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Erhard product range
Non return valves
Types:
tilting disc check valve DN 150 - 1400 PN 10 - 40
DN 80 - 600 PN 10 - 40 swing check valve DN 40 - 800 PN 10 - 16
reflux valve DN 40 - 300 PN 10 - 16 „ECR“ check valve DN 40 - 600 PN 10 - 25
ball check valve DN 50 - 350 PN 10 diaphragm check valve DN 40 - 400 PN 10
Sizes:Pressure:
DN 40 - DN 1400PN 10 – PN 40
NON SLAM nozzle“ type check valve
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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
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SWING type check valve
Non return valves
Design with external shaft – lever and weight
Design with internal shaft
SWING type check valveSWING type check valveDN 40 – 800 PN 10 -16
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SWING type check valve
Non return valves
preferably for sewage (nearly full passage) lever and weight (adjustability) valve disc in stainless steel up to DN 300 with O-Ring seal
SWING type check valveSWING type check valve
Features:
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Tilting disc check valve
Non return valves
with lever and weightdesign with hydraulic damping
DN 150 – 1400 PN 10 - 40
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Non return valves
Tilting disc check valve
Features:
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Tilting disc check valve
Seat ring of stainless steel
O-Ring for resilient seating
Non return valves
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Tilting disc check valve
Design:
Non return valves
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Non return valves
Principle of hydraulic damping cylinder
Valve in fully open position
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Non return valves
Principle of hydraulic damping cylinder
Valve 45° closed
Valve closes without damping
Oil has free movement
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Non return valves
Principle of hydraulic damping cylinder
Valve closedOil must pass the flow control valve
damped closing
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Tilting disc check valve
Examples for use of hydraulic damping:
Non return valves
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Tilting disc check valveHeadloss characteristic
Non return valves
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Tilting disc check valve
Full opening device (opening cylinder)
Non return valves
Pneumatic cylinder
Valves is in fully open position also at low flow velocities
Low headloss
Energy saving
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Tilting disc check valve
Recommendation for installation:
Non return valves
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Tilting disc check valve
Arrangement of lever and weight:
Non return valves
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NON SLAM Nozzle check valve
Features:
silent closing low headloss short face- to face dimension resilient seated inside enamelled
DN 80- 600 PN 10 - 40
Non return valves
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DN 80 - 300 PN 10 - 40
Common features:
Internal body: zinc-free bronze
Outside: EKB epoxy Inside: vitreous enamel
Guide bushes: special plastic material
Guide rod, spring: stainless steel
ERHARD NON SLAM Nozzle Check Valve Types
DN 350 - 600 PN 10 - 16
Rubber-coated valve disc
Rubber-coated valve ring
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v0
a = dv/dt
vRmax
T0
TR
TStime t
Forw
ard
flow
Ref
luxFlow velocity
Non Return Valves: Hydraulic Characteristics
Flow retardation
0 m/s
In short, steep pipelines, the water column stops quickly, i.e. flow retardation a is high !
In long, flat pipelines, the water column does not stop quickly, i.e. flow retardation a is low !
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0
0,2
0,4
0,6
0,8
1
1,2
1,4
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Flow retardation dv / dt in m / s²
Ref
lux
velo
city
v i
n m
/ s
DIN
swin
g ch
eck
valv
e
Check valve with
slanted seat
Diaphragm check valve
Tilting disc check valve with
slanted seat and spring Nozzle check valve
ERHARD NON SLAM Nozzle Check Valve
Tilti
ng d
isc ch
eck v
alve
with w
eight
-load
ed le
ver
Reflux Preventers: Dynamic Characteristics
Long, flat pipelines
Short, steep pipelines
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Waterhammer:
Max waterhammer according to formula of „Joukowsky“
p
avg
= max. waterhammer (m WC)
= surgewave velocity in water ( = 1200m/s)
= change in flow velocity (m/s)
= acceleration of earth (m/s²)
gvap
Non return valves
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Calculation of the max. waterhammer at different reflux velocities
)(12281,9
11200 WSmp
)(2481,9
2,01200 WSmp
Non return valves
Reflux velocity – 1 m/s
Reflux velocity – 0,2 m/s
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Reflux check valve
DN 40 – 300 PN 10 - 16body with epoxy – enamel or rubber liningbody with epoxy – enamel or rubber lining
water and sewage
with rubberlined disc
Non return valves
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ball check valve
DN 50 – 350 PN 10DN 50 – 350 PN 10
for sewage
ball of steel rubber coated
epoxy coating
Non return valves
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diaphragm check valve
DN 40 – 400 PN 10
for water
soft closing
Non return valves
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„ECR“ check valve
DN 40 – 400 PN 10 - 25wafer type
for use in water
with NBR sealing
quick acting
Non return valves