Access 4.x

Fan air flow calculation


Access utilizes differential pressure method for air volume (flow) calculation.

The manometer (digital pressure transmitter) is used to measure differential pressure (Δp) on the inlet ring of the fan.



The simplified formula to calculate flow is:



k - describes the characteristics of fan’s impeller. It is usually provided on the informational sticker on the fan or in catalog data.

Default value in Access is [100] - must be replaced with the correct value.

x - defines root factor. Default is 0.5 - meaning square root. Normally it shouldn’t be changed.

Variable

Available options & Selection

Note


Activate display of flow

Configuration > Functions > Fan control

Flow presentation

| No | Yes |

Select | Yes | for activation of flow display


Interface to the pressure transmitters

Configuration > I/O allocation settings > Analog inputs

Flow supply air

Any available I/O

Measuring of fan inlet cone pressure

Flow extract air


Flow calculation

Configuration > Functions > Fan control > Flow calculation supply air

K-factor

[100]

Check fan label/datasheet for the right k-factor value

X-factor

[0.5]


Configuration > Functions > Fan control > Flow calculation extract air

K-factor

[100]

Check fan label/datasheet for the right k-factor value

X-factor

[0.5]