Often described as the final control element, the control valve is a critical piece of equipment in the management of conditions such as flow, pressure, temperature and liquid level and leakage. Control valves do so by partially opening or closing in response to signals received from process controllers that compare a setpoint against a process variable.
Control valves generally regulate pressure and/or flow rate, and are available for any pressure. Though sliding-stem globe and angle valves are widely considered the most common and versatile types of control valves, in the range of zero leakage valves for on/off function, triple eccentric butterfly valves are on the rise. This type of construction can provide a lot of advantages, from 100% zero leakage, compactness, easy and frictionless functioning, through to long maintenance-free operations. All of which is leading to increasing popularity. 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 throttling trim cartridge Sharktooth, which is used to turn its triple offset butterfly valves into complete control valves. This revised design is equal in control performance to a globe valve or rotary plug valve, but incorporating improved shut-off capabilities. By combining the throttling trim cartridge together with the triple offset butterfly valve series TRI-CON, the TRI-SHARK was created – a zero leakage shut-off and control triple offset butterfly valve.
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