In Cahoots – Interconnections of Fire Protection Systems with Ancillary Equipment


Expertise Includes:

    • Commercial Kitchen Fires
    • Fire Protection Systems
    • Industrial Process Hazards
    • Fire Suppression Systems
    • Scope of Damage/Cost of Repair
    • Fires & Explosions Analysis: Origin & Cause
    • Combustible Dust Explosions
    • Codes & Standards Analysis

Fire protection is an expanse that I am both fascinated by and passionate about. To prove it, I could show you my sprinkler collection… the old ones, the new ones, the sizes, the features!  But instead, I will share some information to show you the relationship between fire protection systems and other systems that you may have never thought about!

Fire protection, suppression, and alarm systems often do not act alone. They can be in cahoots with life safety systems or other equipment or building systems to mitigate fires and help firefighters. Many, but not all, of these functions are associated with fire alarm systems. Many, but not all, of these functions are customary and expected. Some of these functions will automatically reset when the alarm or system is reset, but not all!

Fire Alarm Systems

Fire alarm systems are often thought of as systems that notify you of something – that relay information to building occupants and to alarm monitoring companies. This is certainly true, but they can be involved in much more as it relates to fire safety. In NFPA 72, these are known as “emergency control function interfaces.”

Elevators. When a fire alarm is triggered by smoke detectors or other initiating devices, an Elevator Phase I Emergency Recall is also activated via a relay / control module. Generally, this function cancels all calls for the elevator and moves the elevator to a preset recall floor, which is commonly the ground floor, to make it available for firefighters to use. If there was a condition that could compromise the elevator’s safety, such as a waterflow alarm for a sprinkler in the hoistway or fire detection active in an elevator machine room, a shunt trip would activate to turn off power to the elevator. This simultaneously activates a flashing firefighter hat light in the elevator car as a warning to firefighters.

An elevator control switch – incorporating a fusible disconnect and shunt trip in one. Three alarm relays are to the left of the main switch (Courtesy of Colley Elevator).

Air-Handling & Ventilation. Activation of a fire alarm can shut down regular air handling equipment and close fire dampers. This limits the spread of fire and smoke. Other air-handling systems, like stairway pressurization or smoke control systems, may turn on.  Smoke control system removes smoke from a building. Stairway pressurization pushes fresh air into an evacuation stairwell, keeping smoke out.

Have you seen those very large, helicopter-like fans at your warehouse club or home improvement store? Known as High Volume Low Speed (HVLS) fans, they are required to be interlocked to shut down on activation of a sprinkler waterflow for the area served by the fan. These fans move so much air that, in a fire scenario, if left running, they can disrupt the development of the heat plume and prevent or slow sprinkler activation. They would also disperse smoke.

An HVLS in a big-box retailer.

Effect on certain doors. Powered fire door holders lose power, so that those fire doors close. This action limits the spread of fire and smoke. Electrically locked doors in an egress path will unlock in the direction that takes you to an exit.

Talking Back. Sprinkler devices, kitchen suppression systems, and other “dumb” devices can have modules or switches to facilitate their connection to a fire alarm control panel (FACP).

Suppression Systems: Shuttin’ it down, Closing it up

A fire suppression system often cannot be effective without certain conditions being met, such as

  • shutting off energy or fuel feeding a fire scenario,
  • closing up an enclosure,
  • shutting down ventilation

Consider a total flooding system being used to protect a computer room or data center. The activation of the total flooding system would typically be arranged to shut down the room’s ventilation, close dampers and activate an Emergency Power Off (EPO) switch (shunt trip again) to the equipment in the room.

Commercial Kitchen Fire Suppression Systems

When this type of fire suppression system is activated by the release of a fusible link on a tensioned cable, it will also function to shut off the energy source to the protected equipment. Take a natural gas deep fryer, for example; its fire suppression system will close the gas valve on activation. An electric deep fryer will have a shunt trip to shut off the power to the fryer on activation of the fire suppression system. Why is this? A fire involving the oil in a fryer can re-ignite after a suppression system activates if the oil continues to be heated.

The release of the cable during a test of a kitchen fire suppression system caused this gas valve to close

As briefly mentioned above, a suppression system’s controls can be interconnected to a fire alarm system or other accessories.  Activation of the system should also shut down make-up or supply air fans (exhaust fans remain on), be interconnected with the building’s main FACP if there is one, and activate an audible alarm or visual indicator.

The snap-action switch among the otherwise mechanical suppression system connects the controls with auxiliary functions.

Equipment shut down for discreet fire hazards

Pumping of ignitable liquids or hydraulic fluid may be interlocked with a sprinkler water flow alarm or local heat detectors. This can be accomplished with a connection to a machine’s emergency stop circuit. With air-operated pumping, such as a paint or coating operation, this might be accomplished by closing a valve on the air line supplying the pumping equipment.

The activation of special protection systems on machining centers will ideally not only shut down the machine, but also hydraulic systems. Where ignitable coolant is used, valves to the machine from central coolant systems will ideally shut down as well.

Take-aways and final words

  • For the assurance of complete and proper functioning, a system should be functionally tested, and the testing should include integrated systems. Annex A.5.1.3 in NFPA 4 says, it “simulates real-world conditions,” and “the test is performed with no bypasses or disabled points or features, which should represent the real-world, day-to-day configuration and outcome (output result) if an incident or emergency event actually occurred.” Enhanced content under NFPA 72 Chapter 14 ITM says, “In practice, the inspection, testing, and maintenance of interfaced systems — such as sprinkler systems, smoke exhaust systems, HVAC systems, elevators, and similar systems — are often conducted at the same time as the inspection, testing, and maintenance of the fire alarm and signaling system. End-to-end testing of a fire alarm or signaling system integrated to monitor or control other building fire or life safety systems and features is the preferred means of testing.”
  • Pre-arrange functional end-to-end testing to avoid unwelcome, unanticipated shutdown of interconnected equipment.
  • The complete and proper functioning of a fire protection, suppression, or alarm system may involve additional trades / disciplines / systems.
  • It may be advisable to have signage at FACPs, sprinkler system inspector’s test connections etc., advising of interlocked equipment, especially if that is production equipment and the owner may not be anticipating an unplanned shutdown of the equipment.
  • Have the right people available for resetting the interconnected equipment when functional or end-to-end testing is done.

Sounds like a lot! How often does this need to be done?!

  • At installation & commissioning
  • Periodically (and it depends on what you have)
  • When existing systems are modified

The bottom line is, to make sure that everything works as needed during a fire:

  • systems should be functionally tested and
  • interconnected systems should be tested together.

Amy Anderson, PE, CFEI, has a Bachelor of Science in Chemical Engineering from Clemson University and is a licensed Professional Engineer in Fire Protection, as well as a Certified Fire and Explosion Investigator. Amy has over 20 years of engineering experience including property loss prevention engineering specializing in fire protection, chemical and pharmaceutical facilities. She has partnered with clients to identify, assess, avoid, and reduce risk at their commercial and industrial properties. Additionally, she has assisted with the development of building and fire protection specifications, reviewed plans and performed site visits. She has reviewed project documents for compliance with applicable standards – construction, fire protection, process, and combustible dust hazards. Amy is a member of the National Association of Fire Investigators, the Society of Fire Protection Engineers, the National Fire Protection Association and the American Institute of Chemical Engineers.

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