Explosion Proof Stainless Steel Ball Valves - Positioner

Stainless steel ball valves utilize a machined or soldered spherical ball to block or enable fluid flow. The ball is connected to a stem which in turn is connected to either a handle (for manual use) or a motor for automated use. Turning the stem rotates the ball and either exposes the bore to the fluid path or blocks it. With their superior corrosion resistance and sturdy construction stainless steel ball valves are commonly used for high pressure saline or corrosive media applications. Industrial grade valves are usually rated to 1000 psi or higher. Stainless steel ball valves are either a “trunnion pin” or “floating ball” design. In a trunnion pin design, the ball is held in place by a pin at the base of the valve body. This design is more common for larger valves (greater than 6” in diameter). In a floating pin design, as the name implies, the ball “floats” atop of and is held in place by the valve seats. Some features that differentiate higher quality valves include being cast from a higher grade of stainless (316 vs 304), a stainless steel ball (316 vs other alloys), a solid vs plated steel ball, and high quality sealing materials. Sealing materials can vary by application but reinforced Teflon (RTFE) is commonly used as it provides excellent sealing performance for a wide range of applications and is chemically inert. Positioning actuators throttle the valve to the desired position via an internal servo-controller. Changing the input signal (usually 4-20mA or 0- 10V) results in a corresponding and proportional change in the position of the valve. If there is a total loss of power the valve remains in the last known position. If the control signal is lost, the actuator can be programmed to fail open or fail close. Electric positioning actuators come in a variety of torque ratings, from as low as 20Nm to 600Nm or more. Common voltages are 24VDC and 120VAC. Some features that differentiate higher quality electric positioning actuators include a self-calibrating controller, an all-metal gear drive, a weatherproof enclosure (normally IP 67 NEMA 4X or higher), a thermostatic heater to prevent internal condensation, a manual override mechanism and a dome position indicator.