Is your home prepared against the dangers of fire? It can strike without warning, and even with modern technology can get out of control very quickly. Here are a few things to keep in mind when defending your home against fire.
The two main types are ionization and photoelectric, although Consumer Reports recently stated that more than 80 percent of commercial smoke detectors are the ionization style, using a low-level radiation source and responding faster to flames. Photoelectric units are quicker to detect fires than smolder before bursting into flame.
Smoke-detector failures occur because of improper installation, worn-out batteries, or public utility power to the detector being intentionally disconnected because of recurring false alarms. Testing their operational readiness can be done with an aerosol-canned “Smoke Detector Tester” that simulates the full range of fire conditions by emitting smoke-type particles of all sizes. Besides testing, every building that uses smoke detectors should carry a reserve supply of backup batteries as well as detectors. New Kodak 9-volt lithium batteries will last more than twice as long as alkaline batteries. And it is cheaper and easier to replace a detector than to repair one with a defective signaling circuit or other problem. Cleaning instructions — and dust/dirt removal certainly should be done at least annually — often are embossed on each detector, and usually require a cotton-tipped swab and alcohol.
Where large numbers of hard-wired detectors are present, there are building-wide microcircuitry systems that automatically and electronically monitor the operating condition, and even the sensitivity of every detector, every few seconds. Where false alarms are a problem — due to radio frequency interference, conducted noise, dust, high air velocities, peak humidity, sophisticated detectors with built-in detection mechanisms minimize the frequency of and susceptibility to false alarms.
All devices, mechanical or electrical, eventually can fail. It is particularly important, however, that alarm systems be in continual readiness — for alarms save lives.
Pull-alarm stations, mandated by code, operate by completing an electrical circuit when mechanically activated. The stations can be set to ring alarms in their local area or throughout the building — but just as important, the fire department or an alarm company’s central station should be notified. Other alarms–bells, sirens, chimes, strobe lights, public address systems–are triggered by electrical hookup to pull-boxes, smoke detectors, and the sprinkler system.
What can go wrong with alarms? With pull-stations, there can be a loss of building power, a dead backup battery pack, or a misalignment in the pull mechanism. Other alarms can fail because of a problem in the pull-boxes, detectors or sprinklers, or in the signal wiring that hooks those alarms up to the initiating devices.
What’s to be done about it? Inspections, circuit checks, being on the lookout for “trouble” lights–all are worth doing. But it also is vital, periodically, to activate the alarms and physically test them–first giving advance warning to building occupants and the fire department or supervisory service that a test will be conducted. With detector-tripped alarms, a random sampling often is sufficient to test both the detectors and alarm system. Fire alarm/control cable is checked with electronic voltmeters, and can be either the type protected in conduit or the newer Teflon wiring that is fire code-approved without the need for costly conduit.
Important for alarm systems are “trouble” signals, which occur when a fault appears in a device or the circuit of a protective system. Circuits that normally are supervised in that way include main power as well as alarm-initiating and alarm-indicating circuits. In local and auxiliary systems, “trouble” signals usually are sounded in areas where maintenance personnel are present. Also used in conjunction with alarms are “smart” systems that delay the alarm slightly (up to 60 seconds) to reconfirm whether the detector is signaling a fire or false alarm.
Just as Sandel fabrics cover combustibles to prevent fires, the extinguisher’s function is to interrupt the fire by sealing off or replacing the oxygen. It does that by smothering the fuel with a dry chemical or a vaporizing liquid such as Halon. Each has its role in putting out fires of Class A (ordinary combustible materials), Class B (flammable liquids), and Class C (electrical). Every unit’s cylinder has pictographs of the fire classes that it extinguishes.
A typical fire extinguisher has a “duration of discharge” of only 10 to 18 seconds. It is vital, therefore, that it operate efficiently. Testing laboratories maintain standards for the construction and performance of extinguishers; only those units that have been lab-rated should be purchased.
Extinguisher inspections should be done monthly. Some of the points to check include: Is the correct unit for that area in the right place, properly mounted, ready for use, or in need of repair? Check the cylinder condition, look for obstructions in the nozzle or hose, note the pressure gauge reading, and see if the safety seal has been broken. Is there a durable tag on the unit to record inspection and recharging dates?
The need for professional maintenance is evident when one considers the problems that crop up with extinguishers. They encompass caking of dry chemical contents due to moisture inside the cylinder, defective pressure gauges, improper charging, lack of required hydrostatic testing, obstruction of expellant piping, and many more. A maintenance check can involve disassembling the entire extinguisher, examining its parts, cleaning, replacing defective parts, reassembling, recharging, and repressuring.