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3. Installation
3.1. The pressure reducing valve should be installed in a horizontal pipe with the operating
part including the adjust unit turned upwards, with suitable bypass and isolating
valves.
3.2. To prevent water hammer and vibrations caused by incoming condensate it is
necessary to install a steam trap before the pressure reducing valve.
3.3. If you expect the average flow velocity to rise above 30m/sec, it is recommended to
increase the size of the pipe.
3.4. Pressure reducing valves may not be installed parallel. These valves are to be used
individually and independently.
3.5. In case the pressure reducing ratio exceeds 20 : 1 (for instance the secondary
pressure is lower than 0,8 bar at 16 bar primary pressure), the pressure reduction is
to be made in two steps. In that case, a distance of at least 3 meters has to be kept
between the two pressure reducing valves.
3.6. The distance between the pressure reducing valve and a solenoid valve must be of at
least 3 meters, if a solenoid valve with on/off function is installed upstream or
downstream of the pressure reducing valve. Otherwise, the pressure reducing valve
may not function in a stable way while the valve is opening or closing.
3.7. If a control valve is installed downstream of the pressure reducing valve, the distance
between the pressure reducing valve and the control valve must be of at least 2
meters. The disregard of this recommendation may cause an unstable function of the
pressure reducing valve as well.
3.8. As a pressure reducing valve used for steam normally does not close completely, it is
recommended to install a steam trap downstream for the case that the steam flow
comes to zero and condensate is arising in the steam line behind the pressure
reducing valve (dead end service).
3.9. To prevent an unusual rise of the outlet pressure a safety valve has to be installed.
3.10. The pipe in which the pressure reducing valve is installed, must be fixed so that the
weight and the vibration of the pipe do not directly influence the pressure reducing
valve.
3.11. Blow down the piping that leads to the PRV’s inlet from any dirt and scale before the
first start-up of the pressure reducing valve. This is particularly important in case of the
start-up of the pressure reducing valve after a long time of shut-down.
3.12. Before a long shut-down of the pressure reducing valve the condensate must be
completely discharged from the pipe. Furthermore the stop valves before and behind
the pressure reducing valve have to be closed.
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