air receiver, it vents the compressor exhaust. It goes between the compressor exhaust and a non return valve on the air receiver. The idea is that the cylinder retains its air, but when the motor starts, the compressor exhaust is vented to atmosphere. This allows the motor to get up to speed more easily. Once the unloading valve closes, the air goes into the air receiver.

HTH Mark Rand RTFM

Many thanks for the explanation Mark, I presume the non-return valve is what Sealey refer to as the Check Valve. As my compressor is a much lower power than the Sealey and has a self-mating port from the compressor body straight into the air receiver I guess the concern of starting the motor isn't so great. So do you think should I just leave the pressure switch unloading port unconnected?

Next to source the brassware to connect the bits together. There look to be many possible sources having Googled "pneumatic couplings" - anyone recommend some favourites?

Mike

Yes you can do that. As long as the motor is strong enough to start again with an almost full tank. You'll find that out. :-)

Nick

Thanks Nick, I have checked out re-starting with a full tank and all seems to be well, there's no pitch change from the motor.

I just noted I should have been more careful when I said my compressor was less powerful - I meant flow rate not max pressure. The switch I have does match up with receiver rating. Although for my needs I could probably reduce the switch operating pressure but there doesn't appear, at first sight, to be scope for that.

Mike

Just for clarification: The relief valve has an open end inside of the pressure switch. There is no connection to the tank. As Mark said, it is intended to vent the connection between the compressor and the tank (reed-valves on both ends of that connection). So you simply can leave it unconnected.

Nick