The stabilizing jet feature is used to monitor and control a fume hood stabilizing jet fan. The status of the stabilizing jet fan is shared with other functions to determine exhaust volume setpoints and generate alarms. The stabilizing jet fan is turned on and off based on fume hood sash position and, fume exhaust air volume flow.

A differential pressure switch is normally used to determine if the stabilizing jet fan is operating properly. Occasionally a differential pressure switch is not installed. The stabilizing jet alarm will always be off when the binary input for the differential pressure switch is not present.

Description

Parameter

Default value

Setpoint for stabilizing jet fan speed
▶ The speed signal to the stabilizing jet fan when the fan is operating. Set according to the fume hood manufacturer’s instruction.

SpStbFanSpd

42 [%]

Switch-off sash position for stabilizing jet fan
▶ The stabilizing jet fan will be off when the sash is below this position. Set according to the fume hood manufacturer’s instruction. Only used with FhSash15.

SwiOffSshpFan

4.0 [cm]
1.6 [in]

Switch-on sash position for stabilizing jet fan
▶ The stabilizing jet fan will be on when the sash is above this position. Set according to the fume hood manufacturer’s instruction. Only used with FhSash15.

SwiOnSshpFan

8.0 [cm]
3.1 [in]

Switch-off area for stabilizing jet fan
▶ The stabilizing jet fan will be off when the face area is less than this value. Set according to the fume hood manufacturer’s instruction. Only used with FhSash11…14.

SwiOffAreaFan

0.06 [m2]
0.65 [ft2]

Switch-on area for stabilizing jet fan
▶ The stabilizing jet fan will be on when the face area is greater than this value. Set according to the fume hood manufacturer’s instruction. Only used with FhSash11…15.

SwiOnAreaFan

0.12 [m2]
1.29 [ft2]

Switch-off point for exhaust air volume flow for stabilizing jet fan
▶ The stabilizing jet fan will be turned off if FhAirFlEh < SwiOffAflEhFan for a time longer than DlyOffFanAirFl. Set according to the fume hood manufacturer’s instruction.

SwiOffAflEhFan

150 [m3/h]
88.3 [ft3/min]
41.67 [l/s]