TRI-SHARK … 100 % Control Valve , 100 % Tight
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Zwick developed the patented throttling trim cartridge Sharktooth which turns its triple offset butterfly valves into excellent control valves . This revised design is equivalent in control performance to a globe valve or rotary plug valve , but has much better shut-off characteristics . Combining the Sharktooth throttling trim cartridge with the TRI-CON triple offset butterfly valve series creates TRI-SHARK , the leakagefree shut-off and control triple offset butterfly valve .
This control valve offers a multitude of advantages . On the one hand this valve includes all the above mentioned advantages of triple eccentric butterfly valves , and on the other hand , this valve combination has all the special characteristics of an excellent control valve . Now only one type of valve can be used for both open-close and control applications . The throttling cartridge ( Fig . 1 ) is designed closed to the swivel movement of the butterfly disc in order to keep the flow between disc and cartridge as low as possible . Furthermore the cartridge is manufactured with several , optimized slots that divide the flow and release a precisely calculated cross-section when the valve opens or closes . With the throttling trim cartridge the valve ´ s flow characteristic is changed to an equal percentage flow characteristic , which is known as the preferred inherent flow characteristic for the majority of control applications . TRI-SHARK ´ s flow characteristic ensures that the valve provides an
effective control range at 5 up to 30 degrees 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 degrees of travel . TRI-SHARK valves significantly extend this range through its ´ throttling trim cartridge . The design of the cartridge and valve , in terms of flow , is such that ideal flow control is possible in this range .
Further advantages of TRI-SHARK valves are anti-cavitation properties . The flow is divided by the slots and reduces cavitation , as the vapor bubbles created in the area of the cartridge slots reach a smaller size due to the lower flow rate of each channel . As a result , the energy generated when the vapor bubbles implode is lower . In addition , TRI-SHARK valves are able to direct water jets concentrically to the center of the pipe , especially at small opening angles , thus converting the kinetic energy to a lower level in the fluid before contacting the pipe wall . Thus less damages , e . g . at the pipe wall , can occur . As the mass flow through the Sharktooth choke slots is divided into smaller parts , the sound frequency increases , and the resulting development is that sound can be more easily absorbed by the pipe because the frequency is in a range where the human ear is less likely to perceive it . Another very important aspect of the throttling trim cartridge is that the dynamic torque reduced by the altered pressure field . This means that at critical opening angles and flow conditions in relation to the dynamic torque that occurs a smaller actuator with less torque can be used .
TRI-SHARK can be offered in various designs . In addition to the standard Lug-Type and Sharktooth design ( DN900 , Fig . 2 ), integrated versions like double flange ( DN200 , Fig . 3 ) and valves with buttweld ends ( DN800 , DN700 Trim , Fig . 4 ) are also available .
Compared to other control valves , TRI-SHARK valves offer enormous advantages in terms of purchase cost , weight and geometric dimensions , with excellent tightness and outstanding control characteristics , especially for larger diameters .
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