Erhard product range Non return valves Sizes: Pressure: DN 40 - DN 1400 PN 10 – PN 40 Types: tilting disc check valve DN 150 - 1400 PN 10 - 40 swing check valve DN 40 - 800 PN 10 - 16 NON SLAM nozzle“ type check valve DN 80 - 600 PN 10 - 40 reflux valve DN 40 - 300 PN 10 - 16 „ECR“ check valve DN 40 - 600 PN 10 - 25 Soweit vollständig ball check valve DN 50 - 350 PN 10 diaphragm check valve DN 40 - 400 PN 10

Erhard product range Non return valves Criteria for selection: flow media (water, sewage) size pressure rating headloss space requirement closing time (damping) indication of position (visual, electric) price Soweit vollständig

Non return valves SWING type check valve SWING type check valve DN 40 – 800 PN 10 -16 Design with external shaft – lever and weight Design with internal shaft Soweit vollständig

Non return valves SWING type check valve SWING type check valve Features: preferably for sewage (nearly full passage) lever and weight (adjustability) valve disc in stainless steel up to DN 300 with O-Ring seal Soweit vollständig

Tilting disc check valve Non return valves Tilting disc check valve DN 150 – 1400 PN 10 - 40 Soweit vollständig design with hydraulic damping with lever and weight

Tilting disc check valve Non return valves Tilting disc check valve Features: Soweit vollständig

Tilting disc check valve Non return valves Tilting disc check valve Seat ring of stainless steel Soweit vollständig O-Ring for resilient seating

Tilting disc check valve Non return valves Tilting disc check valve Design: Soweit vollständig

Principle of hydraulic damping cylinder Non return valves Principle of hydraulic damping cylinder Valve in fully open position Soweit vollständig

Principle of hydraulic damping cylinder Non return valves Principle of hydraulic damping cylinder Valve 45° closed Valve closes without damping Oil has free movement Soweit vollständig

Principle of hydraulic damping cylinder Non return valves Principle of hydraulic damping cylinder Valve closed Oil must pass the flow control valve damped closing Soweit vollständig

Tilting disc check valve Non return valves Tilting disc check valve Examples for use of hydraulic damping: Soweit vollständig

Tilting disc check valve Non return valves Tilting disc check valve Headloss characteristic Soweit vollständig

Tilting disc check valve Non return valves Tilting disc check valve Full opening device (opening cylinder) Pneumatic cylinder Valves is in fully open position also at low flow velocities Soweit vollständig Low headloss Energy saving

Tilting disc check valve Non return valves Tilting disc check valve Recommendation for installation: Soweit vollständig

Tilting disc check valve Non return valves Tilting disc check valve Arrangement of lever and weight: Soweit vollständig

NON SLAM Nozzle check valve Non return valves NON SLAM Nozzle check valve DN 80- 600 PN 10 - 40 Features: silent closing low headloss short face- to face dimension resilient seated inside enamelled Soweit vollständig

ERHARD NON SLAM Nozzle Check Valve Types DN 80 - 300 PN 10 - 40 Rubber-coated valve disc Common features: Internal body: zinc-free bronze Outside: EKB epoxy Inside: vitreous enamel Guide bushes: special plastic material Guide rod, spring: stainless steel DN 350 - 600 PN 10 - 16 Rubber-coated valve ring

Non Return Valves: Hydraulic Characteristics Flow velocity Flow retardation v0 In short, steep pipelines, the water column stops quickly, i.e. flow retardation a is high ! a = dv/dt In long, flat pipelines, the water column does not stop quickly, i.e. flow retardation a is low ! Forward flow TR 0 m/s time t TS T0 Reflux vRmax

Reflux Preventers: Dynamic Characteristics 1,4 1,2 1 Tilting disc check valve with weight-loaded lever DIN swing check valve 0,8 Check valve with slanted seat Diaphragm check valve 0,6 Reflux velocity v in m / s 0,4 Nozzle check valve Tilting disc check valve with slanted seat and spring 0,2 ERHARD NON SLAM Nozzle Check Valve 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Long, flat pipelines Short, steep pipelines Flow retardation dv / dt in m / s²

Non return valves Waterhammer: Max waterhammer according to formula of „Joukowsky“ = max. waterhammer (m WC) Soweit vollständig = surgewave velocity in water ( = 1200m/s) = change in flow velocity (m/s) = acceleration of earth (m/s²)

Calculation of the max. waterhammer at different reflux velocities Non return valves Calculation of the max. waterhammer at different reflux velocities Reflux velocity – 1 m/s Reflux velocity – 0,2 m/s Soweit vollständig

Non return valves Reflux check valve DN 40 – 300 PN 10 - 16 body with epoxy – enamel or rubber lining body with epoxy – enamel or rubber lining water and sewage with rubberlined disc Soweit vollständig

Non return valves ball check valve DN 50 – 350 PN 10 DN 50 – 350 PN 10 for sewage ball of steel rubber coated epoxy coating Soweit vollständig

Non return valves diaphragm check valve DN 40 – 400 PN 10 for water soft closing Soweit vollständig

Non return valves „ECR“ check valve DN 40 – 400 PN 10 - 25 wafer type with NBR sealing for use in water quick acting Soweit vollständig