filtration duty
also called what it filters
What a filter is built to clean, and in what service — engine oil, transmission fluid, hydraulic fluid, petrol, diesel, intake air, cabin air, dust-laden air, compressed air, beverage, water. It is a DUTY and not a bare substance, deliberately: intake air and cabin air are the same substance and utterly different jobs, and it is the job that sets the media chemistry, the pressure the body must survive and the flow it must pass. It is intrinsic and NOT a fitment (REFINE-LOG 2026-08-25): a duty is not a cross-reference to another product, no vehicle is named, and nothing about an oil filter changes when a model that used it is discontinued. Concern identity, so NOT axis-eligible: an oil filter and an air filter are two listings, never two cells of one buy box — the same filing as drinkware_type, strainer_type, basket_type and utility_vessel_type.
Filtration duty is answered with one word chosen from the filtration duties list — the same word shared across every product that uses it.
It belongs to identity — who and what it is.
asked by the kinds that answer it
2 kinds answer it, each for a single value. The same question can be reused by unrelated kinds — one meaning, many homes.
asked by kinds that answer it
The same question can be reused by unrelated kinds — one meaning, many homes.
| kind | how many |
|---|---|
| filter | required · one |