BY GERARD J. NAYLIS
Pumps on fire apparatus are mechanical pieces of equipment that require regular maintenance and inspection. The frequency of these activities varies, and a schedule must be followed to ensure that the appropriate inspections and maintenance are done when needed.
Perhaps the most important reason for conducting periodic inspections and performing regular maintenance is that a mechanical failure could directly lead to serious injuries or even fatalities at a fire scene. The firefighters relying on a hoseline that suddenly loses flow and pressure in the heat of a firefight could be needlessly endangered simply because a routine inspection that would have detected the problem was not done.
Daily inspections should be easier to accomplish for career departments because they have staff on duty at the fire station. Volunteer departments may wish to modify the inspection routine of career departments to ensure that items inspected daily in such organizations are inspected at least weekly in volunteer departments, if not more frequently.
ENGAGING THE PUMP
(1) Check the “pump engaged” indicator lights and ensure that the pump is engaged before increasing the throttle. If the indicator does not light, ascertain the cause before proceeding with the pump check. (Photos by author.)
At the start of each shift, the pump operator should start the apparatus. If the apparatus is not connected to a 100-percent exhaust capture device, the apparatus should be moved outside the fire station for the inspection. The pump should be engaged to ensure that the changeover can be done smoothly. In most cases, this will be a power takeoff (PTO) or a split-shaft transmission. In some cases, the pump will have a separate motor to power it. Modern apparatus should have indicator lights in the cab and on the pump panel to show that the pump is engaged. If the indicator lights do not illuminate, you could have a burned-out bulb, a loose wire, or a poor connection. On the other hand, you may have a problem with the pump not engaging. If so, you must determine the cause and address it before you get called to the next alarm (photo 1).
TANK WATER LEVEL
The level of water in the tank should be checked both visually and compared to the tank level indicator on the pump panel (photo 2). In many cases, this tank level indicator is a series of lights showing the tank level in one-quarter increments. Alternatively, there may be a float-type indicator that rises or drops based on the tank’s water level. The tank should always be kept full.
There are multiple reasons for water to escape from the tank. The tank could have a leak, the tank-to-pump valve may not be properly seated, or the valve may be broken. Additionally, there is the possibility that an inattentive pump operator just forgot to fill the tank after the last call. The one thing you do not want to happen is that you pull up to a working fire, need the tank, and then find out that you have no water.
The tank-to-pump valve should be opened to ensure that water flows from the tank to the pump. Next, open the tank fill valve and then slowly raise the pump pressure (photo 3). This allows the pump operator to check the throttle while moving water from the tank to the pump and back into the tank. As this is taking place, the main pump panel pressure gauge should rise (photo 4). If it doesn’t, you may have a faulty gauge.
(2) Check the level of water in the onboard tank visually (i.e., look in the tank); compare with the level indicated by the tank water level gauge.
Check the snubbing control to make sure that someone hasn’t inadvertently left it completely closed. This same process can be used to check the pressure gauge for each discharge. Naturally, this should be done only on discharges that are capped closed and not on preconnected hoselines. All preconnected hoselines should be disconnected and capped before checking the discharge control valve and pressure gauge. After completing that procedure, all preconnected hoselines can be reconnected. This is also the time to make sure that all discharge caps and reducers can be opened and removed.
DISCHARGE CONTROL VALVE
Each discharge control valve should be slowly opened one at a time. A good rule of thumb is that it should take at least three to five seconds to fully open or close any valve. This will prevent damage to the valve and reduce the potential for water hammer. The valve should operate smoothly and easily. If not, note any problems that need to be addressed.
(3) The pump operator should open the tank-to-pump valve and the tank fill valve before raising the engine speed and increasing the pump pressure.
The pressure gauge for each line should rise as the discharge valve is opened. Once the pressure gauges have been checked, the hoselines can be reconnected. If the pressure readings of the main pressure gauge and the fully opened individual discharge gauge do not match, this indicates that one of the gauges is not functioning accurately (photo 5).
(4) Raise the pump pressure to at least 100 psi to make sure that the main pump pressure gauge is working.
After you have checked the pressure gauges, slowly reduce the throttle back to idle and close the tank-to-pump valve and the tank fill valve. Close any discharge valve that was opened, and open the discharge line bleeder valve. This will remove any trapped water and relieve any pressure that may have built up in the valve. Then close the bleeder valves.
PUMP TRANSFER VALVE
If your pump is a two-stage pump, this is the time to exercise the pump transfer valve. This could be an electronic valve, a manual valve (such as with a wheel), or an air-actuated valve. Regardless of how the transfer is effected, make sure that it gets done. Accepted practice is that the transfer be done at idle or at not more than 75-psi pump pressure. Check to see if your pump has provisions to manually transfer the pump stage if the regular transfer valve doesn’t work. If so, make sure that you have the appropriate wrench to turn the manual transfer valve. Should the wrench be unavailable, you would do well to get one and place it in service on the pump.
Often, the following question is raised regarding two-stage pumps: Should they normally be left in the volume or parallel position or left in the pressure or series position?
One school of thought is that leaving the transfer valve in the pressure mode saves the pump operator one additional step, since at most fires the flow discharged is less than 50 percent of the pump’s capacity, which is delivered in the pressure mode.
(6) Pumps equipped with a pressure governor need to be checked in the pressure (psi) mode by increasing to the set pressure and then slowly closing the tank fill valve. The engine speed (rpm) should decrease.
The other school of thought is that leaving the transfer switch in the volume mode position forces frequent exercising of the transfer valve for the very same reason; most fires require less than 50 percent of the pump’s capacity. The important thing is that the transfer valve get regular exercise. Any valve not exercised regularly is more prone to freezing up or becoming problematic. Personally, I prefer to keep the pump in the volume mode position to ensure frequent exercise.
PRESSURE GOVERNOR/PRESSURE RELIEF VALVE
Most pumps have a pressure governor or a pressure relief valve (photo 6). Some have both. Regardless of which type of automatic pressure control device is present, it needs to be exercised and checked frequently. You may also have an external pressure relief valve on the intake side of the pump. Such devices are common on apparatus that use large-diameter hose (LDH).
(7) Primer valves should be included in any pump check.
A simple way to check the operation of these automatic pressure control devices is to open the tank-to-pump valve and the tank fill valve. Slowly raise the pressure to 150 psi. Set the relief valve or the pressure governor for this pressure. Slowly begin to close the fully open tank fill valve. The pressure on the discharge side of the pump should begin to rise. The relief valve should engage within three to 10 seconds once the discharge pressure rises at least 30 psi above the set pressure or position.
If the relief valve is equipped with indicator lights, the yellow indicator light should come on when the relief valve engages. On pumps equipped with a single yellow light, the light should turn off when the pressure falls below the set position. On pumps with yellow indicator lights for open and green indicator lights for closed, the indicator lights should change from yellow back to green when the pressure falls below the set position.
On the pressure governor, you should see a decrease in the engine speed as you close the tank fill valve. Before closing the relief valve, make sure that the pump pressure is brought back down and the relief valve is closed before turning the control switch from the on position to the off position. Once this exercise is completed, reduce the engine speed to idle, thus reducing the pump pressure, and close the tank-to-pump valve and the tank fill valve.
Some pump operators prefer to preset their relief valves. But what is the right pressure at which to preset a relief valve? The answer is that it all depends on your operation, the size of hose, the type of nozzle you use, and the length of the hose stretch; all of these factors impact the pump discharge pressure. The pump operator should calculate the pump discharge pressure and set the relief valve at a pressure approximately 20 to 30 psi above the pump discharge pressure.
Just as during any pump operation, the pump operator should be checking the engine temperature gauge, the oil pressure gauge, and the fuel gauge. Compare the gauges in the cab and on the pump panel. Note discrepancies and address them.
Many jurisdictions operate with their pumps filled with water-that is, the pumps are wet. Additionally, many jurisdictions have public water supplies (hydrants) that provide the water necessary to fight fires. For these two reasons, priming devices-commonly called priming valves or primers-are often overlooked and not exercised regularly (photo 7).
Unfortunately, this means that the primer is not getting the exercise it needs. The pump operator, in checking the primer during the daily or weekly inspection, may detect a faulty primer problem when it is a small and a relatively inexpensive maintenance item. Left unattended, it could get worse. More importantly, you depend on the primer to perform a drafting operation and to prime a dry pump; if that primer isn’t working, you will be unable to complete your mission, and it could imperil the fire attack operation. Simply stated, a fire is not the time to discover that something on your pump is not working.
• • •
Conducting regular pump inspections is the best way to confirm that your pump is ready for a fire. Ignoring this valuable activity could allow a problem to go undetected and become more costly to repair over time. More importantly, neglecting regular pump inspections could lead to a mechanical failure on the fireground that could compromise the fire attack and potentially result in firefighter injuries or deaths. Pump inspections should be done periodically. Ideally, these inspections should be done daily, but in no case should they be done less than weekly. ■
■ GERARD J. NAYLIS has served more than 31 years as a firefighter, company officer, chief officer, and training officer in career and volunteer departments. He has written and lectured extensively on fire-related topics. Naylis is the acquisitions editor for Fire Engineering Books & Videos. He has a bachelor’s degree in fire safety from Jersey City State College and is a member of the New Jersey State Fire Safety Commission.