Valves for drinking water: materials, coatings and approvals
Valves in a drinking water system stay in service for decades in constant contact with water people drink. Beyond pressure and size, the materials and proof of their safety matter.
TAZ Engineering Team · · 6 min
Wetted materials
Ductile or grey iron body with internal and external epoxy coating, EPDM-encapsulated wedge, stainless steel stem, brass or bronze stem nut. Leaded alloys in contact with water are avoided.
Coating
Fusion-bonded epoxy protects against corrosion and deposits. Thickness, continuity and freedom from pores matter, checked with a thickness gauge and holiday detector. Coating damaged during installation must be repaired.
Hygiene approvals
Uzbekistan requires a sanitary-epidemiological conclusion for products in contact with drinking water. European countries run national material approval schemes, for example UBA requirements in Germany, ACS in France and WRAS in the UK. Confirm with the client which document the project needs.
Design choice
Distribution networks mostly use resilient-seated gate valves: full bore and no body cavity for deposits. Large trunk mains use butterfly valves. Buried valves get an extension spindle and surface box.
Checklist
- body, wedge and stem materials
- epoxy coating and thickness
- EPDM rubber
- hygiene approval
- installation type
- flange standard