EN 12845-1 Annex O: P&ID Example

Source: TS EN 12845+A2:2026, Annex O (informative) "Example of P&ID", EN p.163.

This article is short because the source is one page long and consists of a single figure. The entire text of Annex O in the standard is its heading: "Annex O (informative) - Example of P&ID". The body of the annex is an example of a piping and instrumentation diagram.

In this annex the standard gives no binding symbol standard (apart from the symbol key of the example figure itself), no tagging convention, no separate example diagrams for ESFR or CMSA, no foam-water system example, no test point list, no rule for integration with peripheral systems and no revision schedule for the diagram.

Which standard does Annex O belong to?

To EN 12845-1, that is, to TS EN 12845+A2:2026 (EN p.163). The contents list of EN 12845-2:2024 has a single annex: "Annex A (normative) Extract for determining the hazard classification from prEN 12845-1" (EN 12845-2, EN p.2). Therefore there is no such thing as an "EN 12845-2 Annex O".

The status of the annex is informative. Compared with the annexes in the same region:

Source: TS EN 12845+A2:2026, EN p.162-165.

Where does the standard require a P&ID?

Annex O does not create a requirement; the clause that creates the requirement is 4.4.2 i).

Clause 4.4.1 (EN p.24) lists the information to be provided at the design stage: a summary schedule (Clause 4.4.2), complete working drawings of the sprinkler installations (Clause 4.4.3) and details of the water supplies (Clause 4.4.4).

Clause 4.4.2 i) (EN p.24): "A list of the components suitable for sprinkler use included in the system, each identified by supplier's name and model/reference number. If required by the authorities, a Piping and Instrumentation Diagram (P&ID) with a list of all components included in the system, each identified by supplier's name, model, diameter, total number and reference number, should be added. For an example of a P&ID, see the figure in Annex O."

In other words, the standard does not impose a P&ID on every project; it makes it dependent on the authorities requiring it. When it is required, it lists the information fields the diagram must carry: supplier's name, model, diameter, total number, reference number.

The other items of the summary schedule

Clause 4.4.2 (EN p.24) lists the information to be given in the summary schedule as follows:

• a) the name of project;
• b) all drawing or document reference numbers;
• c) all drawing or document issue numbers;
• d) all dates of issue of drawings or documents;
• e) all drawing or document titles;
• f) the type(s) of installation(s) and the nominal diameter(s) of each control valve set;
• g) the number or reference of each control valve set in the system;
• h) the number of sprinklers on each control valve set;
• i) the component list and, where required, the P&ID;
• j) the height of the highest sprinkler on each control valve set;
• k) a statement that the installation has been designed and will be installed in accordance with this European Standard, or details of any deviations from its requirements together with the reasons for them.

Instrument details required on layout drawings

The layout drawings, which complement a P&ID, are governed by Clause 4.4.3.1 (EN p.24-25). The items concerning the instrument and valve side are as follows:

• i) the location and type of control valve sets and location of water motor alarms;
• j) the location and details of any water flow, and air or water pressure alarm switches;
• k) the location and size of any subsidiary valves, subsidiary stop valves and drain valves;
• l) the drainage slope of the pipework;
• n) the location of all test valves;
• o) the location and details of any alarm panel;
• p) the location and details of any fire department inlet connections;
• q) a key to the symbols used.

Source: Clause 4.4.3.1, EN p.24-25.

The presence of a symbol key on the drawing is a requirement (item q); however, the standard does not state which symbol set is to be used and makes no reference to a symbol standard.

Topics not covered in Annex O

• A reference to a binding symbol standard (apart from the LEGEND symbol key in the top right block of the example figure).
• A tagging convention (for example prefix schemes by equipment type).
• Separate P&ID examples for ESFR, CMSA or foam-water systems.
• Integration diagrams for the building management system and the fire alarm system.
• A schedule for the intervals at which the diagram is to be updated.

Field note

Field note (not from the standard, this is engineering interpretation): the place of the P&ID in the standard is not an obligation but a document dependent on the authorities requiring it; on the operator's side, however, gathering valves, switches and test points on a single diagram markedly eases the traceability of the monitoring and alarm signals covered by Annex H and Annex I. If a diagram is to be prepared, completeness of the five information fields listed in Clause 4.4.2 i) is a sufficient criterion for the document to be acceptable.

Frequently Asked Questions

What does EN 12845 Annex O contain?

TS EN 12845+A2:2026 Annex O (EN p.163) is an informative annex and its title is 'Example of P&ID'. Its content is nothing but an example diagram; the figure itself carries a symbol key (LEGEND), but it contains no reference to a binding symbol standard, no tagging convention, no separate examples for ESFR or CMSA and no revision schedule.

Is Annex O an annex of EN 12845-1 or of EN 12845-2?

It is an annex of EN 12845-1, that is, of TS EN 12845+A2:2026 (EN p.163). The only annex of EN 12845-2:2024 is Annex A (EN 12845-2, EN p.2).

Is a P&ID mandatory on a project?

Clause 4.4.2 i) (EN p.24): the summary schedule shall give a list of the components suitable for sprinkler use included in the system, each identified by the supplier's name and model/reference number. If required by the authorities, a Piping and Instrumentation Diagram (P&ID) with a list of all components included in the system, each identified by supplier's name, model, diameter, total number and reference number, should be added. For an example of a P&ID, see the figure in Annex O.

Which documents are required at the design stage?

Clause 4.4.1 (EN p.24): the information provided shall include a summary schedule (4.4.2), complete working drawings of the sprinkler installations (4.4.3) and details of the water supplies (4.4.4).

How are alarm and valve details shown on layout drawings?

Clause 4.4.3.1 (EN p.24-25) lists the information to be given on layout drawings; among these are the location and type of control valve sets and the location of water motor alarms, the location and details of any water flow and air or water pressure alarm switches, the location and size of any subsidiary valves, subsidiary stop valves and drain valves, the location of all test valves, the location and details of any alarm panel, and a key to the symbols used.

References

• TS EN 12845+A2:2026 Annex O (EN p.163)
• TS EN 12845+A2:2026 Annex N (EN p.162), Annex P (EN p.164), Annex Q (EN p.165)
• TS EN 12845+A2:2026 Clause 4.4.1 and 4.4.2 (EN p.24)
• TS EN 12845+A2:2026 Clause 4.4.3.1 (EN p.24-25)
• TS EN 12845-2:2024 Contents (EN p.2)

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