Artificial fireplace logs

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Artificial fireplace logs

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DIVISION OF BUILDING RESEARCH

NATIONAL RESEARCH COUNCIL OF CANADA

TEClHIN ][CAL

NOTJE

No.

581

LIMITED DISTRIBUTION

February 1974

PREPARED BY K. Sumi,

·Y. Tsuchiya, and J.F. Mathieu

CHECKED BY _GWS APPROVED BY NBH

PREPARED FOR _{Department of Consumer and Corporate Affairs}

SUBJECT ARTIFICIAL FIREPLACE LOGS

The Department of Consumer and Corporate Affairs requested the DBR Fire Research Section to examine the fire hazard that may occur as a result of the burning of artificial firelogs in sheet metal stoves and fireplaces. This request was prompted by information received from two fire departments. The Hull Fire Department reported that a fire might have resulted from the use of one of these artificial logs in a sheet metal fireplace. The London Fire Department reported that a galvanized metal liner in a log holder became completely distorted by heat released by an artificial log.

Materials Submitted

Four samples of artificial fireplace logs were submitted for examination. They are listed below along with the main caution notes and other pertinent

information provided on the labels.

1. PINE MOUNTAIN LOG. Great Lakes Carbon Corp., Chicago, Ill. Net weight 6 lb.

Caution: Use only one log at a time. Place on grate at rear of fireplace. Always use screen in front of fireplace.

2. CALIFORNIA CEDAR DURAFLAME. Duraflame Inc., Stockton, Calif. Net weight 6 lb 8 oz. Burns 3 hours. Yields more than 90,000 Btu. Made of wax, cedar sawdust and a special colouring agent.

Caution: Do not burn in sheet metal fireplace, pot-bellied stove or barbeque. Use only one log at a time.

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-2-Never attempt to move or break up log after lighting. Never add "Duraflame" to any existing fire. Do not use for cooking.

3. SMOKEY BEAR FIREPLACE LOG. Husky Industries, Inc., Atlanta, Ga. Net weight 5 lb. 8 oz. Burns for 2 to 3 hours.

Caution: Burn only in properly ventilated area. Use just one log at a time.

4. 3 HOUR LOG. Nikkel Firelog Division, Sacremento, Calif. Net weight 6 lb. Burns for 3 hours.

Caution: Do not burn more than one log at a time. Not for use in stoves, sheet metal fireplaces or barbeques. Do not move or break up log after lighting. Do not use for cooking.

Procedure

The purpose of the present study was to examine the difference in burn-ing characteristics between an artificial log and conventional firewood. The heat of combustion (calorific value), density and burning rate of one of the samples (No.1) was compared with those of white birch.

The calorific value of the two materials was determined by the Parr oxygen bomb calorimeter. For sample No.1, this value was determined for both the inter ior of the log and the outer layer.

In assessing the hazard of fire logs, the rate of heat release appears to be very important. This property, which depends on the rate of burning in

addition to the calorific value, is difficult to determine for two reasons. Firstly, there is no standard test available. Secondly, a firewood having a diameter of about 4 inches will not burn in the absence of additional heat, and therefore cannot be compared to artificial logs of the same diameter that burn in regular fireplaces in 2 to 3 hours. In order to get a comparative measure of the burn-ing rate of sample No. 1 and white birch, the method used was as follows.

A specimen, approximately

It

in. by

It

in. by 2! in., was placed in a wire basket and suspended in a tubular furnace with the axis vertical. The

fur-nace was maintained at 6000

C, and the effluent gases were ignited at the top of the furnace by electric sparks. The weight loss of the specimen was monitored by the use of a transducer system. The average rate of weight loss represen-ting about 60 per cent of the loss (in which the initial and final portions were neglected) and the maximum rate of weight loss were determined for both sam-ple No. 1 and white bir ch.

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,

- 3-Results

The results of the experiments are presented in Table 1.

TABLE I

BURNING CHARACTERISTICS OF ARTIFICIAL LOG AND WHITE BIRCH

Heat of Combustion,

Average Maximum cal/g

Density, Burning Burning Material g/cm3 rate, rate, Interior Exterior g/min g/min of log of log Sample 1 (PINE 8190 8260 0.65 5. 3 9.5 MOUNTAIN LOG) White 4210

--

0.50 4.5 8.0 Birch Discussion

Artificial firelog (Sample No.1) will yield substantially more heat than white birch, which was used as a standard conventional firewood in this study. The calorific value of the artificial log (8, 200 cal/g) was twice as great as that of white birch (4, 200 cal/g). The density of the artificial log (0.65 g/cm3 )

was also higher than that of white birch (0. 50 g/cm3

). The rate of burning of

the two materials under one specified set of conditions was of the same order. Thus, the rate of heat release under ideal conditions in a well-developed fire is expected to be twice as great for the artificial log.

There was very little difference in the calorific value of the artificial log whether the specimens were taken from the exterior or interior of the log.