KITCHEN HOOD TEST

Most building officials require testing and certification of commercial kitchen hoods prior to original service and periodically thereafter.  Following are guidelines for basic testing: procedures:

GUIDELINES BEFORE YOU BEGIN:

Testing and balancing of a system is necessary to insure proper and efficient operation of that system .  When air is removed from a building, that mass of air must be replaced to maintain a constant pressure in the space. Any change in the pressure differential between inside and outside air will in some way affect the operation of a system, most commonly that affect is a negative one.
Air balancing, as well as the simple performance test in International Mechanical Code section 507.16.1 should be
included in all jobs. Requirement in the 2003 IMC, which is currently effective in most parts of the U.S., are as follows:

The simplest means of doing the performance test is using a T-T Puffer from EV Hill. Activate the puffer and
use it to trace effluent around the entire perimeter of the hood, emitting smoke a few inches under the lower edges of the hood. If the smoke goes into the hood, it passes the test. If smoke goes out of the hood, adjustment is needed.

507.16.1 Capture and containment test. The permit holder shall verify capture and containment
performance of the exhaust system. This field test shall be conducted with all appliances under the hood at
operating temperatures. Capture and containment shall be verified visually by observing smoke or steam
produced by actual or simulated cooking, such as with smoke candles, smoke puffers, etc.”
1. A hood with multiple make-up air risers should be balanced according to the cooking load beneath it. For
example, if a hood with multiple make-up air risers has a charbroiler in the center and several ovens on the ends,
the risers should be evenly balanced. This will achieve the most efficient contaminant capture.
a. Perforated supply plenums discharging air around the hood should be set to the designed discharge
velocity.
2. When fan pulleys are adjusted, belts should then be re-checked for correct tension and an amperage reading
should be taken on the motor to make certain it is not overloaded.
3. The prime objective of balancing is to insure that each hood will capture all the contaminants produced by the
equipment it covers without causing undesirable conditions in the kitchen (i.e., excessive negative pressure,
excessive quantities of hot or cold air in the kitchen, etc.).
4. A performance evaluation of the system can be performed only if all the following items have been completed:
a. All fans operational and rotations visually verified by observation of the arrows stamped on them.
b. All filters in place.
c. Equipment under the hood in place and operational.
d. HVAC units in place and operational.

EXTERNAL FACTORS WHICH MAY AFFECT YOUR HOOD PERFORMANCE:

1. HVAC units are generally specified to supply 25% outside air (OA) to the room ventilation. If RTU’s are not
supplying the proper amount of OA to the building, negative pressure will exist.
2. HVAC return grilles located close to a hood can cause performance problems. The return grille competes with the
hood to capture the air in the room. For example, a return grille for a 10-ton HVAC unit can draw anywhere from
3000 to 4000 CFM. This is equivalent to the exhaust of a 10′ to 13′ canopy hood. As a result, a return air grille
located within 6′ of a hood can have a serious effect on that hood’s capture ability.
3. HVAC diffusers located near a hood can create flows in the room that detract from the hood’s ability to capture. If
the HVAC diffuser bounces air off the front of the hood or directs air along the hood and past the end, the air flow
created can draw smoke and contaminants out of the hood.

Following is a guide provided by one building inspection department to assist their clients to comply with building code standards:

Bureau of Construction Codes

Commercial Kitchen Hoods/Smoke Test Procedure

The purpose of exhaust hood smoke capture testing is to ensure containment of heat, steam, vapors, obnoxious odors, smoke, and fumes emitted by the cooking equipment and to prevent condensation accumulation and drippage. Therefore, capture needs to be evaluated at all exposed sides of the hood. In order to enhance statewide uniformity in
the evaluation of kitchen exhaust systems with smoke, the following procedures shall be
required.
While performing a smoke test consideration shall be taken not to adversely affect the operation of other mechanical equipment installed. A final ventilation balance report shall be submitted prior to the capture and containment
test. The ventilation balance report shall agree with the air quantities stipulated on the approved plans and specifications for the installation
Building pressure shall be verified, not to exceed 0.02” water column negative. This shall be verified with all equipment in normal operation and with all the windows and doors closed.

Test Conditions:

Movement of persons is to be minimized.

Interior or exterior doors, windows, drive-thru
windows, and roof hatches are to be kept closed.

All equipment (exhaust, make-up air, rooftop unit, etc) that may effect the performance

of the hood shall be activated during the test.

Equipment Needed:

1. SMOKE CANDLES (cartridges): burn time minimum 45 seconds; volume 50
cubic feet; measures 0.5” Dia. X .375” L; weight 0.0 ox.; smoke.

2. TEST CONTAINER: metal cylindrical container approximately 6” in diameter
and 7” high.

Test Locations:

1. Locate the test container on the cooking surface or inside the cooking vessel or cavity as necessary.

2. Where the test location is to be the cooking surface, adjust the centerline of the test container inward 12 inches from the leading edge of the cooking surface and 12 inches from the hood end, measured horizontally.

3. Where ends are exposed, the test container is to be located 12 inches from the wall and 12 inches inward from the open hood end, measured horizontally.

4. Each subsequent test location is to be 36 inches to the left or right from the previous test location until the full length of the hood is tested.

Cooking Equipment:

1. The cooking equipment shall be tested and operated in a manner similar to normal usage.

2. When deep-fat fryers are included in a bank of cooking equipment, the fryers may be operated using water in place of oil and the temperature adjusted to produce simmering, not vigorous boiling, water, (If oil is used, it must be discarded following the evaluation in order to prevent potential food contamination). The test container is to be located in or on the surface of the fryer basket(s).

3. When ovens are installed (except convection, range, and combi ovens), only the top cavity door is to be open and the heat/steam source activated for all compartments; open means a position 90 degrees from the closed position. The
centerline of the test container is to be located inward a minimum of 12 inches from the front edge and inside the oven cavity. NOTE: Range ovens are to be operated but not tested if the range top gas-fired burners or the electric heating
elements are to be tested.

4. Convection and combination ovens are to operate with all doors closed, the heat source activated in all compartments, and the air circulating fan(s) activated. Locate the top lip of the test container 42” above the floor and in contact with the front of the oven. Where ovens are installed so as to be at the ends of the hood and a full side
curtain or wall is not installed, the lip of the test container is to be located level with the top of the oven cabinet.

5. Conveyor-type ovens shall be set at operating temperatures and the air circulating fan(s) activated. Test container shall be placed at each end of the oven openings.

6. When range tops, gas-fired burners, or electric heating elements are installed, open cooking containers filled with water are to be located on 25% of the burners and heated surfaces and allowed to heat to 180 degrees F. A minimum of 51% of the range surface and heating devices and the range ovens are to be activated.

7. Brazing units, steam jacketed kettles, Chinese wok ranges, and similar cooking equipment are to be filled with water to a level of 2-3 inches or as recommended by the manufacturer; the heating elements activated; and the water allowed to heat but not boil. Covers, if provided, are to be in the open position. The test container is to be located inside the open vessel. NOTE: Chinese wok ranges equipped with continuous water-cooling, should have these devices activated.

Performance Evaluation:

Acceptable performance, consist of capture of all visible smoke generated. A demonstration is a complete testing of all identified test locations. A complete and thorough ventilation system evaluation will ensure that when the system is properly maintained and operated, it will capture effectively.