I'm trying to figure out how to measure the flow of the compressed air. I used a flowmeter for low flow (15 l/min), and it didn't work well...
Have anyone tried to do the same??
Do I need one specific type of flowmeter??
Jofran Oliveira
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bear@apl
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Posted 25 November 2009 - 08:56 AM
Hi Jofran,
The one you used is out of range for the needs of the ejector. We've used a 20-90 lpm meter, and will often exceed 90 lpm (nominal) at higher flows. Unfortunately, I don't have numbers on the top end demand, but I'd say 150-200 lpm is toward the top end of the (nominal) range you'd need.
We use rotameters for this type of flow measurement.
Many of our flowmeters have come from Dwyer - dwyer-inst.com (which also show up on eBay sometimes). Omega also sells rotameters.
We generally use the Dwyer Ratemaster series.
For lowest cost the Minimaster is $21, however, the smaller meters have much lower precision (I think less than 10 demarcations)
MMA-27 - Flowmeter, range 15-150 LPM air.
RMA-25 Flowmeter, range 10-100 LPM air
RMB-54D Flowmeter, range 20-200 SCFH/5-95 LPM air.
RMC-122 Flowmeter, range 2-20 SCFM air (20 SCFM = 283 lpm), unfortunately this series doesn't come in lpm.
There are others on the market as well. Although it would be somewhat crude, you might try the MMA-27. Or look around for other higher range flowmeters.
To determine flow rate at standard conditions (not the nominal reading on the meter), you also need to know the pressure of the air in the rotameter and ideally temp, but the pressure effect is much greater than temp. If you're looking for accurate numbers here, placing a pressure regulator before the rotameter and using that as your valve would allow you to know the pressure in the rotameter to do the conversion calculation.
To be accurate rotameters need to be mounted vertically.
Cheers,
Bear
The one you used is out of range for the needs of the ejector. We've used a 20-90 lpm meter, and will often exceed 90 lpm (nominal) at higher flows. Unfortunately, I don't have numbers on the top end demand, but I'd say 150-200 lpm is toward the top end of the (nominal) range you'd need.
We use rotameters for this type of flow measurement.
Many of our flowmeters have come from Dwyer - dwyer-inst.com (which also show up on eBay sometimes). Omega also sells rotameters.
We generally use the Dwyer Ratemaster series.
For lowest cost the Minimaster is $21, however, the smaller meters have much lower precision (I think less than 10 demarcations)
MMA-27 - Flowmeter, range 15-150 LPM air.
RMA-25 Flowmeter, range 10-100 LPM air
RMB-54D Flowmeter, range 20-200 SCFH/5-95 LPM air.
RMC-122 Flowmeter, range 2-20 SCFM air (20 SCFM = 283 lpm), unfortunately this series doesn't come in lpm.
There are others on the market as well. Although it would be somewhat crude, you might try the MMA-27. Or look around for other higher range flowmeters.
To determine flow rate at standard conditions (not the nominal reading on the meter), you also need to know the pressure of the air in the rotameter and ideally temp, but the pressure effect is much greater than temp. If you're looking for accurate numbers here, placing a pressure regulator before the rotameter and using that as your valve would allow you to know the pressure in the rotameter to do the conversion calculation.
To be accurate rotameters need to be mounted vertically.
Cheers,
Bear
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