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MFD - Frequently Asked Questions

 Smoke Alarms

What types of smoke alarms are available on the market?

There are two types of household smoke alarms in common use.  These are known as ionization or photoelectric type smoke alarms.

How does an ionization type smoke alarm work?

This type of alarm uses a small amount of radioactive material to ionize air in the sensing chamber. As a result, the air chamber becomes conductive permitting current to flow between two charged electrodes. When smoke particles enter the chamber, the conductivity of the chamber air decreases.  When this reduction in conductivity is reduced to a predetermined level, the alarm is set off. Most smoke alarms in use are of this type.

How does a photoelectric type smoke alarm work?

A photoelectric type smoke alarm consists of a light emitting diode and a light sensitive sensor in the sensing chamber.  The presence of suspended smoke particles in the chamber scatters the light beam.  This scattered light is detected and sets off the alarm.

Which type of alarm is more effective?

There is no simple answer to this question.  The two types operate on different principles and therefore may respond differently to various conditions.  Some advantages to each type are set out below:


  • Fastest type to respond to flaming fires.

  • Lowest cost and most commonly sold.

  • Some models have a hush or temporary silence feature that allows silencing without removing the battery.

  • Some models are available with a long life battery.


  • Fastest type to respond to slow smouldering fires and white or gray smoke.

  • Less prone to nuisance alarms from cooking.

Notwithstanding these differences, to achieve ULC listing, both alarms must be tested to the same standard and meet the same requirements.  Photoelectric smoke alarms may respond slightly faster to smouldering fires, while ionization alarms respond slightly faster to flaming fires.  Since you can't predict the type of fire that will occur, it is difficult to recommend which is best.  Both alarms will detect all types of fires that commonly occur in the home.  Installing both types of smoke alarms in your home can enhance fire safety.

Which type of smoke alarm should a homeowner purchase?

It is the consumer's responsibility to assess the circumstances of their household and to select the most appropriate alarm.  However, an important consideration in the purchase of a smoke alarm is conformance to a recognized standard.  In Ontario, CAN/ULC-S531 is the recognized standard for both the ionization and photoelectric types of alarms.  Both ionization and photoelectric type products conforming to this standard are available on the market.  A homeowner will know that a smoke alarm meets the requirements of this standard by the ULC or cUL label on the device.

What maintenance is required for smoke alarms?

The Ontario Fire Code requires that smoke alarms be maintained in operating condition at all times.  Smoke alarms should be maintained in accordance with the manufacturer's instructions.  Occasional light vacuuming will keep the air vents clean.  On battery powered units, check to see that the battery is in place, connected, not corroded and functioning.  Although the test frequency is not prescribed it is recommended that smoke alarms be tested at least once a month.

How many smoke alarms should I have in my home?

Effective March 1, 2006, it is the law for all Ontario homes to have a working smoke alarm on every storey and outside all sleeping areas. With this previously announced Fire Code amendment now in effect, it is hoped there will be a reduction of the number of preventable fire-related injuries and fatalities. The amendment covers single family, semi-detached and town homes, whether owner-occupied or rented.

How should they be installed?

Smoke alarms should be installed according to the manufacturer's instructions.

What are the features I can expect to find on a current smoke alarm model?

These are some features you can expect to find:

  • A "missing battery" indicator,

  • An optional alarm hush or silence feature,

  • The use of a power "on" indicator light to show that ac power is being supplied to 120 volt wired in smoke alarms.

What are long life smoke alarms?

Long life smoke alarms have been designed to use lithium batteries where the battery life is predicted to last 10 years with the normal low battery drain or ionization type smoke alarms.  The smoke alarms are still designed to provide a low battery audible signal as the battery charge is reduced to a level that may make the smoke alarm inoperable.  It should be noted that although these batteries are designed to last 10 years, ongoing testing and maintenance is required as per manufacturers' instructions.

Can long life lithium batteries be used in any smoke alarm?

No. Only battery types recommended by the manufacturer should be used in a smoke alarm.  Incorrect batteries may not provide the operating characteristics expected of the smoke alarm.

How often should a smoke alarm be replaced?

As a rule of thumb, the Midland Fire Department recommends replacing smoke alarms every 10 years or when it has exceeded the manufacturer's recommended life cycle.

What should tenants do if they don't have an alarm?

The Ontario Fire Code states that the owner is responsible for both the installation and maintenance of smoke alarms on a given property. If there is no smoke alarm, tenants should notify the owner in writing.  The owner must then install the alarm upon receipt of notification.  If there is an alarm but the battery has died, the owner must change the battery within two days of receiving written notification.

The tenant should test the alarm weekly.  Use smoke from an extinguished candle and let the alarm go off for at least two minutes.

Why does my smoke alarm go off at lot?

It may be dirty. Clean the unit with a vacuum cleaner - dust particles can and often do set off false alarms.

The alarm may also need to be moved or replaced. It could be too close to the kitchen, bathroom, or heat register.  If the alarm appears to be defective, replace is as soon as possible.

Why does my alarm beep?

It may have a weak or inappropriate battery. Check the manufacturer's instructions.

 Fire Extinguishers

What kind of fire extinguisher should I have?

We recommend a "dry chemical" type for home use, generally type 2A-10BC.

Where can I buy a fire extinguisher?

Refer to the Yellow Pages.  Most hardware outlets and extinguisher-servicing companies have extinguishers for sale which are suitable for home use.

Where should I store my extinguisher?

Store it away from the stove, near the kitchen entrance. Mount the extinguisher on the bracket that comes with it. In your workshop or tool shed, mount the extinguisher away from power tools, near the exit.

How often should I have my fire extinguisher recharged?

Recharge it after each use, or if the gauge shows a loss of pressure. Dry-chemical extinguishers have to be hydrostatically tested and recharged every six years.

 Propane Tanks

Where should I store my propane tank?

All propane tanks should be stored outside or in a detached shed. They should be protected from the elements and should be at least one metre from any openings to the building.

How should I dispose of my old tank?

Take all expired propane tanks back to an outlet that refills them. Do not keep them and do not include them with your regular garbage pick-up.

 General Questions

Why can't I use elevators during an alarm?

  • Elevators can become smoke shafts during a fire.

  • The power could fail, leaving you trapped in the elevator car.

  • The door could open at the fire floor and expose you to extreme heat and smoke.

  • Firefighters need the elevator to transport people and equipment to the upper floors as quickly as possible.

Why can't stairwell doors be left open for better ventilation?

These doors protect the stairwell from smoke, heat and hot gases so that people can safely evacuate from the building. A door which is wedged open would allow the smoke to fill the stairwell and upper floors of the building.

Can I have an open fire in my yard or on my property?

No. The Ontario Fire Code states that open air burning is not allowed except for small cooking fires.  This applies to outdoor fireplaces, including "chimineas". Although these may be sold in local stores, they are prohibited within the Town of Midland.

How often should I have my woodstove or fireplace chimney cleaned?

Chimneys should be cleaned at least annually, more frequently if used extensively, by a qualified W.E.T.T. (Wood Energy Technology Transfer Inc.) certified chimney sweep.  These can be found by checking the yellow pages of the phone book.

Can I store my gasoline container or propane cylinder indoors?

No. Gasoline and propane should be stored outdoors in a well vented area.