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P v
=
vapor pressure adjusted for temperature and
atmospheric pressure,psig (kPa) = - 14.2 psig
(-97.5 kPa) for water at 60°F (16°C), measured
at sea level
P u
=
upstream pressure
The VAG EKN
®
Butterfly Valve has the correct dimensions when
the computed σ-value lies above the limit curve of σ k . The recom-
mended control range lies between 10-100% opening degree.
Below that no reasonable control can be guaranteed. If cracking
noises or vibrations occur while the valve is being put into opera-
tion, the actual operation conditions should be checked. In case
of changed operation conditions, the equipment may have to be
recalculated. If the computed σ-value lies below the limit curves
of σ k cavitation will occur.
To remedy the problems, we recommend:
• Changing the downstream pressure
• Choosing a different place of installation
If the σ-value lies above the limit curves of σ k the noise is caused
by other criteria and the pipeline will have to be checked.
3.3.2 Maximum permissible flow velocity
While the medium flows through or against the valve disk, the
disk is exposed to forces of flow whose impact is determined by
the flow velocity of the medium in the pipeline. Similar to a wing
profile, a greater lift (or buoyancy) is generated at higher flow ve-
locity and a changed angle of incidence. The same is true for the
disk inside the valve. The buoyancy generated is perceived as
torque at the drive shaft.
Caution:
VAG EKN
®
Butterfly Valves type AWWA are designed/
sized for the following velocities in liquid media:
• Pressure rating class 150 A: 8 ft/s (2,4 m/s)
• Pressure rating class 150 B: 16 ft/s (4,9 m/s)
3.4 Permissible and impermissible modes of
operation /
Caution
VAG EKN AWWA Butterfly Valves are designed acc. AWWA 504
standard with maximum working pressure of 150 psi g and a ma-
ximum full open velocity of 16 ft / sec. Temperature range acc.
AWWA is 33° - 125° F.
The VAG EKN
®
Butterfly Valve has its limit stop in the gearbox.
This stop limits both the open and the closed position. Due to the
automatic lock of the gear, it suffices to touch the end position.
Do not tighten it as this will not improve the tightness of the valve.
Do not permit operation of any valve at pressure above the ra-
ted pressure of the valve. Do not exceed 300 ft.-lb. input torque
on actuators with wrench nuts, 200 lb. rim pull input torque for
handwheels and chainwheels. If portable auxiliary actuators are
used, size the actuator or use a torque limiting device to prevent
application of torque exceeding 300ft. lbs. If an oversize actuator
with no means of limiting torque is used, stop the actuator before
valve is fully opened or closed against stops and complete the
operation manually. Be sure to check actuator directional switch
against direction indicated on wrench nut, handwheel or records
before applying opening and closing torque.
Permanent operation of the valve in throttle position will result in
its increased wear and tear. The throttling operational limits ac-
cording to Section 3.3.1 need to be established.
4
Installation into the pipeline
[psig (kPa)]
•
Danger:
pipeline (-flanges) during installation!
Death or serious injury can result if persons remain between valve
and pipeline!
- Never stand under a suspended load!
- Lift the valve carefully until it is freely suspended.
- Avoid valve's tilting by always moving it cautiously during lif-
ting and transport.
- Make sure that no person stays in hazardous area.
4.1 Conditions required on site
When installing the valve between two pipeline flanges, these
must be coplanar and in alignment. If the pipes are not in align-
ment, they must be aligned before installation of the valve, as
otherwise this may result in impermissibly high loads acting on
the valve body during operation, which may eventually even lead
to fracture.
Caution:
When installing the valve into the pipeline, make sure it
is as stress-free as possible. In plant piping, install so as to mini-
mize bending of valve connection with pipe loading. It is recom-
mended that valves be installed into piping system in accordance
with AWWA M-44 in order to prevent any undue piping stress,
deflection or bending that may affect the performance of the val-
ve. Make sure valve disc, when opened, will not contact pipe port.
This is especially necessary on pipe with linings and when wafer
valves are used. Check manufacturer for minimum pipe I.D. requi-
red for clearance.
Prepare pipe ends and install valves in accordance with the pipe
manufacturer's instructions for the joint used. Do no deflect pipe/
valve joint. Do not use valve as jack to pull pipe into alignment.
In case of works around the valve causing dirt (e.g. painting, ma-
sonry or working with concrete), the valve must be protected by
adequate covering.
For assembly in drinking water pipelines, suitable sealing mate-
rials, lubricants and process materials must be used which are
approved for use in drinking water pipelines.
Before putting the valve into operation, clean and purge the corre-
sponding pipeline sections.
4.2 Installation location
The installation location of the valve must be selected to provide
sufficient space for function checks and maintenance works (e.g.
dismantling and cleaning of the valve).
If the valve is installed in the open, it must be protected against
extreme atmospheric influences (e.g. formation of ice) by adequa-
te covers.
If the VAG EKN
must be equipped with a cover for buried installation.
Danger of bruise between valve body and
®
Butterfly Valve is installed underground, the gear
VAG Operation and Maintenance Instructions • 6
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