Operation instructions Butterfly Check Valve Series TRI-CHECK, with
counter weight and optional hydraulic damper
ZWICK Armaturen GmbH D-58256 Ennepetal
Instructions No.
Zw-Tri-Check-2016 / Rev.11
3
⇒
the pipe system has been installed by experts and that these systems are regularly inspected.
The stiffness of the body is designed to support the usual additional pipe forces F
z
equal to
π/4٠
DN²
٠
PS. Wafer type butterfly valves may support higher values of additional pipe forces
F
z
(PS = design pressure at ambient temperature)
. Contingent lateral forces taking effects to the valve must not exceed 10% of the forces
mentioned above.
⇒
the valve has been connected to these systems by experts, especially a valve with butt-weld
ends,
⇒
excessive pipe stress is to avoid in any case,
⇒
the operating time of the check valve has been adjusted to the pipe system characteristics,
⇒
the flow velocity in the pipe system is limited to usual values (e.g. 4 m/s for liquid fluids) and
that abnormal conditions such as vibration, water hammer, erosion (i.e. by wet steam),
cavitations and a relevant content of solid – especially abrasive – particulates in the fluid are
agreed by the manufacturer,
⇒
at service temperature between >+50°C and <–20°C the valve and the valve connection
surfaces are protected from contact by the user,
⇒
only experts for pressurized pipe systems operate and maintain the valve unit.
2.3
Special Dangers
Mortal
Danger
The valve shaft is tightened by a stuffing box.
Before the bolting of this stuffing box is
loosened,
be sure, that the pipe system
is
completely depressurized.
Mortal
Danger
Before loosening the locking screw (or the cover plate) at the body or before removing
the valve from the pipe
the pipe system must be completely depressurized
, so no
media can leak from the pipe uncontrolled. Be sure that
the valve is approx. 5°-10°
opened
and remains in this position to equalize the pressure at both sides.
The counter weight and the damper may– if necessary – only be removed, if it is
secure that a possible back swing of the valve disc
can be excluded
. This is
especially important for valves of large diameters.
Danger
Fittings, used as end valve: During normal operation, in particular in case of gaseous,
hot and/or hazardous media a blind flange or a filler cap must be on the free inlet. The
operation of such a fitting is not allowed.
Danger
If an end-of-line valve has to be opened in a pressurized line, this has to take place
very carefully and in a way that keeps spurting out media from causing damage.
Attention when closing such a valve: Avoid getting one’s hand between body and
disc!
Danger
If a valve shall be disassembled from the pipe:
Take care, that the adjacent pipe system
is completely drained
, before the valve is
disassembled from the pipe. Take special care to residual amounts of the fluid that
remain trapped in the valve and/or in the adjacent pipe.
Disconnect the drive/limit switch first (acc. to manufacturer's documentation).
Danger
A check valve is usually operated only by the flow inside the pipe system. Especially a
check valve without damper can be caused to
close abruptly
by a decrease in
pressure or even a slight pressure against the flow direction. The occurring pressure
hammers as well as the mass inertia of the swinging disc can result in forces that are
so enormous that the valve and/or the pipe can be damaged or even burst! Media can
possibly leak from the pipe system.