shallow sewage ejector pump chambers systems

The second component of this calculation is the minimum pressure delivered at each orifice. The pump capacity is based on the orifice diameter (typically 1/8 to 1/4 inch) and the number of orifices in the system. That volume is the amount of liquid needed to fill the laterals and is set by the dose volume to the laterals. The flow required to pressurize the laterals is the volume and pump capacity needed to force effluent evenly out of the orifices. The number and size of the perforations (orifices) in the pressure distribution system will determine the required pump capacity. If the pump will send effluent to a pressure distribution system, you still need to determine the delivery and head requirements, but the process is a bit more complicated. You can then visit the pump supplier and ask what effluent pumps are available that operate within those delivery and hydraulic head requirements. In this flow situation, TDH is determined by adding the elevation difference from the pump to the drop box and calculating the friction loss in the supply pipe to the distribution box. The maximum ensures that effluent has time to flow by gravity out of the drop box to the soil treatment system. The minimum ensures that the pump will run fast enough to keep ahead of appliance discharges from washing machines and dishwashers. If the pump needs to move septic tank effluent to a drop box at a higher elevation, from which it will flow by gravity to the trenches, it needs to deliver at least 10 gpm and no more than 45 gpm at the drop box. Every pump has a distinct operating curve based on the amount of water that needs to be delivered (in gallons per minute, or gpm) and the total dynamic head (TDH, in feet) that the pump must overcome to send effluent where it needs to go.

The right pump for the job is determined by the conditions at the site and by the reason for the pump. (And we know that changes happen.) This is all the more critical for installers who also work on repairs and troubleshooting. That way, the installer will understand how any changes made during the installation will affect the pump. While a good designer will account for the necessary design elements and will have the “right” answer, everyone installing a system with pumps should understand how that pump was selected.

As educators, we often hear them say, in effect, “I don’t need to know that because I can follow the plan - that’s the designer’s job.” Nowhere is this more common than in selecting the right pump for a system. Installers often work off the designs of others. Get Pumps articles, news and videos right in your inbox! Sign up now.

Shallow sewage ejector pump chambers systems