Your pump stopped working. Great. Now what do you do?
The good news is that pumps, despite their complexities, are pretty predictable machines. There are just a few types of common pump failures that account for a majority of all issues. More often than not, addressing these issues to get a failed pump back up and running is straightforward, if you don’t mind getting your hands dirty.
In today’s blog we’ll be covering 5 of the most common pump failures, how to fix them, and how to spot the warning signs before failure.
Pump Fluid Issues
The hydraulic fluid in any industrial pump is going to be doing a lot of heavy lifting. For that reason, the fluid needs to be kept in top shape so the pump can continue working as intended. Although most hydraulic pump systems are well isolated from external factors, there are a few cases in which the fluid can become a hazard—which can spell disaster for your pump, if not fixed quickly.
Cavitation
Most common pump failures can be traced back to cavitation. It’s important to remember here that hydraulic fluid in a centrifugal pump is under immense pressure. Cavitation occurs when the pressure in a region of the system drops below the fluid’s vapor pressure—often due to a leak—which causes small bubbles of vaporized hydraulic fluid to form. Those bubbles then travel to high pressure areas where they pop, creating massive pressure disturbances that can cause surrounding components to become dislodged or collide with one another. This is typically a result of poor pump maintenance.
Early signs of cavitation come in the form of unusual operating quirks, like a higher than normal operating temperature or louder noise than normal. While cavitation itself isn’t going to take your pump down on its own, it’s the first step in a domino effect where those symptoms can cause internal components to fail due to acute impacts or excess wear over time.
Fixing cavitation involves identifying where pressure is low within the fluid system. The impeller is a good place to start. Check for old gaskets and seals that may need to be replaced, and take a look at the filter’s condition. Regularly cleaning the filter can prevent any unwanted debris from getting lodged in a place where it can create a pressure leak. Although addressing cavitation is fairly straightforward, it’s often followed by much more demanding repairs and replacements of parts that were damaged as a result.
Viscosity & Flow
When evaluating pump fluid after a failure, it’s also important to note the fluid’s viscosity and how it might have changed during operating conditions. The fluid may have what appears to be the right viscosity at room temp, but if it’s running at extremely elevated or lowered temperatures then it could become too viscous or too lean for the pump, which can also result in part failures.
Seal & Gasket Issues
When fluid escapes the system, that’s a whole other issue. Leaks often occur due to seal and gasket failures. When these components fail, it’s not just about the fluid that can escape, but also the contaminants that can enter the system ranging from air bubbles to other types of fluid and even debris.
Depending on where the leak occurs, it can either be very simple or extremely challenging to identify this kind of failure. Leaks can happen at the primary face between two seals, or at a secondary seal hidden within the system. Not all seals are easy to access either, so if one seal looks to be in good shape, the failure could lie somewhere deeper in the pump. You should be able to visibly identify the problem seal once you find it, as it should show some signs of wear like distortion or misalignment.
The fix is as simple as can be: replace the seal. It’s also worth checking your hydraulic fluid filter to make sure it’s not contaminated. With the right tools to disassemble and reassemble the pump, this can be completed in just one afternoon. Some seals can be tricky to find replacements for, so we recommend keeping a few on hand if you can source them or seeking assistance from a custom seal manufacturer if they’re not available on the market.
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Bearing & Coupling Issues
Bearings and couplings are prone to their own set of mechanical issues, most commonly abrasion due to poor lubrication, and misalignment. They can also warp, bend, or break depending on the severity and duration of those conditions.
Poor Lubrication
Many bearing failures can be traced back to insufficient lubrication. Poor lubrication can be identified by excess heat, increased vibrations, and unusual noises during operation. A poorly lubricated bearing can also experience mechanical wear, so keep an eye out for concentrated metal dust and shavings when inspecting the bearing and its surrounding area. Just like with the seals and gaskets, the fix here is to completely replace the part and follow up with a regular maintenance schedule that includes adequate lubrication.
Misalignment
Couplings are also subject to lubrication issues, but are more commonly afflicted by misalignment. Misalignment can occur for a variety of reasons, with overloading as a leading cause. The most prevalent symptom of misalignment is excess vibration or wobbling.
Although this may seem like another simple replacement, operating a pump with a coupling that’s out of alignment for even a short time can have dire consequences. Misalignment can have a ripple effect on the rest of the pump and the motor, so be sure to fully inspect the system and identify any other issues or part failures before attempting to operate it again.
Impeller Issues
Many other common pump failures can be traced back to issues with the impeller. The impeller is largely responsible for a pump’s primary function: propelling liquid at high pressures. As such, it’s susceptible to wear over time even if the entire system runs perfectly. The type of wear that the impeller is exposed will often depend on the type of fluid that is being pumped by the system. Some impeller issues may also arise in connection to issues rooted elsewhere in the system.
Deposits
Certain fluids can leave behind deposits that build up on the impeller over time. These deposits can disrupt the impeller’s balance and fluid flow, resulting in poor performance. If your impeller is caked with deposits, cleaning the impeller with a chemical agent and carefully reinstalling it should have your pump running as good as new. It’s best to avoid physical agitation as much as possible to prevent damage to the impeller.
Erosion
With more abrasive fluids, it’s common for the impeller’s features to erode with use. With less sharp edges and defined features, the pump’s performance will decrease over time. There’s no way to reclaim or replace material that’s been eroded away. Once the impeller has eroded to the point where performance is approaching suboptimal, your best bet is to replace the worn impeller with a new one.
Distortion, Cracks, & Fractures
Things like excessive loads, imbalance, and even manufacturing defects can cause physical damage to the impeller. How this impacts performance can range drastically depending on the extent of damage, from mild dips in performance to catastrophic failure.
These phenomena can also occur as a result of cavitation, which we mentioned earlier. When cavitation occurs, damage is very likely to happen around the impeller where stark changes in pressure take place.
All damaged impellers will need to be replaced. It’s just a matter of when. For instance, an impeller that’s slightly distorted may start with only mild performance issues, but those will increase over time as the impeller becomes more out of balance. A sudden fracture on the other hand will halt operations immediately.
Improper Operating Conditions
Running a pump outside of its intended operating conditions is never a good idea. Overloading, dry running, and fluid incompatibility are all issues that can very quickly lead to irreparable damage and pump failure. A pump may be able to work outside of its specified operating conditions for a time, but you can’t rely on them to run at peak performance, or for very long.
When selecting your next pump—because you will need another one sooner or later—be sure to thoroughly evaluate whether it meets your needs. Check for features like load capacity, operating temperature, and fluid compatibility. It’s also worth investigating maintenance requirements for the pump, including maintenance schedules and ease of access to the pump’s inner workings.
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