..document in which the items of electrical apparatus, their electrical parameters and those of the interconnecting wiring are specified.

DSD Example

Descriptive System Document example from En 60079-25

DSD example

DSD Example

Descriptive System Document example from En 60079-25

DSD example

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 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.

Using standard site installation or circuit diagrams is rarely adequate as a DSD.

All Intrinsic safe systems require DSD(s) putting on record every aspect of the Intrinsic safety loops, this could be one drawing per loop or for many similar loops where but each loop must be clearly identified and contain the following information:

  • Gas Groups, Protection level, & Temperature rating
  • Cable requirements & parameters
  • Earth & bonding points
  • Justification for simple apparatus
  • 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 neccesarily 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.


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