May 21 2024

10 Reasons to Upgrade Your Lift Station


Here are 10 reasons to upgrade an aging lift station to a dry pit submersible pump.

1. Energy Savings: Most dry pit submersible pumps include a high efficiency motor, typically IE3 rated. IE3 is a motor efficiency level, as certified by the International Electrotechnical Commission standard (IEC 60034), which guarantees that the motor will perform at or above a certain efficiency level. Many aging pumps have motors that are either not IE rated at all or have older National Electrical Manufacturers Association (NEMA) motors. IE3 is equivalent to NEMA Premium Efficient, so any motors that are NEMA high efficiency or standard efficiency are less efficient. Higher efficiency motors lead to less energy consumption for the same performance, and thus lower energy costs.

2. Longer Motor Life: As an extension to the energy savings benefit, dry run submersible motors also tend to have a longer life span than their less efficient counterparts. Motors can fail for many reasons, but a major culprit of motor failure is heat. The United States Department of Energy (DOE) states that “For every 10 C rise in operating temperature, the insulation life is reduced by half.” (DOE, Nov 2012). The Law of Conservation of Energy states that all energy that goes in, must come out. The efficiency equates to the amount of the input energy that is converted into pump performance. The rest of that energy is lost in other ways— mainly heat. So, a higher efficiency motor creates less heat, and thus lasts longer.

3. Flood Resistant: Flooding of dry pit lift stations can occur almost anywhere. Some floods are due to weather events like hurricanes and heavy rains, but some floods can be due to failures. If a force main breaks, a valve fails or a pump clogs, a lift station can flood even in the desert. Traditional dry pit pumps are typically equipped with a NEMA style motor that cannot be submerged and would be susceptible to failure during a flood event. These dry wells often include a small sump pump that will mitigate the flooding by pumping the water back into the wet well portion of the lift station. A dry pit submersible pump in a dry well lift station will not only not fail during a flood event, it can continue normal operation.

4. Increased Operating Volumes: Because the motor for a dry pit submersible pump can operate continuously while unsubmerged, the required minimum submergence in a wet well is lower than compared to a traditional submersible pump that requires the submergence for cooling. Every wet well has a designated operating volume, which is typically the volume between the “on” level and the “off” level. A dry run submersible motor lowers the “off” level but allows the “on” level to stay in the same location, thus increasing the operating volume of the station. Older stations may not be fully equipped to deal with a growing population, but a larger operating volume can help upgrade the station to better handle it (Image 1).

5. Installation Flexibility: A dry pit submersible pump can be installed in a variety of ways. The same pump can be installed in a wet pit on legs or a guide rail system, a dry pit—vertically on a stand with a suction elbow or horizontally on a bracket system, similar to an end suction style pump. Many manufacturers also offer a rolling cart system for horizontal installations. These allow the motor end to be serviced without disturbing the suction and discharge piping, which makes the pump easy to service when needed. This flexibility makes retrofitting pumps into existing stations easier and more cost effective (Image 2).

6. Ease of Installation: This benefit applies mostly to dry pit submersible pumps replacing traditional dry pit pumps, and it really stems from the fact that dry pit submersible pumps have close-coupled motors. First, there is no need for coupling alignment. Note that not all traditional dry pit pumps use couplings, but those that do need to be aligned on-site during install. Because dry pit submersible pump ends are built directly on the motor shaft, no alignment is needed. Second, the seal chambers are completely sealed. A seal chamber on a traditional dry pit pump needs to be pressurized, often with clear water. This adds complexity and cost to the install. Sometimes, it even adds another pump to the project.

7. Solids Handling Capability: Along with technological advances in the motor portion, the design of the pump end has also made strides throughout recent years. This includes different designs of nonclog impellers, chopper pumps and cutter pumps. The percentage of solids in the modern waste stream has also increased, and older solids handling pumps, whether submersible or dry pit, are not equipped to handle it. New impeller geometries, designed with sophisticated computational fluid dynamic (CFD) software, are superior in solids handling applications. Chopper and cutter pumps may also be used for applications with heavy solids loads.

8. Robust Construction: Wastewater pumps can be found in a wide variety of applications, and each require different performance. As a result, they need to be designed to handle even the most challenging situations. Manufacturers include Class H insulation in their motor designs to protect the stator windings from being damaged and permanently greased high-capacity bearings for more time between maintenance.

9. Diverse Materials for Many Applications: Along with the advancements in motor and pump design, strides have been made in material offerings. Lift station applications may need to deal with components that are not traditional sewage, like chemicals and abrasives, and the appropriate pump materials need to be chosen to handle that. Pumps are no longer just cast iron; dry pit submersible pumps can come in all varieties of cast iron, steel, bronze and other types of materials.

10. Additional Sensors: As technology becomes more sophisticated, it becomes more important to protect the equipment. More recently, dry pit submersibles, especially larger pumps, come equipped with many sensors to monitor the operation and health of the pump. These include temperature sensing devices for the motor, bearings and seals, vibration sensors (both at the seal chamber and top of the pump), and even electrical sensors to monitor the electrical health of the motor. Essentially, whatever a user could want to monitor, there is a sensor out there for it.Whether only one or many of these reasons apply, upgrading to a dry pit submersible could be worth the expense to do so.

Check out Barnes Dry Pit Submersible Pump today.


Article first published in Pumps & Systems magazine in January 2022.