A practical sequence for matching a model to a project: measure the lift, add line losses, check inflow, then confirm the electrical platform.
Start from the lift, not the model number
The first number that decides a selection is the vertical distance from the unit outlet to the highest point of the discharge line. That figure, not the fixture count, sets the minimum head the unit has to deliver.
Measure from the discharge outlet of the lifting device to the highest point the pipe reaches before it falls to the sewer. If the pipe rises through a ceiling void before dropping, the highest point is the ceiling, not the sewer connection. Most selection errors come from measuring to the sewer instead.
Add the losses that the lift does not show
Every bend, non-return valve and metre of horizontal pipe consumes head. A short route with four bends can cost more head than two extra metres of vertical lift. Add the losses to the vertical lift before comparing with the maximum head of a model.
Once the total is known, keep a working margin rather than selecting at the absolute maximum. A unit running at its published limit has no reserve for a partially blocked line or a heavier fixture load later.
Check the inflow against tank volume
Flow tells you how fast the unit can move water; tank volume tells you how much it can hold while the pump is between cycles. A washing machine or a group of washroom fixtures discharges in bursts, so tank volume matters as much as flow.
For a single bathroom group, a compact unit with a cutting impeller is normally sufficient. For several washrooms or a whole building, the DMJ station range scales by tank volume from 25 litres to 460 litres.
Confirm the electrical platform before quoting
European Type units run on 220–240V / 50Hz at 2850 RPM; American Type units run on 110V / 60Hz at 3450 RPM. The two platforms are not interchangeable, and the model suffix changes with the market.
Send the site voltage, frequency, measured lift, discharge line length and fixture list with your inquiry, and the selection can be confirmed against the catalog instead of against an assumption.
Parameters quoted in this note come from the 2026 English catalog. Where a figure is still under verification, the model page marks it rather than estimating it.
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