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Copyright © AVK Holding A/S, original version, rev. 11, 08-Mar-2022
5. Principle of operation
AVK S870 plunger valve is mainly designed for water flow rate and pressure regulation in a
pipeline, unlike to butterfly and gate valve, which design provided only ON/OFF duty. The AVK
Plunger valve can be operated by an external actuator such as:
•Gearbox with hand wheel
•Electrical actuator
•Pneumatic actuator etc.
Required set up conditions, flow rates and differential pressures, can be achieved by axial
movement of the plunger, operated by crank mechanism. The relation between flow rate and
opening level is linear, making valve operation easier. Low operating torque is possible to
achieve due to pressure equilibrium on internal chamber. Small differential pressures can be
reached, when opening level approach to 50%.
The plunger is placed in the middle of the valve, water flow is sliding through round- shaped
chamber and four water paths, designed to increase flow velocity and pressure drop down. Four
bronze guide rails ensure no vibration during work and accurate alignment throughout full valve
stroke, mounted by bolts give possibility for maintenance service. "T" shape main seal located in
safety flow area ensuring minimal wear and guarantee long service life.
Cavitation can be avoided and guarantee no damage, by using anti-cavitation trims, slotted type
for medium differential pressures and perforated type for high differential pressures. Both types
designed to move cavitation bubbles into the center of valve outlet, therefore the AVK Plunger
valve can fully fulfil special control functions over a wide range in water supply systems.
6. Health and safety at work
Make sure all relevant Health and Safety issues and regulations are adhered to prior to and
during installation or maintenance work carried out on this product. It is the end user's
responsibility to ensure that safe working practices are followed at all times.
Whenever AVK’s products are installed, operated or maintained the inherent dangers of
pressurized liquids and gasses must be addressed. Before work on a valve or other piping
component is undertaken, that may involve the release of internal pressure, the valve or line
must be fully isolated, depressurized and drained prior to commencing the work. FAILURE TO
COMPLY WITH THIS MAY RESULT IN SEVERE INJURY OR DEATH.
All workers handling the product must be aware of the weight of the components or assemblies
to be handled and manipulated during installation and maintenance.
It is essential that staff undertaking these operations are adequately trained and it is the
responsibility of the end user that only trained and competent staff undertake these duties.
This manual has been designed to assist, but it cannot replace quality training in the workplace.
However, the AVK technical staff is always available and ready to answer questions relating to
specific problems that may not be covered by this manual.
AVK’s products are designed to be fit for purpose and to a high reliability standard. This
provides a safe, low risk product when used correctly for the purpose for which it was designed.
However, this assumes that the equipment is used and maintained in accordance with this
manual, and the user is advised to study it and to make it available to all staff that may need to
refer to it.
