Pump output

[jim painter]

Hi, is there a calculation to figure out what cfm a pump is putting out. I have a replacement pump on mine but it doesn't build pressure as quick as the old pump. It was replaced under warranty but I have a feeling it is a cheaper unit. If it helps it's a 200 litre tank, and 3 hp motor.

Thanks.

 

[octo0072000]

3HP i would expect a 14 cfm pump
if under warranty just complain it's not working as per previous pump was

 

[FranV8]

I think the FAD (free air delivery, actual amount of air you'd compress) would be more like 9cfm. Iirc it's about 3cfm per horsepower.

 

[jim painter]

It was a warranty about a week before it packed up. So not in warranty anymore. With the previous pump it took about 4.5 mins to full pressure. Now it's just over 8 mins but not a problem with the pump. Just slow pressure build up.

 

[rtbcomp]

Did the new pump come with a larger pulley?

 

[brightspark]

It was a warranty about a week before it packed up. So not in warranty anymore. With the previous pump it took about 4.5 mins to full pressure. Now it's just over 8 mins but not a problem with the pump. Just slow pressure build up.

the original one wasnt designed to run of a 1450rpm motor was it and your new pump of a 2800rpm ??as it seems to have doubled its time to build up. id ask the supplier its running speed if i was u

 

[jim painter]

Hi,

Pump came with the pulley fitted, same size as original.

Bright spark: I never even thought of that. I will have to check. Would it damage the pump if I used a faster rpm motor? Ie are pumps designed to run at certain rpm? Or can they run faster if required.

Thanks

 

[brightspark]

Hi,

Pump came with the pulley fitted, same size as original.

Bright spark: I never even thought of that. I will have to check. Would it damage the pump if I used a faster rpm motor? Ie are pumps designed to run at certain rpm? Or can they run faster if required.

Thanks

they normaly run at a set speed depending on the type . increasing the speed will damage it

 

[jim painter]

I thought it wouldn't be that easy lol. Will get onto the company tomorrow.

Thanks for the advice.

 

[eil]

This might be of use if you like doing sums http://www.cambscompressors.co.uk/UserFiles/File/Calculating Air Compressor Flow Rates.pdf