Restoring Pump to Service After Fireground Operation
The Volunteers Corner
As a pump operator—or pumper engineer—the condition of the apparatus is your responsibility. However, your most important responsibility is the condition of the pump because if the pump fails, your pumper is nothing more than a hose wagon.
The pump manual that was delivered with your apparatus details maintenance procedures recommended by the pump manufacturer, and it is not our purpose to go into a full preventive maintenance program. However, pump operators can follow some procedures in shutting down a pump after operating at a fire that will do much to ensure the reliability of the pump at the next fire.
Oddly enough, it is within reason to say that shutting down the pump actually starts before the order to do so is given. The demand for water lessens as overhaul begins. As the search for hidden fire continues, the pump operator finds that the line—or lines off his pump are shut down for relatively long periods.
Pump overheating: This is the time to check frequently for indications of pump overheating. As the impeller spins, the energy that normally adds pressure to the water as it passes through the pump becomes noticeable as heat. When no water is passing through them, some pumps heat more than others. When a pump starts to build up a significant amount of heat, you can feel it by placing your hand on a large suction intake.
You can prevent—or reduce—this heat buildup by passing water through the pump. If you are pumping from draft or a hydrant, you can discharge water to the ground through an open hose bleeder valve. Generally it isn’t necessary to flow much water through a pump to hold down the temperature. If you are pumping from a booster tank, open the tank fill valve (pump to tank) or charge the booster line and put the open nozzle in the tank fill hole.
When you get the order to shut down the pump, reduce the engine speed gradually by turning the micrometer throttle. Never hit that red button with the heel of your hand and slam the micrometer throttle to the idle position. That puts a needless and inexcusable strain on the engine.
After closing all hose gates, open the bleeders to relieve pressure in the hose lines and make it easier to disconnect the lines.
Relief and transfer valves: At this point, the pump operator plays it by ear, according to what is happening on the fireground and how he has been pumping. Between now and the time he backs into the station, the operator wants, among other things, to check the transfer valve, relief valve or pressure governor, and water trickle through the pump packing gland.
If his company is going to take some time picking up hose, he can use this time to operate the transfer valve a few times to keep it in good operating condition. At the same time, he also can operate the relief valve or pressure governor. If these checks cannot be made on the fireground, then they should be made outside the station. The transfer valve should be left in the position specified.
A wet pump is necessary for these checks, so if the pumper is not connected to a hydrant, the operator should open the tank to pump valve and make sure the pump is full.
Packing gland trickle: Sometime during a pumping job, an operator should look at the pump packing gland to see how much water is passing through it. It should be a slight trickle at 50 to 60 psi on the pump—slightly more (usually more of a spray) at higher pressures. The “trickle” should be large enough to protect the pump shaft and little enough for the pump to pass the standard vacuum test. You should also check the packing gland leakage after finishing a pumping job.
Without doing a full vacuum test, the operator can pull a vacuum on the main pump by using the priming pump. Disengage the priming pump, watch the vacuum gage needle to see that it doesn’t indicate an unusual loss of vacuum and listen for leaks.
If the pump is carried dry, open pump and other drains. If the pump is carried wet, fill with water from the booster tank and then check for a full pump by engaging the pump and developing about 100 psi. If you can’t get that pressure, operate the priming pump with the tank valve still open until all air has been exhausted from the pump.
If the pumper has a rotary priming pump, operate this pump—with manual control where possible—until oil starts to run out the priming pump discharge so that the vanes are now coated with oil.
Priming oil tank: Back at the station, check the oil level in the priming tank and make certain that oil is not continuing to flow from the tank. In some systems, the copper tubing from the tank to the priming pump has a loop with a pinhole at the top. This hole must be kept clean so that it will end the syphoning action when priming ceases.
The operator also must check the booster tank level and fill with water if necessary and at least once a week he should check the oil level in the pump gear case. Replenish with the grade of oil recommended by the pump manufacturer. Your pump manual will also tell how and when the pump and its accessories should be greased.
After finishing a pumping job, it is advisable to flush all drains with clean water. If you have been pumping dirty water or salt water, then you should back-flush the pump for about 20 minutes by attaching a line from a clean water source or hydrant to a hose gate and letting water flow first out suction inlets and finally all hose gates. This will also clear a lot of sand, rust scale and other debris from the pump. Check the strainers before recapping the suction inlets.