




Anti-hammer relief valve
![]() | A pressure relief valve is a safety appliance which is capable of instantaneously evacuating a high flow rate. It protects networks against overpressure due to sudden changes in flow rates (water hammer effects) for example when closing a valve too quickly or in case of sudden moving of air pockets inside the pipes. The range goes from DN60 to DN200, PFA10, 16 or 25 bars. The valve pressure set point has to be indicated by the customer at the order time. |
Material and coating
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Item | Designation | Material | Coating |
1 | Adjusting screw | Stainless steel 18/8 | |
2 | Nut | Stainless steel A2 | |
3 | Nut | Bronze UE 7 | |
4 | Cap | Ductile Iron | Epoxy 200 microns |
5 | Spring holder | Steel XC 38 | |
6 | Spring | Spec Steel | |
7 | Spring holder | Steel XC 38 | |
8 | Pin | Stainless steel | |
9 | Bearing | Bronze UE 7 | |
10 | Clapper | Steel XC 38 | |
11 | Clapper gasket | Polyurethane | |
12 | Upper stem | Stainless steel 18/8 | |
13 | Seat | Stainless steel 18/8 | |
14 | O’ring | Nitrile | |
15 | Skirt | Steel A40 | Epoxy 200 microns |
16 | Flange | Steel XC 38 | Epoxy 200 microns |
17 | Pressure ¼’ gas |
Hydraulic characteristics
The pressure values to be considered are:
- PMS : network maximum service Pressure,
- Valve pressure set point : Pressure at beginning of opening,
- Overpressure: Pressure increase, compared with the pressure set point, to reach the maximum drained flow rate.
The valve pressure set point has to be indicated by the customer at the order time.
The valve pressure set point is given by the network maximum service Pressure (PMS) increased by 5 to 10 %.
Maximum drained flow rate
Choice of DN
DN of the appliance is determined as a function of the flow rate to be evacuated. As a general rule we should choose the flow rate of the pipe on which the relied valve is located.
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Installation
The pressure relief valve is to be installed in a vertical position as close as possible to the source of the water hammer effects.
If it is installed in a manhole, an evacuation pipe must be provided. An isolating valve is recommended to enable work to be carried out on the relief valve (regulating, maintenance…) without interrupting the operation of the network.
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DN | H | Lx1 |
mm | mm | mm |
60/65 | 1200 | 1500 |
80 | 1200 | 1500 |
100 | 1200 | 1500 |
125 | 1500 | 1700 |
150 | 1700 | 1700 |
200 | 1700 | 1700 |