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A more complex example of a P&ID. A piping and instrumentation diagram (P&ID) is defined as follows: A diagram which shows the interconnection of process equipment and the instrumentation used to control the process. In the process industry, a standard set of symbols is used to prepare drawings of processes.
ISO 10628 Diagrams for the chemical and petrochemical industry specifies the classification, content, and representation of flow diagrams. It does not apply to electrical engineering diagrams.
Some instrumentation is self actuating. For example, pressure regulators maintain a constant pre-set pressure, and rupture discs and pressure safety valves open at pre-set pressures. [3] Instrumentation includes facilities for operating personnel to intervene in the plant either locally or from a control room.
A PFD can be computer generated from process simulators (see List of Chemical Process Simulators), CAD packages, or flow chart software using a library of chemical engineering symbols. Rules and symbols are available from standardization organizations such as DIN, ISO or ANSI. Often PFDs are produced on large sheets of paper.
Orifice plate showing vena contracta. An orifice plate is a thin plate with a hole in it, which is usually placed in a pipe. When a fluid (whether liquid or gaseous) passes through the orifice, its pressure builds up slightly upstream of the orifice [1] but as the fluid is forced to converge to pass through the hole, the velocity increases and the fluid pressure decreases.
ISO 14617 Graphical symbols for diagrams is a library of graphical symbols for diagrams used in technical applications. [1] ISO 14617 consists of the following parts: Part 1: General information and indexes; Part 2: Symbols having general application; Part 3: Connections and related devices; Part 4: Actuators and related devices
A restrictive flow orifice (RFO) is a type of orifice plate.They are used to limit the potential danger, damage, or wastage of an uncontrolled flow from, for example, a compressed gas cylinder [1] [2] They are generally not limiting the flow during normal operation but if a fault or failure occurs causing uncontrolled flow the orifice will present a restriction, limiting the flow.
A simplified version of the definition is: The k v factor of a valve indicates "The water flow in m 3 /h, at a pressure drop across the valve of 1 kgf/cm 2 when the valve is completely open. The complete definition also says that the flow medium must have a density of 1000 kg/m 3 and a kinematic viscosity of 10 −6 m 2 /s , e.g. water.