TPi March 2016

products & developments

Dual-function valves Among zero-leakage valves for open/ close function, triple eccentric butterfly valves are on the rise. This type of construction can provide advantages that include 100 per cent zero leakage, compactness, easy and frictionless functioning, and long maintenance-free operation.

applications. The throttling trim cartridge is close to the pivoting motion of the valve’s disc to keep the flow between disc and cartridge as low as possible. The cartridge is manufactured with multiple optimised slots that divide the flow and clear an exact calculated cross section while opening or closing the valve. With the throttling trim cartridge, the valve’s flow is changed to an equal percentage flow, which is a preferred inherent flow characteristic for many control applications. Tri-Shark’s flow characteristic ensures that the valve is able to provide an effective control range at 5° to 30° of travel – the control area where traditional triple eccentric butterfly valves seem to reach their limits. Typical butterfly valves have good control limits between 30° and 70° of travel. Tri-Shark valves extend this range through the throttling trim cartridge. Further advantages of Tri-Shark valves are anti-cavitation properties. The flow is divided through the slots and reduces cavitation, because the occurring steam bubbles in the cartridges slots’ area reach a smaller dimension by the smaller flow rate of each channel. Therefore the occurring energy is less when the steam bubbles implode. Especially at small opening angels, Tri- Shark valves are able to conduct water jets concentric to the pipeline’s centre, converting kinetic energy to a smaller level in fluid prior to contacting the pipe wall. This can reduce the occurrence of damage, eg at the pipe wall. As the mass flow is divided into smaller parts through Sharktooth’s throttling slots the sound frequency rises, and the sound can be absorbed more easily through the pipeline because the frequency is in a region where human ears will notice it less. Another important aspect of the throttling trim cartridge is that the dynamic torque is reduced by the changed pressure field. At critical opening angles and flow conditions with regards to the occurring dynamic torque, a smaller actuator with less torque can be used.

For fixed limits, triple eccentric butterfly valves can be used for control and/ or throttling applications. To extend the range and create an efficient high- performance control valve, Zwick and Yeary Controls developed the Tri-Shark triple offset butterfly valve. In collaboration with Yeary Controls, Zwick developed the patented Sharktooth throttling trim cartridge, which is used to turn the triple offset butterfly valves into control valves. This revised design is claimed to be equal in control performance to a globe valve or rotary plug valve, while incorporating better shut-off capabilities. By combining the Sharktooth throttling trim cartridge with the Tri-Con triple offset butterfly valve series, Zwick created the Tri-Shark zero-leakage shut-off and control triple offset butterfly valve. This control valve combines the benefits of a triple eccentric butterfly valve with the special qualities of a control valve, enabling just one style of valve to be used for both on-off and control

Butt weld Tri-Shark

type design and Sharktooth (DN900), integrated versions such as double flange (DN200) and valves with butt weld ends (DN800, DN700 Trim) are available. Zwick Armaturen GmbH – Germany info@zwick-gmbh.de www.zwick-armaturen.de

WIRE 2016 11/A32 booth

Ultrasonic • High Pressure • Steam

Tube, Wire, Strip & Cable Cleaning Systems

Sharktooth disc clearance

Mechanical Cleaning with Textiles or Brushes Dry or Liquid Supported Cleaning Wire, Cable, Tube

GEO-REINIGUNGSTECHNIK GmbH www.geo-reinigungstechnik.de info@geo-reinigungstechnik.de

Tri-Shark can be supplied in different types. In addition to the standard lug-

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March 2016 Tube Products International