Air Movement
COURSE NARRATION
This course is available with audio narration.
To listen, click the icon to the right to begin the audio track.
This Module may contain material reproduced with permission from NFPA 96-2017, Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations, Copyright© 2016, National Fire Protection Association. This material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety which can be viewed for free access or purchased through the NFPA web site at www.nfpa.org (http://www.nfpa.org/).
NOTE: This material has not been reviewed, approved or endorsed by NFPA. NFPA is neither a sponsor of nor affiliated with KEC Concepts and has neither endorsed nor approved of the goods and/or services of KEC Concepts.
It is the position of KEC Concepts LLC and its affiliates that it will not be the leader, trainer or have the perception of implementing an official safety program for an organization, whether the safety material is for technicians, managers or business owners. KEC Concepts LLC and its affiliates can offer and provide educational material and direction to OSHA documents/regulations/hazard assessment material for the participant to improve your safety program. This content is not intended to serve as an organization’s official company safety program
Let’s Get Started
Welcome to the KEC Concepts new employee on-boarding course about Air Movement. The educational content of this module was created to introduce new kitchen exhaust cleaning professionals to the following topics:
- Fan Function & Types
- Fundamentals of Fan Unit Inspection and Maintenance
A quiz on this material will follow the presentation.
LEARN THE FUNDAMENTALS OF AIR MOVEMENT
There are multiple types of supplied air within a commercial cooking facility. The air inside the facility usually comes from 3 different sources.
1 – Transfer air, classified as freestanding fresh air that can transfer in and out of an area.
2 – Supply and return air provided by the HVAC system.
3 – Exhaust and make-up air, which is provided by the kitchen ventilation system.
Balancing these air systems in a commercial cooking facility can be challenging because these air sources are independent of each other and co-mingle in one space.
As professional kitchen exhaust cleaning technicians, inspecting, cleaning, maintaining, and caring for air movement systems is a significant part of our job.
A typical upblast fan unit with rooftop termination
An exhaust fan unit creates an air draft in the hood canopy and the duct system to remove vapors and effluent. The make-up or replacement air fan unit handles “replacing” the amount of air exhausted and brings clean, fresh air back into the cooking area.
A typical make-up air unit which brings fresh air back into the kitchen
An obstruction in a make-up air unit
DID YOU KNOW?This “circle of air” is what makes the kitchen environment comfortable for kitchen employees. Remove one side of this “air equation,” and things can become disastrous.
Measurements of exhaust and make-up air are a precise mechanical science. They’re based on the type of cooking equipment utilized, duct size and fan unit speed and capacity. For these reasons, fans have different capabilities and come in many different styles and designs. Some fan requirements are listed in the NFPA 96. These requirements apply to upblast fan units, in-line fan units, utility set exhaust fans, and replacement air fan units.
Let’s look at the definitions and some of the terms we will use.
DEFINITIONS
- Air Flow – Also referred to as Air Volume, is the measurement of the amount of air moved per unit of time, measured in cubic feet per minute (or CFM). *
- Air Intakes – An opening in a building’s envelope with the purpose to allow outside air to be drawn into the structure to replace inside air that is removed by exhaust systems or to improve the quality of the inside air by providing a source of air having a lower concentration of odors, suspended particles, or heating content. *
- Air Velocity – The distance air travels per unit of time, measured in feet per minute (or FPM). *
- Make-up Air (Replacement Air) – These terms may be used interchangeably. As air enters a building, and an equal amount of air must be exhausted from the building. Fan forced and passive air which is brought into an area designed to compensate and replace depleted air or combustible air from the same area. *
*All above-noted definitions are referenced from NFPA 96 2017
SAFETY TIP
As kitchen exhaust cleaning technicians, safety should always be our priority. When we are working in and around hazardous energy sources such as exhaust fan units, we must ensure the units cannot be accidentally started or energized causing, property damage, bodily harm or a fatality. You must follow proper procedures according to the OSHA Standard for the control of Hazardous energy. OSHA 3120 (link) addresses the practice and procedures that should be utilized to disable machinery or equipment, thereby preventing the release of hazardous energy while employees perform service and maintenance. The standard outlines measures for controlling hazardous energies—electrical, mechanical, hydraulic, pneumatic, chemical, thermal, and other energy sources.
It is your responsibility to:
- Identify the energy source and shut down affected equipment
- Notify any affected employees
- Shut down equipment using standard procedures
- Isolate equipment from the energy source
- Lockout/Tagout the energy source
- Release any stored energy
- Verify isolation of energy (amp meter, blocks, etc.)
- Perform proper service
- Clear the area and verify conditions before releasing the equipment from Lockout/Tagout control.
Your employer is responsible for your company safety program which should include Lock Out Tag Out (LOTO). If you have specific questions, you should ask your supervisor, and you can visit www.osha.gov.
The main goals of an efficient kitchen ventilation system are:
- To introduce sufficient clean, fresh outside air and remove or exhaust excess contaminated air for the adequate comfort of the occupants of the kitchen.
- To provide adequate outside air which allows proper combustion in for open-flame appliances, and reduces the risk of carbon monoxide poisoning.
- To dilute and remove by-products of the cooking process such as odors, vapors, steam, and combustion from open-flame and oil-burning appliances.
- To run smoothly, free of vibration and excess noise.
- To be easy to clean and remove any grease build-up by reducing the loss of efficiency and fire exposure.
As a kitchen exhaust cleaning professional, you must be the eyes and the ears for a restaurant owner or operator when inspecting the exhaust and make-up air units. If a fan unit is not running, or not running correctly, smoothly and quietly, you must document the deficiency in your written service report and notify the customer as soon as possible. If cleaning is required, correctly clean the unit and ensure it is operating correctly post-cleaning.
TECH TALK
When you encounter an upblast fan unit that is in need of cleaning, follow section 8.1.2.1 of the NFPA 96. This section states that upblast fans shall be hinged and have a flexible weatherproof electrical conduit and service hold-open retainers. These requirements allow you to properly clean and service the fan unit while it is in place instead of prematurely damaging the fan unit by laying it on its side on the roof, an action that could also damage the roof. Before you start to clean, check and make sure the hinge kit has been installed correctly on the same side as the conduit, so the fan can easily tilt back. Check the hinge to make sure it is in good condition and has no broken or damaged parts. Remember, hinges are an NFPA 96 requirement, and they make your duties easy and safe.
Below are the key factors that determine how much air a kitchen ventilation system should sufficiently produce.
- The volume of cooking that is occurring within the kitchen
- The type of cooking equipment and appliances used in the kitchen
- The type of structure and location of the kitchen
- The building’s HVAC system, which provides heating and air conditioning
- Local code regulations
Upblast fan units on proper hinge kits
DID YOU KNOW?Cleaning and maintaining rooftop exhaust fans is critical for kitchen exhaust cleaning professionals; however, it can be a challenging part of the job. Rooftop exhaust fans have multiple surfaces for grease accumulation including fan blades and the motor casing. It is imperative that they are properly cleaned and maintained. Exhaust system fan units can fail and wear out prematurely due to heavy grease build up which puts stress on areas such as the fan motor, fan blades, bearings and drive belts.
Examples of heavy grease buildup on fan hardware
Upblast Fan Unit Overview
TECH TALK
A grease containment unit cannot hold more than 1 gallon of grease and must be easily accessible for cleaning and maintenance. The size limit is designed to reduce the amount of combustible fuel source for the fan should a fire occur. An air movement fan unit will allow water and grease to escape from all sides of the fan unit because the fan housing and fan base are separated by a continuous space about ¼” between the two parts of the fan.
When a fan unit is installed, code requirements state an exhaust system must terminate outside the building with a fan or duct and through the roof or a wall.
Upblast fan units are extremely popular and easy to service. They are often installed in commercial exhaust systems because of their light-weight aluminum construction, low-cost and easy installation.
This type of fan is well suited for one-story free-standing restaurants, systems with minimal ductwork, and use in short distances to move air.
There are clearance requirements for exhaust fan units and make up air units.
An upblast fan must also have a hinge kit and be supplied with a flexible weatherproof electrical conduit and a service hold-open retainer. The hinge kit allows a technician to properly tip the fan back for proper inspection and cleaning without laying the fan on the roof membrane and causing damage to the fan housing. The flexible conduit allows the fan to tipped back for proper cleaning without damage to electrical wires and the hold-open retainer is a safety measure to keep the fan from injuring personnel while performing service.
A proper hinge kit installation
Examples of improper hinges on upblast fans
DID YOU KNOW?There are different types of upblast fans, some are designed for simple air movement in a system, and others are designed specifically for grease applications. A grease upblast fan unit will have a liquid-tight weld from the body of the fan to the base, with only a drain hole allowing water and grease to escape from the inside of the fan housing. The drain hole also has a grease containment unit that will capture fluids (water and grease) that escape through the drain hole.
In-Line Exhaust Fans
In-line exhaust fan units are used in instances where space is not available for an up-blast or utility set fan. The in-line fan unit configuration is one where the fan blades are inside the duct, or in-line with the airflow, but the motor, belts, and pulleys must be outside the airflow and protected by a grease-tight housing.
Utility Set Exhaust Fans
An example of a utility set fan unit
A utility set fan unit is usually a high-volume unit designed to move air very quickly and move lots of air volume through an exhaust system. They are typically found in Hotels, Hospitals, Malls or High-rise Buildings. They are also commonly used is solid fuel cooking or high-temperature applications.
Always ensure components and removable parts of a fan unit are properly reassembled.
If a utility set fan is installed inside of a building, it must be in an accessible area with adequate space to allow service personnel to service, maintain or remove the fan unit.
Proper photo documentation is an important part of your service.
SAFETY TIP
You should always be thinking about safety as the first concern in any situation you encounter. When we are working in and around fans, many times near the edge of a roof or on wall-mount termination units, we must always remember the requirements of the OSHA standard for fall protection. Most conventional systems to prevent falls from occurring include:
- Guardrail Systems
- Toe Boards Safety
- Net Systems
- Personal Fall Arrest Systems
- Training
- Safe Work Practices
- Warning Signs
- Limiting Personnel Into An Area
- OSHA has specific training on this topic, which can be found at www.osha.gov. 1926.501 Subpart M
- Your employer is responsible for providing a safe work environment for their employees, if you have questions, ask your supervisor.
- This information is provided for training and information purposes. It is not intended and should not be construed as an OSHA approved Safety Program for you or your employer.
DID YOU KNOW?Utility set fans must have a drain directed to an easily accessible and visible grease receptacle not larger than 1 gallon. This size limit is to minimize the amount of combustible fuel if a fire should occur.
AIRFLOW OVERVIEW
Airflow is the measurement of the amount of air movement per unit of time (usually measured in CFM, or cubic feet per minute). Calculating air flow can be very involved based on cooking equipment, duct size, and pressure drop (negative air pressure). A fan unit must provide a minimum 1500 and maximum 2300 cubic feet per minute (CFM) of airflow, with 1750 CFM being a recommended average airflow.
As a kitchen exhaust cleaning technician, you may not be involved in testing, repairing or correcting proper airflow, however, you do need to be able to identify signs that a system may not be operating correctly, and document those issues in your service report to inform the customer of the issue. Any test data or performance tests acceptable to the AHJ should be displayed or provided.
Communication with the customer regarding the condition of their system is a must.
Exhaust Fan Operations
DID YOU KNOW?When an exhaust system is operating, and the fire-extinguishing system is discharged due to a fire, the exhaust fan unit must continue to operate after the extinguishing system has been activated. The only time the exhaust fan unit is allowed to shut down is when it is required by a listed component of the ventilation system or by the design of the extinguishing system.
When an exhaust system is not operating, the exhaust fan unit does not have to start if the extinguishing system is activated. With technical advances in kitchen exhaust system design, NFPA 96 requires the exhaust fan unit be provided with a means for the fan unit to activate when an appliance under the hood is turned on.
Exhaust/Make-Up Air Basic Operation Test*
Before you begin the process of cleaning a commercial kitchen exhaust system, you must verify that the system is operational from both the exhaust and make-up air fan units. If you do not confirm that both systems are operating correctly before you start, and they do not function properly after your service, that can be a problem. It quickly becomes your problem if you did not check the system before starting. You could end up being responsible for something that is not your fault. Always verify the system is operational before beginning your service.
What is wrong with this picture?
If the system is not powered on, you must find the system startup switch or power supply whenever possible and power on the system. You must verify the presence of airflow in both the make-up air and exhaust air. Audible air movement through the exhaust hood typically indicates air flow. However, an anemometer will give you an accurate air velocity reading.
If possible, the owner(s)/operator(s) of the system must be interviewed to determine if any issues or problems with the system have been experienced.
During your basic operation inspection and testing, if any make-up or exhaust air system deficiencies are uncovered, you must provide notification as soon as possible to the owner/operator of the system. This notification should be documented in writing on your service report.
Inspection of belts, pulleys, motors and electrical switches is critical to identify deficiencies if present.
You should inspect the belts and drives of the fan to ensure proper operation. As a kitchen exhaust cleaning professional, you should inspect and document any operational issues for the customer even if you are not providing repair and maintenance service for the fan units Prior to your inspection, the fan must be locked out and tagged out to avoid injury, and your inspection should not begin until all fan motion has stopped.
The motor compartment of the exhaust fan must be opened and a visual inspection performed on all belts and drives. If you identify deficiencies such as cracked or loose belts or a non-operational fan unit, you must document any deficiencies in your project service report.
PRE-CLEANING ENERGY SOURCE PROTECTION
Before the start of the cleaning process, all electrical switches and switches on the exhaust fans (that could be activated accidentally) must be locked out and tagged out in accordance with OSHA and the requirements established by the AHJ.
REVIEW
There are different types of air movement within a commercial kitchen. Whether it is exhaust air, replacement air or HVAC air, they all play a role in the kitchen environment. The goal is to balance all air supplies, removing smoke, odors, and other effluents from the indoor environment and bring fresh, clean air back into the area for a pleasant experience for customers and employees alike.
While fans may come in different configurations such as up-blast, in-line or utility-set, the primary function of an exhaust fan unit is to create proper air movement, or airflow and air velocity to expel effluent from the kitchen. At the same time, the replacement air must bring cool, clean, fresh air back into the kitchen.
As exhaust cleaning professionals, we have a responsibility to inspect and test the system for proper operation, properly clean the system every time, provide documentation of the discovered deficiencies and inform the system owner/operator in writing as soon as possible. Always remember that our level of professionalism is defined by our ability to identify issues with a system and properly and accurately report those issues back to the facility.
Exhaust Fan Unit Overview