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Direct Pressure Control with General Exhaust

Demo. Laboratory Space Pressurization-----Direct Pressure Control with General Exhaust 


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Laboratory design parameters:

Laboratory size(volume) = 5m*4.4m*3m=66m3

1500 bench-mounted fumehoods(2sets)=230CMHmin*-1150CFM max*

Flow offset =230CMH

Minimum ventilation flow= 990CMH* (ACPH = 15t/h)

Cooling flow 792CMH*(ACPH = 12t/h)

Design pressure = -1.0Pa

Design temperature= 25℃

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Model selection

Room Pressure ControllerTSI Sureflow™ Model 8636 Room Pressure Controller;

Face Velocity Controller for FumehoodTSI Model FHC50-01 Fume Hood Controller;

Static Pressure Controller for Exhaust Fan and MAUTSI Sureflow™ Model 8635-ST Static Pressure Controller.


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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 8636 Room Pressure Controller simultaneously controls room pressure differential, ventilation and temperature in the laboratory.


Room Pressure Control Sequence of Operation

The room controller continuously measures the differential pressure between Demo.Lab and office. If the room pressure differential becomes less negative, the room controller closes the supply damper until the supply airflow reaches its minimum ventilation or cooling flow and then opens the general exhaust damper until room pressure differential achieves setpoint. If the room pressure differential becomes too negative, the room pressure controller closes the general exhaust before opening the supply damper until room pressure differential achieves setpoint.

 

Ventilation Control Sequence of Operation

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