Control valves are used in a wide range of capacity, from butterfly valves with a rated flow coefficient (KVs) of more than 50 000 m³/h, enough capacity to fill an Olympic swimming pool within three minutes, down to microflow valves with rated flow capacity that would take more than 20 hours to fill a glass of water.
Typically, microflow control valves are globe valves with a seat diameter of 2 mm or less, where the plug is either parabolic or a V-notch type. The turndown ratio and control performance of such a valve is mainly dependent on the tolerances between plug and seat ring. Assuming a control ratio of 20:1 and following the rule of thumb that a KV of 1 m³/h corresponds to 28 mm² vena contracta area, on such valve trim the tolerance between plug and seat ring must be less than 3 μm. Besides the challenge to produce such high-precision parts, this kind of trim can only be used on clean process fluids and, due to the thermal expansion, only within a restricted temperature range.
Arca’s new patent-pending approach is based on a rotary sliding gate valve, where two slices with lapped surfaces are installed in the valve pressed together by a spring and differential pressure. This enables zero-tolerance without any limitation due to thermal expansion. Each slice has one or more bores for the flow passage. Normally the flow passage of such sliding gate valve is only open when the bores overlap. Especially with small rated flow coefficient (small bores) this results in the on/off characteristic of the valve. In this new design one of the slices is equipped with a tangential flow channel, which leads and expands into the bore of this slice. This enables a smooth control behaviour with sufficient opening angle (more than 60 degrees).
The slices can be made of any material (even ceramics), which makes the trim resistant to process fluid and pressure drop. Although the valve plug movement is quarter-turn, a standard globe valve housing DN 15–25 rated PN16–PN 250 is used. This makes the design economical and allows changing from a standard valve to the new design, even in existing applications.
First flow characteristic and critical flow factor FL measurements up to 150 bar differential pressure have proven the performance of this approach, even under pressure drops up to 250 bar.
Compact valve position indicator Emerson Automation Solutions
Valves, Actuators & Pump Control
Emerson’s new TopWorx DVR Switchbox is an entry-level addition to the DV Series of valve position indicators. It combines a durable resin enclosure, compact size, and a patented cam design that provides a reliable valve position feedback for water and wastewater systems, food and beverage production lines, and industrial utilities.
Read more...Precision, control and performance in regulators and control valves Valve & Automation
Valves, Actuators & Pump Control
Cashco has long been a trusted name in industrial control solutions, offering a broad range of regulators and control valves designed to meet the rigorous demands of various industries. There are two key Cashco product lines, its regulators and the Ranger QCT control valve.
Read more...Advanced solutions for valves Bearing Man Group t/a BMG
Valves, Actuators & Pump Control
BMG delivers state-of-the-art valve solutions to diverse industries across Africa, in collaboration with InterApp, a global leader in the design and manufacture of high-quality valves.
Read more...ENERGYValves expands operations
Valves, Actuators & Pump Control
ENERGYValves is expanding its operations with a new facility in Cape Town. The new premises will significantly enhance the company’s capacity to serve the Cape Town market and surrounding areas.
Read more...Inspection system for leak detection in valves in hazardous areas Extech Safety Systems
Valves, Actuators & Pump Control
Leaking valves in industrial plants not only lead to loss, safety risks and possible contamination and pollution, but also result in high economic costs. Therefore, valves in hazardous areas require regular proper inspection and preventive maintenance to ensure their functionality.
Read more...Valve & Automation is exclusive agent for Cashco Valve & Automation
News
Valve specialist, Valve & Automation, supplies total valve and control solutions to key process industries throughout southern Africa. The company has now been appointed as the exclusive agent for US company, Cashco for the supply of control valves, regulators, tank equipment and flame arrestors.
Read more...High-flow solenoid valve Emerson Automation Solutions
Valves, Actuators & Pump Control
Emerson has introduced the new ASCO Series 327C solenoid valve, which features a direct-acting, high-flow design that provides superior flow-to-power ratio. It permits high flows at minimum power levels, making it ideal for use in power plants, refineries, and chemical processing facilities.
Read more...New system improves performance of magnetic drive pumps
Valves, Actuators & Pump Control
KSB Pumps and Valves has introduced its ground-breaking MagnoProtect system for the local petrochemical, chemical and general industry markets ,to enhance the safety and performance of its magnetic drive pumps.
Read more...Emerson software optimises maintenance Emerson Automation Solutions
Valves, Actuators & Pump Control
Emerson has announced the Plantweb Insight Valve Health Application, a powerful software tool that combines Fisher control valve expertise with advanced analytic algorithms. The new app makes it possible for users to visualise an entire connected fleet of valves, while prioritising actions based on the health index of each valve.
printer friendly version