Valve bodies and bonnets are made from ductile iron with internal and external fusion bonded epoxy (FBE) or equivalent coatings to provide long-term corrosion protection. All non-metallic sealing elements (wedge coating, O-rings, etc.) comply with EN 681-1 and are selected for continuous contact with drinking water, so they do not adversely affect the taste, odour, colour or hygienic quality of the water. End connections and face-to-face dimensions follow EN 558 and relevant EN 1092 flange standards for network compatibility.
For functional performance, EN 1074-1/2 seat tightness tests are performed at 0.5 bar (low pressure) and 1.1 × PFA (high pressure) with water. After closing the valve using the specified maximum operating torque (MOT), the resilient seat must achieve Leakage Rate A (no visible leakage). Operating torque and mechanical strength are checked against EN 1074-2 limits for the chosen operating device (handwheel, lever, T-key, or ring-key with bar), including minimum strength torque (mST) tests to confirm that the stem, wedge and drive components safely withstand torques above MOT.
Ductile iron NRS resilient-seated gate valves, NRS, DN750 PN10, EN 1074 compliant, face-to-face according to EN 558 Series 14 (DIN 3352 F4), gear operated, EPDM fully encapsulated disc for potable water service.
Pressure and strength performance are further verified by EN 1074-1 type tests:
- Obturator differential pressure resistance tests, confirming that the wedge and internal components withstand high differential pressure and still operate correctly.
- Leak-tightness to internal pressure, ensuring no unacceptable internal leakage through the closed valve.
- Where required by the installation conditions, external pressure / vacuum tests (Annex D of EN 1074-1) to check resistance to external water ingress or negative pressure.
Durability is demonstrated by endurance testing under pressure: at least 250 full open/close cycles at PFA for manually operated valves in the DN 50–500 range, and 2 500 cycles for actuated valves. After cycling, the valve must still pass shell strength and seat tightness tests and remain operable within the MOT limits. For potable water use, disinfection resistance is verified by exposing internal wetted surfaces to chlorinated water (typically 50 mg/l free chlorine for 48 h) and confirming that seat tightness is maintained.
Hydraulic performance is defined by a Kv flow coefficient declared by Metalsin; when tested to EN 1267, the measured Kv is at least 90% of the declared value (testing not required for full-bore / clear-way designs). Each valve is permanently marked, as size permits, with DN, PN, shell material, manufacturer ID, year of manufacture and relevant EN reference, and every production batch is subject to routine shell and seat leak tests, plus visual inspection of coatings and workmanship. Technical datasheets, installation instructions and EN 1074-1 / EN 1074-2 test documentation are available on request.
