air compressors

[Randy88]

Can anybody tell me anything about rotary or screw air compressors, I have no experience with anything other than two stage cylinder type compressors. The adds say 100,000 hour life and such things but my knowledge is only from what I read in adds. Other than the price difference and the life expectancy what else is there to them, less moving parts I take it and longer life but how about cold weather and maintenance, do they start and stop like a two stage once it gets up to pressure? How do the hydraulic driven ones like are on service trucks work as for starting and stopping and are they worth the price.

We are currently using the air supply off the truck brakes to run air tools but its not enough, we knew that from day one but now its to the point we need to do something different. We've looked at hydraulic driven two stage compressors, gas engine compressors and electric motors driven off my bobcat but have kinda ruled it out for now due to operating in cold weather, I'd like the welder generator with an air pack but I don't want to trade in my bobcat and don't want to spend that much just to get the air compressor. Any ideas or thoughts? what do others do and how do you like it and what would you do differently if given a choice.

 

[Greg]

Probably a gasoline engine powered unit is your best bet. Small air cooled gasoline engines have become very dependable and are excellent starting engines. Get one with an electric starter, use premium gasoline in it with out ethanol and it should work fine for you.

 

[fast_st]

Screw compressors put out a lot of air and a bit of noise. Generally they will be used in high volume applications (towed air compressors) They're more sensitive to dirt and contamination and they definitely cost more but you gain more cfm for a same sized package/hp. For a 6-9 K you can get an engine belt driven, electric clutched screw compressor. But in bang for the buck, a good used gas engine two stage compressor will fit the bill. If its not constant use, snaggle a used one from a good name, Quincy or Ingersoll Rand.

 

[dayexco]

we have one of these, absolutely LOVE it, only dif, ours is like 2 yrs old, has a Honda motor on it. can pump a 500' long 8" sewer main to 5 p.s.i. for testing in about 3-4 mins if you don't have any leaks. and the generator is real handy too. very well built unit.


http://www.deere.com/en_US/parts/homeandworkshop/products/compresserators/ac2_cg40s.html

on edit, we have a 50' hose on a reel on our truck, and we use this for putting together mechanical joint water main fittings. has NO problem keeping up with a 1/2" impact!

 

[norite]

Rotary compressors have traditionally been for engine driven/ tow behind compressors and larger. I see you can now buy them down to about 10hp as electric driven shop compressors.

Any gas/diesel/lpg motor driven compressor is usually set up with an unloader to keep excess pressure from building up when the pressure reaches max. Most tow behind and larger rotary compressors have relatively tiny air tanks and run all the time while in use.

I am thinking that for a welding/service truck the ultimate setup is one of the new inverter based diesel engine welder/generators that have lots of AC power, even 3 phase and can power an electric air compressor, plasma cutter and even another electric welder, as well as lights and power tools.

 

[fast_st]

Now if you did get a free standing one, put a check valved male fitting on the tank and clip that to a 120 psi dump over valve from your second stage air brake tank then your extra air volume would pre-charge the bigger tank on the way to the job, (assuming your air compressor cut out pressure is 135) That JD unit is bitchin indeed.

http://www.vmac.ca/ these guys seem to have a lot of big dollar solutions to air on the road but I'm cheap.

 

[Randy88]

fast_st those are nice units but I too am too cheap to spend that kind of money, which brings me back to an engine driven two stage compressor, anybody have any experience with the small diesel units, I'm thinking they are air cooled but not sure, about 10-20 hp, do they start in cold weather and are like most other diesel engines or more like the air cooled gas engines, a pain in the *ss most of the time and not spend the extra money on the diesel?? Don't know of anyone who ever had one before, I"ve been around the smaller kubota diesel's and those start great even in cold weather but I know nothing about these smaller compressor engines. I've seen the lister diesels and some others, any idea's.