As a fire pump dealer, we have a unique perspective on the life of a fire pump. We operate and test new equipment and are often called in to replace and repair old pumps. They are often asked when is the best time to replace a specific fire pump, or how long to wait for a new fire pump. Therefore, these questions gave life to the idea of writing about the life expectancy of a fire pump. In this article, we will focus on the fire pump itself, not the motors, controllers, motors, or other items that are often found in an engine room.
Fire pump performance
So when should a fire pump be replaced? If a fire pump owner is testing and maintaining equipment per NFPA 25, the answer to this question often depends on the hydraulic performance of the pump in question. The pump has been tested and may not have passed the flow test. For example, if the pump is rated at 1000 GPM at 100 psi, and when evaluating the performance test results, the pump now provides a 1000 GPM rise at 93 psi, the pump may need to be replaced against fires based solely on performance deficiency.
Over time, fire pump performance can deteriorate due to gradual wear of the inner casing or impeller. Another factor may be the age or appearance of the fire pump or both. Is there still a reliable source for spare parts available? Is the condition of the pump a high risk of damaging the pump once it is opened for maintenance? If the answer to the question was “No” and the final answer was “Yes, it might be time to replace your fire pump.”
Consult a spraying contractor
It should be mentioned here that if you are considering replacing an old fire pump, you should consult with a sprinkler contractor to evaluate the entire sprinkler system to ensure that a new pump of the same size still meets the current code requirements. You don’t want to invest in new equipment, only to find that the spray request in the building has changed since the “old pump” was originally installed.
But fire pumps are often idle and not working at all (unless of course there is a fire). This leaves many people with a false sense of confidence that the pump will last forever. After all, most of the listed pumps are made of cast iron, steel, and bronze. That should last a long time, right? The answer is yes, but there are many reasons. What affects the life of a fire pump?
Several factors determine the estimated service life of a fire pump. From them:
1. The type of fire pump
2. The quality of the water used
3. The environment of the machine room in which it is installed
4. How is the pump installed?
5. How is the pump tested and maintained?
The type of bomb will have a big impact. Simply put, some types of fire pumps are designed to last longer than others. By “type” we mean whether the pump has a horizontal split design or a converging end-suction (or vertical recessed) design.
Horizontal fire pump
The horizontal split pump, for example, is designed to be extremely durable and long-lasting. The impeller is hydraulically and dynamically balanced controlled, and there are two sets of bearings to help keep thrust and vibration under control. The impellers are designed to allow water to enter the fan from both sides, which, if connected to the tubes by NFPA 20 guidelines, will allow minimal vibration. The motor or motor used with a horizontal split pump design will need.
A coupling or shaft to connect to the pump, simplifying the design. Most manufacturers’ horizontal split pumps, if properly installed and maintained, should last 25-40 years.
This, of course, does not mean that you will get a 25-year warranty! Reason? Many other factors are under the control of the manufacturer.
Built-in vertical fire pump
However, vertical in-line fire pumps have a relatively shorter half-life. These pumps use a motor shaft instead of a pump shaft and have a motor connected directly to the pump housing. The impeller is designed to draw water from one side of the casing. Designed in this way to save money and used primarily for water flows between 50 gallons per minute and 750 gallons per minute.
Under ideal conditions, the average life expectancy of this type of fire pump design is usually between 7 and 15 years.
Water quality
The quality of the water will also affect. Without getting into the discussion of chemistry, the cleaner the water, the better the life expectancy of a fire pump. This is especially the case when a fire pump draws water from a chlorinated supply, such as a swimming pool. Even if the impeller material were made from a strong bronze alloy, the chlorine in the water would eventually make its way into the air in the room, accelerating the corrosion of any steel components. But even “clean” water, if left for long periods, can produce microorganisms that can gradually corrode inside the pump.
Beware of humid environments
The pump room environment will have a major impact on the service life of the fire pump. As a general rule of thumb, the more humid the air, the more the ingredients will deteriorate. The main difference here is that the outer surfaces are now affected, as opposed to the internal components. Electronic control equipment may have heaters or thermostats to control humidity, but the pump is fully exposed. Over time, exposure to a humid environment will cause rust on the steel and cast iron components of the fire pump.
The importance of a correct installation of fire pumps
The way the pump is installed can also be a factor. NFPA 20 guides the proper installation of fire pumps, especially horizontal split case fire pumps. With this type of pump, it is best to have a smooth, straight pull on the pump, so that the water can enter the impeller with as much balanced laminar flow as possible. This not only helps the pump run better but also eliminates unnecessary stress on the pump shaft and bearings. If a suction elbow with a centerline plane parallel to the pump axis (or, in simpler terms, a horizontal elbow feeding a horizontal pump) provides a fire pump, it reduces the life expectancy of the rotating elements of the bomb. The greater the volume of water that is expected to be pumped, the more problems there will be with inadequate suction piping in the expected life of a fire pump.
Fire pump maintenance
What about the ongoing maintenance of a fire pump? Is the fire pump in a dark room and no one is operating it? NFPA 25 contains very specific standards not only regarding the frequency and type of pump operation but a list of maintenance that must be performed to keep the pump (and the motor and controls) in their optimal condition. The stricter the maintenance schedule is practised with the use of a fire pump, the longer the life of the fire pump equipment is expected.
In the case of a horizontal fire pump, some of the simplest maintenance procedures end up being the most important during the life of the pump. The Fill Adjustment will probably be at the top of the list. It’s easy to do – tighten the gland screws to hold about one point per second on each side of the packing box (check with each manufacturer for specific instructions). This will keep the packing moisture and elasticity and reduce wear on the pump shaft. Also, checking bearing lubrication can extend bearing life. Changing bearings can be labour intensive, but preserving bearings from too little (or too much) grease can significantly delay the need for replacement. Again, check the manufacturer’s instructions for the correct procedure and make sure a qualified and experienced technician does the job.