Members of the Fire Apparatus Manufacturers’ Association (FAMA) are experts at building big trucks with big horsepower and big water flow. These capabilities are exactly what the fire service needs for putting out big fires. It is not, however, what you either need or want for testing hose, nozzles, and couplings.
Annual Testing is Essential
While the importance of proper equipment testing and maintenance is indisputable, it still seems that there are departments where this is message is often ignored. Several years ago, I visited a large fire department and was surprised that it did not perform annual hose or pump testing. When it comes to putting water on a fire, you need a pump, and you need hose. Failure of either will mean you can’t get the job done. If you are not testing both at least annually, you risk failing at the main thing you need for fire suppression.
Another important reason to test hose annually is because it is required by the Insurance Services Office (ISO) system. Proper hose testing records are one of the check boxes on an ISO audit. Loss of an ISO rating not only means you are less effective as a department, it can also mean money out of your tax payers pockets in the form of higher insurance premiums.
Safe Testing Procedures are Essential
The proper method of testing hose is found in National Fire Protection Association (NFPA) 1962, Standard for the Care, Use, Inspection, Service Testing, and Replacement of Fire Hose, Couplings, Nozzles, and Fire Hose Appliances. There are two procedures that NFPA 1962 specifies: testing using a hose testing machine or using a stationary pump or pump on a fire department apparatus. While both these methods are described in the body of the standard, the second method comes with two important caveats. First and foremost is the warning that points out because of the risk of “catastrophic failure during the service testing of fire hose, it is vital that safety precautions be taken to prevent exposure of anyone to this danger.” The safety risk of hose testing using a fire apparatus stems from the very high horsepower that the apparatus can produce.
The second caveat is found in the annex to the standard. It points out the potential for damaging the pump by running the pump at high pressures and no flow. This situation can cause cavitation and high pump temperatures. The high heat created can also pose an additional safety risk.
Real Life Safety Risks
More than 25 years ago I was involved in a hose testing operation at my paid-per-call fire department for which the pump of our fire apparatus supplied the test pressure. Because of the lack of available space, we had the hose laid out in the fire station bays and apron. During the pressure test, one of the hose lengths failed and propelled a galvanized garbage can against the wall and flattened it. Luckily it was a garbage can and not a firefighter. This example is a graphic demonstration of how much power is available through the apparatus pump.
The important part of safety we ignored was limiting the flow to the hose being tested. NFPA 1962 addresses this when using the fire apparatus pump by requiring that a gate valve with a ¼-inch hole drilled through the gate be used between the pump and the fire hose test layout. The small hole is intended to prevent the large surge of water volume that will otherwise flow through the test hose if a hose or coupling fails.
When the energy (horsepower) being transferred from the apparatus engine to the pump is not being used to move water (low or no flow), the energy will be absorbed by the water and transferred into heat. A single-stage centrifugal pump, when operated at 200 pounds per square inch deadheaded without fresh water replacement, can heat up the water at a rate of 36°F per minute. It does not take long for water to heat to a point that can injure firefighters performing hose testing if they are exposed to this overheated water.
Real-Life Pump Damage Risk
When I worked in the Waterous service department, I received a small box of brass pieces from a fire department. The pieces were from the impeller of a fire pump. The department had used its pump for two high-pressure low-flow situations. The first was to test hose, and the second to clean off the apron at their station.
High-pressure low-flow use can severely damage your pump. For a centrifugal pump to increase its discharge pressure, more pump (engine) speed is required. The faster the pump spins the more flow it wants to produce. When the flow of water discharging from the impeller is restricted (as when hose testing), the water recirculates within the pump volute. This is known as discharge recirculation or discharge cavitation. The jackhammering effect of cavitation can cause physical damage to the impeller exit way and the discharge side of the volute (pump body).
Excessive heat can also be detrimental to the fire pump. Packings/mechanical seals can be damaged or worn prematurely when exposed to high temperatures. In severe cases, the entire pump may seize up when overheated. For these reasons, centrifugal fire pumps should never be run at full shut-off (zero flow). Some water should be circulating through the pump at all times to keep it cool.
Hose Testing Machines Are the Answer
The best way to pressure test hose and couplings is to use a hose testing machine. These devices produce the necessary high pressure without producing much water flow. The risks produced by using a high-horsepower pump are eliminated. If you find that the test machine takes too long to fill the test hoses, prefill your hose using the apparatus at low pressure and flow before coupling them to the machine.
Hose Test Services
I am currently on a fire department that started using a hose testing machine quite a few years ago. We found that testing hose is a time-consuming activity for a paid-per-call department, and it cut into our training time. Five years ago, we started hiring an outside testing company that came in and tested all of our hose within a couple of days. Using a hose test agency is a good way to stay current with your annual hose testing and avoid the risks to personnel and equipment.
Keep it Safe
FAMA members care deeply about firefighter safety, and we never want one of our apparatus involved in an incident where someone is injured. We also want your apparatus working in prime condition so it is always ready to respond. This is why our safety manual points out the risks of using your fire apparatus for hose testing and why we urge the fire service to avoid using apparatus for hose, coupling, and nozzle testing.
FAMA is committed to the manufacture and sale of safe, efficient emergency response vehicles and equipment. FAMA urges fire departments to evaluate the full range of safety features offered by its member companies.