PUMP MAINTENANCE An Easy Way to Save Money
“it seems we often give proper attention to the chassis, body and drive train but neglect the pump. This is a serious oversight because if the pump does not operate properly, we probably will not be able to extinguish the fire.”
All of us understand that water remains the most cost-effective extinguishing agent available to the fire fighter. However, the cost of apparatus needed to put the water on the fire has continued to rise, in most cases lengthening the time a pumper must remain in service before it can be replaced.
Complete preventive maintenance is important in keeping apparatus at peak efficiency throughout its career. It seems we often give proper attention to the chassis, body and drive train but neglect the pump. This is a serious oversight because if the pump does not operate properly, we probably will not be able to extinguish the fire.
So who cares? If yours is a typical department, your pumper is in front-line service until it fails (usually at the worst possible moment). And nobody is happy when a pumper or engine goes down. The captain has to make excuses, the deputy chief has to move another engine into cover and the chief usually has to explain to the commissioners or city manager why a new parking lot was created!
We can prevent this by the establishment, in writing, of a complete preventive maintenance program including pumps. This is the first step in discovering minor problems and defects before they turn into major ones. Sound like a monumental task> In reality it is as simple as consulting the operation and maintenance manual that came with your apparatus. In the case of pumps, all six major pump manufacturers in the United States list in their operating manuals the periodic maintenance needed to ensure continued operation of their pumps. These instructions are usually divided into segments covering the maintenance required after each use as well as weekly, monthly and yearly. Hale Pump Company and Waterous also provide a reminder plate for mounting on the pump panel.
Every pump manufacturer has weekly, monthly and annual recommended checks or tests for their pumps. At a very minimum you should follow their recommendations. After all, they manufacture the equipment and they should know best what should be done to keep it in peak condition.
60 percent of failures …
Probably 60 percent of pumping system failures are caused by ancillary equipment and not the major pump. Pump manufacturers’ maintenance schedules list the required maintenance for the relief valve, transfer valve (if applicable), primer and packing glands. Because each unit is different, it is best to consult the specific pump manual before undertaking the maintenance. A general rule of thumb, proven by many years of experience, is that the more you use the accessory the better it will perform.
Several different configurations of pump packing are used by pump manufacturers, but they all serve the same purpose – to seal out air along the pump shaft. Due to the lubrication properties of the packings, they must have cooling water to avoid losing their lubrication, thus rendering the packing useless. This lubrication is accomplished by allowing water to flow through the lantern rings in the packing and allowing a small amount to follow the shaft of the pump onto the ground. The rate of flow must be regulated to prevent too much or too little leakage. Usually, 10 drops a minute at 70-psi discharge pressure is ideal. Once again, consult your manual for proper adjustment of packing. The manual will also make a recommendation as to how often to replace the packing.
You should be aware that most of the portable and engine-driven pumps produced today are using mechanical seals to seal out the air in lieu of packing. Selfadjusting (they are spring loaded) mechanical seals do not require a separate cooling line nor water to be dropped outside the pump case. If you have portables that use mechanical seals, you should not have water dripping around the shaftunless the seal is damaged. A damaged seal can prevent priming and should be replaced as soon as possible.
Midship pumps could use mechanical seals but unless the fire service pushes for this change it probably will not happen in the near future.
The drive unit of the pump is not only responsible for providing power to the pump, it also transmits power to the rear axle for road operation of the apparatus. Contrary to what some believe, the oil in the pump gear case is not transmitted nor is it a part of the engine oil system. It is entirely separate and it does require some specialized maintenance to keep it in peak operating condition. It always must be kept full with clean oil of the proper E.P. rating. By checking periodically (each month or 20 operating hours) you can watch for proper level as well as for foreign particles or water entering the drive unit. Water is a drive unit’s worst enemy and is usually caused by excessive leakage from the packing.
It’s interesting to note that many think that water enters a gear box by following the pump shaft and entering the top of the gear box through the water and oil seal near the pump shaft gear. Our experience at Hale would indicate that this is probably not the case. Most likely the water from the packing or from other pump leaks (flanges, fittings, etc.) falls on the input drive shaft. When the shaft is hot, the water is drawn into the pump (almost like a siphon) along the shaft. A “rain shield” or cover over the input shaft as well as a flinger ring (water-repelling ring) on this shaft will in most cases eliminate the problem. A 2 ½ -inch hose gasket on the input shaft will act as a flinger ring.
While under the apparatus checking the drive unit oil level, it is a good idea to check the driveline bolts. They should be snugged up and the flanges inspected for any signs of wear. Also, check the journals (crosses) and lubricate as required. Remember, if you replace the driveline bolts, always use at least grade 5 case-hardened bolts. They have three lines on the top.
The priming systems on all pumpers should be checked and operated at least on a monthly basis. If you carry and use hard suction hose you should be doing a priming check with the hose attached every six months. A proper priming check is done as follows:
- Close the discharge gates and remove caps. Close all drains.
- Remove the suction tube cap and connect the suction hose.
- Install the cap on the suction hose.
- Activate the primer and run it until you get 22 inches on your vacuum gage. Caution: Operate primer no more than 30 seconds. Release the primer and stop the engine.
- Check for leaks. If the pump does not lose more than 10 inches in 10 minutes, your pump and accessories are tight enough to provide good suction capabilities under most conditions.
- If the pump cannot hold a vacuum, disconnect the suction hose and repeat the above test. If the pump holds vacuum, then the suction hose or suction hose couplings are causing a vacuum leak. Replace hose or gaskets as necessary.
- Repeat the test with the suction tube capped.
- If you still have a vacuum leak, listen for air leaks. If none is heard you might try pressurizing the pump from another pumper (about 150 to 200 psi). Watch for leaks at flanges or pipe junc tions
- If the leak cannot be found, you might try tightening the packing a bit. I personally do not like to tighten packing except as a last resort.
- Refill the priming oil tank with the proper grade oil before placing the engine back in service. Check to ensure that the small vacuum breaker hole in priming line near or on the primer tank top is open.
On an annual basis, preferably right before the cold season, you should disconnect the lines from your pump to the multidrain and blow them clear with an air gun. This removes any clogs and debris and ensures you of proper drainage of all cavities when you activate the multidrain. Also, this is a good time to change the gearbox oil and run a yearly performance test to determine the overall condition of the pump.
The general maintenance tips shown here are nothing special and should be familiar to you if you have an effective maintenance program in your department. If all this is new to you then it is time for you to sit down and draw up a workable program.
Consult the manufacturer of your pump. Provide him with the pump serial number and he will be able to send you all the information you need to enable you to get your pump on the right track to a long, healthy life.
Bob Barraclough is a lifelong fire fighter, and was fire marshal on the nuclear-powered aircraft carrier USS Enterprise.