Running 2 compressors v. 1

[bimmridder]

At 150-200 feet of pipe, nice "tank".

[Inkworks]

Thread resurrection.... I'm up against max for my current compressor, when the big auto and the pad printers are running the 5hp. 18.5CFM@100PSI piston type compressor is on 70-80% of the time, which is way too much and it's starting to show the signs of the over-work.

I don't have 3-phase here and adding it would be $20-20K. I have found an identical compressor in new-used condition for a decent price and I'm wondering about running it in tandem. I don't like the idea of setting one up to kick in at a higher pressure and one at a lower as it still means one would be going flat out most of the time,and the other one kicking in only if pressure drops too low, which it wouldn't really do as one will keep up, but over heats doing so. instead I'm thinking of getting a large relay and letting one pressure switch activate it to start and stop both compressors simultaneously and having both tanks piped together to act like one big tank.

Also if one compressor craps out, the other can carry the workload for a while.

Any errors in my thought process? I'd save about $3k over upgrading to a bigger compressor.

All input welcomed.

[jvanick]

as long as they're both piston compressors, I wouldn't see why that wouldn't work.

I like the idea of running them in tandem as well...  makes it easier to know when to maintain them, takes the load off a bit, etc.

-J

[Binkspot]

There are usually two sets of contact on the pressure switch. Assuming the compressors have a set of contractors to start and stop them you can wire both motor controllers to run off of one common pressure switch.

[jsheridan]

I don't have 3-phase here and adding it would be $20-20K.

If you have single phase 230 then you could use a 7.5 HP Screw type. Plenty of air, usually has a dryer attached and it's quiet.

http://www.aircompressorsdirect.com/air-compressor-style-reviews/18-rotary-screw-single-phase-air-compressor-reviews.html

[ZooCity]

We ran a CPN 7.5 and it was just enough for us. Much prefer having the 15hp now. We have three air knives at different stations and they guzzle air when in use.  But yeah, screw type total air system rated for continuous run is the ticket most times.  7.5hp ones are pretty affordable.

[Inkworks]

$4-6K (which is now 5.2 - 7.8K Canadian due to our Canadian Peso's current exchange rate.) will definitely fix my problem, I'm just wondering if it can be fixed properly for less. With the digging I did today I can wire both up to a magnetic or contact relay and have one pressure switch activate both simultaneously, the trick now seems to be bleeding the air off of both of the compressor heads at kick-out. (That's the PSHHHHHHHHH you hear when the compressor kicks off so the motor doesn't fight the pressure during it's next start-up.) I can "T" the bleed-off hoses and hook them both up to the same blow-off valve, but I'm not sure the two pumps wouldn't be "fighting" each other through the hoses.

Not as simple as first thought I guess. I may still buy the used on and take apart the switch and see if I can't rig something up. i like a challenge.