Fire Alarm Systems - INACTIVE

By Sylvia Rosen

If you're looking for a fire alarm for your business, it's a good idea to understand the basics of fire alarm technology. Fire alarm circuits are pretty simple and use two main types of detectors:

1. Optical fire alarms use a light, a sensor, and an on-board chip.
2. Physical fire alarms use a sensor that monitors the air for smoke particles.

The pros and cons of optical fire alarms

Also called photoelectric fire alarms, these devices have fire alarm system circuits with a light and a light-resistance-receptor sensor. When smoke interferes with light traveling from the light bulb to the receptor, the resistance and voltage increases. This completes the circuit for the on-board chip and triggers the alarm.

Here are several advantages to consider of an optical fire alarm:

• Quicker to respond to a slow fire than a physical alarm.
• Less likely to go off from cooking fumes.
• More effective in eliminating false alarms.

Disadvantages of an optical fire alarm include:

• Can be set off by excess dust; not advised for installation in a laundry room or workshop.
• Can be fooled by steam or spider webs.

The pros and cons of physical fire alarms

Physical alarms use a slightly different fire alarm circuit. Instead of having a light sensor, they use a particle sensor. Air is drawn past an optical laser and the composition of the air is analyzed. If smoke particles are detected, then an alarm is sounded.

Here are some of the major advantages of a physical fire alarm:

• Reacts faster than a photoelectric alarm to rapidly spreading flames.
• Less expensive than a photoelectric alarm.
• May be equipped with a hush button to temporarily stop an alarm without removing a battery.

Disadvantages of a physical fire alarm include:

• Can be fooled by chemical or paint particles in the air.
• Can be set off by steam; installation isn't recommended near a bathroom or laundry room.

Selecting the right fire alarm circuit for your business

Selecting the right fire alarm circuit, and therefore the right fire alarm, for your business can be tricky. You need an alarm that will be sensitive enough to warn you when there is a real fire threat. Yet, you also need a fire alarm circuit that will be able to function in your work environment without continuously firing off false alarms. For example, in a workshop that is filled with dust particles, an air-sampling detector is not the best option as the dust particles could be read as smoke particles.

The size of your business also will impact what type of fire alarm circuit will work best for your company. Small companies will want to use single unit fire alarm systems that have independent circuits, while larger companies will want to use addressable fire alarm systems that have a loop circuit.

Proper installation is key

To ensure that your fire alarm circuits will work properly, you need to have your fire alarm systems professionally installed. This will most likely mean hiring a licensed and bonded technician.

These professionals will ensure your units are wired properly and that their installation follows NFPA and NEC regulations. These are also the people that you will want to contact when you are having problems with your system or when you need to reset the circuits.

Even though you won't be directly responsible for installation as a business owner, it's recommended that you become familiar with the National Fire Alarm Code from the National Fire Protection Association. This document will provide up-to-date information on fire alarm installation requirements, testing, maintenance, and the use of fire detection in a business setting.