Choosing the right sewage pump for the job
Sewage pumps have been around for a long time, but they seem to get more popular every year. Gravity is an age-old problem, and as long as people are building or expanding places to live, the need for sewage pumps is not likely to go away. There is no lack of options available, but how do you choose the right pump for your application?
The first thing to consider is the application itself and what type of wastewater is creating the demand for the pump. Is it a residential property or commercial? If residential, is it for an additional bathroom or the entire house? If commercial, will it be seeing public usage? All of these things go into determining what type of sewage pump system you should consider.
Sewage pump vs. grinder pump
Even though they are used in similar applications, there is a big difference between a solids-handling pump and a grinder pump. Quite often the terms are used interchangeably, which is inaccurate.
A solids-handling pump is specially designed to pass solids through the pump without much alteration of the material its passing. According to Sump and Sewage Pump Manufacturers Association guidelines, a solids-handling pump should be able to pass at least a 2-inch sphere in order to handle common residential waste.
Meanwhile, a grinder pump will use an integral cutting system to grind the solids before pumping them. Both options have their advantages, but you should understand the difference before choosing a pump.
A solids-handling pump will usually be the less expensive option. Without a cutting system, there are fewer components involved and it will be more energy efficient for the amount of wastewater it moves.
However, large solids can make their way into a solids-handling impeller and clog it, where a grinder pump is able to grind the material into a slurry to be easily pumped away. The growing popularity of disposable wipes has been known to wreak havoc on municipal pumping systems and has increased the demand for grinder pumps.
Most residential sewage pumps end up being the solids-handling type for the reasons pointed out above — mostly the cost and availability. They do a fine job with everyday usage and waste, but be careful in apartment buildings or anywhere end-users are detached from the effects and maintenance of servicing these pumps.
Duplex vs. simplex
A simplex system is a term used to describe a system with only a single sewage pump. A duplex system would be a system that utilizes dual pumps. Obviously, a single pump would be less expensive than two — so when is a duplex system needed?
The short answer is: You would want a duplex system whenever you cannot accommodate for downtime on the system. It’s a fact of life that all mechanical components will eventually fail. Even with a high-quality product or strong warranty, you may be faced with a time when the pump does not operate when needed. A high-level alarm is also strongly recommended to give some warning of a failure and give notice before damages occur. But unless you have a second pump to take over, any fixture draining into the pump system will also be inoperable until the failed pump is serviced.
For many commercial businesses a duplex system is mandatory. It’s not as if a restaurant can tell its patrons not to use the bathroom. A temporary closure would be more expensive to a business than both the pumps and the service.
Another advantage to using a duplex system is it will lengthen the lifetime of your pumps. With one pump handling the load, it is asked to perform around the clock whenever it is needed. Two pumps sharing the load will even out the wear, and theoretically, you should be getting twice as long of service out of each pump. It’s important to note that for a properly sized duplex system, each pump should be capable of pumping the required load. That way you have true redundancy and backup, should the need arise.
Attention should be paid upfront to finding the right size pump to match the application. There is a common misconception in pumps that larger horsepower is always better. But in wastewater, too large of a pump could have a negative effect on the life expectancy and usage of a sewage pump.
An oversized pump is going to run hotter, be less efficient and cost more than a pump that is sized correctly. There are various tools available to help someone choose the right horsepower pump for their application. Pump manufacturers will publish all of their performance curves and usually have them available online. There are also several entities that will offer a sizing guideline to assist someone who is trying to size a sewage pump on their own.
If you have questions, it’s not a bad idea to go directly to the source. Speaking with a company’s technical support team over the phone or by email can also get you the answers you require. In the end, it would be in everybody’s best interests to have a pump system operating as well as it can, for as long as it can. RJ 2.0