This Part of BS 1646 specifies symbols for the representation of process computer and shared/control functions in the field of process measurement and control.
The symbols established in this part have been developed to be used in conjunction with the symbols devised in BS 1646-1 and BS 1646-2 and are supplementary.
They are intended to provide a means to illustrate process computer and/or shared display/control functions in the field of process measurement and control and may be used separately or combined with the symbols of BS 1646-1 and BS 1646-2. They will enable users to show and identify in a simple form the functions of instruments, the process computer and shared display/control functions or any combination of these.
It is permissible to use the basic symbol for computer based functions (see 3.1) throughout for any software based digital system. This is not intended to preclude the use of the basic symbol for shared display/control functions (see 3.2) if the user considers this to be appropriate.
The symbols are intentionally limited to the identification on process flow diagrams, etc and do not provide a means of illustrating specific instruments or parts thereof.
The letter code for function identification is given in the Tables of BS 1646-1 and BS 1646-2.
The application methods are shown in the examples.
NOTE The titles of the publications referred to in this standard are listed on Inside back cover.