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Measuring Airflow
Overview
ELXC and ELXC-UVi Ventilators are factory engineered to operate at a specific exhaust volume, CFM (Cubic
Feet per Minute), based on, primarily, the type of cooking appliance, their associated energy input, and the
exact model of the Ventilator. Smoke capture, grease extraction efficiency and heat removal are dependent
upon the proper exhaust volume (Airflow) through the Ventilator. If the exhaust volume is below design,
smoke, grease and heat may escape the confines of the Ventilator creating an uncomfortable kitchen for the
operators. It will also reduce grease extraction efficiency of the XGS Extractors resulting in additional grease
depositing in the duct system and exhaust fan. This can lead to sanitation problems and fire hazards if left
uncorrected. If the exhaust volume is higher than design, more energy will be used to operate the exhaust
fan, excessive noise levels may result, and grease can be pulled through the Extractors depositing in the duct
and fan. Operating the Ventilator at higher or lower airflows than design will result in the entire kitchen
ventilation system being out of balance.
It is important that at initial installation of the Ventilator the exhaust volume is measured to verify that
it meets design. It is also recommended that the exhaust volume be measured once every two or three
years to insure that the exhaust fan is operating properly. The exhaust volume for each Ventilator section is
stamped on the Ventilator Nameplate (refer to Figure 5-4-1 on page 5-4).
Measuring Airflow
The Ventilator exhaust volume is determined by measuring the air inlet velocity and using FPM to CFM
Table T-5-4-1 to convert the recorded velocity FPM, to an exhaust volume in CFM Per Lineal Ft. of Ventila-
tor. This method requires an Anemometer and the recommended unit is a Pacer rotating vain Model DA40
or DA4000 Digital Anemometer. These instruments can be purchased from Gaylord Industries.
To measure the air inlet velocity and confirm the exhaust volume, proceed as follows:
Instructions
1. For safety purposes turn off the cooking equipment and allow to cool.
2. Confirm that all XGS Extractors are clean and in place.
3. Close all Extractor Access Doors.
4. If model ELXC-UVi Series, make sure all UV Module Access Doors are in closed and latched.
5. Turn on the exhaust fan.
6. Attach the cable from the sensing head to the meter (refer to Figures 5-3-1 and 5-3-2).
7. Attach the handle sections to the sensing head.
8. Beginning at one end of the Ventilator, place the sensing head into the inlet slot with the handle in the
horizontal position as shown in Figure 5-3-1.
9. Using the 16 second averaging feature on the meter, slide the sensing head along the entire length of
the slot, slowly, at a rate that would last approximately 16 seconds. If you reach the end of the Air Inlet
Slot before the 16 second interval has elapsed, continue moving the probe head back the other direction
(without removing it) until the 16 second interval has expired.
Measuring Airflow
5-1
Chapter 5 - Testing and Repair
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