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139
Canopy Exhaust Volume Measurement
7.
Remove the tape holding the exhaust relief valve(s) open and close them. Close
the intake valve. Turn on the external blower.
8.
Position the probe of the thermal anemometer against
the intake slot on the right side of the canopy, such
that the sensor portion of the probe is centered front to
back of the opening, with the bottom of probe sitting
on the bottom of the inlet wrapper, and in the plane of
the canopy side wall, as shown.
9.
Adjust the exhaust system to its lowest stable volume.
10.
If needed, readjust the exhaust system blower speed or
the exhaust damper until thermal anemometer reads
250 +/- 10 FPM. This is equal to an inflow volume of approximately 50 CFM.
Thus, the average intake velocity multiplied by 5 will yield the approximate
make-up air volume.
11.
With the Logic+ still running, turn off the exhaust blower or close the damper.
Within 15 seconds, the relief flap(s) of the canopy will open, the audible alarm
will sound, the Logic+ display will display “Canopy Alarm, and the unit blower
will run at full speed.”
12.
Reset the exhaust system to normal operation. The unit is now calibrated.
Note: Because the Logic+’s motor runs at full speed during a canopy alarm, you may
have to turn the Logic+’s blower off to reset the unit’s alarm condition, once the
exhaust system is operational.
Cabinet Set-up for
Canopy Connection
All 3-foot
Models
All 4-foot
Models
All 5-foot
Models
All 6-foot
Models
Labconco Canopy P/N
3889200
3889201
3889202
3889203
Canopy Slot Area (F
2
)
.12
.12
.12
.12
Canopy Inflow Range (CFM)
50-100
50-100
50-100
50-100
Nominal Canopy Slot Velocity (FPM)
240-260
240-260
240-260
240-260
Nominal Canopy Slot Volume (CFM)
50
50
50
50
Canopy Vacuum (In. H
2
O)
0.1-0.15
0.1-0.15
0.1-0.15
0.1-0.15
Note: Because the Logic+’s motor runs at full speed during a canopy alarm, you may
have to turn the Logic+’s blower off to reset the unit’s canopy alarm condition, once
the exhaust system is operational.
1 – The canopy can operate with a minimum make-up air volume of 20 CFM; however, unstable exhaust
systems may require increasing the volume up to 100 CFM to prevent frequent canopy alarms.
