Can some one suggest a proper flow meter for the following application.

process Fluid: Air
Flow Normal/Max: 2000 nm3/hr / 4000 nm3/hr
inlet pressure: 7.0 kg/cm2
temperature: 40 deg c
pipe dia: 3" 40 sch

 

you can go for orifice type primary flow element. we can design orifice for you. if you want, we can give you details of the calculations for sizing of the orifice. For more details see our site www.saasblg.com

D.N.Sharma

 

A Coriolis Mass flow meter would give you great measurement. I put together a sizing with you flow data and actually a 2" meter would best fit your process giving you roughly 0.3% Accuracies. If you went with a 3" your measured error would be 0.7%.

Please contact me with questions - 832-457-7888

 

If you need measure NORMAL m3/h, you can use Thermal Dispersion flow meters, or of course Coriolis. But they are expensive. (also Coriolis will produce some pressure loss not always permitted...)

Anyway, your process data look like typical "compressed air" for service purposes (not process). So, if P and T are more or less stable, you can select a cheaper and robust vortex meter.This will measure m3/h (not NORMAL), but you can approximate the results with a fixed factor (some models I know -e.g. Prowirl- allow you to enter the mean density at operating conditions, to do such correction)

 

Orifice Plate has been most standard instrument on such application but over the years engineers have realized energy loss associated with orifice plate flow measurement as well as long term non-reliability of the instrument due to wear & tear. Some of more reliable & almost zero energy loss devices could be Averaging Pitot Tube, Thermal Mass Flow Meter, Insertion Turbine Flow Meter etc. Inline meters are generally sized on the flow range & to catch the best possible flow range they neck down the meter size & in doing so increases the pressure loss or energy loss.

Looking at your application wherein accuracy is not that critical hence you are looking for a reliable technology at reasonable price, I would zero on Averaging Pitot Tube or Thermal Mass Flow Meter. Averaging Pitot Tube for volumetric or Mass while Thermal Mass if direct mass measurement is required. Thermal Mass are little expensive. Third choice could be Vortex provided it maintains the same line size & cover most of the flow range.

A perfect balance on price & technology for monitoring application, I would strongly recommend Averaging Pitot Tube.