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Pump Impeller Types and Applications: How to Protect Your Pump Impellers from Damage

We often remind clients that the pumps in their properties are like the hearts of their buildings, propelling vital fluids to where they need to go to keep everything functioning smoothly. Most pumps that we service at Antler Pumps contain an impeller, an essential part in the job pumps perform. Here’s what property owners and managers should know about pump impeller types and applications, along with common impeller problems and how to prevent them from causing malfunctions. When you catch small pump problems early, you can avoid them morphing into larger, much more expensive ones that cause unpleasant disruptions for you, your staff, and building occupants.

Pump Impeller Types and Applications

Function dictates design

Centrifugal pumps have been used for centuries to move fluids. In buildings you manage, centrifugal pumps are most likely employed to transport water for drinking, bathing, cooling, and heat. The key part to accomplish this in a centrifugal pump is the impeller.

The impeller looks like a fan or windmill, with vanes (blades) that rotate to move fluid. When the impeller rotates quickly, centrifugal force is generated just like during the spin cycle of a clothes washer. Water is pushed outward and away from the impeller eye (center) toward the outlet end (exit) of the pump.

Pump impellers can be designed and mounted in different ways depending on their intended use. Categorization of pump impellers varies by nomenclature from source to source, but here are some common pump impeller terms that you should know:

• – Open – no cover over the impeller vanes, usually used when moving solids, including waste, not liquids
• – Closed – the impeller is shrouded on both sides, most frequently used to transport clean fluids
• – Semi-open – covered on one side, usually with very wide channels for moving sewage and other waste
• – Vortex – designed to produce a vortex so minimum amounts of particulate matter in fluid touch the pump parts to reduce clogging, often used in submersible pumps
• – Cutter – macerates solids or semi-solids as it moves fluids, used in sewage grinder pumps
• – Mixed flow (aka semi-axial) – creates diagonal flow of fluid being transported, used to prevent settling at the bottom of the tank it sits in
• – Flexible – the vanes are made of curved rubber, used for many types of material, particularly commercial food processing

Common Pump Impeller Problems

Potential pump failure

Pumps in general can experience problems from a host of sources, including inadequate or damaged electrical supply, motor issues, casing leaks, valve malfunction, and loose mountings. In many instances, in spite of these concerns, the pump may continue to run, albeit less efficiently than at top performance.

However, there are also pump problems that are specific to the impeller, which can cause the pump to shut down entirely. The most common of these include:

• – Clogging caused by particulates (sediment, mineral deposits, etc.) or waste caught in the impeller blades
• – Fouling, when microscopic material builds up on the impeller or nearby parts
• – Corrosion, usually due to an acidic environment over a long period of time
• – Imbalance due to wear or mounting error, when unequal radial forces cause suboptimal fluid transport and potentially vibration
• – Loosening, typically the result of vibration, worn parts, and poor maintenance
• – Cavitation, the worst kind of pump damage, often preceded by turbulent (versus laminar) flow, where a lack of suction pressure causes bubbles to form that then collapse and implode on the impeller’s surface, resulting in pitting and rapid erosion

How to Prevent Pump Impeller Malfunction

Maintenance and recognizing warning signs

Understanding and watching for the signs of impending pump impeller malfunction is important if you want to prevent costly and inconvenient pump damage. If you notice any of these problems below with a pump in your property, you should notify your pump experts at once, especially if DIY fixes don’t solve the issue. You may observe or hear several of these symptoms simultaneously:

• – Excessive vibration that isn’t resolved by checking or tightening the mounting system
• – Loud or unusual noises coming from the interior of the pump
• – Ground water or waste backing up past submersible pumps, like sewage ejector pumps and sump pumps
• – Reduced fluid emanating from the pump
• – Signs of sediment, rust, or mineral scale building up on other pump parts, which means they’re probably present on the impeller too
• – The presence of bacteria or microbes in water
• – Very low pH water in the boiler system (should be neutral or slightly alkaline)
• – Oil or other lubricants leaking into the fluid being transported
• – Inconsistent pump pressure, either by direct observation or detected by pump controls
• – Pump shutting off when it shouldn’t or running only intermittently

You can prevent many of these issues by performing regular pump maintenance on your own, but regular professional servicing is a must to keep your pumps healthy – to follow the metaphor in the introduction, like going to the doctor to make sure your heart is pumping properly. The older or more troublesome a pump is, the more often you should have it checked over by experts to avoid total malfunction.

Should the team at Antler Pumps detect a problem with one of your pumps’ impellers, there are various solutions we can employ, including cleaning, lubricating, trimming, and remounting. There are also several types of impeller repair we can sometimes perform, including gas welding, surfacing, epoxy, and quick steel repairs, depending on the impeller materials, design, usage, and the problem at hand.

To schedule routine maintenance or deal with a pump impeller problem at your property, call Antler Pumps today at 212-534-2500. Don’t let a pump issue turn into disaster. Reach out as soon as you notice something is wrong.