Flowserve Valtek Mark, Safety Manual

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2. Mark Series Device Description
The Valtek Mark Series control valve offers superior performance in liquid and gaseous services,
while also permitting easy, fast and inexpensive maintenance.
The spring-cylinder actuated Mark Series valve provides stiffness and maintains high positioning
accuracy, repeatability, controlled high speed, and faithful response. The Mark Series valve actuator
handles up to 150 psig (10.3 barg) supply air and has the thrust to shut off against much higher fluid
pressures.
The Mark Series valve is designed so the spring, supply air pressure and fluid pressure itself combine
to produce exceptionally tight shutoff. A self-aligning seat ring further enhances the shutoff capability
of the Mark Series valve. Additionally, the Mark Series
valve’s high degree of parts interchangeability,
fewer inventory parts are required. In addition, the actuator is lighter, smaller and easier to handle
than comparable diaphragm actuators.
The Mark Series of valves can be categorized into the following segments:
Mark One (FCD VLENIM0001-01 07.07; FCD FCAIM0100-01): globe and angle design managing a
pressure drop between upstream and downstream pressure changes.
Mark One 3-Way (FCD VLAIM003-03): globe and angle design designed for applications requiring
the combining or diverting of fluids by way of an added 3-way adaptor.
Mark Six (FCD VLAIM006): globe and angle design specifically for cryogenic applications requiring a
cold box extension.
Survivor (FCD VLENIM0036-04): a sweep angle type control valve uniquely designed for use in
erosive, corrosive, and flashing applications.
3. Designing a Safety Instrumented Function using a
Flowserve Valtek Mark Series Valve
3.1 Safety Function
When de-energized, the Mark Series valve moves to its fail-safe position. Depending on the version
specified Fail
– Closed or Fail - Open, the Mark Series will extend the valve plug to close off the flow
path through the valve body or open the flow path through the valve body.
The Mark Series valves are intended to be part of final element subsystem as defined per IEC 61508
and the achieved SIL level of the designed function must be verified by the designer.
3.2 Environmental limits
The designer of a SIF must check that the product is rated for use within the expected environmental
limits. For SIL rated valves the minimum operating temperature is -40°F/-40°C , for other
environmental limits refer to the various Valtek Mark Series valve Technical Bulletins.
3.3 Application limits
The materials of construction of a Mark Series valve are specified in various Valtek Mark Series valve
Technical Bulletins. It is especially important that the designer check for material compatibility
considering on-site chemical contaminants, temperature/pressure limitations, and air supply
conditions. If the Mark Series valve is used outside of the application limits or with incompatible
materials, the reliability data provided becomes invalid.