How to Select a PVU
The tank depth and float settings must be known in order to select the appropriate PVU for the system. Once float settings are determined, select a pump vault that will satisfy the required float settings and also position the pump vault inlet holes at their optimum elevation.
Step 1: Determine tank depth (TD). Tank depth is measured from the inside bottom of the tank to the outside top of the tank.
Step 2: Determine cartridge height (CH).
- Residential application: 18-inch min. cartridge height
- Residential recirculating application: 24-inch min. cartridge height
- Commercial application: 24-inch min. cartridge height
Step 3: Determine float setting elevations for the system. Float settings are measured down from the outside top of the tank (bottom of pump vault support pipes) to the center of the float collar.
Step 4: Select the proper vault height (VH) by selecting the proper tank depth range on the chart below with the matching cartridge height (CH). Verify that the off point (OP) you calculated in Step 3 falls within the range listed in the “off point range” column.
Step 5: Verify that the off point is above the minimum liquid level of the pump (MLLp) using the following equation: TD-OP > MLLp + G.
Ronald Crites and George Tchobanoglous. Small and Decentralized Wastewater Management Systems. Boston: McGraw-Hill, 1998.