As intrinsic safety protection is a system concept each installed system must be documented to justify compliance as opposed to most other protection methods which tend to apply to individual parts of a system.
Consequently the Descriptive System Document, known as DSD, is a mandatory, document providing a record of compliance of each intrinsic safety loop/circuit.
The DSD documents the system - equipment and cabling, lists safety parameters and compares them with cable calculations for circuitĀ verification.
The documentation can be presented in a number of ways, within the EN60079-25 Annex E examples are given for "A possible format" using a traditional drawings style although a more tabular style can be easier if generating large numbers of DSD's.
It is quite common to produce DSD's in a word processor or spreadsheet format which is generally easier to create and view than traditional drawings.
- Gas Groups, Protection level & Temperature ratings
- Details of all equipment in the loop inc. Junction boxes
- Connection/Terminal details
- Safety parameters comparison
- Non Hazardous area equipment connection verification
- Cable requirements & parameters
- Earth & bonding points
- Unique ID number for the DSD
- Signed and dated by system designer
It is the responsibility of the site to have these documents.
As intrinsic safety is a system concept quite often the equipment suppliers are not in a position to create the DSD.
For example when Supplier A provides control room equipment (barriers), supplier B the Field equipment and supplier C does the installation, no one supplier necessarily has all the information to create the DSD.
Where a single supplier is supplying the complete IS system e.g. on a skid, then they may be expected to provide the DSD.
However it is the sites ultimate responsibility for these documents.
From site survey to complete Descriptive system Documentation please contact us if you require assistance with producing DSD's.