Sump and Sewage Lag Pump & Alarm Float Settings

We presented suggestions for the pumps off float level and the lead pump on float level in the last few articles. You may review those by clicking on the “Past Articles” area of the website.
We know the minimum submergence or float off setting by contacting R L Deppmann for the pump selection or by using the rules of thumb identified in our May 3rd article. We can determine the lead pump on setting from using the basin diameter and the information shared in our May 31st article. Sometimes it is acceptable and possibly required to allow effluent to back up into the piping system but in general if the sump depth is not causing a problem with water tables or other obstructions then the maximum water level would be the bottom of the lowest inlet connection to the sump.

Today we look at the lag or standby pump float setting and alarm setting. These floats must fit between the lead pump on and the bottom of the inlet. The less space between these settings, the less depth required on the sump.

The recommendation is a 6” or more between the floats. We also recommend the use of 3 floats with the lag pump and alarm at the same level. (See MMM of May 10 2010)

Next week we will begin a discussion about motor specifications.