Grease Filter Efficiency Test Method - Food Service Technology ...

The optical particle counter (OPC) along with the diluter and cascade impactors were used to
characterize the non-condensable particulate matter, and the EPA Method 5 sampling train
was used to determine the total grease vapor of the effluent generated when cooking
hamburger. It was found in initial testing when cooking hamburger that a dilution ratio of
50:1 was required to keep the total aerosol concentration below the maximum concentration
limit specified by the manufacturer of 10 7 particles per ft 3 . The OPC, with 50:1 dilution, was
also used to determine the collection efficiency of grease baffles and filters while cooking
hamburger and when generating oleic acid particles using aerosol generators.
Two aerosol generators were used to measure the aerosol spatial uniformity in the exhaust
duct. An ATI Model TDA-4B aerosol generator was used to generate small oleic acid
particles with a mass mean size of approximately 0.3 µm diameter and a modified TSI Model
3450 Vibrating Orifice Aerosol Generator (VOAG) was used to generate large oleic acid
particles with a mass mean size of approximately 5 µm diameter. The VOAG was modified
by replacing the vibrating orifice with an Alltech nebulizer. The syringe pump liquid feed
system was replaced with a constant liquid feed pressurized vessel. The modified VOAG
was also used for the grease baffle and filter collection efficiency tests. A neutralization
column, containing six NRD Model 2U500 Staticmaster Po210 (500 µCi) radioactive
sources, was used to bring the generated aerosols to a Boltzmann charge distribution [2].
Ancillary equipment was used to measure pressures, temperatures and relative humidity
(RH). A Curtin Matheson Scientific Nova barometer was used to measure the barometric
pressure. The room temperature was measured using a mercury thermometer. Griddle, hood,
and in duct temperature measurements were made using Type K thermocouples (20 gage
with glass braid insulation; 900 °F) connected to a Keithley 2700 Multimeter/Data
Acquisition System. Magnehelic pressure gauges models 2000-00 (0-0.25 in. H 2 0) and
2001C (0-1.5 in. H 2 0) were used to measure the pressure drop across the grease baffles and
filters, respectively. The RH was maintained and measured using a Vaporstream Model
VLC-9-1 humidifier system.
Appendices E and F give a detailed description of the test and sampling procedures, and
Appendices G and H detail the analytic procedures.
3.2 TEST FACILITY CHARACTERIZATION.
3.2.1 Calibration of Griddle
The griddle was calibrated in accordance with ASTM Standard F 1275-99 [3]. Six Type K
thermocouples were welded to the surface, 3 in. from one side, 6 in. between and 5 in. from
the back, of the griddle. The thermocouples were connected to a Keithley 2700
Multimeter/Data Acquisition System which converted the thermocouple emf voltages to
temperatures and displayed the temperatures. The calibration procedure is given in Appendix
D.
3.2.2 Calibration of Test Airflow Rate
To perform the test airflow rate calibration, three ½ in. diameter holes were drilled in the
exhaust duct at the sampling location shown in Figure 3.1, one hole at the bottom of the duct,
and at 60° on either side of the bottom of the duct. A support fixture was fabricated and
attached to the duct using a large hose clamp so that it could be rotated to the three different
access holes. The hot-film anemometer was used to measure the time averaged velocity in
the duct. This device had been sent to the manufacturer for recalibration prior to the
measurements. A cylindrical sleeve was designed and fabricated to slide through a hole in
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