172-65613A-03 (DR8-3P/DR8-3EP/DR8-6P/DR8-6EP) 11 Jun 2020
5
Correct Usage of the DR8 Direct-acting Pressure
Reducing Valve
Install properly and DO NOT use this product outside the recommended
operating pressure, temperature and other specification ranges.
Improper use may result in such hazards as damage to the product or
malfunctions which may lead to serious accidents. Local regulations
may restrict the use of this product to below the conditions quoted.
CAUTION
1. The DR8 should be operated only within its specifications.
2. Installing an ON/OFF valve (solenoid valve or motorized valve)
Motorized
Valve
DR-8
Inlet Side
Steam
Trap
DR-8
Motorized
Valve
Outlet Side
Steam
Trap
If an on-off valve, such as a motorized valve, is required to stop supply of
steam to the steam-using equipment, install it at the inlet side of the DR8. If a
solenoid valve is installed at the outlet of the DR8, it will cause heavy
chattering and may lead to damage of the DR8. (When the on-off valve opens,
the secondary pressure of the DR8 changes from zero to the set pressure,
passing through an area of the reducing ratio of less than 30:1, where
adjustment is impossible, chattering occurs momentarily.) To save energy, it is
recommended to install the on-off valve as near to the boiler, as possible.
NOTE: To prevent water hammer, it is recommended that a slow-acting
motorized on-off valve be used. In particular, if a fast-acting on-off
solenoid valve is used for frequent temperature control, the potential
water hammer effect can damage the steam-using equipment and the
DR8.
3. Installing a control and/or safety valve
Steam-using
Equipment
Safety
(Relief)
Valve
Control
Valve
DR-8
Steam
Trap
Steam
Trap
Inlet
Valve
Outlet
Valve
Pressure
Gauge
Safety
(Relief)
Valve
Control
Valve
DR-8
Steam-using
Equipment
Steam
Trap
Steam
Trap
Inlet
Valve
Outlet
Valve
Pressure
Gauge
A control valve (i.e. for temperature control) installed between the DR8 and
the steam-using equipment (downstream of the DR8) may raise the pressure
between the DR8 and the control valve when the control valve is closed,
depending on the spatial relationship. Therefore, a safety valve should be
installed downstream of the control valve.
NOTE: When installing a safety valve to protect steam-using equipment, be
sure to install it on, or directly before, the inlet of the steam-using
equipment. If the safety valve is installed between the DR8 and a
control valve, an eventual pressure rise could activate the safety valve.
