Ventilation systems remove cooking heat, effluent and odors in commercial foodservice operations. Custom by nature, foodservice design consultants often size this equipment based on the appliances that will reside beneath the hood.
This engineered system includes a number of components. Exhaust hoods typically hang over the cookline and in the dishwashing area. The hood’s size and shape will vary depending on the equipment underneath. The various filtering options or grease removal apparatuses available range from low-tech baffle systems to high-efficiency extractors. The type that best suits a foodservice operation depends on the ventilation process, the system’s design and the level of grease extraction necessary. Utilizing more filters can help control grease buildup that serves as fuel.
Exhaust fans represent another component of ventilation systems. Operators can mount these units on either the facility’s roof or an outside wall.
When unbalanced or poorly designed, kitchen exhaust systems can allow heat and smoke to spill into the kitchen, negatively impacting air quality, back-of-house temperatures and utility bills. The load generated by cooking units will determine how much make up or replacement air is necessary to balance the environment. A lack of replacement air can create negative pressure in the kitchen, which can compromise the operation of cooking equipment. The air velocity around the hood also needs to be minimized or the ventilation system may be compromised.
These systems also include fire suppression equipment and controls. Most incorporate tanks of chemical agents that can help contain or extinguish fires. Newer systems have unlimited water supplies for this purpose. When a sensor at the duct connection gets to a certain temperature, this fire suppression system will activate electronically. Also, bigger hoods with more overhang and end panels can help contain fires.
Due to sanitation requirements, hoods need to be either 100 percent stainless steel or stainless in exposed areas, such as food zones. Automated cleaning systems are available, and an ultraviolet light option inside hoods helps break down grease in high-volume applications.
This equipment is categorized by use. Type I ventilation systems are grease rated for positioning over grease-producing appliances, while Type II or B units, also called vapor hoods, are designated to handle heat and steam over dishwashers and some oven types.
Ventilation systems must be in compliance with NFDA 96, which provides preventive and operative fire safety requirements intended to reduce the potential fire hazard of both public and private commercial cooking operations.
UL 710 requirements cover Type I commercial kitchen exhaust hoods intended for placement over commercial cooking equipment. These hoods are evaluated relative to minimum exhaust air flow required and maximum supply air flow allowed for capture and containment of cooking effluents under laboratory conditions. These codes, in addition to NFPA 70, the International Mechanical Code (IMC) and the Uniform Mechanical Code (UMC), cover products rated 600 volts or less.
To increase energy efficiency, operators can add hood side panels to capture and contain heat and smoke. There also are newer technologies that help minimize smoke and odors to create cleaner air.
Several types of variable or demand control ventilation systems fluctuate the exhaust volume to accommodate varying degrees of cooking activity. With these units, fan speeds are automatically adjusted up or down as needed. This puts less demand on the system, saves energy and creates a quieter atmosphere.