> as lemmas
pre-filter
pre-filter v.
Brit. 
/(ˌ)priːˈfɪltə/
, /(ˌ)priːˈfɪltə/U.S. /ˌpriˈfɪltər/
/ˌpriˈfɪltər/ΚΠ
1928 Daily Gleaner (Kingston, Jamaica) 2 May 19/1 After this preliminary affining treatment the refiner melts the washed sugar which is then defecated or pre-filtered with Kieselguhr.
1991 Power Sept. 30/3 Pre-filtering the gas upstream of the SCR unit will extend the life of the catalyst.
prefilter
prefilter n. /(ˌ)priːˈfɪltə/, /ˌpriˈfɪltər/
Brit. /ˈpriːfɪltə/
, /ˈpriːfɪltə//(ˌ)priːˈfɪltə/U.S. /ˈpriˌfɪltər/
, /ˈpriˌfɪltər//ˌpriˈfɪltər/ΚΠ
1911 Times Engin. Suppl. 30 Aug. 20/4 (advt.) Filtration plant for waterworks... Prefilters and appurtenances, filtered water reservoir..as shown and specified.
2002 Fine Woodworking Mar. 117/2 Many respirators come with a prefilter in front of the charcoal filter canister.
<
as lemmas