pH Transmitter Calculation

A pH transmitter has a calibrated range of 4 pH to 10 pH, with a 4-20 mA output signal. Calculate the pH sensed by the transmitter if its output signal is 11.3 mA.
First, we must convert the milliamp value into a percentage. Following the same technique we
used for the control valve problem:

Next, we take this percentage value and translate it into a pH value, given the transmitter’s
measurement span of 6 pH (10 pH − 4 pH)and offset of 4 pH:

Therefore, the transmitter’s 11.3 mA output signal reflects a measured pH value of 8.56 pH.