How the Bowl Fills
Waste motor oil (WMO) typically contains 3–5% solids. Solids concentrate against the bowl wall while clean oil overflows the inner dam and exits. When the bowl is full, sludge overflows into the clean oil output and separation efficiency drops to near zero.
Calculating Drain Interval
The US Filtermaxx open-bowl centrifuge holds approximately 165 cubic inches of sludge:
| Contamination Level | Formula | Gallons Between Draining |
|---|---|---|
| 5% solids (heavily contaminated) | 165 ÷ 0.05 = 3,300 in³ ÷ 231 = | ~14 gallons |
| 3% solids (typical WMO) | 165 ÷ 0.03 = 5,500 in³ ÷ 231 = | ~24 gallons |
Optimal range: 14 to 24 gallons between drainings for standard WMO.
Bowl Volume Reference
| Bowl Capacity | At 5% Solids | At 3% Solids |
|---|---|---|
| 1 pint (28.9 in³) | ~2.5 gallons | ~4.2 gallons |
| 1 quart (57.75 in³) | ~5 gallons | ~8.3 gallons |
| US Filtermaxx (165 in³) | ~14 gallons | ~24 gallons |
Automating the Drain Cycle
US Filtermaxx automatic controllers handle drain cycling without operator intervention — enabling unattended cleaning of up to 1,000 gallons per day.
Automatic Controller Features
- Programmable run time and drain duration
- Integrated heater control for consistent oil temperature
- Available for 120V/240V single-phase and 230V 3-phase
- Compatible with all US Filtermaxx models and most competitor centrifuges