Jackson Carter

Cavitation is a very serious issue that plagues many water pump owners, and can cause damage to your impeller while slowing down the job you need your pump for in the first place. How do you avoid cavitation? First, let’s talk about what cavitation is, what types of cavitation exist, and then how to prevent or fix this issue.

When not stored correctly, a water pump's internal components can sustain serious damage. Whether that’s the casing or mechanical seals being damaged due to cold weather, the suction and discharge ports not being sealed and allowing debris in, or the pump seal being damaged due to improper storage, it's vitally important to store your water pump properly and safely.

Have you ever thought about how altitude might affect a water pump? A lot of people don’t, but it is a very important thing to be aware of, as it can positively or negatively impact the performance of your water pump. Altitude can affect the performance of a water pump much more than you may realize. Whether it is increasing the fuel needed to operate a pump at an increased altitude, decreasing or even increasing the pump's efficiency, or causing other problems in the water pump, there is much more to operating a pump at a higher or lower altitude than you may have initially thought.

Let’s talk about how a higher altitude affects a pump. The higher the altitude is in a given location, the lower the pressure will be. This happens because as you go higher, the oxygen thins out and becomes less dense. Oxygen is a gas, meaning that as the altitude increases, the oxygen decreases in density. Essentially, this means that there is less air the higher you go. The opposite is true if you decrease in altitude. The farther down you go, the denser oxygen becomes, and the more air there is. As this pertains to pumping water, this thinning or increasing of the density of air affects the pressure of the pump. The higher the altitude, the thinner the air as you already know. But the air getting thinner also means that there is less pressure the higher you go, and the lower you go, the more the pressure increases. The pressure loss is the biggest part that affects a water pump, and it is called atmospheric pressure.

The lower the atmospheric pressure, the harder it will be for the pump to do its job, which is to pump water or other liquids from one location to another. The decrease in pressure, due to higher altitude, means that the pump will have to work much harder. This also means that the water pump will lose how far it can pump the water or other liquid (total dynamic head loss). Furthermore, the lack of pressure means less suction power (suction lift) and pumping power the higher you go. This is obviously not a good thing, as a pump's purpose is to move liquid, and if it can’t do that as well as it is supposed to, significant losses will be experienced, and the manufacturer's attainable specifications and attainability will not be able to be met. Simply put, if the pump manufacturer states that there is maximum total dynamic head of 200’ and maximum of 500 GPM (gallons per minute) at 4,000 feet above sea level, you can expect that those numbers will be significantly lower (see chart below).

Specific gravity suggests that water can be pumped from less than or equal to 26 feet down when operating at sea level, which is to say that when you’re at sea level with a water pump, you can only expect your pump to have a maximum suction lift of 26 feet or less. This number increases as you go lower than sea level, because there is more atmospheric pressure. The higher you go, however, the less suction lift you can expect from the pump. The general rule of thumb is that for every 1,000 feet above sea level, subtract 2 feet from the 26-foot number of suction lift. One way to improve this issue is to place the water pump as close to the liquid source as possible, so it has less distance to travel when trying to draw water from the source to the pump.

The suction lift in a pump is the pressure on the suction side of the pump, meaning the part of the pump that sucks up water and other liquids using pressure. The higher you go, the less effective it is. Here is a chart showing the effects of increased elevation on suction lift.

Altitude

Suction Lift (Feet)

Sea Level	10	15	20	25
2000 Feet	8.8	13.2	17.6	22
4000 Feet	7.8	11.7	15.6	19.5
6000 Feet	6.9	10.4	13.8	17.3
8000 Feet	6.2	9.3	12.4	15.5
10000 Feet	5.7	8.6	11.4	14.3

Another important part of a higher altitude and its effects on a water pump is the engine fuel. A gas or diesel engine will burn more fuel at a higher elevation because the oxygen is thinning/decreasing in density. Gas and diesel engines rely on certain specific oxygen contents, and the higher you go, the less there are of these oxygen contents, essentially meaning that the engine must work harder to function, thereby burning more fuel. It also means that the engine's rpm (revolutions per minute) slow down, which also decreases the GPM (gallons per minute) and total head the higher you go. This can be a major problem, as many people may not account for the extra money of more fuel because of the higher altitude nor consider the combined effects of pump capability loss due to altitude, in addition to losses from the gas or diesel engine. Gasoline and diesel engines lose approximately 3-3.5% of their power for every 1,000 feet of elevation above sea level. The following is a chart showing how the increase in elevation affects the engine, which in turn affects the GPM and head of the pump.

Altitude	Discharge Flow (% GPM Loss)	Discharge Head (% Foot Loss)
Sea Level	100%	100%
2000 Feet	97%	95%
4000 Feet	95%	91%
6000 Feet	93%	87%
8000 Feet	91%	83%
10000 Feet	88%	78%

There is no solution that involves fixing or upgrading your gas or diesel engine to prevent or improve this. However, one very easy solution to this problem would be to buy an electric engine. This would help improve two things immediately: one would be the elimination of extra fuel you would burn in a gas or diesel engine at a higher altitude. An electric engine would mean no fuel cost, and would cost much less to run, depending on the size. The second thing an electric engine would improve would be the GPM and head of the water pump when compared to a pump with an engine. Because an electric motor is not affected by altitude or atmospheric pressure (though the pump head is), it could operate at full capacity, and keep the GPM and head at 100%, which is what any pump owner wants. Another thing to bear in mind is the size and power of the water pump itself. A pump that might do well at, or a little above sea level might not be strong enough to meet your pumping needs at a higher elevation of say 6,000 feet. Always be aware of how high the altitude is going to be where you are using the water pump before buying it, as your specific elevation may require a stronger pump.

Overall, using a water pump at a higher altitude can lead to complications and a decrease in efficiency, especially with pumps that use a gas or diesel engine. There are, however, some solutions to this problem: buying an electric engine, placing the pump close to the water/liquid source, and investing in a more powerful pump. Despite this, there is no sure-fire way of beating any sort of deficiency with a water pump at a higher elevation, because there is nothing that can be done about the higher elevation/altitude. It’s good to always be aware that your water pump may not be performing as well as it could because of a lack of oxygen or low atmospheric pressure. Being ready for a possible decrease in your pump’s power is always a good idea and knowing what the problem might be could help you save money and time, both of which are extremely important to everyone.

If you will be pumping at higher elevations, we would encourage you to speak to one of our Applications Specialists. They would be more than happy to help you find the correct water pump for pumping water at higher elevations.

Absolute Water Pumps is happy to announce that we now offer the Pacer IPW Series of potable water pumps from Pacer Pumps. Often used by firefighters and the oil industry, Pacer potable pumps are reliable, corrosion resistant, lightweight and safe for drinking water applications.

Shop Centrifugal Water Pumps online now at www.absolutewaterpumps.com.