As a starting point, the NP44AG suits one to three machines and the NP46AG suits three to five or more. Where several machines are installed, it is often better to group them and provide a trap per group rather than running long drain lines back to a single unit.
Beyond machine count, sizing depends on the total drain flow rate, the wash programs in use, the type of load, and the constraints of the site. Exact per-model discharge volumes are not standardised in published specifications because they vary with cylinder size, water levels, the number of rinses, and extract efficiency.
The lint trap sizing guide sets out the full comparison. For a precise selection, send us the machine specifications, the total drain flow rate in litres per second, and your site constraints.