Airmaster compressor help required

[bloobloo]

I have aquired an Airmaster compressor today that somebody was throwing out, brought it home and give it a quick once over to check for any major disasters waiting to happen etc and started her up. she runs well and builds up pressure quickly, now then this is the bit that confuses me! when it gets up to about 115psi it knocks itself off as it should, BUT instead of the green on button stayin in, it pops out as if the red stop button has been pressed.
Also there seems to be something missing (photo's will explain better)
Branching off from the inlet pipe from the pump to the receiver on the union is a smaller 6mm copper pipe that leads to what looks like a pressure valve of sorts, with a threaded end leading to nothing! where should this go or what is missing?
Any help greatly appreciated, thanks, Mike


Ps: gaurd removed for illustration purposes only!

 

[rtbcomp]

There is a valve in the pressure switch which relieves pressure when the motor stops.

Does the machine hiss when it stops?

Does it restart when pressure drops?

Does air come out of the 6mm pipe when the pump is running?

 

[eil]

Just in before me rtb

 

[eil]

I see what you mean with the T-piece that 6mm pipe is normally connected to the pressure switch so as to unload the pressure from between the comp and tank

 

[bloobloo]

There is a valve in the pressure switch which relieves pressure when the motor stops.

Does the machine hiss when it stops?

Does it restart when pressure drops?

Does air come out of the 6mm pipe when the pump is running?

thanks for the speedy reply rtb, first of all there is no hiss when it stops, the 6mm pipe goes to a valve as shown in the pics, when i first started her up air was leaking from the fitting until i nipped it up, and no it doesn't restart when the pressure drops, its as if the pressure switch has pushed the red stop button.
One noticable thing occurs though, when the pump stops once its reached pressure, and i let air out to say 80psi, if i try to turn the pump back on it trips the electric, would i be right in thinking this is due to having pressure in the pump, making it harder for the motor to turn the pump therefore requiring a greater load on the supply?

my other compressor makes a hiss when the pump stops like you mention, the hiss comes from a 3" block looking thingy that says MEAD on the side of it. there is nothing like this on the airmaster, i was presumiong the tee valve looking thing on the end of the 6mm pipe in the pic was somethig similar to this?

 

[eil]

Got it in one there bloo, its not unloading. look to see if there is another connection under the switch for the 6mm pipe

 

[bloobloo]

I see what you mean with the T-piece that 6mm pipe is normally connected to the pressure switch so as to unload the pressure from between the comp and tank

eil, i have looked at the pressure switch but can't see anywhere where the tee would connect though! any ideas?

bearing in mind that who knows what could have been done to it before i owned it!

(also the reason why it was getting binned too lol)

just seems too good to chuck in the skip to me though

 

[eil]

That T looks like a pressure relief valve which adjusts with the knob that is pictured nearer the gauge, it looks as if someone has fitted it just because it fits the nut on the 6mm pipe and shouldn't be there, meaning you would have to empty all of the receiver before starting up again.

 

[bloobloo]

just took pressure switch apart to have a better look, now i think im onto something with this one but cant be sure! the unthreaded end of the tee seems to be a perfect fir for a hole under the black box, kinda hard to explain!, ill go take a couple pics and post asap to show you all.

got the pics, what u think?

also what is the threaded part of the tee for?

 

[Gary900r]

The unthreaded end should fit in the hole you found. It should be held in place by a grub screw. However there should also be a small brass rod in the tee which will extent into the main part of the pressure switch. When high pressure
is reached the brass rod will be mechanically pushed down to open the relief valve at the same time as the motor stops.

The threaded part of the tee is there to allow fitting of a silencer or to connect a pipe to duct the venting air away from the compressor.

 

[bloobloo]

ahhhh right that makes sense! Would that also prevent the green on button from being released, keeping it switched on for when the pressure drops?
Also does anybody know if the spare parts are readily available for this model, the brass rod isn't a problem i can soon knock someting up like that, but forsafety's sake i may just buy new aswell

 

[rtbcomp]

The green button is probably an overload trip. Because you get no hiss when it stops it means the pressure between the pump and tank isn't being released, this means the motor tries to start under full load, causing the trip to trip.

I'd replace the pressure switch (£15.00 from Machine Mart), this will take 6mm nylon push-fit pipe to the dump valve, so follow the thin copper pipe to the non-return valve on the tank, install a 6mm push-fit fitting and replace the copper pipe with 6mm Nylon.

 

[bloobloo]

The green button is on the left hand side in the pic and is marked "on" the red button to the right obviously marked "off"


Then again for the sake of a few quid it would make more sense to follow RTB's advice and get a new pressure switch from MM!Also what about regulators and the like? all the tank has fitted to it at the moment is two taps.

 

[Gary900r]

The green button is simply a on button. When pressed it engages a mechanical catch which holds it in the on position allowing the machine to start. The catch is released when either the red stop button or the overload mechanically releases the catch which stops the machine.
It would be better to get a new pressure switch rather than trying to get the old one to work.
I would fit a combined filter regulator unit ond then move the outlets downstream of the filter/reg.