Another compressor CFM / FAD question.

[flanajb]

Evening all. I'm still trying to source that elusive and quiet < 65db single phase compressor that will give me a 12 FAD @ 7 BAR. I spotted a Sealey 3HP screw compressor with a 100 litre tank. Spec states

• Noise Level: 59dB(A)
• Maximum Free Air Delivery cfm(ltr/min): 10.6(300)
• Maximum Pressure: 131psi/9bar
• Receiver Capacity: 100ltr

What I want to know is whether stated FAD is minimum and I could eek out greater FAD if I only require delivered pressure to be 7 bar? Does that theory hold true or is FAD constant regardless of pressure required?

Thanks

 

[gaz1]

this one i got is a 40 litre tank but because its a belt drive its quietish within reason

http://www.mig-welding.co.uk/forum/threads/compressor.65826/

this is what ive found on it

compressor Elektra Beckum LP200 / 10 / 40W The specifications are as follows: - Container 40 liters - 10 bar pressure - Engine Power 1,5KW - built in 1985 - working volume 200 ltr./ min. - Compr. Speed 1320 min.

It sounds like the Luftmenge, working volume 200lpm, is the FAD which at about 7cfm is not a bad figure. Elektra Bekum is now Metabo.

@skotl his air compressor

http://www.mig-welding.co.uk/forum/...ter-for-a-10bar-compressor.52935/#post-615373

According to the specs, it is;
• Air displacement: 14CFM
• Motor: 3HP
• Tank Capacity: 90 Litre air receiver
• Max Working Pressure: 150psi (10BAR)

 

[addjunkie]

Air displacment is the volume of air sucked in 14 cfm when compressed reduces the volume as the pressure increases, equates to about 9.5 cfm.

If you ignore heat and the little bit of water vapour oil mist in the air, it follows the basic gas laws quite well.

P1 xV1/T1=P2xV2/T2

 

[pedrobedro]

Fad is usually measured at 90psi which is what most air tools run at. You are looking at something industrial and will need a 3 phase supply to power it if you want 12cfm Fad at 105psi.

 

[Chris Stevens]

Its possible to get 12cfm FAD using 240v supply, but this means twin 3hp motors running dual pumps. Very small receivers also mean compressor will be running pretty much all the time, which may or may not be a major problem.

 

[flanajb]

The 3HP screw compressor I listed does states 300 l/min which is what the gun requires. Like has already been mentioned, I am unsure at what pressure the 300 l/min figure equates too. I have already investigated dual pumps and a standard compressor is a no go. Noise output is crucial and a standard compressor is far too noisy and relations with the neighbors is important.

 

[Chris Stevens]

The 3HP screw compressor I listed does states 300 l/min which is what the gun requires. Like has already been mentioned, I am unsure at what pressure the 300 l/min figure equates too. I have already investigated dual pumps and a standard compressor is a no go. Noise output is crucial and a standard compressor is far too noisy and relations with the neighbors is important.

Have you heard the noise produced by budget price screw compressor? Quality one linked to a large receiver might work for you, but unless you have 3 phase supply you would be struggling to get the FAD you need.

 

[pedrobedro]

Its possible to get 12cfm FAD using 240v supply, but this means twin 3hp motors running dual pumps. Very small receivers also mean compressor will be running pretty much all the time, which may or may not be a major problem.

They will not run at less than 65db with that setup though as he requests in his first post

 

[Chris Stevens]

I think the OP is probably going to need to be looking at 2 quality screw compressors, linked to a largish receiver to achieve what he is looking for. Shame he doesnt outline the purpose of compressor, as electric tool may well be feasible and probably a good deal less money than 2x screw compressors?

 

[colnerov]

Hi, In post 6, he mentions the gun needs that, so I'm guessing he's media blasting.

I would think he needs a big compressor with a hush kit but that has cost implications.

Colin

 

[flanajb]

I basically need the compressor to power a hopper gun that is used to spray mortar.

 

[flanajb]

So could I in theory some how wire 2 of these together?

http://www.ebay.co.uk/itm/Draper-Ex...408731?hash=item51e4a5989b:g:57oAAOSw~oFXL7SS

 

[gaz1]

you could wire in 2 motor compressors from 1 switch they both join to the pipes as one feed from both compressor tank therefore improving your output rating or so ive read from other peoples posts

100 litre

http://www.ebay.co.uk/itm/Bambi-MD-...405991?hash=item2ef3c71467:g:0~MAAOSwvzRXx-7E

80 litre

http://www.ebay.co.uk/itm/Silent-Oi...258071?hash=item1c6dcd5757:g:npQAAOSwEjFXfK7L

jump to 7 mins on video for sound levels

 

[flanajb]

I have been told by Sealey that the 3HP single phase screw compressor has a FAD of 10.6 CFM @ 9 bar. Anyone able to give me an idea how I would calculate the FAD @ 7 bar?

 

[RaceDiagnostics]

How about two of these.

https://www.gumtree.com/p/air-compressors/clarke-silent-air-compressor-shhh-100-ltr/1184707809

 

[pedrobedro]

I have been told by Sealey that the 3HP single phase screw compressor has a FAD of 10.6 CFM @ 9 bar. Anyone able to give me an idea how I would calculate the FAD @ 7 bar?

I don't know how to calculate what you want but the figure given above sounds very optimistic to me from my limited experience with compressors.

 

[addjunkie]

PxV/T= a constant.

Therefore p1xv1/t=p2xv2/t

Now assume temp is equal,p1xv1/p2=v2.

All units would need to be converted to either imperial or si...si makes the maths easier. Answer wouldnt be perfect but would be near enough for pit work as air doesnt follow the gas laws quite as a perfect gas. This equation ignores time so would be for 1 minute.

 

[flanajb]

Now, I think I might be in luck. A company called Air Industrial Equipment based in Harlow do a Air Industrial HW25S-inverter compressor. Spec is a 5.5hp motor delivery 17cfm FAD @ 7 bar and runs at 71db. £2500 inc vat though :-(

 

[brightspark]

Christ id want 6 compressors for that price and change why don't u just get a machine mart twin pump twin motor single phase comp half that price and bigger cfm. I run one I bought cheap for 80 quid with one duff motor it gets hammered shot blasting