After the dry air pump put wet pump makers Pesco and Garwin out of the business, those who used them relied on overhauled pumps. Then, in the 1980s, dry pumps got vilified, and interest in wet pumps returned. Airwolf, known for its line of oil filters, obtained the Pesco data and some of its manufacturing equipment, updated the design, received the necessary certification and started selling wet pump replacements for all 200- and 400-series dry pumps.
