A customer asked: How do I find the sum to two flow transmitters, provide a visual warning of an overflow condition and record total flow from the transmitters? We suggested a system that is composed of Action I/Q modules utilizing the Q498 Math Module and the Q108 Field Configurable Limit Alarm. Two flow transmitters and a chart recorder complete the system.

Each flow transmitter (FT) draws 4 to 20mA from the 24V DC power supply based on product flow. The two 4-20mA signals are fed into the Q498 Math Module. The Q498 is a highly configurable multi-input module capable of providing various math functions such as addition, subtraction, multiplication, etc. In this application, the signals are summed together.

The Q108's input terminals are connected in series with the chart recorder. Both the Q108 and chart recorder are configured for a current input. When flow exceeds a predetermined setpoint, the Q108 limit alarm "Trips".