How does the output of my differential pressure unit relate to the pressure applied?

Our low differential pressure transducers typically have either a current or voltage output; though we do offer transducers were the output is field selectable. 

For a current output the option is 4 to 20 mA.

For a voltage output the options are usually 0 to 5 VDC or 0 to 10 VDC. 

The output signal is proportional to the pressure that is applied. 

Example:

A pressure transducer has a unidirectional range of 0-10"WC and an output signal of 4 to 20 mA. 

It would have an output of 4 mA at 0 pressure, 12 mA at 5"WC, and 20 mA at 10"WC. 

A pressure transducer has a bidirectional range of +/-5"WC and an output signal of 0 to 5 VDC. 

It would have an output of 0V at -5”WC, 2.5V at 0”WC, and 5V at 5.0”WC.