Letters to the Editor
The equipment isn’t always at fault for interior pump pressure loss; its operation may be, too
In your December 1987 issue, Lt. Herman Collier wrote a Training Notebook article, “Interior Pump Pressure Loss.” I feel that his article was incomplete in a few ways.
First, he doesn’t mention what size outlets are being used on pump discharge ports. The standard 2½ outlet is installed to deliver 250 gpm. While fire pumps may deliver more gallons per minute through these outlets, there will occur a point when the increase in flow will create back pressure, or resistance to flow. If large-diameter hose is to be supplied through 2Vi-inch discharges, multiple outlets should be used with short lengths of 2’/2-inch, 3-inch, or 3½⅛⅛ hose to feed the supply to a large-diameter Siamese connection.
Also, today’s fire pump manufacturers are providing larger discharge outlets specifically for use in feeding largediameter hose and master stream devices. These outlets can deliver large volumes of water while not wasting the engine revolutions per minute needed to push water through a narrow discharge outlet.
As a vehicle ages, pump performance will decline as wear and tear on the pump increases; the engine and drive train combination will lose some horsepower, and slippage will occur in the automatic transmission. Many pump performance evaluations don’t take these items into consideration. The pump isn’t to be blamed entirely.
Operating the pump within the manufacturer’s guidelines will provide a fire department with a dependable pumper and possibly avoid unnecessary damage and down time. Fire pump manufacturers are in the business of making efficient fire pumps and are trying to satisfy transitions in the fire service. Most are willing to discuss problems associated with existing equipment.
Paul A. Runyon Firefighter
Salt Lake City (Utah) Fire Department
Herman Collier responds:
Yes, I failed to mention the size openings used to discharge the water. An assumption was that the discharge openings are normally 2½-inch. But the size of the connection isn’t evidence of the size piping and valve used to route and control the water.
Most pump manufacturers use 3inch openings on the pump manifold regardless of discharge purpose— large-diameter hose or 2’A-inch. This means that if piping is installed to supply 5-inch hose, it’s connected to a 3inch opening. Unless you specify 2½inch full flow valves, you’ll probably get 2-inch valves on regular outlets.
Supplying large-diameter hose through multiple discharges does work best. But in numerous tests, I found that when both the left and right sides of the pump discharge manifold are used, more gallons per minute can be moved at a lower pressure. This takes into account the radical hydraulic balancing that manufacturers build into the design. By moving water equally into both directions of the pump manifold, less wear is created on the pump case, impellers, and shaft.
I totally agree that pump manufacturers are trying to keep up with the demands of the fire sendee. Sometimes these demands aren’t realistic, however.
Water movement and supply: Neglected fire service knowledge
1 had to write after reading your December 1987 issue. I look forward each month to the excellent articles and features, and have incorporated many of them in training sessions with my personnel. But you’ve really gone above and beyond with “The Big Fire” by Gene Carlson and “How Much Water Can You Move?” by Jack Cottet.
It’s my belief that water movement and supply don’t receive enough attention in the fire service, and both articles wasted no time in getting to the point: Without a proper and continuous water supply, even the most well executed tactical maneuvers become nothing more than reckless and risky gambles. Water supply shouldn’t be a support operation, but a well planned, well trained tactical maneuver.
I’d like to share with your readers two publications that helped me in my work with water supply and movement: National Fire Protection Association Standard 1231 [“Water Supplies for Suburban and Rural Fire Fighting”] and Rural Firefighting Operations— Book Two, The Encyclopedia of Water Supply and Delivery, by Larry Davis of the International Society of Fire Service Instructors. Both are must reading for anyone interested in further understanding or improving a water supply or delivery system. They enabled our department to increase its delivery rate in the first five minutes from barely 500 gpm to more than 1,000 gpm.
I’m looking forward to your continued commitment to excellence in the fire service.
Brian M. Halwachs Assistant Chief National City Fire Department National City, III.
Blending humor and support
Thank you for the great editorial in the November issue, “Ayes in Seattle.” As I read the editorial at my desk, it made me laugh out loud. Your supportive comments, along with your humor, are much appreciated!
Lynn Oliver
Deputy Chief, Fire Division Commander Mercer Island, Wash.
We enjoy hearing from our readers. In addition to sending comments, you’re welcome to send questions that come up as you read articles here; we’ll be happy to forward them to our authors. Whether you have questions or comments, write to Fire Engineering, 250 Fifth Ave., New York, NY 10001.
Even after AIDS data is considered in context, emergency workers should take precautions
The December 1987 Dispatches department included an article titled, “A House bill aims to protect responders from infectious diseases.” This was valuable in that it highlighted legislative efforts to address concerns about AIDS and emergency workers. However, the data needs to be considered in context so it’s not misinterpreted.
Specifically, the article referred to a study by the Johns Hopkins University Hospital in which “16 percent of serious trauma victims between ages 25 and 34 tested positive to antibodies to the AIDS virus, yet none had a known history of AIDS infection.” The Hopkins study included 203 critically ill or severely injured patients, of whom six were seropositive for the HIV antibody. Of these six, all were trauma victims between the ages of 25 and 34,hence the figure of 16 percent.
Several factors must be understood in interpreting these results. First, as the study’s authors indicated, the hospital which conducted the study is in an “indigent urban area.” Of the six seropositive patients, five were gunshot or stab wound victims. While prehospital emergency workers should certainly take precautions to protect themselves against infectious diseases, the results of the Hopkins study aren’t likely to be reflective of the experiences of most emergency workers throughout the country. Even considering the special circumstances of the study’s population, only 3 percent of those patients were HIV positive.
It’s perhaps far more important to exercise certain precautions when handling all patients than to try to define the antibody status of an individual patient. Our approach in Maryland has been to emphasize the importance of good, safe, common-sense guidelines in handling all patients.
It’s likely that the disease and concerns about it will continue for years to come. It’s essential that all emergency workers have good information to protect themselves and still provide excellent care to the patients they serve. Ameen I. Ramzy, M.D.
Fire Surgeon
Baltimore County Fire Department State EMS Director, Maryland
McFadden’s residential fire articles fill the fire attack void
It was with great interest that I read Paul McFadden’s recent Volunteers Comer articles on residential fires. Such articles fill a real training need, as they provide firefighters the opportunity to acquire, improve, or refine their fire attack skills. Despite improved technology and increased awareness of firefighter safety, fire attack remains a skill-oriented activity: The firefighter must avail himself of prior training and experience while attempting extinguishment or extension of the primary search.
Articles such as Mr. McFadden’s are particularly important as many jurisdictions are experiencing a decrease in fire incidence and fire severity. In New York State, for example, fire incidence has dropped 30 percent since 1980. While this development is to be applauded, many firefighters and fire officers aren’t receiving the necessary fire attack experience. The problem is particularly severe in the area of recruit training.
Mr. McFadden’s articles are, through the discussion of fire attack skills, a partial solution to the problem. Hopefully, magazines such as Fire Engineering will recognize their responsibility to provide the forum through which experienced firefighters such as as Mr. McFadden can share their experiences with their less seasoned brothers and sisters. In view of Mr. McFadden’s recent series on residential fires, I commend Fire Engineering.
I also want to commend your decision on the institution of the Random Thoughts column. This feature should enhance the ability of experienced firefighters to communicate with each other and to share their experiences with our less experienced brothers. I’m sure that you will agree that as the incidence of fires declines, the fire service will begin to experience difficulties in obtaining the necessary hands-on, practical experience that allows a recruit firefighter to fully realize the value of any recruit training that has occurred. Magazine departments such as Random Thoughts will provide the vehicle through which the collective experience bank of the fire service can be expanded and shared.
Robert Obermayer Captain
Albany (TV. Y.) Fire Department
Michigan deaths left a legacy
We read your December 1987 editorial, “Who Is to Blame?,” with interest and support. At this time we’re attempting to move beyond fixing blame; maybe we’re making some headway.
The Milford deaths, tragic as they were, did leave a legacy. Michigan has adopted mandatory testing standards for all firefighters entering the service. The law becomes effective October 1. Perhaps we will honor Marsha, Tom, and Bob in a way that will assist new career, volunteer, and on-call firefighters in becoming the proficient professionals demanded today.
Richard G. Powell Executive Secretary Michigan Fire Fighters
Training Council
Practical information helps
I want to commend you on the improvement of Fire Engineering since you’ve become editor. You’ve put together a staff that provides us with a wealth of informative, practical articles that are invaluable aids to our bureau’s operation. Keep up the good work and best wishes for continued success. Robert H. Hotmar Bureau Chief Bureau of Fire Prevention Howell, N.J.
