507.2.1 Type I and Type II hoods. A Type I hood shall be installed at or above all commercial food heat-processing appliances that produce grease vapors or smoke. A Type I or Type II hood shall be installed at or above all commercial food heat-processing appliances that produce fumes, steam, odor or heat.

Interpretation: 
Type I Hood – Commercial food heat-processing appliances that produce grease vapors or smoke (includes pizza restaurants). 
Type II Hood – (produce little, if any, grease-laden vapor) Examples:

·       Pastry
·       Bread
·       Cookies
·       Cakes
·       Convection/small conveyor pizza ovens (conv. stores, etc. ONLY)
·       Steam cooker (does not include steam warmers)
·       Dish washing machines
(Note: Hoods are not required for coffee makers and/or toasters.  Hoods are not required for mobile food holding cabinets (max 3000 watts))

Section 508.1.1 Make Up Air Temperature:  Make up Air – Tempering of Air – optional as required by owner and/or engineer. 

Section 507.9 Clearances for Type I Hoods: The clearance maybe reduced as per Table 308.6 or as Alternate Methods – Use NFPA 96, Chapter 4.2.3.2 (existing construction only)

"Where a clearance reduction system consisting of 0.69 mm (0.027 in.) (22-gauge) sheet metal on 25 mm (1 in.) mineral wool bats or ceramic fiber blanket reinforced with wire mesh or equivalent spaced out 25 mm (1 in.) on noncombustible spacers is provided, there shall be a minimum of 76 mm (3 in.) clearance to combustible material"  

Section 507.17 Performance Test:  Testing shall verify the rate of airflow and verify the capture and containment performance of the exhaust system.  The 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 candles, smoke puffers, etc. (Handout rev. 5/30/03) see Hood Performance Report Interpretation (PDF) and Hood Performance Worksheet (PDF)

Commentary Commitee:
If the water heater (any gas appliance) is located out of the normal travel path no protection is required.  There are several ways to prevent vehicular damage to the water heater (any gas appliance).  These would include pipe bollards extending 3' (ft) above the floor, { 2" schedule 40 steel pipe set in concrete floor; 2" schedule 40 steel pipe set in cored hole in existing concrete floor and sealed with epoxy; 2" schedule 40 steel pipe with ¼" steel plate (welded) anchored to concrete floor with (4) ½" X 2 ½"  (embedment depth 2 ¼") anchor bolts}, curb stops and/or raised pads of not less than 5 ½" set not less than 40" from the water heater.