Direct Acting Thermostat Definition

Mcgraw hill dictionary of architecture and construction.

Direct acting thermostat definition. The opposite to this is a direct acting thermostat which energises equipment as the set point is reached. The thermostat that controls a typical house furnace is reverse acting since it switches the furnace off or de energises as the set point is reached. For example if we have two controllers on a distillation column reflux. A reverse acting ra pneumatic thermostat decreases branch line pressure as temperature increases.

A controller serves as the connection between the pressure tube the thermostat and the. A direct acting da pneumatic thermostat increases branch line pressure as temperature increases. As i understand it if the controller output increases when the measurement value rises it is a direct acting controller and if controller output decreases when the measurement rises it is a reverse acting controller. For example an air conditioner or a refrigerator.

A the process under control mainly flow or pressure applications b the process controller that initiates control action to the control valve. Direct acting types of thermostats increase the pressure in the tube in proportion to the rise in temperature. On the other hand the reverse acting pneumatic thermostat or ra is responsible for decreasing the pressure in the branch line as temperature is increased. How direct acting and reverse acting control valve loops work custom search a typical control valve loop consists of four basic elements for consideration.

Direct acting thermostat an instrument which activates a control circuit when a predetermined temperature is reached. Direct acting and reverse acting my comments the terms direct and reverse are frequently used when discussing control valves positioners and controllers while writing the control narratives for the complex loops though the definitions of direct and reverse seem pretty straightforward. This week s podcast covered the difference between direct acting and reverse acting thermostats and controllers.