Installation
When installing the pressure reducing valve upstream of a hot water tank, installing an expansion
tank, or similar, is recommended to absorb the increase in pressure due to the thermal expansion
of water.
When installing in large buildings, short pipes or expansion valves, and/or similar equipment, is
recommended to limit the increased pressure due to the thermal expansion of water caused by
temperature changes downstream of the pressure reducing valve itself (or downstream of the first
and second stage pressure reducing valves, if two are used).
580
Se ri
es
1° stage
PRV
2° stage
PRV
expansion
expansion
8
7
Downstream set pressure (kPa)
2000
1600
1200
800
400
Cavitation
high risk
Normal working
conditions
Out of working
conditions
Upstream pressure (kPa)
10
0
20
0
40
0
60
0
80
0
1000
1200
Cavitation diagram
14
29
58
87
116
145
174
58
116
174
232
290
Downstream set pressure (PSI)
Upstream pressure (PSI)
To minimize the risk of cavitation within the valve that may result in malfunctioning with erosion
of the valve sealing area, vibrations and noise, it is highly recommended to refer to the working
conditions represented in the above diagram. Due to the numerous factors and variable conditions
experienced such as system pressure, water temperature, air presence, flow rate and velocity,
which may affect the behavior of the pressure reducing valve, it is advisable that the pressure ratio
between the upstream pressure and the downstream set pressure is kept ideally to a value 2:1
and no greater than a value of 3:1 (For example, upstream 150 psi (10 bar), set pressure 75 psi
(5 bar), the pressure ratio = 150/75 = 2:1). In these conditions, the possible risk of cavitation and
malfunctioning is minimized, however this does not exclude the possible effects of the many other
variables within the system under operating conditions. If the pressure ratio exceeds the indicated
limit, the system design pressure or use of 1st stage pressure reducing valves shall be reviewed
(For example, 1st stage reducing pressure from 200 to 100 psi and then 2nd stage from 100 to
58 psi). Piping upstream and downstream of the pressure reducing valve shall be supported in
accordance with the manufacturer’s instructions, and any local authority requirements, to avoid
the creation and transfer of vibration and/or noise into the installation.
