Are Oil Burning Systems Hazardous?
Increase in the Use of This Means of Heating Residence and Other Buildings—Basic Principle of Burners—Various Types Described
IN view of the greatly increased use of oil burning devices for heating private residences the following paper will be found of especial interest. Owing to the extensive boosting of the price of coal and its scarcity arising from strikes and profiteering operations in the coal industry, thousands of householders have turned to oil as a substitute in heating their homes and in consequence hazards have arisen which never existed before. The paper by Mr. Wedger treats the subject in a broad and practical way and will be found of help to fire chiefs who experience this problem:
The heating of our homes by means of oil was practically unknown five years ago. Since that time domestic oil heating has increased by leaps and bounds, owing to the more or less periodical coal strikes and the subsequent shortage in the normal supply of anthracite. During the years 1901 and 1902 there was a similar coal shortage, and many attempts were made to use kerosene oil in house heaters and cooking ranges in a crude way which generally resulted in blocking up smoke pipes and chimneys with lampblack. Since then, and up to the present time, range burners have from time to time appeared for sale in our stores, but no definite attempt was made to utilize oil for house heating on a large scale until 1916.
First Attempt to Heat Residences by Oil
At that time the General Engineering Company was incorporated at Detroit. Mich., for the purpose of developing a system of combustion of liquid fuel for residential heating, and the first public demonstration of this particular oil burning system, now called “The NoKol,” was made on the -so-called “Fuel-less Mondays” inaugurated by the War Department in February, 1918, for the purpose of conserving coal for the war. Today there are in service in homes more than ten thousand of this make of burner in twenty-five states of the United States and in six foreign countries, representing an investment on the part of the public of more than five million dollars.
And this is only one make of burner, which, while it may be the largest, or one of the largest, its output does not begin to represent the total number of homes that are today heated by oil burning devices of some kind.
Great Increase in Massachusetts
In the interests of fire prevention, the rules and regulations of the Department of Public Safety of this Commonwealth require that all makes of light fuel oil burners be submitted to the State Fire Marshal for his approval in writing, before a permit can be issued for their installation and maintenance. The duty of inspecting for his approval has been delegated to Mr. Stuetzel, our fire prevention engineer and myself.
At the present time we have a list of about thirtyfive different burners which have been approved for domestic use, and it is safe to say that these devices are being installed in dwellings in this state at the rate of fifty or more per day.
The situation, as expressed by Commissioner Foote is that, “the people have gone oil burning crazy.” And of necessity, so, because many of them are without coal. And even those who can obtain a supply of coal, are adopting oil because they do not have to shovel or sift it.
“The increasing demand for good oil burners for heating purposes, seems to have stimulated the manufacturers to produce range burners which show a great improvement over those of twenty years ago. The great majority of the American public wants convenience, labor-saving devices and safety from fire, and they are willing to pay for it. Domestic oil burning has come to stay.”
The Question of Added Risk
Some people say there is no more fire risk in oil burning than there is in coal burning. That statement will, I think, admit of some qualification. It must be remembered that the people of our state have been burning hard coal for years, know how to run their fire and how to guard against whatever fire hazard it possesses, generally speaking. I predict that when the public become accustomed to burning oil, to the same extent that they have coal; when the inventors produce a device with the proper refinement of safety attachments, then there will be no more danger in oil than there is in coal. A well known fire chief has very aptly remarked, “There is one advantage in oil heating, and that is we will have no more fires caused by putting hot ashes into a wooden barrel.”
People Passing Through Campaign of Education
Until the public become familiar with oil heating to the extent that they can discriminate between a good oil burner equipped with the proper, automatic safety devices, and some of the cheap and dangerous outfits that are being installed in some places, regardless of state regulations and the nullifying effect on insurance policies, we are liable to have some fires from this cause.
The people are passing through a campaign of education in a new method of house heating and it behooves us, as fire preveutionists, as guardians of the public safety, to guide them to the best of our ability in the selection of burners that promise the greatest degree of safety from fire, both in their installation and their maintenance. This is the purpose in requiring approval of all types of burners by the state fire marshal.
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Are Oil Burning Systems Hazardous?
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Flash Point Fixed at 115 Degrees
For a moment let us see what they are burning in these oil heaters. The rules and regulations provide that no oil that has a flash point below 115 degrees Fahrenheit can be kept for use or burned in a light fuel oil burner.
The flash point of ordinary kerosene oil varies from 115 to 135 deg. Fahr., therefore no oil of a lighter gravity than kerosene can be used. There are several different kinds of oil furnished by the oil companies for this purpose, the most popular is called, “furnace oil.” This oil has a flash point varying from 115 to 124 deg. Fahr. It is similar to kerosene but is dyed red to distinguish it from the regular water-white stock.
Another kind of oil is thin and almost black, having a flash point of about 140 deg. Fahr. And still another kind is clear but has a yellowish tinge, having a flash point from 150 to 160 deg. Fahr. They are all products of petroleum and have high heating value. Being hydrocarbons, they require air or oxygen for their combustion.
Basic Principles of Domestic Burners
Light fuel oil burners for domestic heating vary greatly in construction, but all are based on one of three principles: The first provides for the atomization of the oil by means of air pressure, converting it into a spray or mist, which is blown into a specially constructed fire box in which a pilot light of street gas is constantly burning. Previously to the ignition of this oil mist, it is thoroughly mixed with the proper amount of air which insures almost perfect combustion, and prevents smoke and the deposition of soot or carbon. Burners of this type are designed for intermittent firing and the creation of instantaneous high heat, governed thermostatically by the temperature of the living room of the residence, and also by the temperature of the water in the flow pipe of hot water systems, and by pressure in steam heating systems.
The next type of burner vaporizes the oil previous to its ignition, and then burns the resulting gas in the proper supply of air. This is accomplished by means of a pre-heating tube through which the oil passes and is changed to gas, or vapor, by the heat. Burners of this type are coming on the market which the manufacturers claim will not carbonize or clog up with soot, a trouble which existed in nearly all of the old range burners of 1901. Carbonization is said to be entirely prevented by maintaining a size of preheating chamber proportionate to the diameter of the outlet orifice through which the gas escapes just previous to ignition. These burners are intended for constant firing, the flow of oil being controlled by a manually operated vlave. Air is supplied to the vaporized oil by the natural draft of the chimney.
The third type of burner provides for the ignition of the oil itself in a current of air, supplied either by natural draft or by a small motor-driven fan. The oil flows by gravity to a corrugated disk of iron through which it oozes and flows down over the bevelled corrugations. This disk is previously heated to the ignition temperature of the oil, which temperature is maintained constant by the burning oil. Some of this class of burners are equipped with an oil pilot light which can be increased to the point where it will nearly maintain the heat obtained by the main burner, or can be diminished at will by a manually operated valve. In this case the main burner is controlled by a thermostat in the living room.
Other Types of Burners
There is another kind of burner which is in the atomization class, but which is motorless. Water from the street main passes through a pressurereducing valve into a chamber heated by city gas, where it is converted into steam, the escape of which atomizes the oil on the principle of the aspirator, and blows it through a city gas pilot light. Oil mist is burned in an atmosphere of super-heated steam.
There is still another design of burner in which the oil flows by gravity, drop by drop, falling on a bevelled plate of iron kept very hot by city gas. A motor fan furnishes the air supply.
Then there is another kind of burner of the vaporizing type, having its oil supply under about twenty pounds pressure. The oil is vaporized outside of the heater and the resulting gas passes into an iron receptacle in the fire box where it is mixed with the proper amount of air, and out at the top through a series of lava disks. These lava disks contain a number of very small holes through which the gasair mixture passes and burns on top, acting on the principle of the Meker laboratory gas burner which generates such intense heat.
They are very efficient due to the intimate mixture of gas and air, and are absolutely sootless.
What the Fire Hazard Consists of
The fire hazard in connection with domestic oil burners of the gravity, siphon or pressure types is principally the accidental overflowing of unignited oil, running raw as it is termed, into the former ash pit of the heater and over the cellar floor. This may be caused by the extinguishment of the gas pilot light from any reason whatsoever, or it may be caused by an accumulation of carbon in the orifice tube of a vaporizing burner.
Our rules and regulations require that all burners providing for gravity, siphon of pressure flow of oil, shall be equipped with a device that will automatically prevent the overflowing or flooding of the burner. And all such burners that are approved, are equipped with such a device. This is, of course, unnecessary in systems where the oil is electrically pumped from a level below the burner. In such cases the motor pump is stopped by the opening of a thermostat, normally held closed by the heat of the burner.
Automatic Device to Prevent Flooding
The automatic device to prevent flooding, which was adopted by the first domestic burners made, has been copied by nearly all types of burners placed on the market since that time. The principle of this device is gravity and it is called the safety trip bucket. Oil unignited at the burner from any cause whatsoever, is caught in a receptacle underneath, from which it flows outside of the heater into a small metal container hung upon a lever which operates a valve in the main oil feed pipe. When sufficient oil has run back into this small container to partly fill it, the increased weight of the oil trips the lever and closes the valve. In the atomizing type of burner this action also switches off the motor.
I want to call special attention to this safety trip bucket because it constitutes the most vital part of the apparatus as far as safety goes, and I regret to note that some manufacturers evidently look upon it as the most unimportant.
While the principle of gravity is unchangeable and unaffected by the failure of gas, electricity or any other influence, its connection with the closure of a valve to stop the flow of oil at a certain time, must be accompanied by such refinement of workmanship that it cannot fail. Tin dippers hung up by a wire will not do. Neither will loose and wavering pipe conveyors from the burner catch basin, which may be struck by a dog or cat and diverted so that the returning oil will not fall into the bucket, be accepted. Such pipes must be securely anchored so they cannot get out of place.
A Dangerous Type Not Approved
One style of trip bucket recently submitted for approval had a beautiful weight of nickelled metal sliding upon a rod to effect the positive closing of the valve, and was equipped with a large, inviting brass nut attached to the valve stem to prevent leakage.
If the valve leaked oil on the cellar floor, the first thing the owner would do would be to tighten this nut with a wrench from his automobile, and I proved that only a slight tightening would render the valve so that a twenty pound weight would not close it. No burner is approved with such glaring mistakes in its mechanism, and if manufacturers persist in installing such attachments they are liable to have their approval revoked.
Safety Trip Bucket Must Be “Fool-proof”
The safety trip bucket must be made “fool-proof,” and if it is necessary to have nuts to prevent leakage of valves, they must be covered up so that no one, except the service man, can gain access to them. It is not part of your duty, or mine, to tell anyone how to construct their burners to meet the requirements for safety, but it is most emphatically our duty to reject sloppy and unsafe workmanship, especially in that part of the system which is vital to its safe operation.
It is perhaps strange that the inventors of oil burners have not devised some other method of shutting off the flow of oil in gravity burners when the flame of the burner becomes extinguished. This may be explained, that in their haste to get into the field, it was easier to copy other devices than it was to think out a new principle. There is, however, one exception:
An Ingenious Automatic Cutoff
A Swedish watchmaker in Waltham has patented a method of shutting off the oil based upon the difference in the rate of expansion and contraction between iron and brass, when subjected to heat and cold. It consists of an iron or steel tube inside of a brass tube. The brass tube is fitted at one end with a bevelled rod which enters the end of the steel tube, similar to a needle valve, effecting a tight closure in the steel tube when both are cold. Both tubes are protected by an outside tube of a special alloy, made to stand exposure to high heat. The oil flows through the inside steel tube and soon as heat is applied, the brass tube expanding so much faster than the steel, opens the needle valve and allows the oil to flow out to the burner in the space between the steel and brass tubes.
When the flame of the burner becomes extinguished, the cool oil, flowing through, contracts the brass tube so much faster than the steel, that a tight closure is effected in forty seconds, regardless of the fact that the outside protecting tube may have been red hot.
There are several distinct advantages to this style of automatic cut-off. It is in the fire box of the furnace or heater, out of the way, where it cannot be interfered with by children, dogs or cats. Its action is positive and unchangeable as well as powerful. It is not a question of how hard or how loose the valve works and there are no nuts to tighten. It is not affected by anything except heat and cold and the only moving part to the valve is the simple elongation of the brass tube caused by the natural expansion of the metal when exposed to such heat.
At the present time the Department of Public Safety does not attempt to regulate range oil burners for cooking purposes. They are designed to operate on the vaporizing principle. The oil supply rarely exceeds five or ten gallons, and is fed to the burner by gravity or by pressure, regulated by manually operated valves. It may be necessary later to provide for automatic control of this oil.
Improvements in Devices Stimulated by Demand
The increasing demand for good oil burners for heating purposes, seems to have stimulated the manufacturers to produce range burners which show a great improvement over those of twenty years ago.
New modifications in oil burning apparatus are appearing in the field almost daily, and it is gratifying to note that in many of these late arrivals there is a marked tendency towards better materials and better workmanship. The initial cost is a little more, but what of that? Our automobile costs more than the old horse and buggy, and our electric lights cost more than kerosene lamps. The great majority of the American public wants convenience, labor-saving devices and safety from fire, and they are willing to pay for it. Domestic oil burning has come to stay.
(Excerpts from paper read before the Fire Chiefs’ Club of Massachusetts at its November meeting.)