Hi guys,

Hope you can help me with this problem I'm facing. Our DP Tx is set to a range of 0-850 m3/hr. (calibration range is 0-71 kPa). Can I recalibrate the tx to give the flow reading till 1400m3/hr without changing the orifice plate? According to the orifice plate's datasheet, the adjustable range is 0-112 kPa, the set range is 0-71 kPa. Thanks!

 

For orifice plate Q = k.Sqr(DP)

S0, Q1/Q2= Sqr(DP1/DP2)

For your case, Q1=850, DP1=71, Q2=1400

Solving the above equation we get,

DP2=192 kPa. Your transmitter has a range up to 112 kPa. So you can't use this transmitter.

If you use this transmitter with 112 kPa calibration then when the flow is 1020 m3/hr you will get 20 mA. That is the maximum flow you can see with this transmitter.

 

Hi
I think u cannot use the same orifice also as the max dp available is less than the required dp.So either increase Beta ratio of orifice or change orifice.

 

No need to change the orifice. With the same orifice you can achieve higher DP since the flow is increasing.