Air compressor mechanics/whizzes in here

taipan4, Nov 6, 5:55am
I have bought a compressor & tank no motor or piping & want to pipe it up so when it comes up to pressure it will "freewheel"rather than shut the motor off, which saves the number of motor starts per hour, and means the motor will not start under load, I am prepared to do this pneumatically/electrically using solenoids, pressure swithches etc but not sure of "air/electric" circuitry

richard198, Nov 6, 6:32am
Can't help you but that sort of advice usually comes with a $100/hr price tag!
Good luck!

Edit: I have a compressor with "continuous run" mode and a decent auto electrical knowledge, but would hate to service it! (Shop job for me)

twaymouth, Nov 6, 6:51am
essentially you would need a changeover solenoid connected to the compressors air output, the changeover solenoid would be operated by a pressure switch, when the compressor is up to pressure power is removed from the solenoid and the output from the pump is bled off into the atmosphere. When the pressure in the tank drops power is applied to the solenoid, the compressors output is connected to the tank and the cycle starts again.

ladatrouble, Nov 6, 7:03am
You need a compressor with unloading intake valves - when up to pressure the valves unload and the pump just freewheels. You could get them for some of the older compressors depending on set up,but with all these Chinese jobs out the now nothing is standard.

mrfxit, Nov 6, 7:19am
You can make a simple 1 real easy.

You need>>>>
5mm & 3mm drill bits
50mm of 10mm ID pipe with an internal thread down about 25mm on 1 end
8mm ball bearing
9mm flat washer
50mm of 8mm strong spring
Drill a 5mm hole in the tank
Weld the 10mm pipe on end over the 5mm hole
Drill a couple of 3mm holes just above the base of the welded pipe
Insert ball bearing & spring & tension with a bolt screwed in at the top, to allow the ball to lift off it's seat at the required max pressure

(would pay to drill the side vent holes before welding the pipe on (cleaning swarf /sharp edges etc ou) t& using a large drill to taper a seat in the tank hole for the ball to sit in.)
What strength of spring & tension you need depends on what pressure you want it to relieve at.

easygoer, Nov 6, 7:39am
Go to Hindin Marquip and buy a Load Genie valve, they fit them to their 16RSE compressor, no electrical controls needed as it simply fits to the tanl and the air delivery pipe connects to the top of the valve

taipan4, Nov 6, 7:43am
yup that's pretty much what I had in mind I'm a sparky so wiring no problem thanks

plasticboys, Nov 6, 7:46am
my dads one does what you want but we dont like it get on your nerve in the end. think it open a air velve at 120 psi and just turn over till it drops back a bit

mrfxit, Nov 6, 7:48am
Noisy vents like that need to be piped out side the shed or in to a mower muffler

plasticboys, Nov 6, 7:51am
it is but still noisy as but is 80 cub meter air compresser

wellabolla, Nov 6, 8:09am
Ash air (palmy north) supply the correct as chips.they work on any intake valve just by sending air (at set pressure) backwards into the head.i deal with Shaun.real simple.and ya dont have to drill,cut or weld anywhere near ya tank.Thats just scary

mrfxit, Nov 6, 8:12am
LOL, WELLL you certainly don't seem like a genuine Kiwi

wellabolla, Nov 6, 8:19am
Haha.yeah im the real thing.Been there done that and learnt the first the welder does come in hand very often.amazing what sticks when ya try isnt itlol

mrfxit, Nov 6, 6:03pm
LOL yea blimin amazing what you can weld to heavy galv when you have enough amps/ oxy-acet heat (& how well) *cough cough splutter cough*fumes cloud best to avoid breathing, new galv is best ;-)

joanie32, Nov 7, 2:29am
What he said, theres a branch in christchurch (Judging by your profile thats where you are!) or theres 12 branches around other parts of NZ too.

drew2009, Nov 9, 1:38am
Oh yeah those galv fumes are nasty allright.
Apparently if you drink milk it helps stop the toxicity.
I got a bad case of poisoning a few years ago after welding farm gates all day in the engineering shop jesus i was crook. You don't really notice at the time but it creeps up on you and by the evening your sick asa dog.

grangies, Nov 9, 4:00am
The first thing I would ask myself in your position is. "Do I really need it to be a continuous cycle compressor!"

You mention less motor starts per hour. But would you ever need it running for that amount of time anyway!

We have a 16cfm single phase continuous cycle in our van, for large spray painting areas like launches and yachts, and we need the continuous cycle to avoid pressure drop at the gun.

But it's only ever running for about 30 minutes max at a time, as it gets shut off between paint coats.

A continuous cycle compressor in a home garage etc, could drive you bonkers from the constant noise LOL.

rob_man, Nov 9, 8:44am
I had a look at my Marquip today and the freewheel setup is dead simple, there is what appears to be a pressure release valve on the tank plumbed into a line that goes to all three heads and probably causes the valves to stay open until the pressure drops below a certain point.
I use the freewheel setting a lot and simply turn off the compressor when I'm not using air, otherwise it starts and stops constantly.

johnf_456, Nov 9, 9:14am
That is for real, witnessed that holding metal while someone else did welding.

drog, Feb 13, 8:53pm
Some compressors use a small primary tank which is vented via the pressure switch. Thus the first few strokes of the compressor is 'no load' and the motor gets an easy start.