When selecting analyzers, sample characteristics including quantity and type of
chemical components should be considered carefully.
To prevent sample contamination, avoid sharing of sample lines between
Where available, use of automatic calibration feature is desirable to counter drift
in analyzer performance.
Proper sampling conditioning is important for satisfactory operation of an
Solenoid Valves . Two methods are usually employed to operate solenoid valves:
direct and pilot-operated. Direct operators are those in which the force of the coil core
directly opens or closes the valve. The force required to operate the valve is directly
proportional to the valve's orifice and line pressure. As the size and line pressure
increases, the size of the coil and core increases accordingly. To avoid this limitation,
pilot-operated solenoid valves may be used.
The use of pilot-operated solenoid valves is limited in two ways: by the maximum
differential pressure and by the minimum amount of differential pressure required to
operate the valve. Operational failure may result if either is ignored in the application.
For example, three-way solenoid valves are often used to direct an air supply to, or
exhaust the air from, a pneumatic valve operator. If valve position is critical, two
solenoid valves in the air supply line should be considered, especially when priority
interlocks are necessary. Proper function may not occur if the solenoid valve's minimum
required differential pressure is ignored. In critical cases, the application should be
tested for the various operating modes and the solenoid valve manufacturer consulted
regarding the product's capabilities.