Reducing Smoke-Odor Damage in Advanced Salvage Operations
OVERHAUL AND SALVAGE … IN THEORY AND PRACTICE
—Photo by Lieutenant Robert Kennedy, Philadelphia Fire Bureau
THE SUBJECT of property damage due to smoke and/or odors is one which has received far too little study, from the viewpoint of the salvageman.
We know that smoke is largely a product of combustion; that smoke gives off different densities, colors and odors, as well as irritants, depending upon a number of factors, the most important being the material that is burning. We know that under certain conditions, smoke can cause almost as much property damage as fire itself.
What we don’t know is what makes one substance differ in smell from another. In fact, we don’t know much about the “sense of smell.” As D. H. Radler* says: “For sheer mystery, few things compete with the sense of smell. How it works, only the nose knows . . . and so far, it has kept the secret well.”
We don’t know too much about the relation of certain odors (not always related to smoke) to certain kinds of merchandise and raw naterials. Certain gases give off odors which are colorless but which may have ruinous affect upon foodstuffs, for example. Salvage operations may require rapid removal of such gases and odors from the property involved—and it may be quite an undertaking, although no fire is present. Practically every fire department has been called upon to ventilate buildings of odors emanating from leaky refrigerator systems, faulty heating plants, spilled chemicals and the like. Perhaps not all these departments consider this “salvage” in the strict sense of the word, but nevertheless, it is.
*Science News Letter, December 10, 1955 “Learning Why Noses Know.”
Loss from smoke, fumes and odors is not predictable. It is difficult to anticipate it and prepare defensive measures.
Among the factors which govern it are: type and kind of occupancy, the building and contents involved, the “damageability” and “salvageability” of stocks and furnishings (qualities of absorption, etc.), the fire fighting and protective measures that may be required in the operation, the weather, etc.
—Los Angeles Fire Department photo
Unlike water, smoke and accompanying odors can find their way into all parts of a building, and even penetrate the contents of containers believed to be water and airtight. How many persons have experienced the contamination of a supposedly tight bottle of liquor by common moth balls and gum camphor? Smoke-carrying odors may penetrate structures and cause damage considerable distances from the actual fires which generate them. All of this complicates the problem of salvage.
Odors and smoke deposits are the unpleasant aftermaths of nearly every fire. Depending upon the circumstances, these odors may have a serious effect on the well-being of the individual as well as the prosperity of the enterprise, should it be a business establishment that is involved.
Smoke damage claims against insurance contracts have been a frequent
source of controversy, irritation and litigation, both to the insured and to the company underwriting the insurance risk. This has been especially true where the only damage was the result of smoke and/or odors finding their way into exposed property.
It is because of these and other imponderables which involve the whole broad problem of smoke and odor removal, that the subject has received so little consideration and study. However, it should not be assumed by fire forces performing salvage work that odor removal is impossible or that excellent results cannot be obtained in even the most modest of salvage operations.
Smoke-odor damage certainly can be reduced in some fires involving residences and small commercial establishments, with a minimum amount of effort and service time of fire departments. Small as well as large fire departments and salvage squads can make good use of modern chemical smoke deodorants, with proper coaching and equipment. Even without such facilities, by scientific use of ventilating devices, air movers and smoke ejectors excellent results may be obtained in minimizing smoke-odor damage.
It is true that deodorizing tasks of greater magnitude require a broader technological knowledge and facilities, than are available in the average fire department. Unfortunately, most fire department budgets provide little funds for salvage operations of any kind—and no wherewithal! for dealing with the scientific problem of odor removal.
Unquestionably the key to smoke and odor removal is primarily ventilation. And, as has been pointed out earlier in this series on salvage, ventilation for salvage actually should begin with the first contact with the fire. In fact, many authorities consider ventilation, as pertaining to smoke and odor removal, something that should be “built into” the building at the outset. Many architects and builders agree, and there are con-
cerns which specialize in installing quick-acting vents, smoke ducts and other means of removing or trapping smoke and attendant odors while “shutting off” fire at the same time.
The problem facing salvagemen today, however, is one of venting structures in order to make rescues and further fire attack so as to facilitate to the fullest degree later salvage operations, including smoke-odor removal. This may sound complicated but actually it means opening up an involved building in such manner as will rid it of the most smoke, fumes and accompanying odors, with least risk of involvement of adjoining or neighboring properties. Smoke-carrying odors may travel a long way on the wind. If it is necessary to so vent at the outset of attack that down-wind structures may be involved, all possible effort should he made immediately to see that the exposures to leeward are “buttoned up” and that measures to exhaust or draw off contamination are made ready in such properties as the officer in charge of salvage may believe will most require it.
In this connection it is well to repeat earlier recommendations, to wit: The officer in charge of salvage should contact the officer in charge of fighting the fire and inquire whether, and if so, what ventilation is going to be required, or that may be carried out.
Under no circumstances should any attempt at ventilating fire-involved premises be made except with the specific approval of the officer in charge of the fire, and then only in the manner required by him. Uncontrolled ventilation may cause the fire to get out of hand—and even result in injuries or death to personnel.
Use of deodorants
The application by the fire service of deodorants to remove, or counteract smoke or gas odors is fairly recent. The subject was first broached to the nation’s fire service in an article in FIRE ENGINEERING by the former chief of the Fargo, N. D., Fire Department, Fred J. Wells, entitled “How One Fire Department Reduces Smoke Damage.”
Chief Wells was one of the pioneers in the use of deodorants but he combined the application of chemicals with rapid and thorough structural ventilation. He believed that before odor removal or neutralization can begin, the odor-carrying smoke must first be removed. He found that the temperature of smoke had a bearing upon its penetration into materials, somewhat as does moisture; also that water can carry chemical and other contaminants into materials and these cannot easily be removed or neutralized by any existing salvage methods.
Air movers, properly applied, may be counted upon to exhaust the smoke contents of a structure, as was described in “Fire Sendee Ventilation in Principle and Practice” Part I, November, 1953, by Roi B. Woolley. Much of the secret is early application, particularly where the smoke contains large sooty, tarry particles. In normal dwelling fires, such as occur in attics, the application of air circulators, ejectors and injectors as quickly as possible will not only speed the fire attack but will lessen the opportunity for smokeodors to deeply penetrate household materials and furnishings. Application of air movers after the fire has been extinguished, will further lessen the smoke damage. Just how long this effort should be kept up after salvaging operations have been completed is problematical. In incipient fires it is possible to so rid the house of odors that the application of even simple household chlorophyl remedies may complete the smoke-odor removal operation started by the salvagemen.
Various chemical preparations have been tried in the attempts to remove or actually counteract some odors following fire. Generally this was done with hand sprayers and the vapors were distributed throughout the building area by means of the power blowers used to remove smoke or force fresh air into buildings. While the operations in many instances gave the experimenters hope, in some cases a tell-tale odor remained after application. Repeated spraying, furthermore was not always sufficient.
The main reason was that chlorophyl preparations are primarily atmospheric deodorants. Where the smoke molecules are deeply emlxrdded in material, it is questionable whether common odor control materials will be effective. This led some fire department and salvage officials to believe that it might he advisable to cut out most of the charred wood after a fire before deodorizing.
According to some operators this deep penetration and lack of understanding of the preparations used in odor control led to overapplication, resulting in stains that were difficult to remove from other than impervious surfaces.
Most professional odor removal technicians use chemicals that do not contain chlorophyl. There arc differences of opinion among them concerning the best methods to be employed and the results expected, but all agree that a basic knowledge of the theory of deodorization is essential to successful operations.
The two major points of difference have to do with (1) actual removal of the smoke molecules formed during combustion, and (2) odor-masking by powerful chemical agents. The latter cancels one odor by superimposing another and more powerful odor on the original.
Research by proponents of the first method has led to these observations: The source of odor is a sub-microscopic ball containing a mixture of oils, tars, water and soot. It is formed at the point of combustion when volatiles condense on soot particles as they rise out of the flame. These smoke odor molecules float about an area in clouds of smoke and settle in layers on all exposed surfaces.
The object of the odor removal technique is to free the odor molecules into the atmosphere so they can be removed by ventilation. This is done by “dryfogging” the contaminated area with a chemical solution which attaches itself to the same surfaces as the smoke odor particles. Surface-active agents in the chemical break down the smoke odor particles and release the smoke particles into the air. The volatile oils, the prime odor sources, are released by a combination of evaporation and displacement action. Once airborne, power exhaust fans remove the particles from the premises.
The manufacturers of these chemicals claim they are non-toxic, have no flash point and will not stain. They point out however, that they are not cleaning agents and will not remove soot or smudge. This must be done by any recognized washing or dry-cleaning process.
Odor “masking” by counterirritants
Followers of the masking method dispute some of the points previously mentioned. According to one authority on the subject, odor masking is “the process of cancelling one odor by superimposing another odor to create a more overpowering sensation, preferably pleasant.” The masking agent does not alter the composition of the pre-existing odors, but simply covers such odors during the period of its addition to and presence in the air.
One of the chemicals prepared for this purpose is mixed with water and then sprayed freely over the burned area. If water spray cannot be used, the application is made by saturating asbestos fibers with the chemical and hanging them in the window areas or ventilating systems. This allows the masking odor to penetrate the interior. It can also be used by impregnating sawdust or asbestos crumbs or similar absorbent materials and spreading this over the burnt area.
It is pointed out that no single procedure will apply to all types of incidents. No method is perfect but encouraging results can be obtained in nearly all cases. Some experts suggest that if an air conditioning or other ventilating system is present, it should be employed to speed emergency.
The Editors wish to acknowledge the cooperation of Airkem, Inc. and Rhodia, Inc., both of New York City, for their information on chemical deodorizing.