In TS EN 12845+A2:2026 the valves are gathered in Clause 15 (TS p.110-113 / EN p.107-110): the control valve set, stop valves, ring main valves, drain valves, test valves, flushing connections and pressure gauges. This article gives all the subclauses, the related definitions (Clause 3) and the monitoring provisions (Annex H), each with its source.
Definitions: control valve set and alarm valve types
Clause 3.17 control valve set (TS p.20 / EN p.17): the assembly comprising an alarm valve, a stop valve and all associated valves and fittings for the control of a sprinkler installation.
The alarm valve types are at the start of Clause 3 (TS p.19 / EN p.16) and the numbers are often confused:
| Clause | Term | Definition |
|---|---|---|
| 3.5 | alarm valve, alternate | Alarm valve suitable for a wet, dry or alternate installation |
| 3.6 | alarm valve, dry | Alarm valve suitable for a dry installation; and/or used together with a wet alarm valve for an alternate installation |
| 3.7 | alarm valve, pre-action | Alarm valve suitable for a pre-action installation |
| 3.8 | alarm valve, wet | Alarm valve suitable for a wet installation |
The clauses that follow immediately are not alarm valve definitions: 3.9 is "area of operation", 3.10 "hydraulically most favourable area of operation" and 3.11 "hydraulically most unfavourable area of operation".
The gauge definitions are on the same page: 3.14 'B' gauge, a pressure gauge connected to and at the same level as the alarm valve, indicating the pressure on the upstream side of the valve; 3.16 'C' gauge, connected in the same way and indicating the pressure on the downstream side.
15.1 and 15.2: Control valve set and stop valves
Clause 15.1 (TS p.110 / EN p.107): Each installation shall have a control valve set in accordance with EN 12259-2 or EN 12259-3.
Clause 15.2 Stop valves (TS p.110 / EN p.107): All stop valves which could cut off the water supply to the sprinklers shall:
- close in the clockwise direction;
- be fitted with an indicator that clearly shows whether it is in the open or closed position;
- be secured in the right position by a strap and padlock or secured in an equivalent manner.
The same clause continues: stop valves shall not be installed downstream of the control valve set except as specified in this standard. In order to facilitate testing and maintenance, a stop valve might be installed downstream of the control valve if monitored.
15.3: Ring main valves
Clause 15.3 (TS p.110 / EN p.107): Where sprinkler systems are fed by a ring main supply pipe arrangement on the premises, stop valves shall be installed to isolate the ring into sections, in such a way that no section shall include more than 4 control valve sets.
15.4 and Table 39: Drain valves
Clause 15.4 (TS p.110 / EN p.107): Drain valves shall be fitted as specified in Table 39 to allow drainage from pipework as follows:
- a) immediately downstream of the control valve set or of its downstream stop valve if fitted;
- b) immediately downstream of any subsidiary alarm valve;
- c) immediately downstream of any subsidiary stop valve;
- d) between a dry pipe or subsidiary control valve set and any subsidiary stop valve installed for testing;
- e) any pipe, with the exception of drop pipes to single sprinklers in a wet installation, which cannot be drained through another drain valve.
Further rules (TS p.111 / EN p.108): the valves shall be fitted at the lower end of the pipework and sized as specified in Table 39. The outlet shall be no more than 3 m above the floor and shall be fitted with a suitable plug.
Table 39: Minimum size of drain valves
| Valve principally draining | Minimum diameter of valve and pipe (mm) |
|---|---|
| LH installation | 40 |
| OH or HHP or HHS installation | 50 |
| Subsidiary installation | 50 |
| A zone | 50 |
| Trapped distribution pipes, diameter ≤ 80 | 25 |
| Trapped distribution pipes, diameter > 80 | 40 |
| Trapped range pipes | 25 |
| Trapped pipework between a dry or subsidiary alarm valve and a subsidiary stop valve installed for testing purposes | 15 |
15.5: Test valves
Clause 15.5.1 Alarm and pump set start test valves (TS p.111 / EN p.108): 15 mm test valves shall be fitted, as appropriate, to test the following:
- a) the hydraulic alarm and any electric alarm pressure switch by drawing water from the immediate downstream side of the following: a wet alarm valve, and any downstream main stop valves; an alternate alarm valve;
- b) the hydraulic alarm and any electric alarm pressure switch by drawing water downstream of the main water supply stop valve and from the upstream side of: an alternate alarm valve; a dry pipe alarm valve; a pre-action alarm valve;
- c) any water flow alarm switch installed downstream of the control valve set, by drawing water downstream of the water flow alarm;
- d) an automatic pump set starting device;
- e) any pump or pressure tank house sprinkler alarm flow switch installed upstream of the control valve set.
Clause 15.5.2 Remote test valves (TS p.112 / EN p.109): A test facility shall be provided, incorporating a test valve with any associated fittings and pipework, delivering a flow equivalent to the discharge from a single sprinkler and connected at the hydraulically most remote location on a distribution pipe.
This test valve is used to measure the water delivery time of dry and alternate installations: Clause 11.2.2 (TS p.70 / EN p.67) requires the maximum time between the opening of a single sprinkler and the discharge of water not to exceed the value in Table 18, and requires the test to be carried out with the remote test valve specified in 15.5.2. Table 18: 90 s for LH, 60 s for OH and HH.
15.6: Flushing connections
Clause 15.6 (TS p.112 / EN p.109): Flushing connections, with or without permanently installed valves, shall be fitted on the spur ends of the installation distribution pipes. Flushing connections shall be of the same size as the distribution pipe; for pipes bigger than DN40, DN40 flushing connections might be used if connected to the lower side of the distribution pipe. Flushing connections shall be fitted with a suitable plug.
The same clause states that, in addition to their use for periodic flushing of the pipework, flushing connections might be used to check that water is available and for carrying out pressure and flow tests. It also notes that pipework completely full of water might be damaged by the increase in pressure due to temperature rises, and requires that where complete venting of air in an installation is likely to occur, e.g. in a gridded layout with flushing connections at the extremities, consideration shall be given to the fitting of pressure relief valves.
15.7: Pressure gauges
Clause 15.7.1 General (TS p.112 / EN p.109): Pressure gauge scale divisions shall not exceed: a) 0.2 bar for a maximum scale value less than or equal to 10 bar; b) 0.5 bar for a maximum scale value greater than 10 bar. The maximum scale value shall be of the order of 150 % of the maximum pressure.
Clause 15.7.2 Water supply connections (TS p.112 / EN p.109): Each town main connection shall be fitted with a pressure gauge between the supply pipe stop valve and the non-return valve (the 'A' gauge). Each pump set supply shall be fitted with a damped pressure gauge on the supply pipe immediately downstream of the outlet non-return valve and upstream of any outlet stop valve.
Clause 15.7.3 Control valve set (TS p.112 / EN p.109): A pressure gauge shall be fitted at each of the following locations:
- a) immediately upstream of each control valve set (the 'B' gauge);
- b) immediately downstream of each control valve set (the 'C' gauge);
- c) immediately downstream of each alternate or dry subsidiary control valve set, but upstream of any stop valve.
Additional provision (TS p.113 / EN p.110): The 'B' gauge on dry alarm valves shall have an indicator showing the maximum pressure attained.
'B' is upstream, 'C' is downstream. Water enters the control valve set from the water supply side and leaves it on the installation side; on a vertical riser, therefore, 'B' is physically below the alarm valve and 'C' above it. The standard defines the gauges not as "upper" or "lower" but as upstream and downstream in the direction of flow.
Clause 15.7.4 Removal (TS p.113 / EN p.110): Means shall be provided to enable each pressure gauge to be removed without interruption of the water or air supply to the installation.
The note below Table 6 (TS p.42 / EN p.39) shows the role of the 'C' gauge in the hydraulic calculation: ps is the static head loss in bar due to the height of the highest sprinkler in the array above the 'C' gauge of the control valve set.
Alarm devices: Clause 16
The alarm side of the control valve set is in Clause 16.
Clause 16.1.1 (TS p.113 / EN p.110): Each control valve set shall be provided with a water motor alarm in accordance with EN 12259-4 and an electrical device for remote alarm indication, both located as close as possible to the alarm valve. A single alarm motor and gong might be installed common to a group of wet alarm valves provided that these are situated in the same valve room and an indicator is fitted to each alarm valve to show when it is operating. Each water motor alarm gong shall be prominently marked with the number of the installation.
Clause 16.1.2 (TS p.113 / EN p.110): The water motor shall be installed in such a way that the gong is on the outside of an exterior wall and with its centre line not higher than 6 m above the point of connection to the alarm valve. A strainer, readily accessible for cleaning, shall be fitted between the motor nozzle and the alarm valve connection. The water outlet shall be arranged so that any flow of water can be seen.
Clause 16.1.3 (TS p.113 / EN p.110): The piping shall be 20 mm diameter galvanized steel or non-ferrous metallic material. The equivalent length of pipe between the alarm valve and the water motor shall be no more than 25 m, assuming an equivalent length of 2 m for each change of direction. The pipe shall be fitted with a stop valve located within the premises and shall be provided with a permanent drain through an orifice of no more than 3 mm in diameter.
Clause 16.2.3 (TS p.114 / EN p.111): On dry and pre-action systems, each installation shall be provided with a low air/gas pressure alarm giving visual and audible warning in accordance with Annex I.
Installation type and size: Clause 11
The type of control valve set determines the type of installation.
Clause 11.1.1 (TS p.69 / EN p.66): Wet pipe installations are permanently charged with water under pressure; they shall be installed only in premises where there is no possibility of frost damage and where the ambient temperature will not exceed 95 °C. Only wet pipe installations shall be used for grid and loop systems.
Clause 11.2.1 (TS p.70 / EN p.67): Dry pipe installations are normally charged with air or inert gas under pressure downstream of the dry alarm valve and water under pressure upstream of it. A permanent air/inert gas supply to maintain the pressure in the pipework shall be installed. The installation shall be pressurized to fall within the pressure range recommended by the alarm valve supplier. Dry pipe installations shall be installed only where there is a possibility of frost damage or the temperature exceeds 70 °C, e.g. in drying ovens.
The standard gives no numerical value and no differential ratio for the air and water pressure in a dry system; it leaves the range to the alarm valve supplier.
Clause 11.3.1 (TS p.71 / EN p.68): Alternate installations incorporate either an alternate alarm valve or a composite set consisting of a wet and a dry alarm valve. During the winter months the pipework downstream of the alarm valve is charged with air or inert gas under pressure and upstream with water under pressure; during the rest of the year the system operates as a wet pipe installation.
Clause 11.4.1.2 Type A pre-action installation and 11.4.1.3 Type B (TS p.71 / EN p.68): in Type A the control valve set is actuated by an automatic fire detection system and not by the operation of the sprinklers; the air/inert gas pressure is monitored at all times and at least one quick opening manually operated valve is installed to actuate the pre-action valve in an emergency. In Type B the control valve set is actuated either by the detection system or by the operation of the sprinklers.
Clause 11.1.3, Table 17 (TS p.70 / EN p.67) gives the maximum protected area that a single control valve set may control:
| Hazard class | Maximum protected area per control valve set |
|---|---|
| LH | 10 000 m² |
| OH, including any LH sprinklers | 12 000 m² (except as allowed in Annexes D and F) |
| HH, including any OH and LH sprinklers | 9 000 m² |
Frost protection and monitoring
Clause 8.1.3 Protection against freezing (TS p.45 / EN p.42): The supply pipe and the control valve set shall be kept at a minimum temperature of 4 °C.
Annex H, H.2.2 Stop valves controlling the flow of water to sprinklers (TS p.156 / EN p.153): the position of all stop valves whose closure could prevent sufficient water flowing to the sprinklers shall be monitored, including water supply valves, control valve sets, subsidiary valves and section valves. For normally open valves the alarm shall be initiated as soon as the valve starts to close.
H.2.3 Other stop valves (TS p.156 / EN p.153): the position of all stop valves whose closure could prevent the correct operation of an alarm or indicating device (for example a pressure switch, a hydraulic alarm or a flow switch) shall be monitored; for normally open valves the alarm shall again be initiated as soon as the valve starts to close.
The standard gives no measure such as "the first quarter turn" here; the criterion is that the valve starts to close.
Annex H, H.1 (TS p.156 / EN p.153): All devices used for monitoring shall have a protection of at least IP 54 as specified in EN 60529. No more than 15 non-addressable supervisory alarm devices shall be connected to a common indication.
Valves in maintenance
Clause 20.3.2.7 Stop valves (TS p.124 / EN p.121): in the quarterly routine, all stop valves controlling the flow of water to sprinklers shall be operated to make sure that they are in working order and securely refixed in the correct mode. This includes those on all water supplies, on the alarm valve and all zone or other subsidiary stop valves.
Clause 20.3.3.2 Dry alarm valves (TS p.124 / EN p.121): in the half yearly routine, the moving parts of the dry alarm valves on dry pipe installations and subsidiary extensions, and of any accelerators and exhausters, shall be moved in accordance with the supplier's instructions. NOTE: alternate installations need not be tested in this way, because they are already operated as a result of the changeover from wet to dry and back twice a year.
Clause 20.3.5.3 (TS p.125 / EN p.122): in the 3 year routine, all water supply stop valves, alarm valves and non-return valves shall be examined and, where necessary, replaced or overhauled.
Field note
Read together, the downstream stop valve exception in Clause 15.2 ("if monitored") and the "alarm as soon as the valve starts to close" requirement of Annex H.2.2 show that every isolation point on the installation side has to enter the monitoring architecture. On projects that satisfy the two provisions separately but never connect them, a single unmonitored maintenance valve can blind the whole installation. (This paragraph is engineering commentary.)
Frequently Asked Questions
How does EN 12845 define the control valve set?
TS EN 12845+A2:2026 Clause 3.17 (TS p.20 / EN p.17): a control valve set is the assembly comprising an alarm valve, a stop valve and all associated valves and fittings for the control of a sprinkler installation. Clause 15.1 (TS p.110 / EN p.107) requires each installation to have a control valve set in accordance with EN 12259-2 or EN 12259-3.
What three requirements apply to stop valves?
Clause 15.2 (TS p.110 / EN p.107): all stop valves which could cut off the water supply to the sprinklers shall close in the clockwise direction; be fitted with an indicator that clearly shows whether the valve is in the open or closed position; and be secured in the right position by a strap and padlock or secured in an equivalent manner. In addition, stop valves shall not be installed downstream of the control valve set except as specified in the standard; to facilitate testing and maintenance a stop valve might be installed downstream of the control valve if monitored.
Where are the 'B' and 'C' gauges located?
Clause 15.7.3 (TS p.112 / EN p.109): a 'B' gauge shall be fitted immediately upstream of each control valve set and a 'C' gauge immediately downstream of it; a gauge shall also be fitted immediately downstream of each alternate or dry subsidiary control valve set, but upstream of any stop valve. The definitions are in Clauses 3.14 and 3.16: the 'B' gauge is connected to and at the same level as the alarm valve and indicates the pressure on the upstream side of the valve; the 'C' gauge indicates the pressure on the downstream side (TS p.19 / EN p.16).
How many control valve sets may a ring main section contain?
Clause 15.3 (TS p.110 / EN p.107): where sprinkler systems are fed by a ring main supply pipe arrangement on the premises, stop valves shall be installed to isolate the ring into sections, in such a way that no section shall include more than 4 control valve sets.
When must a normally open stop valve raise an alarm?
Annex H, H.2.2 and H.2.3 (TS p.156 / EN p.153): the position of all stop valves whose closure could prevent sufficient water flowing to the sprinklers shall be monitored; for normally open valves the alarm shall be initiated as soon as the valve starts to close. The standard gives no number of turns and no percentage.
References
- TS EN 12845+A2:2026 Clauses 3.5-3.8 alarm valve types, 3.14 'B' gauge, 3.16 'C' gauge (TS p.19 / EN p.16)
- TS EN 12845+A2:2026 Clause 3.17 Control valve set (TS p.20 / EN p.17)
- TS EN 12845+A2:2026 Clause 8.1.3 Protection against freezing (TS p.45 / EN p.42)
- TS EN 12845+A2:2026 Clauses 11.1.1, 11.1.3, Table 17, 11.2.1, 11.2.2, Table 18 (TS p.69-70 / EN p.66-67)
- TS EN 12845+A2:2026 Clauses 11.3.1, 11.4.1.2, 11.4.1.3 (TS p.71 / EN p.68)
- TS EN 12845+A2:2026 Clauses 15.1, 15.2, 15.3, 15.4 (TS p.110 / EN p.107)
- TS EN 12845+A2:2026 Table 39 Drain valves, Clause 15.5.1 (TS p.111 / EN p.108)
- TS EN 12845+A2:2026 Clauses 15.5.2, 15.6, 15.7.1, 15.7.2, 15.7.3 (TS p.112 / EN p.109)
- TS EN 12845+A2:2026 Clause 15.7.3 dry alarm valve indicator, 15.7.4, 16.1.1, 16.1.2, 16.1.3 (TS p.113 / EN p.110)
- TS EN 12845+A2:2026 Clause 16.2.3 (TS p.114 / EN p.111)
- TS EN 12845+A2:2026 Clause 7.3.1, Table 6 and the ps note (TS p.42 / EN p.39)
- TS EN 12845+A2:2026 Clauses 20.3.2.7, 20.3.3.2 (TS p.124 / EN p.121), 20.3.5.3 (TS p.125 / EN p.122)
- TS EN 12845+A2:2026 Annex H, H.1, H.2.2, H.2.3 (TS p.156 / EN p.153)
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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.