compressor blowing fuse within seconds of starting

[the snooper]

here you go norm, this pic clearly shows the delivery pipe and un loader connection to be one and the same port

 

[jasongtr]

not knowing much about them i still dont have a clue what that means but thanks for trying to explain it. I'm sure once the NRV is fitted it will be ok (fingers crossed)

 

[the snooper]

not knowing much about them i still dont have a clue what that means but thanks for trying to explain it. I'm sure once the NRV is fitted it will be ok (fingers crossed)

what make is your compressor ?

 

[jasongtr]

that pic looks like what i will be fitting tomorrow, the thin pipe goes back to the pressure switch, one end in the tank and one to the pump, think thats right

 

[jasongtr]

its a FIAC compressor, has a clark 3hp motor, no idea if the pump is original so the make is a difficult one really, bit of a mongrel

 

[the snooper]

not knowing much about them i still dont have a clue what that means but thanks for trying to explain it. I'm sure once the NRV is fitted it will be ok (fingers crossed)

trying to simplify it
the delivery pipe delivers air from the pump to the receiver in order to make starting up again easy 2 valves are fitted a non return which stops the receiver feeding air back into the delivery pipe and pump. so your compressor cuts out and the non returns stops back pressure but the delivery pipe still has pressure in it from the fill, so the un loader valve releases the pressure in the delivery pipe so that once it has to start again its not fighting any stored pressure until it reaches full speed

 

[the snooper]

its a FIAC compressor, has a clark 3hp motor, no idea if the pump is original so the make is a difficult one really, bit of a mongrel

anything like this

 

[jasongtr]

makes sense now, so as the nrv wasn't fitted the pipe was pressured back to the pump hence why its leaking from the dipstick tube, the unloader valve wasn't even connected as the thin pipe was just laying onto of the receiver, it will be reconnected though once the NRV is back on

 

[jasongtr]

similar to that, but the pump looks different so i assume the only FIAC component left is the receiver.

 

[the snooper]

makes sense now, so as the nrv wasn't fitted the pipe was pressured back to the pump hence why its leaking from the dipstick tube, the unloader valve wasn't even connected as the thin pipe was just laying onto of the receiver, it will be reconnected though once the NRV is back on

you've got it and the only reason air isn't gushing from your pump is that there are a further 2 valves in the head of the pump usually reed valves one inlet and one out let, once you fit the new valve you should be good to go

 

[jasongtr]

yup i remember those reed valves when i changed the head gasket about 18 months ago

 

[the snooper]

yup i remember those reed valves when i changed the head gasket about 18 months ago

sounds like the guy you bought it off didn't have a clue

 

[jasongtr]

well there is that of course

 

[normspanners]

here you go norm, this pic clearly shows the delivery pipe and un loader connection to be one and the same port

I Know what it does and where it is connected,
but if it not there it cant leak !! neither would the line from the pressure switch because there is NO feed from the switch the unloader line goes TO the pressure switch and is relieved by the pressure switch.
You said

If there is no non return valve, I don't understand why air isnt gushing from the unloader valve as its fully open when the compressor reaches full pressure

It is open to atmosphere

 

[the snooper]

I Know what it does and where it is connected,
but if it not there it cant leak !! neither would the line from the pressure switch because there is NO feed from the switch the unloader line goes TO the pressure switch and is relieved by the pressure switch.
You said

It is open to atmosphere

on a lot of compressors the un loader line is connected directly to the delivery pipe so if you remove the non return valve it would empty the receiver through the un loader valve, I know you say it cant if its not there which is obvious but we were trying to work out what was and wasn't connected

 

[normspanners]

OK
the delivery line was by the sound of it, was a one piece tap hose connected directly from the head to the tank, though I suspect it was a stainless convoluted overbraid hose because a rubber overbraid tap hose would have melted by now.!

 

[jasongtr]

nope was a rubber one

 

[normspanners]

nope was a rubber one

I dont know how that has lasted, I have seen multi wire hyd hose melted bv by the air from the head before now.

 

[the snooper]

I dont know how that has lasted, I have seen multi wire hyd hose melted bv by the air from the head before now.

depends on just how good the compression is I suppose and heat generated

 

[normspanners]

Discharge and Distribution Piping
Here we have more complex considerations:

The discharge air from the compressors can be at 250 •F to 350 •F (for centrifugal, oil-free rotary screw and reciprocating types), or from 200 •F to 220 •F (for lubricant-cooled rotary screw compressors), so the pipe must be able to withstand those temperatures.

Pretty damn hot----- its usually hot enough to change colour of copper pipe.