Static Pressure versus Volume Flow Rate
Static Pressure versus Volume Flow Rate
(OP)
A new centrifugal type exhaust fan is installed to a duct system with any dampers fully open. With the fan (DOL) operating, the static pressure measured in the duct on a manometer is 300 pascals. Plotted on the applicable fan curve, this equates to a volume flow rate of 1800 litres/sec. A volume flow rate of 1100 litres/sec is required for correct operation. Could the static pressure measured in the duct be adjusted with a damper in the duct to reflect the required volume flow rate or is there no way that measured static pressure can be equated to volume flow rate?





RE: Static Pressure versus Volume Flow Rate
You cannot equate a single-point static pressure measurement to flow.
RE: Static Pressure versus Volume Flow Rate
RE: Static Pressure versus Volume Flow Rate
RE: Static Pressure versus Volume Flow Rate
I have a manometer with +ve and -ve inputs. Could a pitot probe be connected to the +ve & a static probe be connected to the -ve to provide me with the (nett) velocity pressure?
RE: Static Pressure versus Volume Flow Rate
If that is what you are doing, then go ahead and just close down your dampers (assuming they are on the inlet side of the fan) until you hit the fan's static pressure that corresponds to you desired flow.
If you have a proper pitot tube, it will have two connections. One for the total pressure port at the tip, and one for static pressure ports located radially. Connected as you note, the preasure reading will be the velocity pressure.
RE: Static Pressure versus Volume Flow Rate
I have not yet acquired a pitot tube. Could you recommend one that could easily be connected to my Comark manometer.
RE: Static Pressure versus Volume Flow Rate
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