REFLECTOR: compressor

Mon Mar 5 14:49:59 CST 2007

There are three factors to consider.  Tank size, pump capacity and duty cycle.

I have an 80 gallon tank with 15 CFM (cubic feet per minute) @ 90 psi (pounds per sq inch) = 5.5 CLM (cubic liters per minute) 6.2 bar and 75% duty cycle.  Even with this size, when running any of the big tools, the duty cycle (percent of time that the pump runs) is over 50%.

I found that price was very sensitive to duty cycle.  My brother does automotive paint work and suggested that unless I was doing commercial work, I should not pay for the duty cycle and additional rugged components.  Actually, he said my arms would give up before the compressor.  He was right.  I found that there are many reasonably priced compressors in an acceptable range.  I found one on sale from a reputable manufacturer and that's how I ended up with the one that I have.

All of that said.  I also run most of the tools on a 30 year old, 10 gallon, 1 HP system when not in the shop.  Works it hard, but it still does the job as long as I don't over do it.

As to horsepower - I think mine is rated at 5, but I really don't think it's accurate.  Start up is 30 amp @ 220 volts.  I don't know the run current.  

- jerry

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of michalk
Sent: Monday, March 05, 2007 1:35 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: compressor

If I recall correctly, they use a dubious method of rating compressor horsepower.  It's either starting current, or stalling current which doesn't help at all.  The specs to look for are airflow at pressure.  I don't remember how to equalize the numbers .. divide one by the other, or multiply them.  Walk around the store comparing them on that number.

Laurence Coen wrote:
> Ben,
> 
> My tank is 13 Gal., and trust me, that is way too small.  My 
> Brother-in-law has automotive repair shop and his compressor is a true 
> 2 HP 240 volt sitting on top of a vertical 30 Gal. tank.  That's what 
> I wish I had.  It makes way more air than my so called 4 HP compressor.
> 
> Larry Coen
> 
> ----- Original Message -----
> From: "Benedikt Harren" <benedikt.harren at airovision.de>
> To: "'Velocity Aircraft Owners and Builders list'" 
> <reflector at tvbf.org>
> Sent: Monday, March 05, 2007 5:25 AM
> Subject: Re: REFLECTOR: compressor
> 
> 
> Larry,
> 
> How big was your tank? I am in germany and output is most probably 
> going to be in liters. I'll try to get a decent powered one with a big tank...
> 
> Ben
> 
> -----Ursprüngliche Nachricht-----
> Von: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] Im 
> Auftrag von Laurence Coen
> Gesendet: Montag, 5. März 2007 18:11
> An: Velocity Aircraft Owners and Builders list
> Betreff: Re: REFLECTOR: compressor
> 
> Ben,
> 
> I have a compressor that is labeled 4 HP.  I don't know how they can 
> claim that since the power in is 1800 watts which is only 2.4 HP.  To 
> make a more accurate comparison, look at the volume delivered at a 
> certain pressure as in cuft/min.  I think that the actual HP of my 
> compressor is less than 2 HP not 4 HP.  It was barely able to do the 
> job.  A large volume tank will also help keep the pressure steady.
> 
> Larry Coen
> N136LC
> SE/RG Franklin/IVO
> 
> ----- Original Message -----
> From: "Benedikt Harren" <benedikt.harren at ebs.de>
> To: <reflector at tvbf.org>
> Sent: Monday, March 05, 2007 2:12 AM
> Subject: REFLECTOR: compressor
> 
> 
>> Dear All,
>>
>> I am new to the reflector. I bought Bob Hugel's Velocity Elite RG 
>> project (fast built wings & fuselage) and shipped it to Germany where 
>> I currently live. I just moved it into my shop 2 days ago and am now 
>> configuring the shop, getting the tools etc. For that matter I was 
>> wondering how big of a compressor I would need to drive a couple of 
>> air tools (one at a time; circular cutter; grinder; dremel). I am 
>> currently looking at 2-3 HP compressors...
>>
>> So far I have been browsing through a couple of the builders' sites 
>> that are out there to familiarize myself with the projects and the 
>> people that are part of the commmunity... I haven't been on a mailing 
>> list like that before and love the concept!
>>
>> I'd appreciate the input
>>
>> Kind regards,
>>
>> Ben Harren
>> N888GF; first things first :-)
>>
>>
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> 
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