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
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
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
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:
Tilting disc check valve
Non return valves
with lever and weightdesign with hydraulic damping
DN 150 – 1400 PN 10 - 40
Non return valves
Tilting disc check valve
Features:
Tilting disc check valve
Seat ring of stainless steel
O-Ring for resilient seating
Non return valves
Tilting disc check valve
Design:
Non return valves
Non return valves
Principle of hydraulic damping cylinder
Valve in fully open position
Non return valves
Principle of hydraulic damping cylinder
Valve 45° closed
Valve closes without damping
Oil has free movement
Non return valves
Principle of hydraulic damping cylinder
Valve closedOil must pass the flow control valve
damped closing
Tilting disc check valve
Examples for use of hydraulic damping:
Non return valves
Tilting disc check valveHeadloss characteristic
Non return valves
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
Tilting disc check valve
Recommendation for installation:
Non return valves
Tilting disc check valve
Arrangement of lever and weight:
Non return valves
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
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
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 !
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
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
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
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
ball check valve
DN 50 – 350 PN 10DN 50 – 350 PN 10
for sewage
ball of steel rubber coated
epoxy coating
Non return valves
diaphragm check valve
DN 40 – 400 PN 10
for water
soft closing
Non return valves
„ECR“ check valve
DN 40 – 400 PN 10 - 25wafer type
for use in water
with NBR sealing
quick acting
Non return valves