Sanitary valves are designed for hygienic applications where the primary concern is to ensure aseptic conditions without the introduction of harmful substances in the media flow. This is accomplished by valve material selection and machining processes.
Sanitary valve bodies are usually made of stainless steel due to superior corrosion resistance. To minimize particle entrapment and possible bacterial growth, the wetted surfaces are polished to a greater degree than industrial valves. Sanitary gaskets and seals are made from chemically inert material such as PTFE, silicone or Viton. Seal material depends on the specifics of the application.
The two most common types of sanitary valves are sanitary ball valves and sanitary butterfly valves. Sanitary ball valves usually have filler material behind the valve seats to minimize internal cavities. This is feature is called “encapsulated seats.” Like their industrial counterparts, sanitary ball valves can withstand high pressures and temperatures. Sanitary butterfly valves are simpler and lower cost but have lower pressure and temperature ratings.
Some features that differentiate higher quality sanitary valves include 316 stainless construction (vs 304), highly polished internals (8-10 Ra), and encapsulated seats.
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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