Running a pump while it is dry is usually one of the worst things you can do to it. Dry running occurs when a pump runs without sufficient liquid flowing through it. When this happens, a surge in pressure, flow or overheating occurs. Elements within the pump casing seize together. This triggers shock waves inside the pump which cause significant damage to the pump, resulting in total failure.
This then creates a domino effect, leading to the possibility of millions of dollars being lost annually through replacement costs for damaged equipment, as well as loss in revenue due to the pump being down. So, what can be done to avoid this?
You don’t need to get into this situation. There are pumps on the market that are self-priming and can run dry indefinitely without doing damage to the pump.
Need to Run Dry? No Problem...
Oftentimes when we think about pumps that have the ability to run dry, we think of positive displacement pumps. Positive displacement pumps self-prime. This means that the pump is able to pull liquid from a level below the pump into the pump port and run without liquid during the time it takes to get liquid back into it.
A small amount of liquid in the pump keeps the parts wetted, helping to prevent instantaneous damage; however, most positive displacement pumps can only run dry for a few minutes before friction heats up the internals and the pump is damaged. Some of the pump types you don’t want to run dry include piston/plunger, centrifugal, progressive cavity, rotary lobe and gear pumps. Each has its own threshold for running dry, but none will fail instantaneously if they accidentally go dry.
If you want total peace of mind and never have to worry about damaging a pump when running dry, there is one on the market just for you. This is why research is key when deciding on which pump to purchase for your specific application.
Running Dry Without Failure
So, what is this magical pump? PVP’s Double Disc Pump can run dry indefinitely without damage. It’s short stroke length allows the pump to incorporate a non-leak sealing trunnion that requires no maintenance, seal water, packing or lubrication.
Penn Valley Pump’s 6” Model 6DDSX76 Double Disc Pump is one of the best pumps on the market to remove sludge and slurry. It is the most common pump size sold and is a solid workhorse for just about any sludge or slurry application you run across.
It is routinely used for higher flow primary sludge applications as well as scum, waste activated sludge (WAS) transfer, digested sludge transfer, thickened sludge transfer and dewatering feed applications, like belt press, centrifuge, rotary press, screw press, RDT and GBT feed. This cast iron pump can run dry without damage and has a low fouling potential. It has a flow range of up to 425 GPM and can handle up to 2” solids as well as line size semi-solids. This pump operates at speeds up to 400 RPM.
Worrying about failure when running a pump dry is now a thing of the past. By doing a little research and purchasing a pump that is self-priming and can run dry indefinitely without doing damage, you can run a worry-free operation.