I Just Got a New Air Compressor

[Iplayfarmer]

...One thing's for sure - if you go with the 5 horse, you're most likely gonna need to fab a new belt guard once you've got it dialed in... Steve

I thought about that as I was falling asleep last night. I'm probably going to just use one of the 6" pulleys that I have lying around for now on the 5 hp motor. I won't be getting the full advantage of the 5 HP motor, but I won't have to modify the belt guard. I can get a larger pulley later if I want.

 

[BukitCase]

Here's the spec sheet on my compressor - just to muddy the waters some more

You posted while I was typing - I think that would be a good place to start, for all your reasons and a few of mine :=)

 

[Iplayfarmer]

Thanks for all the help. I brought the motor home tonight. I am in the process of mounting it to the frame. The holes don't line up so I'm making brackets.

You electrical gurus out there prepare for wiring questions. The next step is to wire the pressure switch and mag starter.

 

[Iplayfarmer]

I forgot to mention that none of my pulleys would mate with the motor. Since I had to buy another pulley anyway, I bought a 7.4" diameter one. That should give me a lot of air without pushing the limit on speed of the compressor.

 

[Iplayfarmer]

Status update...

I have the motor mounted to the tank, and about half of the wiring done. All the wiring is cobbled together from stuff I had laying around. I have the pressure switch wired to the coil for the mag starter, and I have a separate overload switch before the mag starter.

I added the extra overload because the mag is rated at 7.5 KW, and I'm not sure it would effectively protect the motor.

The garage is a mess!! I had to move most of what's in there to get this compressor into place.

 

[BukitCase]

Sounds like you don't need us "electrical gurus" after all :thumbsup:

Things I'd do next with that setup (don't take offense at any of this - my friends kid me about not being able to buy/get ANYTHING without modifying it :laughing: )

1. Find a way to protect that gauge on the end from "heat of battle" moments, BEFORE it gets knocked off (without welding on a pressure vessel, of course)

2. Hopefully that tank has a threaded hole at or near its lowest point - my tank is vertical, and has a bottom drain. I added one of these

New Electronic Auotmatic Tank Drain for Air Compressors - Amazon.com

Got it set for about 5 seconds every hour, and (unlike me) it doesn't forget :confused2:
With a horizontal tank, if necessary I'd shim up the end AWAY from the drain an inch or two just to be sure. Cheaper than buying a new tank or dealing with REALLY wet air.

3. To reclaim some of the lost space, I would look at hinging a "medium duty" bench top to the wall above the compressor, with drop-down legs so I could get to it for any repairs/changes without needing a fork lift (although in my case, it'd probably take me half a day to EMPTY the bench so I could raise it out of the way )

Use any, all, or none of these - my suggestions are (usually) worth at LEAST whatcha paid fer 'em

Get ready to enjoy NOT waiting for the compressor - unless you're sandblasting with a half-inch line, I doubt you'll need more air... Steve

 

[Iplayfarmer]

Sounds like you don't need us "electrical gurus" after all :thumbsup:

Things I'd do next with that setup (don't take offense at any of this - my friends kid me about not being able to buy/get ANYTHING without modifying it :laughing: )

1. Find a way to protect that gauge on the end from "heat of battle" moments, BEFORE it gets knocked off (without welding on a pressure vessel, of course)

I'm still not sure that is where the gauge is going to go permanently. After moving the compressor into place I realized it might be nicer to have the gauge higher where it is easier to see.

2. Hopefully that tank has a threaded hole at or near its lowest point - my tank is vertical, and has a bottom drain. I added one of these

New Electronic Auotmatic Tank Drain for Air Compressors - Amazon.com

Got it set for about 5 seconds every hour, and (unlike me) it doesn't forget :confused2:
With a horizontal tank, if necessary I'd shim up the end AWAY from the drain an inch or two just to be sure. Cheaper than buying a new tank or dealing with REALLY wet air.

I put a new drain in the tank, but I hadn't thought about tilting it. I may just do that. The idea of an automatic drain is nice, but I currently have only $61 into this whole contraption. It's hard to justify the extra $100. For now I'll just have to set reminders and drain the water regularly.

3. To reclaim some of the lost space, I would look at hinging a "medium duty" bench top to the wall above the compressor, with drop-down legs so I could get to it for any repairs/changes without needing a fork lift (although in my case, it'd probably take me half a day to EMPTY the bench so I could raise it out of the way )

I may re-organize that peg board above the compressor to make better use of the different space. The real problem is my lathe. The right 2 feet of the new compressor is in space that used to be occupied with the Lathe. I don't use the lathe much anymore. I may just find a place to store it for now and figure out a home for it after I get my new workshop built.

Use any, all, or none of these - my suggestions are (usually) worth at LEAST whatcha paid fer 'em

Get ready to enjoy NOT waiting for the compressor - unless you're sandblasting with a half-inch line, I doubt you'll need more air... Steve

Thanks for all the suggestions and help. This is why I love this site.

 

[Stimw]

Another suggestion, if you mount the tank feet to 4 X 4 's or 6 X 6 's you will get less vibration and you can shim it for tilting.

 

[Iplayfarmer]

Another suggestion, if you mount the tank feet to 4 X 4 's or 6 X 6 's you will get less vibration and you can shim it for tilting.

The tank us on rubber feet. Will the boards still help?

 

[BukitCase]

If the rubber feet are original equipment for that compressor/tank, probably won't help with sound level but would still help if you want to tilt the tank for better drainage -

If the rubber feet are someone's attempt at quieting, they could be either helping, hindering, or neither.

This gets into the realm of mass-spring-mass calculations - ever seen a sign on a long suspension bridge that said "no dogs allowed"? This isn't because the bridge maintenance crew doesn't wanna clean up your pooch's messes, it's because of RESONANCE. (Another term for mass-spring-mass effect) -

In the case of the bridge/dog, typically a dog will go into a trot when it's going somewhere - it's a very constant series of "little jumps", so to speak. If that particular dog's weight and "frequency of thumps" happens to coincide with a harmonic of the bridge's natural resonance, it works just like pushing your kid on a swing - if you time the pushes right, he'll go higher and higher. In the case of the bridge, there have been cases of dogs destroying a bridge under the wrong circumstances.

In the case of your compressor, the air pump will have a specific resonant frequency based on rpm (which you just changed by changing motor speed slightly, and pulley ratio) - the mass of the entire unit also enters into the resonance of the device - the rubber feet are the "spring", and the earth (considered infinite for calculation purposes usually) is the other "mass" - hence the "mass-spring-mass calculation.

There are two instances when a spring is NOT a spring - these are at either end of its travel. So if the rubber feet are compressed enough (due to being too small or soft or both) then they are no longer "springs", and might as well not even be there.

If those rubber feet are the wrong hardness (called shore value) they will either compress too much, or not enough - they need to be near the middle of their range between uncompressed and flattened to work well. If their travel during "thumps" of the compressor gets too close to either end of their range, you'll get noise transfer to whatever the compressor is sitting on. Once it gets to your floor, part will be deadened by the earth under the slab and part will transfer to walls and ceiling, which will amplify the noise (typically)

Oh man, just realized I drifted into "auto" mode - sorry. Did I mention that I do some acoustical consulting from time to time? :confused2:

Shorter answer - oh yeah, that was the FIRST sentence ...Steve

 

[Iplayfarmer]

I've had the pump running for a few seconds at a time and it's pretty quiet.

 

[BukitCase]

In that case, ignore all but the first sentence of my last post

That's one of the things I love about my DevAir - you can stand right next to it and carry on a conversation while it's running. Wouldn't wanna try that with my little oil-less "hot dog" portable - I'd probably end up deaf AND hoarse before long... Steve

 

[Iplayfarmer]

Quieting down my air supply has been one of my goals in getting this belt driven compressor. I had originally hoped to put it down in the basement of my new workshop, but this BIG horizontal tank doesn't fit down there. I'm looking at a long day at work, but hopefully I can get some time tonight to get the overload switch wired up and plug it in. After that I still need to do a little more plumbing.

I'm excited to blow out the sprinkler system this fall. I've always had to cycle the old compressor a number of times because it couldn't keep up. This one will definately be better. I accept that I may still need to cycle it a few times, but likely not nearly as much.

 

[BukitCase]

Yup, blowing down the outside water is one of MANY uses our compressor gets to do, along with (wife) cleaning out the vacuum cleaner and rug machine, etc -

It's gotten to the point where wife and I BOTH are only half joking when either of us comments that "if either of us AND the compressor dies at the same time, guess which one'll get replaced FIRST :laughing:

 

[Iplayfarmer]

Yup, blowing down the outside water is one of MANY uses our compressor gets to do, along with (wife) cleaning out the vacuum cleaner and rug machine, etc -

It's gotten to the point where wife and I BOTH are only half joking when either of us comments that "if either of us AND the compressor dies at the same time, guess which one'll get replaced FIRST :laughing:

My wife has asked that I run an air line into the house. She's seen the benefit and wants air in her salon to clean off her clippers, etc. I'm planning to put it in when I dig for power out to my new workshop.

 

[Iplayfarmer]

It's all wired and temporarily plumbed. All of my fancy switches, etc. worked great. I ran it through a few cycles to double check everything. (It takes a long time with a blow gun to drop the pressure on a 80 gallon tank.) I need some 1/4" npt fittings to connect my regulator. When I get those I'll redo some of the plumbing.

I do need to change the pressure switch settings. It's currently set to shut off at about 50 PSI. Who runs their compressor at 50 PSI??? I wonder if that's all the more that little 2 hp motor would comfortably do with the 6 inch pulley it had on it.

 

[BukitCase]

Can you tell if that's the original pressure switch? It sounds to me like maybe someone replaced it, and could only find a switch for a water pump. Those are typically preset for either 30-50, or 40-60 pounds range.

I've seen some water pump switches that will adjust high enough for compressor duty, others not. Hopefully yours is the good kind... Steve

Although you're right, that pump is rated for more than twice the power you started with and it's possible someone used a "cheater" phase converter, which would lower the available power even further to about 2/3 of nameplate.

 

[Iplayfarmer]

It looks like a water pump switch. The label on the switch has presets at 30 and 60. I didn't have time to fiddle with it last night, but I think I can adjust it some. It probably won't get up into the 145 psi range where I want to be, but I should be able to get above 50.

If I can get 90 psi out of this switch I'll keep it for a while. If I can't I'll get a new one pretty quick.

 

[BukitCase]

I'd be a bit cautious going too high - if it IS a water pump switch, the diaphragm may not be rated much over maybe 100 psi -

If the diaphragm ruptures, not only will it keep the compressor running, (the switch would think you had ZERO pressure)but if the resulting hole isn't bigger than the compressor's capability, pressure will build until the NEXT wimpiest thing blows.

Hopefully that would NOT be the TANK (can you say "shrapnel"??!?)

If the resulting hole IS bigger than the pump can keep up with, it'll just burn out your motor. Neither situation is good for morale

If you're not sure, one temporary solution (kind of a PITA) would be to ONLY turn on the compressor when you're gonna use air - at least that way, someone will be there if/when she blows... Steve

 

[Iplayfarmer]

I'd be a bit cautious going too high - if it IS a water pump switch, the diaphragm may not be rated much over maybe 100 psi -

If the diaphragm ruptures, not only will it keep the compressor running, (the switch would think you had ZERO pressure)but if the resulting hole isn't bigger than the compressor's capability, pressure will build until the NEXT wimpiest thing blows.

Hopefully that would NOT be the TANK (can you say "shrapnel"??!?)

I do have an overpressure pop-off valve right above the pressure gauge that should protect me from the shrapnel scenario. I'd really rather not burn up the pump or the motor, though. In my stash of fancy process control components I have a few timers. I have considered wiring a timer into the control side of the mag switch that will automatically turn everything off if the motor runs for an unusual amount of time. It would be overkill if I had to buy the parts, but I have them, and I don't have any other use planned for them.

If the resulting hole IS bigger than the pump can keep up with, it'll just burn out your motor. Neither situation is good for morale

If you're not sure, one temporary solution (kind of a PITA) would be to ONLY turn on the compressor when you're gonna use air - at least that way, someone will be there if/when she blows... Steve

The "Only turn it on when you're gonna use air" philosophy is a given anyway for the first few uses at least. Since I have cobbled this unit together from various sources and had to re-engineer some of the components I want a good track record of reliable starts and stops before I trust it to stay plugged in without me present.