Commercial Kitchen Exhaust | California Mechanical Code

Commercial Kitchen Exhaust Regulations

The kitchen exhaust is the heart of any commercial kitchen ventilation system. It manages the grease vapors, odors, contamination, moisture, toxic and combustible gases found in the air.

However, if it is not installed correctly, it will compromise the safety of your commercial kitchen. That is why California State has a mechanical code section. The list was updated in 2019 for the general requirements for the commercial kitchen exhaust.

Commercial Hoods Type 1

According to the general commercial kitchen exhaust, the type 1 hoods will be installed at or above any kitchen equipment that produces comparable smoke or grease. (CMC Section 508).

Where the type1 hood should be installed

  • Ovens
  • Hot-top ranges
  • Deep-fat fryers
  • Grills
  • Broilers

Construction of Type 1 Hoods

The type 1 hoods should be constructed using steel that should not be less than 0.048 inches in thickness. If it is made using stainless steel, it should not be less than 0.036 inches in thickness.

If you are not planning to use steel or stainless steel to make the hoods in your commercial kitchen, ensure the state approves the material used. It should also have the equivalent strength and should be corrosion and fire resistance. (Section 508.3).

Construction of Type II Hoods

When it comes to constructing type II steel, you need to make sure that the steel is not less than 0.024 inches in thickness. If you are using copper to make type II hoods, ensure that the sheets do not weigh less than 0.017 ounces per square inch.

The type II hoods will need to have their joints and seems to be substantially tight. There should not be any use of solder used to construct the hood unless it is used to seal a joint seam. (Section 508.4).

Grease Vapor

When installing the wall-mounted hood, it needs to be well assembled and tightly fit against the back wall to not allow the grease vapor to pass behind the hood.

If there is even the tiniest space that permits the steam to escape, then your commercial kitchen will not be compliant with the regulation set by the state of California. (Section 508.6).

Seams Joints and Penetrations

When it comes to the Commercial kitchen exhaust, it is essential for the seams, joints, and penetration to be liquid-tight and continuous external weld to the hood’s lower outermost perimeter. (Section 508.7)

Canopy Size and Location

When installing the commercial kitchen exhaust, it is essential to ensure that the inner part of the edge shall overhang or extend a horizontal distance. But it should not go beyond 6″ beyond the edge of the cooking surface.

It is also essential to make sure that the cooking surface on the open side and the vertical distance between the lip of the hood and the cooking surface do not go over 4 feet.(Section 508.10.1)

Grease Removal Device, Installation

The commercial kitchen exhaust needs to give ample distance between the grease removing deice and the cooking surface. It should not be lesson than 18 inches.(Section 509.2)

Grease Removal Device Protection

The grease removal device needs to be installed appropriately to ensure that it is well protected from any combustion gas outlets.

It should also be protected from impingement that might take place during the regular operation of the cooking appliances. The state also requires that the distance between the grease removal device and the flue outlet be less than 18 inches.

In addition, it should also be accompanied by the installation of a steel or stainless-steel baffle plate. The place should be put between the heat source and the grease removal device.(Section 509.2.2)

Grease Drip Trays

The other important part of the commercial kitchen exhaust is the grease drip trays. They should be put beneath their lower edges. The tray needs to be the least size that is needed to collect the grease.

It should be pitched to drain into a container that is not bigger than 1 gallon. The container needs to be metallically accompanied and enclosed.(Section 509.2.4)

Exhaust Duct System

When installing the ducts, it is important to ensure that it does not pass through the walls. It should be installed with not less than 2% slope on the horizontal runs and should be up 75 feet.

It should less than 8% slope on the horizontal runs that are not more than 75 feet.

The factory-built grease ducts shall be installed by the listing and the manufacturer’s installation direction. Ducts will be installed without forming any dips or traps.

It is important for the duct system serving type 1 hood to be made and fixed in such as that grease cannot be pocketed. It should also not slop over 14 per lineal food to the hoods.

It should also not approve the grease reservoir. If the ducts are over 75 feet in length, they should not be less than 1 inch per linear foot. (Section 510.0)

Sign of Being Placed

It is important to ensure that there is a clear sign on the access panel. The sigh should read ACCESS PANEL- DO NOT OBSTRUCT. (Section 510.1.5)

Type II Exhaust Duct System

The ducts system that is serving type II should be constructed using rigid metallic materials. It should also brace and support. In case it is subjected to positive pressure, it also needs to be sealed. (Section 510.1.7)

510.3 Openings

The system news to have openings at any side that is more accessible.

Access panel for cleaning should be offered in the duct or the hood wing

Exhaust fans ductwork connected to both sides should have access for cleaning and inspection.

If the opening is not possible or large enough to allow leaning, it should be offered to 12 feet intervals.

It should also have a support system for horizontal ducts system that is 24 inches and bigger than a cross-sectional dimension. It should be designed for the weight of the ductworks and should be around 800 pounds at the point in the duct systems.

Welded duct to duct connection (Section 510.5.3.2),

  • 1 telescope joint
  • Bell-type joint
  • Flange with the edge weld
  • Flange with filled weld
  • But welded connected will not be allowed.

Exterior Installation

The outer part of the ductwork should be vertical when possible. It should be installed and have support on the outer part of the building. If you use fasteners, it is important to make sure that they do not get into the duct walls. (Section 510.6)

Final Thought

Being compliant with the commercial kitchen exhaust will help in keeping you and your employees safe. It will also ensure that you do not end up getting on the wrong side of the State of California state.

Reference Code: California Mechanical Code 2019