Why is Energy dissipation an important factor in control valve selection?
All Control valves cause pressure drop in the fluid as it passes through the valve.
What effect does the positioner cam have on the valve characteristic?
The feedback cam in the positioner controls the relationship between the control signal and valve position. With a linear cam at 50% signal the valve will be 50% open.
How is the characteristic determined in a globe valve?
There are several ways of altering the characteristic in a globe valve depending on the particular design.
Why is reduced trim required in control valves?
Control valves sizing is according to the requirements of application and must meet both CV and speed criteria.
What is Live-Loaded Control Valve Packing?
Control Valve packing is usually the last line of defense against valve leakage. The packing of the Control Valve can be Ptfe v ring or flexible graphite packing. Which packing material is best for your application usually depends on the temperature of the valve.
Are safety valves, regulators, and isolating valves all examples of control valves?
control Valves are used to respond to signals from an external control device to control flow at variable levels between full or partial opening and closing, and to compare “set point” with “process variable” . The Control Valve, often referred to as the “final control element” , is a critical part of any control loop that affects the whole process.
Why do Oxygen valves require degreasing?
Grease will react with gaseous or liquid oxygen and catch fire at a certain pressure and temperature. The reaction of grease with oxygen can cause combustion or explosion.
What materials can be used for Oxygen Service?
All organic and inorganic materials react with gaseous or liquid oxygen at a given pressure and temperature. That would cause a fire or an explosion. Due to these inherent hazards, process system design and control valve material selection are important.
What is meant by Cryogenic for control valves?
THINKTANK control valves are used in many cryogenic application, what is meant by Cryogenic? General for used in liquefied gases, such as liquid nitrogen and liquid helium, the condition temperature usually achive minus 196 degrees Celcius(-320 degrees Fahrenheit).
Specific Gravity is the Ratio of the Density of a Liquid to the density of Water, What is the Specific Gravity of a Gas?
Specific Gravity (Relative Density) SG also called relative density that is ratio of the density of a substance to that of a standard substance
What is Vapor Pressure
The vapor pressure of a liquid is the equilibrium pressure of a vapor above its liquid (or solid); that is, the pressure of the vapor resulting from evaporation of a liquid (or solid) above a sample of the liquid (or solid) in a closed container.
Is Flow Through a Control Valve Turbulent or Laminar?
Any process flow through piping and control valves is almost always considered as turbulent. The reason being the process has to go through so many twists and turns, expansion, reduction in piping, and elbows, valves, etc.
