AXIAL FAN RIG

[Jinder]

I am trying to set up an axial fan rig. I have calculated the max. mass flow through it, and now need to find out what size ORIFICE PLATE should be used. I have a copy of BS 1042, but this is since 1943, far too old with imperial units not metric. This has examples of how to calculate the orifice plate size but isnt too helpful for this day and age. I have looked at the new updated British Standard on-line but it is only in parts and still doesn't give sufficient detail.

I need an equation that is used to find this out. How can I find this out? which British Standard covers this flow measurement?

Any suggestions would be most appreciated! (This is the 1st time I have used this)

 

[Caper2]

What pressures are you trying to obtain? If you are in the incompressible flow range (ASHRAE says V<13,000 fpm) then you may use
Delta P=Co*(vel/4006.7)^2
where Delta P is the pressure drop
Co is the loss coefficient
Vel is the velocity
The loss coefficients are listed in 'Industrial Ventilation Design' handbook or ASHRAE for all fitting, obstructions, etc. ASHRAE handles perf plate, that can be modelled inot a single orifice.

Caution, if you are using an axial fan, system curves are steep, meaning you can have a large drop in flow with small increase in pressure drop...ie. centrifugal fans are better suited for PD's.