Plenty of companies sell pressure switches. Far fewer actually make them in Britain.

F. Bamford (Instruments) Ltd designs and manufactures the Ajax XP flameproof pressure switch in Stockport, under ISO 9001 and ATEX. Mechanical, electro-mechanical and electronic engineering all sit under one roof, so technical questions get answered by people who understand the product. For oil and gas buyers who value UK manufacture and traceability, it is a solid option.