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 throttling trim cartridge with the TRI-CON triple offset butterfly valve series creates TRI-SHARK, the leakage-free 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 is designed to close 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 fewer 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.
ZWICK is a leading manufacturer of valves which meet highest requirements and quality standards. The product range contains metal-seated butterfly valves known as series TRI-CON, the check valves series TRI-CHECK and the TRI-BLOCK series, ZWICK’s Double Block and Bleed Design. 30 years experience ...