Mechanical valve symbols.
The following symbols are generally in accordance with BS 1553-1 and BS 5070
Symbols for different line types
Symbols for pipe supports.
Symbols for line fitting.
Symbols for Valves.
Symbols for valve actuators
Symbols for instruments.
Symbols for flow instruments.
Instrument Identifier symbols.
|Measured Variable ||Type of Conditioner ||Type of Component |
|F = Flow ||R = Recorder ||T = Transmitter |
|L = Level ||I = Indicator ||M = Modifier |
|P = Pressure ||C = Controller ||E = Element |
|Q = Quantity ||A = Alarm || |
|T = Temperature || |
Connexion Solenoid Valve symbols from the UK's premier solenoid valve suppliers
Symbols for Process Equipment.
The level of detail for the equipment relates to the type of schematic being produced. A Process Flow Sheet will only show the basic level of information sufficient to show the essential process flow paths. An Engineering Line Diagram of P & ID drawing will show a much more detailed representation.
Process plant equipment symbols. Plant 1.
Process plant equipment symbols - Plant 2
Process plant equipment symbols - Plant 3
Symbols for line tagging and equipment identification.
Reading pneumatic symbols.
5/2 way valve with 5 ports and 2 position (conditions)
Typically ports A and B connected to pneumatic cylinder.
1. Valve failsafe spring with inlet P pressurised with flow to B, A exhausting to EA.
2. Valve actuated with inlet P pressurised with flow to A, B exhausting to EB.
The block symbolises the possible valve function. Example a 5/2 valve schematic with 2 blocks describing the two possible valve functions or positions. A 5/3 valve schematic will show three blocks describing the three possible valve functions.
Pneumatic or fluid valves can be operated in several ways. Hand operated including levers, push and or pull buttons, air or fluid pilot operated remotely or internally by pneumatic or fluid pressure signals or solenoid actuated directly by electrical signal.
Exhaust port symbol.
The inverted triangle symbol denotes an exhaust port. The letters EA indicate an exhaust port for the A circuit, and EB denotes exhaust port for B circuit.
The arrow symbol denotes the flow direction of gas or liquid media into and out of the valve ports.. Pressure or inlet from port P. Depending on which on which of the valve blocks is in function the gas or liquid media flow is directed to port A or port B accordingly. A line with an arrow on each end denotes ability to control flow in both directions.
The return spring.
The spring symbol defines the AT REST position of the valve. The spring pushes from the side that is in drawn on and will return the valve to its failsafe position unless actuated otherwise.
The T symbol.
The T symbol indicated that this port is closed and is neither passing or exhausting any media.
The P inlet port symbol.
The P symbol denotes the air or liquid media pressure inlet or the number 1 can also indicate inlet port.