air compressor power draw by type.

[Chris.A]

so im building my service truck and outfitting it with a diesel gen and have been looking at air compressors and what hp ratings i can run with the gen. which is an 8000 watt.

i have many ideas and would like a bit of insight if some is known. prettymuch what i worry about is the load when starting under pressure. due to cfm im pretty sure i need between 2-4hp based on compressor type. prices vary greatly. with piston oilless being the cheapest and going up.

i dont need a ton of cfm 7cfm at 90 and a 20 gal tank would prob get the job done and ive seen quite a few options in diffrent build types that makes me think.

1.0 and 1.5 motors with a piston on each end seems to be the cheap route. with 2.2cfm(1hp) and 3.35cfm(1.5hp) and it seems they just add motors to the tank. from what ive seen up to 4 motors.

would 4 1hp motors pull less then a single 4hp? possibly have a timer switch? if 1 isnt cutting it a 2nd etc kicks in say 15 or 20 sec later?

what about ditching the piston all together eastwood has some lofty claims for a 2000$ 4hp compressor 30 gal continuous duty scroll compressor. 12.7cfm @90psi. claiming performance of a 60 gal compressor.

what would amps be on a startup under pressure? would they be the same or would a scroll compressor be easier to start? or being continuous duty is it just bleeding off excess air like some gas compressors? and as long as u drain tank each sitting you never have the hard start? states 115 cut in and 145 cut out

scroll compressors are costly but much quieter also at around 60db claimed. 4hp 220 3 wire plug using 10awg wire states 17 full load amps.

has anyone worked on projects like this before? small spaces and limited power trying to get as much as you can?

 

[The Cobbler]

why wouldn't you just get a gas powered compressor?

 

[Chris.A]

trucks diesel gen is diesel. i mean i could get another fuel powered device but ide like to stick with diesel and the 50 gal of diesel the truck already holds. i could also add a pulley to the gen to power a belt drive compressor.

but yea last truck was all gas kinda like keeping things uniform so no mistakes are made with fuels.

and even that truck came from outfitter with gas 2cyl gen 8500 and it had an electric air compressor.

also comes down to neatness and the space. tanks mounted by frame and compressors etc mounted in the power room cabinet with gen. i could prob mount a compressor head over the gen and add a belt. or mount electric units but dont think i can go for a whole nother fuel run unit and keep it inside a box protected

if you were wondering its a built in diesel gen. not a portable unit

 

[The Cobbler]

ok then, why not get a diesel generator ?

 

[Chris.A]

if only diesel compressors were priced like gas ones. 600$-3500$ for gas is much diffrent then 3000$-7000$ for diesel or 6000$-10000$ for a diesel multi unit gen/compressor.

but then i would also have 2 diesel engines running always. but yes it is an option

 

[Snapped-off]

What kind of work are you doing with a diesel service truck/genset where you need such a small compressor?

Air N Arc® ALL-IN-ONE Power Systems®Air N Arc® ALL-IN-ONE Power Systems® - Vanair - Mobile Power Solutions

Air N Arc® ALL-IN-ONE Power System® provides up to six forms of power in one compact machine for a complete workstation in your truck.

vanair.com

I'm partial to these but sounds like your truck is already partially set up.

I'd just get a compressor head and a motor and run lines to remote tanks you mentioned on the frame.

 

[wyliesdiesels]

so im building my service truck and outfitting it with a diesel gen and have been looking at air compressors and what hp ratings i can run with the gen. which is an 8000 watt.

i have many ideas and would like a bit of insight if some is known. pretty much what i worry about is the load when starting under pressure. due to cfm im pretty sure i need between 2-4hp based on compressor type. prices vary greatly. with piston oilless being the cheapest and going up.

unless the unloader is jammed, the compressor shouldnt be starting under pressure....

i dont need a ton of cfm 7cfm at 90 and a 20 gal tank would prob get the job done and ive seen quite a few options in diffrent build types that makes me think.

1.0 and 1.5 motors with a piston on each end seems to be the cheap route. with 2.2cfm(1hp) and 3.35cfm(1.5hp) and it seems they just add motors to the tank. from what ive seen up to 4 motors.

would 4 1hp motors pull less then a single 4hp? possibly have a timer switch? if 1 isnt cutting it a 2nd etc kicks in say 15 or 20 sec later?

what about ditching the piston all together eastwood has some lofty claims for a 2000$ 4hp compressor 30 gal continuous duty scroll compressor. 12.7cfm @90psi. claiming performance of a 60 gal compressor.

what would amps be on a startup under pressure? would they be the same or would a scroll compressor be easier to start? or being continuous duty is it just bleeding off excess air like some gas compressors? and as long as u drain tank each sitting you never have the hard start? states 115 cut in and 145 cut out

scroll compressors are costly but much quieter also at around 60db claimed. 4hp 220 3 wire plug using 10awg wire states 17 full load amps.

has anyone worked on projects like this before? small spaces and limited power trying to get as much as you can?

forget running a generator to run a compressor. youre just wasting money on inefficiencies. just get a gas powered compressor

 

[walta]

It is Just too inefficient to burn fuel to make mechanical energy turn that energy into electricity only to turn it back into mechanical energy to turn the compressor. Just get one of the engines to turn the compressor and burn 33% of the fuel.

Would one of the kits offer on this site fit your truck?

GM Duramax Engine Driven Compressor Kit

1090303

www.littleshopmfg.com

The kits use a common automotive AC compressor. Seems like you might be able to make it work with a trip to the junk yard.

Walta

 

[micromind]

Generally speaking, an 8000 watt generator will start and run a 2HP electric motor driving an air compressor. This is an actual 2HP industrial motor, not one of those '16,000 HP........runs on standard house current' ones.

If the compressor pump is cold, it'll struggle and might not start, especially if the generator is cold too.

Look at the motor RPM, one that runs at a bit less than 1800 RPM is far better than a bit less than 3600.

Belt drive is better than direct drive, with a belt driven model, if it has trouble starting when cold, you can get a smaller motor pulley. CFMs will be lower but it'll start at a lower temperature.

 

[Citation]

Are scroll compressors like that Eastwood going to be happy getting bounced around on a truck? Beyond just powering the compressor, I would be concerned about durability. Some compressors appear to be designed for duty on the open back of a service truck. I wouldn't assume all are happy with such service. At minimum I would assume any electric compressor is going to be unhappy with rain. Even if you have the compressor covered, I'm not sure which ones would be happy getting bounced around all the time.