Two position valves switch back and forth between Load and Inject, or Position A and Position B. Selectors ( multiposition valves) operate in continuous revolutions by incremental steps. There are several ways to actuate each type of valve, along with a number of supporting controllers and devices to interface the actuators with computer-controlled systems.
Microelectric actuators feature automatic valve alignment, high-speed switching, and compact size.
The standard actuator, very robust and dependable, is more economical but substantially larger than the microelectric actuator.
Air actuators are useful in situations where any spark could be disastrous, where heat could compromise an electric actuator, or where electricity just isn't available.
The universal actuator allows instrument manufacturers to use a single motor and control software to operate virtually any Valco or Cheminert rotary valve - two position or selector.
Manual actuation offers the advantages of simplicity and low cost.
Valves in ovens require a standoff assembly to keep the actuator out of the heated zone. If a valve is not going to be heated beyond the temperature range of the actuator, closemount hardware often makes the cleanest installation.