Tips to Avoid Trappings of Working With Mantraps
When the fire alarm panel and the HVAC control system are located inside the same room, the cable between the two may not necessarily have to be monitored for circuit integrity.
“Monitoring for integrity shall not be required for the circuit of an alarm notification appliance installed in the same room with the central control equipment, provided that the notification appliance circuit conductors are installed in conduit or are equivalently protected against mechanical injury” (Section 4.4.7.1.5, NFPA 72, 2007 Edition).
One way to accomplish this is to provide a normally-closed circuit through a Form C relay. If something should happen to the connection, the HVAC controller will assume that the fire alarm panel has gone into alarm causing the heating/cooling system to cease operations.
HVAC-fire alarm system integration can also be achieved through the use of one or more duct-type smoke detectors, with or without a remote test station (RTS). A duct detector is typically installed on the return side of the ventilation system.
Access Control System Integration
Another aspect of fire alarm integration when using a mantrap is access control. Here, code requires that the locking mechanism be automatically depowered on both entrance doors when the fire alarm system goes into alarm.
A Study in Physical Screening
I was recently directly involved in an installation at a bank that included a vestibule. In this case, the local AHJ devoted time and effort to assure the safety of the bank’s employees and customers.
We were expected to install a separate fire alarm system inside the bank consisting of a smoke detector in the bank lobby; several notification appliance devices, both inside the vestibule and outside in the bank lobby, and a duct smoke detector in the forced-air furnace that serves the bank’s heating/cooling needs.
“The fire alarm panel was a four-zone model made by Potter,” says Andy Gordon, senior technician with Abbott Fire & Security of Canton, Ohio. “We installed a System Sensor 2WTB, spot-type smoke detector in the bank’s lobby, which is a two-wire model. A second 2WTB was used to protect the fire alarm panel itself.”
A duct detector, installed in the return air duct of a forced-air heating/cooling system, provides the HVAC shutdown required by the local jurisdiction. In this case, operating power is derived from the fire alarm system, which has a back-up battery system. The HVAC contractor chose to disconnect the 24VAC that supplies the furnace controls when detection occurs. But Gordon as
ked the general contractor to have him tie in the entire furnace system so the ventilation fan shuts down, too.
The fire alarm system also integrates with the access control portion of Novacomm’s Access Control VestibuleTM. In this case, an Altronix power supply listed for access control and fire integration was used by the security company. Gordon merely provided a set of NC relay contacts, connecting it to the power supply motherboard, which had a set of terminals especially for the fire alarm interface. Thus, if fire is detected by any smoke detector, spot- or duct-type, both the incoming and outgoing doors of the vestibule entrance will be depowered so the occupant can quickly withdraw in either direction.
“We connected the normally closed contacts from an auxiliary relay inside the fire alarm panel to the input of the access control power supply, which was listed for use with fire alarms and access control systems,” says Gordon. “When a fire is detected our relay opens up, causing the access control power supply to drop power to the door locks in the vestibule.”
A visual-only notification appliance device was included in the egress section of the vestibule at the request of the local AHJ. Another audio/visual device was installed in the bank lobby, both of which will amply notify the occupants if a fire should be detected by the building fire alarm system.
If you enjoyed this article and want to receive more valuable industry content like this, click here to sign up for our FREE digital newsletters!
About the Author
Al Colombo
Al Colombo is a long-time trade journalist and professional in the security and life-safety markets. His work includes more than 40 years in security and life-safety as an installer, salesman, service tech, trade journalist, project manager,and an operations manager. You can contact Colombo through TpromoCom, a consultancy agency based in Canton, Ohio, by emailing [email protected], call 330-956-9003, visit www.Tpromo.Com.
Related Content
Security Is Our Business, Too
For professionals who recommend, buy and install all types of electronic security equipment, a free subscription to Commercial Integrator + Security Sales & Integration is like having a consultant on call. You’ll find an ideal balance of technology and business coverage, with installation tips and techniques for products and updates on how to add to your bottom line.
A FREE subscription to the top resource for security and integration industry will prove to be invaluable.
