| | Rostra Vernatherm is a manufacturer of thermostatic, pressure, and flow controls. Vernatherm has been a provider of controls to many industries, such as aerospace, medical, automotive, and specialty use for more than 50 years. Vernatherm also manufactures custom valves to suit any purpose with state of the art equipment.
Located in Bristol, CT USA, Vernatherm prides them selves as being the leader in the thermal control industry. Vernatherm's product line includes wax based actuators, thermal control valves, pressure relief valves; dump valves, needle valves, and micro actuators. All products manufactured in Bristol CT, USA.
Where size and weight are critically important, such as in aerospace, automotive, and medical technologies; miniature actuators are changing the way designers approach a problem. Stand alone, self energized, wax driven actuators have drastically reduced in size, the smallest wax actuator now measures .172” in diameter, and .187” in length, its applications are limitless.
Wax actuators are small cylindrical shaped devices in which a few grams of paraffin are hermetically sealed. Motive force is obtained from the 15-30 percent volumetric expansion of paraffin that occurs during the solid-to-liquid phase change when the actuator is heated. The expansion vs. temperature relationship is a function of a paraffin formulation: As the actuator is heated through the melting range, the paraffin begins to melt and expand, creating hydrostatic pressure. The pressure is translated to piston extension through a high pressure/high efficiency hermetic seal. Full extension is reached when the paraffin is fully melted. On cooling, the paraffin begins to solidify after thermal hysteresis. As the paraffin solidifies, the actuator retracts to the starting position with aid of a return load. Repeated heating and cooling extends and retracts the actuator. New developments in wax formulas and machining are responsible for size reduction and application growth.
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