hi friends

i have problem in our dp type flow transmitter. its flow varies between 125 lb/hr 129, 135, 120. we use glycol for sealing liquid.

plz give me suggestion. both impulse line cleared no choking in foul oil taping point to sealing liquid bottle steam stracing provide orifice connection point to seal bottle.

 

Have a look at the size of your transmitter. If the transmitter is to big its natural acceptable errors might be to coarse for your application.

In short this means that the closer the max capability of your transmitter is to the span value of your calibration the more accurate the transmitter will be.

The main problem is that sometimes some technicians or design engineers install a very big transmitter on a small DP application like this to ensure that the transmitter will not be over pressurized by the line pressure. This sounds like a good idea but the problem is but they forget that the bigger the transmitter, the bigger the natural error becomes, and if such a transmitter is installed on a small span like a DP flow, these natural errors might be enough to cause inaccuracies in the flow measurement. These error are always there and are non-linear and the errors can and will occur in any direction making it very confusing when you see these errors in your flow transmitter for the first time, especially if you have checked and double checked your calibration already. Bottom line is to always ensure that your calibrated span is as close as possible to the max capability of your transmitter and don't select a transmitter that is to big for your flow or DP level application.

Simple example, if your calibrated span is -100mmH2O to +300mmH2O select a transmitter that have a capability of say -500mmH2O to +500mmH2O.