The system will then operate off the lag pump. This may be an indication of a failure of a lead pump. The alarm will sound when the lag pump operates. The pumps will alternate as mentioned above and both pumps will operate in a surge condition. Now the operation will be: Pumps off – Lead pump on – Lag pump on and high-level alarm. Look at the use of three floats and an automatic alternator with lead-lag control in the starter panel. If you do not, there is no indication of a lead pump failure. The building management system (BMS) should treat this as an alarm condition. If you use a four-float system, your specification should require a pump run status contact closure to the BMS on the lag pump operation. Just as in the simplex system there will have to be some fast action. At that point, both the lead pump and the lag pump have failed to pump out the basin. The challenge with a simple four-float system comes with the annunciation of the alarm. Locate the lag pump float 6” below the alarm float. As a “rule of thumb” we suggest locating the alarm float 6” below the lowest inlet. The level changes with the depth of the basin. You may also wire the alarm float to a separate circuit, so it has the power to alarm if the circuit operating the pumps is inoperative or has failed.Īnother advantage of the four-float system is the ability to create a storage difference between the lag float and the alarm float. If there is an unusual surge load, both pumps will operate. Normally the pumps have an alternator that automatically switches which pump acts as the lead pump. They are: Pumps off – Lead pump on – Lag pump on – High-level alarm on. Many specifications we see require four floats. If we carry the same logic into the duplex system, we will require four floats. Once that alarm sounds or makes building management system (BMS) contact, something must happen right now. This simplex system would require three floats: Pump off – Pump on – high level alarm. A high-level alarm would indicate the failure of the pump to keep up with the load. The spacing of these are determined by the required volume to meet the minimum run time of the pump. In a larger simplex pumping system with larger storage, we require an on float and an off float. If the flow is very low, as in a residential sump, we could use a single float with an on-off range of a few inches. Simplex Sump & Sewage Control in Buildings The decision about control is about whether you want to use three or four floats in the basin of a duplex pump. This may result in a specification that is not clear resulting in poor or incorrect selections. I often see specifications that were clearly created by adding different recommendations to existing standard specifications. Sump and sewage specifications should be very simple. When the system is larger, we can still settle on the everyday pump control. In residential systems, a small fractional horsepower pump comes with a mounted on/off float switch and we do not even think about it. See our Return Policy for more details.Commercial and Institutional control of basin mounted sump and sewage pumps does not have to be complicated. Therefore it is considered a 'Custom Product' and cannot be returned for a refund. This item is custom built to our customers' site specific needs. Two 2-pole definite purpose contactors (100,000 cycle rating).360 degree red alarm light, High decibel audible buzzer (100 dB).Includes 10' Wide Angle Mechanical Float Switch with Piggyback Plug.Includes Quick-Disconnect 10' Power Cord with Plug.2'' NPT Vertical Female Discharge, 2'' Solids Handling.2'' SCH 40 Discharge Pipe Sealed with Grommet.Risers Available To Bring Access To Grade.Heavy Duty Fiberglass Designed For Direct Burial.

Duplex sewage ejector pump systems