Reverse Action Control and Direct Action Control

Hi there,

Reverse action - the opposite to what your signal is doing. i.e. signal increases but valve closes because air signal is removed in proportion to your input signal.

Direct action - signal increases - valve opens.

Download the fischer control valve handbook from the emmerson web site. Youw ill get a much better understanding of the principle.

Regards,

Craig

Reverse action example:

• When the temperature rises above a certain setpoint, turn off the heater.

Direct action example:

• When the temperature rises above a certain setpoint, turn on the cooling fan.