LETTERS TO THE EDITOR

LETTERS TO THE EDITOR

What we’ve learned about BLEVE

Editor’s note: “What We Didn’t Learn from the Waverly Tragedy,” in the February 1992 issue of Fire Engineering, generated some interesting discussion about BLEVEs. In what follows, the author of the article quotes a number of sources to capture the essence of that discussion.

Responding to the article I wrote, “What We Didn’t Learn from the Waverly Tragedy,” New York Fire Department Deputy Chief Ted Goldfarb wrote a useful letter, noting that “…many fire service professionals do not understand the true mechanism of a BLEVE.” (Goldfarb was the author of a 1977 WNYF magazine article, “The BLEVE.”) Here, we will briefly address the BLEVE phenomenon.

Goldfarb states, “One of the reasons that few people understand the exact nature of a BLEVE is that most fire service publications highlighted BLEVEs that occurred with propane and other LPGs and never mentioned that BLEVEs can occur with other liquids, even nonflammable liquids such as water.”

NFPA’s Society of Fire Protection Engineers Handbook of Fire Protection Engineering explains: “A boiling liquid expanding vapor explosion (BLEVE) is the violent rupture of a pressure vessel containing saturated liquid/vapor at a temperature well above its normal (atmospheric pressure) boiling point. The resulting flash evaporation of a large fraction of the liquid produces a large vapor cloud. If the vapor is flammable and if an ignition source is present at the time of vessel rupture, the vapor cloud bums in the form of a large rising fireball.”

In “Quantity BLEVE Hazards” in the February 1991 issue of Chemical Engineering Progress, Richard W. Prugh observes, “The sudden decrease in pressure results in the explosive vaporization of a fraction of the liquid and a cloud of vapor and mist with the accompanying blast effects…any liquefied vapor—flammable or nonflammable—can cause a BLEVE.”

Prugh continues, “Historically, most BLEVEs involve flammable liquids, and most BLEVE releases are ignited by surrounding fire and result in a fireball. Certainly, the most important cause of BLEVEs is fire. The typical incident scenario is a fire surrounding a container of liquid, and the heat input to the container causes the liquid to boil.”

In addressing BLEVEs caused by mechanical damage, as happened in Waverly, Prugh notes, “Another important cause of BLEVEs is damage to the liquefied-vapor container. Container failure can be caused ..by impact, as occurred during the movement of a tank car at Waverly…[in which] the tank car ruptured explosively…and the contents ignited almost immediately and burned as a fireball.”

Goldfarb continues, “This expansion of the liquid to a vapor releases an enormous amount of energy. It is this expansion energy that causes the container to fall into many pieces and propel pieces of the container great distances. If the liquid is flammable, the resulting vapor air mixture may ignite in the classic fireball if an ignition source is present. If the liquid was water or another nonflammable liquid, the result would just be container failure and the propulsion of the pieces of the container.”

In describing an “explosion of a vessel containing cold liquid,” Prugh further notes, “The bursting of a liquid-filled container where the temperature of the liquid is below the atmospheric-pressure boiling point produces blast effects that are orders of magnitude smaller than those of gas-filled containers. The failure of a vessel subjected to a hydrostatic test illustrates this type of explosion.”

In describing a massive LPG BLEVE, the Handbook of Fire Protection Engineering states, “Reports of BLEVE in the San Juan Izhuatepec (Mexico City) 1984 disaster included at least one involving a 420,000-gallon capacity LPG sphere approximately onehalf full at the time of the incident,” and reported the actual observed fireball diameter as 1,200 feet.

“In reality, a BLEVE is a physical reaction, not a chemical reaction or fire. A fire might result from a BLEVE, but it is not necessarily the cause of it,” explains Goldfarb.

Stephen L. Hermann

Hazardous Materials Coordinator Arizona Dept, of Public Safety

Preplans work for trusses

There have been numerous pros and cons in regards to the timber truss roof. A recent fire to which our department responded could have been another disaster in which several firefighters had been killed or injured due to bowstring truss collapse. But this wasn’t the case because we had preplanned. (The hazards apply not only to wood truss roofs but to any roof style and construction. You need to know the buildings in your town, village, or city. This is where preplans are essential.)

WINNERS IN SHOW DRAWINGS

Fire Engineering Books & Videos would like to congratulate the winners of our video give-away at the California State Instructors’ Conference in San Jose and at the FDIC in Cincinnati.

San Jose

Day 1 — Winner of “Collapse of Burning Buildings” series: Keith Marshall, City of Burlingame (CA) Fire Department.

Day 2—Winner of “Forcible Entry” video series: John Trenner, Carmel-bythe-Sea (CA) Fire Department.

Day 3—Winner of “Master Stream,” “Flashover,” and “Backdraft”: Dennis Macey, Medford, OR.

Cincinnati

Day 1 —Winner of “Collapse of Burning Buildings” series: Leonard Hardy, Maury (NC) Volunteer Fire & Rescue. Day 2—Winner of “Forcible Entry” video series: Brent Smith, Plain City (OH) Fire Department.

Day 3—Winner of “Master Stream,” “Flashover,” and “Backdraft”: Thomas Owens, Frederick County Fire & Rescue Department, Winchester, VA.

On April 30, 1991, we responded to a call for “tires on fire” from a tire company/warehouse. It generally would have been a minor alarm, but our structure fire alarm was toned after the second call, informing us that a building possibly could be involved. A mutual-aid company was brought in with us. The chief left for the scene, and I took the engine company out and followed. When the chief arrived, he informed us of “a fully involved structure.”

After arrival and setup, my crew and I advanced a 2’/2-inch line through the office and into the shop bay area. We were met by heavy smoke and heat. 1 asked command for the next engine company to ventilate the skylights. When this was done, I could count the cross members of the truss—they were still intact. I again contacted command and asked for 10 minutes to conduct an interior attack. My crew set the 2’/i-inch nozzle to straight stream and was told to work the truss from side to side and top down to approximately eight feet below the truss. Even though the fire had been burning approximately 20 to 30 minutes prior to arrival, we were able to knock down most of the burning truss and continue an offensive mode of attack within the 10minute limit.

Inside there were almost 70 truck tires, machines, and a storage area with flammable materials fully involved. After three hours, the fire was suppressed and overhaul completed.

The reason? Truss roof preplan. The building has been preplanned approximately eight months prior to the fire. Three pages of information, a survey, and floor plans were compiled. The roof was typed as a ribbed/ trussed/bowstring arch with heavy wood members. It spanned approximately 70 feet and had long stretches of 2-by-10s spliced together with bolts, not as in today’s construction, which uses gusset plates. Only in one storage area did a portion of the truss crack. It had heavy alligator charring but didn’t burn through. Another storage area, an addition with a flat wood roof, failed and burned through. The building had no sprinklers, and this was the first fire to occur in the building.

The department’s knowledge of the building, preplans, going over these preplans during several drills, and the mutual aid made it possible for the owners to be back in partial operation within a day and a half.

Matt Maciaga

Captain

Dixmoor (IL) Fire Department

A request for a donor

I have been a firefighter with the Yuba City (CA) Fire Department for five years. I am writing in hopes that this request to assist in finding a bone marrow donor for my wife, Silvia, will reach as many firefighters as possible.

Silvia, a 27-year-old mother of three boys, has been diagnosed with leukemia and has been in and out of the hospital since November 1991. She has been receiving chemotherapy, but her doctors feel that this treatment can put her in remission only for approximately three months. Her best hope for recovery is to have a bone marrow transplant.

One way everyone can contribute is to have their tissue type included in the National Marrow Donor Registry’. This is easy to do, takes little time, and can be done by contacting the local blood center or calling 1 (800) 6541249. You will be directed to the nearest testing location. The testing takes only 10 minutes. The small amount of blood taken enables the center to type an individual’s tissue and enter the information in the National Registry. When a leukemia patient needs a bone marrow donor, the Registry searches for a perfect match.

The chances of someone’s tissue matching another person’s is one in 100 to one in one million. Therefore, it is critical that everyone be in this Registry, since there may be only one person in this world who can save the life of a particular leukemia patient.

Silvia is of Hispanic heritage, and the chance of obtaining an exact match is greater with individuals of the same ethnic group. I encourage individuals of all nationalities to be tested for their tissue types in the hope of saving my wife’s life.

If further information is needed, please contact: Eli Flores, (916) 6711154; Mike Rose, (916) 671-3726; John Limas, (916) 673-1472; or the Yuba City Fire Department, (916) 741-4689.

Eli Flores

Yuba City (CA) Fire Department

Compliance and other comments

As a longtime subscriber to Fire Engineering, the March 1992 issue stands out as superior. The magazine continues to publish articles that are thought-provoking. They are full of the technical information needed by today’s fire service. I also have come to enjoy the banter found in letters to the editor, particularly when often biased differences of opinion challenge the validity of statements by the various authors.

In the March issue, the following articles stand out and are must-reads: “SOPs: Key to Good Leadership,” page 91; “The Politics of Incident Management,” page 53; “Editor’s Opinion,” page 6, and “OSHA Compliance: Word to the Wise,” page 75. They prompt some personal thoughts.

The fire service is being plummeted into the abyss of compliance issues. As suggested by the editorial, enforcement and the legal necessities so impact the service provider that satisfaction of the letter of the law will become the driving force. More and more fire chiefs will scurry for the cover of compliance documentation. Gregory G. Noll’s statement on page 54, “…performance of., emergency responder often is suspect.” will become the next pitfall for litigation. No matter how good the SOP, some changing situation will demand a high level of sophisticated and rational forethought based on life experience to save the day. And as sure as I am writing this, some court will make an award because someone improvised and it worked. Of course, the damage already done will be presented as evidence that the SOP either was not followed or was not correct. We cannot win because there are too many of our own who will attest that a different way is better.

It is for exactly that reason Windsor Locks, Connecticut, won, the driver won, the public won, but so did OSHA. It is needless to say who paid. In my mind, the fire service lost.

How many times have we heard the answer, “It didn’t feel right!” to the question, “How did you know to get out before the place fell in?” We can write the SOP and try to comply, but remember, it takes “street smarts” to survive on the foreground. We cannot be lulled into forgetting what the SOP is intended to do. It should point us in the right direction. It must not replace thinking smart.

Gary V. Nesslage

Chief of Department

Germantown (OH) Fire Department

Regulating the editorial

In reading Bill Manning’s March 1992 editorial “Regulating the Rescue,” I have only two questions. Did first responders from the Windsor Locks Fire Department identify the product and recognize the fact that they were performing a rescue within a greater hazardous-materials incident before deciding to effect a vehicle extrication? And if so, were all personnel in full protective clothing with self-contained breathing apparatus in place, working within the control of an incident command system before beginning the rescue operation itself?

If these steps were taken, then I agree with the presumption that the rescue was performed with prudence and within all expected fire service standards of care. If not, Manning should look long and hard at the reality of today’s fire service response to chemical emergencies and how far firefighter safety has come as a result of learning from past mistakes.

There can be no more “smoke eaters” and “kick the door down” rescue tactics. No rescue can be worth needlessly risking the lives of inadequately trained rescuers, no matter how dedicated they may be. Our job as emergency response personnel is to protect life and property based on sound mitigation techniques, not heroism—to be part of the solution, not part of the problem.

I agree that it should not take OSHA compliance efforts to change the tactics and methods of the fire service. It should only take the countless training videos of firefighters who have been injured or lost their lives while performing traditional fire and rescue activities after identifying the presence of a greater hazardous-materials incident.

Christopher R. Post

Fire Engineer

Squaw Valley Fire Department

Olympic Valley, California

Technician

Placer County Haz-Mat

Response Team

Reluctantly, I must take exception to Bill Manning’s editorial in the March issue.

Fan article blows up a controversy

Editor’s note: The following letters are in response to “Selecting PPV Blowers,” which appeared in the February 1992 issue of Fire Engineering.

As a disciple of PPV theory and practice over the last five years, I was pleased to see the article, “Selecting PPV Blowers,” in the February 1992 issue of Fire Engineering. I share some of the author’s thoughts and opinions; however, there are several points of interest that should be addressed. Taken at face value, the article could be construed as being somewhat biased.

1. Although I agree with the author in his statement that blowers with shrouds offer somewhat more protection than caged blowers when damaged as a result of a fall, there is a more important issue that should be addressed: Any blower w’hen subjected to a fall that results in a deflection of the shroud or cage surrounding its blades has the potential for breaking or having its blades damaged.

Proper training in blower placement and setup will eliminate opportunities for blowers to be knocked over or fall. In all cases where a blower is utilized in a position that makes it susceptible to falling, a member should continuously be assigned to the unit.

2. In areas of loose debris, leaves, sand, etc., a salvage cover may be spread underneath a blower to prevent the loose debris from being picked up by the blower and pulled through the blades. All blowers will pick up a certain amount of loose debris when operated in areas consisting of such. I agree with the author that plastic or polycarbonate blades are more susceptible to nicks and cracks than blades made of other materials, but with proper training and deployment practices, situations for blade damage can be reduced or eliminated. Blowers that utilize a plastic or polycarbonate blade are very effective.
3. The author alludes to temperature conditions that blowers may encounter when deployed. Any blower located or set up in an area where it is subjected to a temperature of 1,000°F or higher has not been set up properly or is not being utilized as designed. Gas-powered blowers are designed to be operated in an oxygen-sufficient atmosphere outside a structure. (Blowers may be utilized within structures under certain nonextreme conditions.) If the 1,000°F temperature is being produced by radiant heat, the blower is being deployed at the wrong location or the structure is beyond an offensive attack. In such cases, the blower is not needed.
4. The author states that adjusting blowers should be so easy that it can be done “at night while half asleep.” This is true. Training is the way to accomplish this objective. Blowers that may require additional steps to be properly deployed may also have other advantages that are beneficial to the user.
5. In the section entitled “Air Production,” the author points out that blowers should be rated by an independent rating agency. He fails to reveal, however, that only blowers equipped with shrouds can be rated by AMCA. Blowers that have a cage surrounding the blades are excluded because of the testing method AMCA uses. Because of this, individual manufacturers of blowers with cages rate their own blowers. Comparisons of advertised cfm ratings can be misleading. An example would be comparing apples to oranges. The best way to determine the best blower in terms of cfm production is to set up several blowers side by side. Utilize some type of practical evolution in which smoke removal or air movement can be adequately gauged. A common testing procedure is needed to compare all blowers. Until one is established, one-on-one comparisons are best.
6. In the author’s attention to stackable blowers, he minimizes the advantages of units that can be used either together or individually. For most departments, this feature is advantageous because of versatility. As individual units, stackables are quite sufficient for most PPV applications on residential and small commercial structures. They are also very adequate when two blowers are needed at two separate locations. If a higher rate of cfm is required for fire attack purposes, the blowers can be stacked together as a single unit. Contrary to the author’s opinion or experiences, I have found the stackables to be quite stable when deployed properly. Again, training is the answer to proficiency when setting up any PPV blower(s). As a matter of record, I teach students to crank the top blower first. The reason is that the top section of the door is the most critical in terms of obtaining a seal.
7. Finally, the author completely ignores electric motor-driven fans as a viable alternative to PPV blowers. There are still quite a number of departments who can’t afford to purchase new PPV blowers. For those departments, it is important to realize that their existing fans can be used in a PPV-type application. Stacking of electric fans is highly recommended, since electric fans cannot produce nearly the amount of cfm as a PPV blower. If done correctly, electric fans will be less efficient than a PPV blower but will be much more efficient than if used in a negative-pressure mode.

In light of the competitiveness of the PPV blower market, it is important for the prospective purchaser to understand all of the options available to him or her. It is also important to know what methods afford each blower an equal chance when comparing one blower with another. The last, but not least, factor to consider when purchasing a blower is the reputation and experience of the manufacturer and its representatives. Spend the extra time to challenge or verify what a sales representative claims about his blower and his competitor’s blower. It will become very evident who is there to help you make the right decisions and who is there to simply help you buy their product.

Rusty Horton

Assistant Chief

Jnno (SC) Fire District

I am writing to express my strong concerns over the content of the article “Selecting PPV Blowers.”

As a respected magazine in the fire industry, I recognize that Fire Engineering must strive to be relevant and address issues important to your readers. However, I think the topic of equipment selection is very sensitive and should receive extra attention. Some of the information in this article is incorrect and misleading.

The author implies that aluminum blades can withstand temperatures up to 1,000°F. They cannot. Our blowers offer either composite or die cast aluminum blades similar to those described. Therefore, we do not necessarily promote a specific blade material. For the record, however, plain aluminum wall melt at very high temperatures but suffers a substantial loss of material strength long before that temperature is reached. Accordingly, aluminum blades are rated for temperatures of — 60°F to 300°F, with a maximum allowable tip speed of 250 ft/sec.

Continued on page 54.

Composite polyamide blades are rated for – 50° F to 250° F but have a maximum allowable tip speed of over 395 ft/sec. To the best of our knowledge, these ranges are comparable to all other similarly manufactured blades. The author does a serious disservice to firefighters by implying that any blower can be operated at or near 1,000°F: Gasoline would vaporize from engine fuel tanks [and ignite |, rubber tires would melt, etc., any one of which would endanger the safety of firefighters.

The author states that water mist application is ineffective. Water application through a blower has been shown to reduce the ambient temperature during overhaul. Water mist also has been used successfully to mitigate the spread of some hazardous gases such as anhydrous ammonia. Finally, water mist has been very effective in lowering the core body temperature of overheated firefighters (firefighter rehab).

Regarding the use of w ater turbinedriven blowers, we must respond. Water-powered turbines are virtually maintenance-free and are effective tor supplying more horsepower to the fan without the inevitable increase in engine weight and size.

The article in question was misleading, inaccurate, and biased.

James W. Leonard

General Manager

Typhoon Ventilation Systems

Hate Products, Inc.

1 was appalled at the content of “Selecting PPV Blowers.” Not only was it a biased article, it was also very demeaning to firefighters.

At one point the author says to make sure the unit is high enough off the ground so it does not suck in rocks and pebbles, and later he says to make sure the rubber feet are not too small so the unit can be set up in sand or soft dirt. Does he think firefighters are going to set up the blowers in sand and soft dirt and create themselves one hell of a sandstorm? Firefighters know better!

The author’s discussion of blade material takes the same approach that one of our competitors has used to discredit the competition. He states that the temperature of the blades goes “from 70°F in the station to 0°F ambient temperature to higher than 1,000°F from the fire.” The truth is that when using a blower to vent a building, the 1,()00°F heat is driven to an area aw ay from the blower, and the blade is not exposed to the heat unless the blower is used in the wrong manner. Again, he makes a statement that slams the intelligence of a firefighter.

The author’s innuendo that water application through the blower does not work is erroneous. I have personally observed this tactic used to put out a large hotel fire that had gone to three alarms. It was so smoky the seat could not be found until smoke ejectors were used with fog to blow’ the mist into the fire area.

He also says that a direct drive blower is harder to crank than a belt drive unit, but he forgets that most blowers use the same engines no matter w ho makes the blower. It takes the same effort to pull the rope starter on a Honda engine no matter whose blower it is on.

This article was written solely for the benefit of one manufacturer, and it should have been disclaimed as such. As a firefighter and as a manufacturer, I take exception to this biased article.

Ervin D. Weinmeister

President

Super Vacuum Manufacturing

Company, Inc.

“Selecting PPV Blowers” was extremely biased toward one particular brand of positive-pressure blower.

We agree with the author’s statement that “a closed shroud produces a more definite cone of air”; however, to us, it logically follows that the blower must be placed farther back from the entrance being pressurized to create a seal —not closer, as he states. The farther back you go, the less velocity, thrust, and pressure will be emphasized on the opening being used for PPV. Passing fire personnel, side winds, or any large objects can and will disrupt the air flow and the ventilation process. Air can be pulled in only one direction—from the back of the shroud.

The author feels that the closed shroud is safer when the blower is knocked over or someone runs into it That asset should be balanced with other considerations. Consider the following: In order to meet OSHA requirements, the back shroud must have a w ire spacing of no more than ½ inch. This is the standard throughout the fan industry and will allow’ debris of up to ½ inch in size to pass through the shroud. Therefore, a solid shroud with less than a ’/.-inch space from the tip of the blade to the shroud somehow has to let a lb-inch piece of debris pass through it. The debris must go ! through the ‘ t-inch gap between the tip of the blade and the solid shroud; it j cannot drop out. Rocks, leaves, paper, j brush, clothing, rags, curtains, sheetj rock, lath, plaster, etc. have been | sucked through or kicked up into all styles of blowers. If a strong amount of air is being generated and debris is present, then debris is going to pass through the blower. It is important | with any style of blower that eyeprotection be worn at all times.

Continued on page 56.

The size of the house/structure | most fire departments are called to on | a daily basis ranges from 1,000 to j 3,000 square feet. We found that from | 8,000 to 20.000 elm are necessary to j pressurize structures of this size. Rej member, the higher the efrn, the larger the exit opening can be and the faster positive-pressure ventilation will enhance fireground operations Will a bigger blower overpressurize the structure and force heat and smoke back toward the firefighter, as the author states? If PPV is used properly and the exit opening is the right size in comparison with the efrn being introduced, then the answer is no. If PPV is not set up properly, then it could happen. Proper training is always important before using any attack tool.

We take exception to the author’s comments on wooden blades and direct-drive blowers. The wooden blade is light, yet strong, and is resistant to extreme weather changes. The j light weight of the laminated maple prop/one-piece-hub assembly allows us to direct-drive the prop to the crank shaft, providing maximum power distribution to the blade. All engines in our units have automatic decompression for fast and easy starting.

The author suggests that the blower be rated by the Air Movement Control Association. The current rating program applies only to solid shroud fans. We have been working with the A MCA for the past three years to establish a standard for rating highpowered, open-shrouded, positivepressure ventilators. The new standard will be AMCA 230. All our models will be tested to this standard as soon as it is finalized.

The author says that he believes the “water application through the blower” to be a waste of money, and furthermore that it makes the floor slipperyand wets the firefighters as they enter the structure. The last time we looked, the primary attack tool, other than the firefighter, was water — usually in the form of a dense stream ejected from a hose. We fail to see how an extremely light mist, which evaporates in seconds, can create any additional hazard for professionals accustomed to dealing with those conditions. In addition, the mist assists in attacking the fire bycarrying a heavier concentration of air flow through the entire structure, removing heat, gases, chemicals, and soot away from the advancing firefighter.

We were extremely disappointed by the lack of accurate information offered in this article.

Dan Raczykowski

President

Unifire Power Blowers, Inc.

Continued on page 52.

While I empathize with the problems of volunteer fire departments and districts complying with the multitude of regulations they face and I don’t feel that levying fines necessarily is the best way to address noncompliance, the message I have received from this editorial is that “the end justifies the means.”

I realize we don’t have all the details of what happened from the brief summary provided in the editorial. The key step missing in the description between the time the firefighters arrived on scene and the time they performed the successful extrication is a size-up of the situation. If the description had said that they checked for leaks, noted the four-digit placard on the trailer identifying the load, and/or accounted for visible fumes or vapors before deciding to enter the area from the upwind side of the accident, I would be more comfortable with the editorial position. However, the column implies that it was not until the chief arrived and the rescue was in progress that these things were done. My concern is that these firefighters subscribe to the old “smoke eaters” theory of operations.

Near the end of the editorial, Manning asks whether OSHA’s response would have been the same had a Department of Labor official been in the crushed cab. Would the editor’s comments have been the same if any of the firefighters had been overcome by formaldehyde vapors during this rescue?

One suggestion—to try to make this letter constructive rather than totally critical—is that this department and other departments invest in copies of the Department of Transportation Emergency Response Guidebook (DOT P5800.5, S3-S5 per copy), which can be carried in the glove box of first responders’ private vehicles. It provides a quick resource during size-up of this kind of incident.

Dean Cooley

Geysers Power Plant Fire Brigade

I have just finished reading Editor’s Opinion in theMarch issue and want to say that I agree with it So often those who sit in the office and who have never responded to or have never seen an emergency make these so-called regulations. Continue the excellent work.

Chuck Holman

hire i’mining Manager

Palisades Nuclear Power Plant

Pill Manning responds: hike all thought-provoking, controversial subjects. the March Kditor’s Opinion elicited a great response, both written and verbal, for and against. Many of you responded in favor of the piece by way of the reader service card. My thanks to all those who commented on both sides of the issue. I’d like to clarify my position.

If the rescue had been performed within all expected fire service standards of care, the department would not have been cited in violation of OSI1A regulations. 1 am sure that each and every department is at a different stage of compliance with the hundreds of standards it must address. How well or how quickly the fire service is able to adopt these standards in its dailv operations is a kev factor in reducing firefighter injuries and fatalities and is a function of acceptance to change, training, and getting the dollars to put it all in place.

1 am equally certain that there is no such thing as a perfect operation and that there are lessons to be learned from every operation. In no way do 1 presume to judge —on page 6. no less — how closely the operations of any department come to the ideal. However. 1 will stand behind the conviction that, based on the responders’ experience, training, si/eup. and risk-benefit analysis, the rescue operation was deemed appropriate because it fell within an acceptable level of risk. I must stress that the CONN-OSHA citation was given for failure to monitor the atmosphere and not for failure to wear appropriate respiratory protection or protective gear and that the chief arrived on the scene with first-responding firefighters. at which time he immediately established the incident command system. A discussion of the time between arrival and product identification is best handled within the confines of a department critique.

The March editorial was not an espousal of unsafe fireground practices or reckless macho behavior, nor was it an indictment of safety regulations. Nor am I so naive as to look the other w ay so long as nobody’s been hurt or killed. I, in keeping with the goal of this publication, join with many in efforts to preserve the fire service’s greatest resource, its members, and believe that the safety of firefighters is paramount.

However, I feel just as strongly that the fire service must be afforded the opportunity to realize its mission, and feel sickened when a department receives a public scolding for a conscientious attempt to fulfill that mission as best it can under unique circumstances.

Filter out information

After reading the March 1992 article on diesel exhaust and soot, I can’t help but worry that the information on the filtration units might be misinterpreted. Departments attempting to comply with NFPA 1500 recommendations on exhaust emissions might infer from this article that this diesel filtration unit is a solution. It is not.

Diesel filtration units do not direct exhaust emissions out of the building, as per NFPA 1500. They are filters, and as filters take care of only one symptom of the problem—-the visible particulate. The rest of the exhaust — including carbon monoxide, oxides of sulfur and nitrogen, and others—still will be dumped into the building. Therefore, the building still will contain it.

I can’t help but wonder if the combination of a hot exhaust system and a filter containing diesel exhaust particulate isn’t resulting in the generation of other gases and compounds that might also be contaminating our firehouses. It would be ironic if this “solution” actually has turned into the problem we were trying to solve in the first place.

Wallace C. Thomas Jr.

Bridgeport, Connecticut

Picture what you preach

I cannot adequately express my shock over the photographs that accompany the article “Truck Company Drills at Acquired Structures,” which appeared in the March 1992 issue of Fire Engineering.

In one photo, a firefighter appears to be operating a power saw without a backup man. At another portion of the roof, operations are being performed without use of a roof ladder. It also appears that the helmet visor of the firefighter in the left foreground is not down. None of the firefighters on the roof is wearing SCBA.

In another photo, in addition to the venting procedure being performed without SCBA or a roof ladder, the incorrect body position of the firefighter with the power saw would cause both him and his partner to fall off the roof should the saw kick back. I have found through experience that it is much easier to operate the saw from a flat position, allowing the roof to take much of the saw’s weight. Then, by tipping the running saw forward, the cut can be made. The depth of the cut is controlled totally by the angle of the saw, allowing the user to cut just the plywood surface and no supports.

I realize that this article attempts to promote safety during training, but since “a picture is worth a thousand words,” the photographs need to match the message of the text.

It is my opinion that—as in the military—we in the fire service must “train like we fight,” so that when the jobs come in we can “fight like we train.”

Christopher Barrella

Firefighter-EMT

Fairfield (NJ) Fire Department

Bill Manning responds: Thank you for your comments and your dedication to safety. We share your “train like we fight” philosophy. On the day of this drill, hot and humid weather precluded use of SCBAs. Your other observations are duly noted. Some of the photos we used in the article were not the best choices to illustrate the safe techniques that were covered in the text. However, we encourage all readers to use all the photos in our publication—whether you agree or disagree with the practices shown therein—to positively enhance your discussions about fire tactics and fire training.