Compressor fill time sanity check

Also remember your electric motor needs time to cool itself after the large inrush of starting current.
Generally I avoid more than 6 motor starts an hour on a compressor.
I have to run my compressor on continuous because of large starting currents.
 
sdelivery said:
I see a 3450 rpm motor but I don't see the pump specs. What pulleys are you running i.e. what is your actual pump rpm? Let's see the pump outlet to tank inlet fittings and piping.....you joined two tanks , which is a good idea what size and type of material did you plumb them with?
In the last 5 or so years they have been using a lot of b.s. ways to rate compressor outputs and this is probably why you're not impressed with the performance.
BUT without SEEING it I don't know what else I can say.
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I’m running the stock pulleys that came with the pump and motor so I have to expect that the pump is running at the designed rpm.
The only pump specs I have are what is in the post above.
The pump to tank inlet is the one that came with the pump 1/2” id copper.

The tanks are joined with a 3/8 id whip.
 
Increase the size of your connection between tanks and avoid hose. verify the specs on your pressure relief valve(s) just to be sure there flow rate is high enough. I have seen pressure relief valves designed for smaller systems used on larger systems to save money. Just run the number and you should be able to get the specs both relief pressure and cfm.
 
DavidR8 said:
I’m running the stock pulleys that came with the pump and motor so I have to expect that the pump is running at the designed rpm.
The only pump specs I have are what is in the post above.
The pump to tank inlet is the one that came with the pump 1/2” id copper.

The tanks are joined with a 3/8 id whip.
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I did some digging on the part number and they don't really break down details like the difference between CFM displaced and CFM delivered, but they do list it as SCFM (Standardized CFM) which accounts for atmospheric conditions, so it's probably CFM delivered. Still, compressor companies are listing what they get with a new unit, in perfect conditions so I suspect they're all optimistic when they list the CFM.

I re-ran the calculator and it says 5 minutes. Throw in a few leaks, smaller connection to the second tank with realistic conditions and 8 minutes isn't crazy. With the leaks fixed and maybe a bigger connection to the second pipe if you're down in the 6-7 minute range I'd say the pump is working fine.

A buddy at work overhauled an older Saylor-Beall a couple of years ago (80gal, 5hp) and called the S-B folks to order parts and ask a few questions. He asked about fill time when he was deciding how far to take the overhaul and the guy said if it was 10 minutes or less it wasn't time for a rebuild. On paper I think the fill time should be around 8 minutes (I have a similar 80gal, 5hp S-B).
 
But output cfm at 0 psig is higher than the output cfm at any pressure.
I have seen so.e new compressors at the stores advertising output cfm that I felt wasn't right.well reading all the documentation they are advertising some units and cfm ratings that can only be achieved at 0 psig
 
A few misnomers (marketing gimmicks) as too inflated numbers on compressors and motor driven tools. The motor is rated in SPL which is peak Hp, not continuous Hp. The peak horsepower number is taken from the fraction of a second when the motor first kicks on and the start windings engage. That number can be many times higher than the continuous HP. A true single phase 5Hp motor will draw around 26-28A. The compressor is rated in SCFM, which is based on ideal conditions, calculated, actual performance is measured in CFM at a given pressure which is lower. The pump rating you have from what I gather is also based on a true 3 Hp motor, not peak Hp, the rated air output is at a pump speed of 1000 RPM. CFM is affected by pump speed and pressure, the RPM will decrease as the pressure increases, and CFM will continue to decline. A number of factors that effect the air fill times, so more like a 2.5 Hp motor driving an 8 CFM @90 PSI air pump.
Motor: MC019000AV MC019000SJ
5 HP, SPL
230/240 VOLT
3450 RPM
56 FRAME
14.5 AMPS
5/8″ SHAFT SIZE
 
mksj said:
The compressor is rated in SCFM, which is based on ideal conditions, calculated, actual performance is measured in CFM at a given pressure which is lower.
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Not an argument, but the data plate does show SCFM as 10.2 @ 90psi, so that should be CFM delivered (in standard conditions).
 
Separated the two tanks this afternoon. Checked belt tension.
Turns out the belt was loose, likely because it was brand new so has worn in.
Cut the 0-60 psi time in more than half; 3 mins vs 1:22.
Time to 125 psi is now 3:22 on a single tank. Not under any illusions that adding the second tank will mean 6:44 to 125psi but it suspect it won’t be far off.
 
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Wow, that's great. Now with the other tank?
Did I see your set up in another post with the tanks mounted high?
I like the space savings.
 
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