Model selection：

Room Pressure Controller：TSI Sureflow™ Model 8681/8682 Adaptive Offset Controller;

Face Velocity Controller for Fumehood：TSI Model FHC50-01 Fume Hood Controller;

Static Pressure Controller for Exhaust Fan and MAU：TSI Sureflow™ Model 8635-ST Static Pressure Controller.

Controlsequence of Face Velocity Controller for Fumehoods:

The Model FHC50-01 fume hood controller uses a sidewall sensor to maintain constant fume hood face velocity. The sidewall sensor can be used to monitor actual face velocity or to correct face velocity disturbances, providing the ultimate in safety and response. If the average face velocity is higher than the pre-set value, the controller will reduce the exhaust volume by adjusting the "quick-response damper" until the face velocity re-stabilize at the pre-set value. If the face velocity is lower than the pre-set value, the controller will increase the exhaust volume until the face velocity re-stabilize at the pre-set value. When unoccupied, the controller will maintain face velocity in "standby" status setting.

Controlsequence of Static Pressure Controller for Fans and MAUs:

The Model Sureflow 8635-ST Controller use a static-pressure sensor to maintain static pressure of exhaust fans and MAUs stable at a pre-set value. If the measured value is higher than the setpoint, the controller will reduce the exhaust fans or MAUs drive speed back to the set-value. If the measured value is lower than the setpoint, the controller increases the exhaust fans or MAUs drive speed back to the set-value. When unoccupied, the controller will maintain static pressure value in "standby" status setting.

General Sequence of Operation

The TSI Sureflow™ Model 8681/8682 AOC Room Pressure Controller simultaneously controls room balance, room pressure, ventilation and temperature in the laboratory.

Room Balance and Room Pressure Control Sequence of Operation

The room controller continuously measures and maintains a constant flow offset between supply and exhaust volumes. If the offset becomes too large, indicating that the room balance is too negative, the room controller closes the general exhaust and then opens the supply to its maximum setpoint. If the offset becomes too small, indicating that the room balance is not negative enough or positive, the room controller closes the supply to its minimum ventilation or cooling flow and then opens the general exhaust.

The room controller simultaneously measures the room pressure differential and resets the flow offset to maintain pressure at setpoint. If the room pressure differential is too negative, the room controller decreases the control offset to its minimum setpoint until room pressure setpoint is reached. If the room pressure differential is not negative enough, the room controller increases the control offset to its maximum setpoint until room pressure setpoint is reached. 

Ventilation Control Sequence of Operation

The room controller continuously measures and maintains the supply air volume at or above its minimum setpoint. 

Temperature Control Sequence of Operation

The room controller continuously measures the room temperature. If the room temperature rises above setpoint, the room controller closes the reheat valve and then opens the supply air valve until either the room temperature reaches setpoint or the supply air volume reaches its cooling maximum setpoint. If the room temperature falls below setpoint, the room controller reduces the supply air volume to its minimum ventilation or room balance flow and then opens the reheat valve until room temperature achieves setpoint.