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.
On/Off electric actuators open and close the valve via an electric motor. Upon receipt of a continuous signal, the motor runs until the valve is rotated 90 degrees, completely closing or opening the valve. When the valve reaches the closed or open position, an internal cam on the actuator strikes a limit switch and shuts off the motor. If the electric signal is lost mid-stroke, the valve stays in mid-stroke position.
Electric actuators come in a variety of torque ratings, from as low as 15Nm to 600Nm or more. Common voltages are 24VDC and 120VAC.
Some features that differentiate higher quality electric actuators include 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.
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