Understanding Pressure Range Codes for the P55
The pressure range for the P55 is identified in the model number by a range code. This is a two-digit number that is used to determine the full scale pressure range of that P55 transducer. Understading the pressure range code for the P55 also helps you determine the diaphragm needed to rerange your transducer.
All P55 transducers are zero-based transducers – that means they are always calibrated from zero pressure to some greater full scale pressure. P55D models are differential pressure transducers and the output always starts at 0 differential – that is, the pressure on both the + and – ports is equal (normally ambient atmosphere or zero gage pressure).
P55A models measure absolute pressure and are based at 0 psia.
The full scale measurement range of the P55s depends on the Range Code ordered. Listed below is the location of the range code in the model number and the range chart showing the corresponding full scale pressures:
A P55D with a unidirectional voltage output and range code 42 will be calibrated as follows:
0 Vdc = 0 psid to +5 Vdc = 20.00 psid
The output will be linear in between: 2.500 Vdc = 10 psid, etc
For unidirectional current output versions, the output signal is 4 to 20 mA and the -42 would be calibrated:
4 mA = 0 psid to 20 mA = 20.00 psid.
Note: Full Scale Calibrations in Between Range Codes May Be Specified on the PO
The same P55D with a voltage output and range code 42 could be calibrated as follows:
0 Vdc = 0 psid, +5 Vdc = 15.00 psid
The range code in the model number must be greater or equal to the full scale calibrations.
Note: Calibrations May be Specified by the Purchaser in any Engineering Units
So the -42 range could be calibrated 0 to 550 In H2O, for example or 0 to 500 In H2O.
You can find out more on the P55 here.