Prototype compressor driven by bicycle wheel.
by Rodney
(Los Angeles)
Hello,
I am trying to build a prototype which needs to have a compressor as one of the parts. I want to mount a compressor to a bicycle wheel (the wheel being the prime mover) So I need the compressor to be either a vane, screw or gear pump/compressor.
It will need to be light and cheap structurally (hopefully plastic).
I am wondering if I can use an existing pump like an auto fuel pump or something like that to compress air. It would seem as long as the pump is positive displacement I would be able to compress air with it. What is your thought on this?
Thanks,
Rodney
Bill stumbles with a reply...
Hi Rodney....whew, very interesting issue. Glad you took the time to write in.
The issue, as I see it, and one that I don't see the answer to in your question is, how much air at what pressure do you need to generate with the bicycle driven compressor?
Can you use a positive displacement pump as a compressor? Sure.
Can you drive the shaft of that pump from any rotary drive source (including a bicycle wheel)? Sure.
I don't have any concrete suggestions except that you need to narrow down flow and pressure requirements to help determine whatever style of compressor you ultimately decide on.
Anyone out there have any thoughts for Rodney? I'll post this query up on my blog to see if anyone there can help too.
Cheers,
Bill
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Craftsman electric air compresser sparking heavily behind fan.
by Shaun
(Yonkers, NY)
Question says it all. Makes pressure but sparking gets worse and it smokes. Do I trash it or is there something serviceable?
Bill answers...
Hi Shaun...
Many compressor motors are TEFC. Totally Enclosed Fan Cooled. The fan is connected to the same shaft that extends out the other end of the motor, and runs at the same speed as the motor.
When you say your motor is sparking behind the fan, it's my experience that sparking of the motor brushes is common. Just run your electric drill in the dark to see what I mean.
However, it does sound as though your motor is on the way to complete failure.
Can the electric motor be fixed? Normally yes. And the fix may be less expensive than the purchase of a new one.
Check your local listings for electric motor re-build or re-wind shops. They'll handle that for you.
As to "trashing it", do you mean the whole thing or just the motor?
I've just added a page on this site for people to buy or sell used compressors, working or not. If you want to get rid of yours, maybe someone will buy it for parts. Here's that page. If you hurry, you can be the first to post!
Cheers,
Bill
Operating cost of Cylinder
by Mike
(Ohio, USA)
Need to put together an operating cost of Air Cylinder compared to Electric Cylinder. I can figure the Electric Cylinder need help with the Air. Details - 4" Bore 6" Stroke 3 cycles per minute. Electric cost $0.20/kwH. Air Compressor 200HP 480VAC.
Bill answers...
Hey Mike, welcome to you, and thank you for writing in.
I can tell you that your compressor should generate about 4CFM of compressed air for every HP of motor, so you're generating about 800 CFM of compressed air at 90 PSI.
You can figure out approximately how much air your air cylinder will be using by using the information on this page.
That will tell you how much of your compressor's output your air cylinder will use.
You'll need to figure out how much it costs to run your air compressor. Compressor running costs calculations can be found here.
That should do it.
Cheers,
Bill
Overhaul an older air compressor
by Nick
To whom it may concern
I have just been given a rarely used 15 year old air compressor from my father in-law, he was a tradesman and it was a good tool.
It is now in need of some "TLC" an overhaul and I need some handy tips to do this, all the things I need to do to make it safe, can you help?
Many thanks
Nick.
Bill answers...
Hey Nick, nice to hear from you.
A visual inspection, of course, to make sure that there's nothing obvious, like a hole in the air tank.
Then an oil change if it's an oil lubricated compressor.
Inspect further the power cord to make sure there's not breaks or shorts, check to make sure the tank drain valve is closed, then fire it up.
If the tank is empty, as it should be, the compressor should start.
The first time you run it, monitor the air pressure in the tank as the compressor works. If the air pressure gets up to 150 PSI without the compressor shutting off, pull the plug.
Then, manually open the PRV valve, and let the compressor blow down. Push the PRV valve closed, and plug the compressor in again.
You've done that to try and make sure the PRV is able to release if the pressure in the tank reaches too high a level.
Monitor closely if the pressure goes past 150 PSI in the tank. If the PRV doesn't open and blow off the pressure as the tank pressure is exceeding 190 PSI, that may not mean that you've got a PRV problem. It may be that your compressor is good for higher pressures, but you'll need to find out.
All things being equal, most DIY type air compressors will hit cut-out pressure around 120-150 PSI and the compressor should shut off somewhere around there.
If that happens, away you go. Enjoy using your compressor. If it doesn't, write back in.
Check out PRV valves, for more info on them.
Cheers,
Bill
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Trying to find connecting rod and head torque specs.
I have a old craftsman 150 psi twin cylinder 2hp air compressor that i want to rebuild. Model #106.153782. I need to know what to torque the connecting rod bolts to and also the torque for the head bolts.
Bill responds...
I'm putting this inquiry into the "miscellaneous troubleshooting" page in the hopes that someone out there can help.
I take it you don't have the manual? It seems to me that finding manuals for older compressors is like trying to find a useful politician; there's lots of them around, just not many of them do you any good!
Since I haven't been able to find a source for old compressor manuals anywhere, I've created a page that will allow folks to post their needs, and tell others if they have a manual. Here is that page. You may want, in the hopes that the manual has the information you need, post your request there.
Or, click on the repairs button from the Nav bar, and see if any of the posted companies are near enough for you to ask them for specs. They may be able to help too, as I suspect the torquing specs for various compressors should be fairly close?
Cheers,
Bill
Oil leak through air filter
by milind
(pune)
There is oil leak thru air filter which in turn falls on the ground generating heat in compressor body.
Bill answers...
Howdy Milind. Nice to hear from India, and thank you for stopping by.
If I understand you correctly, you have oil leaking out the compressor intake filter?
That being the case, I don't understand how it "falls on the ground generating heat in compressor body." How does oil falling on the ground generate heat?
In any case, the first thing I'd want to check is the oil level in the sump. It's a common occurrence for folks to overfill their oil reservoirs, and in so doing, oil is then forced back out somewhere.
If you've got a leaky intake valve, and oil is bypassing the piston seals, then you can have oil wicking out the intake filter too.
Cheers,
Bill
$3000 compressor purchase.
by Greg
I will like to make a purchase for a used air compressor in the $ 3000 range.
Do you have in stock in that range?
Please email me details and a quote on that ASAP.Is there a charge on using a Visa or Mastercard for payment?
Hi Greg:
First off, I don't sell compressors on this site. Some of my advertisers do, and you would have to contact them directly to see if they have a compressor for you.
Second, I don't think you should necessarily be looking at buying a compressor based on the budget you have available.
You need to do your homework to determine what size of compressor you need for your compressed air applications. See this page regarding sizing your compressor.
Once you've determined your needs in CFM and PSI, then you can approach compressor vendors and ask if they have a compressor that provides those.
Also, give some consideration to where your compressor will be situated. Check out location, for more details.
Cheers,
Bill
Bearing cap gasket
How do i remove it?
Bill answers...kind of!
Howdy, and thanks for writing in.
Answering your question would be kind of like answering "how long is a piece of string?"
You need to provide a whole lot more detail about your air compressor than you have. A good place to start would be what make, what HP and what voltage?
Even then, unless I have actually done the task, and in the case of a bearing cap gasket I haven't, so I'm not sure I can help anyway, though I'd try.
Send a photo in too. That always helps figure out what folks are asking about.
What I suggest is that you look at the Repair page (click from the Nav bar) and see if any of those companies are close enough to provide you some help.
Cheers,
Bill
Using a Speedaire compressor model 4Z705A
by Franni
(Dewittville,NY)
I have a Speedaire compressor (electric) I use it just to fill my golf cart tire. I see only one knob at the top of the compressor with an off/on switch on the side. Should there be other knobs? There gage around the knob, I can turn the knob but there is no numbers around it. They may have been rubbed out. I need some guidance in how to use this air compressor.
Thank you, franni
Bill answers...
He Franni, welcome to you and other folks from New York.
I think you would very much benefit from reading The Home Compressor, available from the home page of this site.
Your compressor will have a tank that the compressor pumps air into, and from which you get air when you open the appropriate valve or use a tool.
There will be an exit from the tank through an air regulator. Read more about air regulators here.
Read the pages on the air regulator, and it will tell you why there aren't numbers on the regulators itself (no, they haven't rubbed off).
If you could send along a digital photo of your compressor, I could be more specific.
Cheers,
Bill
Jun-Air compressor with dessicant towers (model 2000-40MD2) has pressure stalls
by Andy LiWang
(UC Merced, Merced, CA)
The compressor is always off for a minute. The pumping times, however, alternate between 1 and 3 minutes. Is this normal? During the 3 minute pumping time, there are two "phsst" sounds spaced by a couple of minutes. The first "phsst" sound coincides with a tank pressure stall until the second "phsst" sound. After the second "phsst" sound, the tank pressure builds until the reaching the cutout pressure.
Is this normal?
Just recently, the pumping times have been increasing. It is due to the lengthening duration of the pressure stall. Is this pressure stall due to the air compressor using air to dry out one of the two dessicant towers? Indeed, during the pressure stall, air is rushing out of the hose connected to the drain bottle.
Any advice would be *greatly* appreciated!
Andy LiWang
UC Merced
Merced, CA 95301
Bill answers...
Hi Andy, nice to hear from you.
Your term "pressure stall" is foreign to me. Does this mean that your compressor stops running, or does it mean that while the compressor is still running the pressure doesn't build for a few seconds?
As to the "psshhht" sound, that normally happens when the compressor reaches the cut-out pressure, and unloads the air over the piston.
The unloader valve normally doesn't operate while the compressor is running.
That you have twin desiccant driers with your compressor is, I suspect, the reason you are seeing the anomaly you are.
In a twin tower dryer set up, air alternatively flows to one of the two towers while the other one is re-generating. I suspect the intermittent "psshhht" sound is occurring after the air flow switches towers, and the now un-used tower is venting air to aid in the re-generation.
You really need to talk to the folks at Jun Air about your issue though. It's a product specific one. Contact them at http://www.jun-air.com.
Cheers,
Bill
Taskforce 3 gal. 1.5 HP
by S. Dunlap
(Midland, TX)
My line fitting on the bottom of one of the pressure gauges has broken off, It has a spring inside the cap and the cap has a fitting inside it has broken.
How do I get replacement for this part?
Bill answers...
Hello S. Dunlap. Welcome to you. And all the other visitors from Texas too.
Listen, I'm having a really hard time understanding what it is you're looking for. Sorry about that, sometimes I'm a bit slow.
Usually you have 2 pressure gauges on a DIY type compressor. One is to display the pressure in the tank, and the other is to display the pressure setting that you have set for your downstream pressure, and it's usually threaded into a regulator which is in the discharge line from the tank to your air line coupling.
Could it be the regulator that you are referring to? Can you send in a photo?
Bill
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Don't know where 1/4" line goes
by Daniel
(Riverside Ca.)
1/4" line that comes off the compressor head next to the supply line to the tank.
If i plumb it back to tank as soon as it builds about thirty pounds of pressure it stalls the motor and the breaker trips.
Where should this line go to? do i need to put a check valve there(so air pressure won't build up in the head?, or does it go back to the crank case like most compressor do (this one doesn't have a port or fitting to connect to on the crank case.
Bill answers...
Hello Daniel:
It would have been good if you'd been able to send along a photo for me to see.
Let me ask you. Does the line that runs from the compressor head into the tank have any other connections? It should be entering the tank through a check valve, but does it go anywhere else.
Here's what I'm guessing. I don't know what kind of compressor you have, but if the line that runs from the compressor head to the tank does not Tee off to the pressure switch / unloader valve, then I think that the extra line that isn't connected now may run to the unloader valve.
The unloader valve dumps the air over the piston after the compressor reaches cut-out pressure, to make the restart easier.
Cheers,
Bill
