In TS EN 12845+A2:2026 there is a single clause and a single paragraph under the heading "monthly routine": Clause 20.2.3, TS p.123 / EN p.120. This article reproduces that paragraph in full, states plainly which numerical values the standard does not give, and establishes the relationship of the monthly check with the other periods on the basis of the standard. Source: TS EN 12845+A2:2026, Clauses 20.2 and 20.3.
The full text of Clause 20.2.3
The electrolyte level and density of all lead-acid cells (including those for diesel engine starter batteries and control panel power supplies) shall be checked. If the density is low, the battery charger shall be checked and, if this is operating correctly, the affected battery or batteries shall be replaced.
That is the whole of the monthly routine. The clause has no subclauses, checklist or acceptance criteria.
Three binding elements follow from the text:
- Scope: all lead-acid cells. The standard extends the scope with two examples: diesel engine starter batteries and batteries for control panel power supplies. Panel supply batteries, not only the diesel pump battery bank, therefore fall within the monthly check.
- Two quantities measured: the electrolyte level and the electrolyte density.
- Decision chain: density low, then check the charger first, then replace the battery if the charger is operating correctly. The standard does not separately state what to do if the charger turns out to be faulty; the requirement to replace the battery is tied solely to the condition that the charger is operating correctly.
The numbers the standard does not give
A common mistake is to attribute numerical acceptance criteria to Clause 20.2.3. None of the following appears in the text of TS EN 12845+A2:2026:
- A specific gravity band (for example "1.265 to 1.285 fully charged")
- A temperature correction factor
- A permissible density difference between cells
- The distance the electrolyte level shall remain above the plates
- Float or boost charging voltage, or float current
- Battery life or replacement age
- An open circuit battery voltage threshold or a terminal tightening torque
The standard explicitly leaves the place of these values to the supplier. Clause 20.3.1.1 Procedures (TS p.123 / EN p.120): "In addition to the schedule given in this clause, all procedures recommended by component suppliers shall be carried out." If a measurement band is to be used, its source is therefore the documentation of the battery or charger manufacturer, not EN 12845.
The only place in the standard where a hydrometer is mentioned relates to a different subject: Clause 11.1.2.2 (TS p.69 / EN p.66) requires the specific gravity of the prepared solution in pipe sections protected by antifreeze solution to be checked with a suitable hydrometer. This has nothing to do with battery electrolyte.
Also, the battery provisions under 10.9 have been removed in A2:2026
In TS EN 12845+A2:2026, Clause 10.9 on the diesel pump set consists of only three subclauses (TS p.68-69 / EN p.65-66):
- 10.9.1 General: diesel driven pump sets and their auxiliaries shall comply with EN 17451. Sufficient fresh air shall be available in the pump room at all times to keep the diesel pump set operating within the limits specified by the manufacturer and within EN 17451.
- 10.9.2 Starting alarm indication: four conditions shall be indicated by warning lamps both locally and in a location with responsible personnel: a) pump running, b) start failure, c) common faults, d) automatic mode off.
- 10.9.3 Site commissioning test: shall be carried out in accordance with EN 17451.
The practical consequence: provisions such as the number of battery sets, the battery standard or the charger cell voltage are no longer to be sought in EN 12845; they have been transferred to EN 17451. There are no subclauses from 10.9.4 onwards in the A2:2026 text.
There is one dangling cross reference in the text, and knowing it is useful during an audit: Clause 20.3.4.3 (TS p.125 / EN p.122) states in the yearly routine that "the failure to start alarm shall be tested in accordance with 10.9.7.2", but there is no clause 10.9.7.2 in A2:2026. The second sentence of the same clause is applicable: immediately after this test the engine shall be started using the manual starting system.
The place of the monthly check in the period architecture
| Period | Clause | Battery related content | Page |
|---|---|---|---|
| Weekly | 20.2.2.4 | On diesel engines the fuel and engine lubricating oil levels are checked; the automatic starting condition is simulated by reducing the water pressure at the starting device; when the pump starts, the starting pressure is checked and recorded | TS p.122 / EN p.119 |
| Weekly | 20.2.2.5 | The engine is run for 20 min (or the period recommended by the supplier), stopped and immediately restarted using the manual start test button; on closed circuit cooling the water level in the primary circuit is checked | TS p.122-123 / EN p.119-120 |
| Monthly | 20.2.3 | Electrolyte level and density of all lead-acid cells | TS p.123 / EN p.120 |
| Yearly | 20.3.4.3 | Diesel engine failed-to-start alarm test followed by starting with the manual system | TS p.125 / EN p.122 |
The manual restart step of the weekly routine and the monthly battery check complement each other: the weekly test actually loads the starting circuit, while the monthly check looks at the state of the cell chemistry.
The alarm equivalent of a battery or supply fault
A problem found during the monthly check has its counterpart in the monitoring architecture of the system.
Clause 10.9.2 (TS p.69 / EN p.66) requires four warning lamps on the diesel pump set (pump running, start failure, common faults, automatic mode off). Clause 18.2.6.2 (TS p.119-120 / EN p.116-117) requires these alarms to be marked both at the pump set control panel and in the location with responsible personnel with the following wording: "diesel fire pump starter switched off", "diesel fire pump failure to start", "pump running", "diesel controller fault". The manually operated shut down mechanism is labelled 'SPRINKLER PUMP SHUT-OFF'.
Annex I, Table I.1 (TS p.158 / EN p.155) gives the alarm types. For the diesel pump set: automatic mode off B, start failure B, running A, common fault B. For the electric pump set (10.8.5.1): demand B, start failure B, running A, no power B. Annex I, I.2 (TS p.159 / EN p.156): technical faults such as a power failure that could prevent the correct operation of the system in a fire shall be indicated as level B (trouble alarm).
Annex H, H.2.6 Electrical power (TS p.157 / EN p.154) requires the power supply to electric pump sets or other critical electrical equipment to be monitored: an indication shall be given if one or more phases fail at any point in the main supply, in the control circuit or in the control unit of the electric or diesel pump set.
The only measurable threshold on the fuel side is in Annex H: H.2.4 Liquid levels (TS p.156 / EN p.153) requires an indication before the water storage level falls by more than 10% of the nominal filling level and before the fuel level falls by more than 25% of the nominal filling level. This is a fuel provision, not a battery provision, but it is read together with the monthly diesel check.
Pump room conditions
The environmental condition that directly affects the result of the monthly battery check is numerical in the standard. Clause 10.3.3 Temperature (TS p.61 / EN p.58): the pump set compartment shall be maintained at or above 4 °C for electrically driven pump sets and 10 °C for diesel driven pump sets. Clause 10.3.4 Ventilation (TS p.61 / EN p.58): adequate ventilation in accordance with the supplier's recommendations shall be provided for diesel pump set compartments. Annex H, H.2.7 (TS p.157 / EN p.154) requires the minimum temperature of the sprinkler valve and pump rooms to be monitored, with an indication if the temperature falls below the required minimum level.
Field note
Because Clause 20.2.3 gives no acceptance criterion, a monthly form that carries the measured value and the source of the criterion (the battery manufacturer's data sheet) side by side prevents disputes at the yearly inspection. Likewise, because of the words "control panel power supplies", the form should contain a line not only for the diesel starter battery but also for the panel batteries. (This paragraph is engineering commentary.)
Frequently Asked Questions
What exactly does the EN 12845 monthly routine cover?
Batteries only. TS EN 12845+A2:2026 Clause 20.2.3 (TS p.123 / EN p.120): 'The electrolyte level and density of all lead-acid cells (including those for diesel engine starter batteries and control panel power supplies) shall be checked. If the density is low, the battery charger shall be checked and, if this is operating correctly, the affected battery or batteries shall be replaced.' There is no other item in the monthly routine.
Which density value does the standard require?
None. Clause 20.2.3 gives no numerical specific gravity band, no temperature correction, no cell to cell difference limit, no electrolyte height, no float or boost voltage and no battery life. The numerical meaning of 'if the density is low' is the component supplier's data; Clause 20.3.1.1 (TS p.123 / EN p.120) requires that all procedures recommended by component suppliers are also carried out.
Which alarm corresponds to the result of the monthly battery check?
On a diesel pump set, Clause 10.9.2 (TS p.69 / EN p.66) requires four conditions to be indicated by warning lamps both locally and in a location with responsible personnel: pump running, start failure, common faults, automatic mode off. Annex I Table I.1 (TS p.158 / EN p.155) classifies the 'running' signal as type A and the other three as type B (technical) alarms.
How is the monthly routine separated from the weekly routine?
The weekly routine is Clause 20.2.2 and is carried out at intervals of not more than 7 days: pressure gauge readings, water levels, main stop valve positions, sounding of the water motor alarm for at least 30 s, automatic pump starting test and running the diesel engine for 20 min. The monthly routine is only the battery check of Clause 20.2.3 (TS p.122-123 / EN p.119-120).
Who performs the monthly check and where is it recorded?
Clause 20.2 is the user's inspection and checking programme; Clause 20.1.1 (TS p.121 / EN p.118) requires the user to appoint a responsible person and a deputy and to display their contact details in the sprinkler valve room. Clause 20.1.2 requires records and a logbook to be kept and held on the premises.
References
- TS EN 12845+A2:2026 Clause 20.2.3 Monthly routine (TS p.123 / EN p.120)
- TS EN 12845+A2:2026 Clause 20.2.2.4 and 20.2.2.5 Weekly routine (TS p.122-123 / EN p.119-120)
- TS EN 12845+A2:2026 Clause 20.1.1 and 20.1.2 (TS p.121 / EN p.118)
- TS EN 12845+A2:2026 Clause 20.3.1.1 Procedures, 20.3.1.2 Records (TS p.123 / EN p.120)
- TS EN 12845+A2:2026 Clause 20.3.4.3 Diesel engine failure to start test (TS p.125 / EN p.122)
- TS EN 12845+A2:2026 Clause 10.3.3 Temperature, 10.3.4 Ventilation (TS p.61 / EN p.58)
- TS EN 12845+A2:2026 Clause 10.8.5.1, 10.9.1, 10.9.2, 10.9.3 (TS p.68-69 / EN p.65-66)
- TS EN 12845+A2:2026 Clause 11.1.2.2 Protection by antifreeze solution (TS p.69 / EN p.66)
- TS EN 12845+A2:2026 Clause 18.2.6.2 Diesel pump set labels (TS p.119-120 / EN p.116-117)
- TS EN 12845+A2:2026 Annex H, H.2.4 Liquid levels (TS p.156 / EN p.153), H.2.6 Electrical power and H.2.7 Temperature (TS p.157 / EN p.154)
- TS EN 12845+A2:2026 Annex I, Table I.1 and I.2 (TS p.158-159 / EN p.155-156)
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Download MEP Calc on the App StoreTS EN 12845+A2:2026 (EN 12845:2015+A2:2026) Fixed firefighting systems — Automatic sprinkler systems — Design, installation and maintenance; TS EN 12845-2:2025 (EN 12845-2:2024) ESFR and CMSA sprinkler systems. Every figure in this article is taken from the published standard text; clause, table and page references are listed under References. General information only, not a substitute for the standard or for a design review.