Dry Running Pumps: Why Is It Harmful?

Dry running a pump can cause all kinds of serious problems, yet many operators are unaware of the dangers. When a pump runs dry, it generates heat and force it was never designed to handle, leading to wear and tear that can quickly add up to inflated repair costs. Avoiding dry running is highly important, but it makes sense to learn how negative it can be in order to fully understand the severity of the phenomenon. 

What Is Dry Running?

When a pump runs dry, it runs without any liquid going through it. This is always a bad idea, as it puts an inordinate amount of strain on the pump’s moving parts.

Instead of circulating fluid, a dry running pump pushes nothing but air around, leading to friction, heat, and destruction of delicate internals. A hydraulic pump is normally designed to run while filled with fluid. As it runs, the fluid inside it helps to preserve its internal pieces, cooling them and even assisting in centreing moving elements such as the rotor.

Pumps that operate at particularly high pressure can suffer considerable cavitation simply from fluid-derived vapor; completely dry running a finely tuned pump is significantly worse for its longevity. Even self-priming pumps should only be run once the proper amount of fluid is inside, as they can withstand only partial dry conditions while priming themselves.

Running your hydraulic pump dry is likely to result in disaster, wearing it out prematurely via the aforementioned heat, violent vibrations, or complete lock-up/seizure of important parts, costing you money to fix or replace.

Damage Caused by Dry Running

Running a hydraulic pump dry can lead to a large variety of issues with the pump’s parts and the rest of your hydraulic system as well. Here are a few common problems that dry running can cause:

Housing Damage

High temperatures caused by dry running can ruin your pump, pitting its housing and causing leaks.¹ If heat and pressure are excessive enough, the housing boss may deform, potentially stopping your impeller from rotating freely and rendering your pump functionally useless. In many cases, a severely damaged, leaking pump is likely to need replacing, which can run your costs up much further than anticipated.

Impeller Damage

As is the case for the housing of your pump, the impeller is susceptible to damage done by excessive heat during use. Dry running your pump causes friction, and this friction is strong enough to heat up the impeller, causing it to melt.² Even minor melting is severely detrimental to your pump’s performance, potentially causing it to seize up and stop working at all. Taking it apart for repair is usually an involved and costly exercise best avoided through preventive operating practices.

System Contamination

Internal wear caused by dry running your pump can lead to additional wear throughout the entirety of your system. This is generally caused by either excessive heat or metal particles scraped from disintegrating moving pieces within your pump travelling through the rest of your system. Metal particles, in particular, can cut and clog valve components, pipes, and tubes, leading to system failure over time.

How to Avoid Dry Run of Pump

Shorten Emptying Operations

You may need to run your pump dry for short periods of time to empty the system completely, but it is best to keep such instances as brief as possible. Once your tank or system has been emptied by the pump, it should be turned off. Do not allow it to keep running for more than a minute without any fluid.

Oversee Pumping Procedures Start to Finish

Keeping someone in charge of monitoring your pump as it runs can help avoid unintended dry running problems. Often, a pump may be left running until a job is completed. If the pump performs its function faster than intended and all fluid is purged from the system, it will run dry and damage itself until an operator returns to turn it off. Having someone manage the pump at all times is crucial to keeping it functional.

Use a Pump Protection/Control Device

Some companies have found an automatic means of controlling their pumps’ functions from afar. By leveraging special protective devices and control systems, it is possible to automatically stop a pump that is in danger of running dry, preserving its internal parts and averting expensive disasters.³ However, such devices incur an additional cost.

At White House Products, Ltd., we offer all manner of pump parts to patch up a system damaged by dry running. We can also provide complete replacements as needed. Call our technical support team at +44 (0)1475 742500 to learn how we can help get your pump working again.

Sources:

1. https://www.marchpump.com/blog/what-is-dry-running/
2. https://www.worldpumps.com/content/features/how-to-overcome-the-challenge-of-dry-running
3. https://www.worldpumps.com/content/features/how-to-overcome-the-challenge-of-dry-running