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Only filters as approved together with the nozzle shall be used.

Pressure reducing orifice assemblies shall be permanently marked to identify the size of the orifice. This marking shall be readily visible after the assembly is installed.

Detection, actuation and control systems may be either automatic or manual. Where they are automatic, provision shall also be made for manual operation.

Detection, actuation, alarm and control systems shall be installed, tested and maintained in accordance with appropriate national standards.

Unless otherwise specified in a national standard, 24 h minimum standby sources of energy shall be used to provide for operation of the detection, signalling, control and actuation requirements of the system.

Automatic detection shall be by any method or device acceptable to the authority and shall be capable of early detection and indication of heat, flame, smoke, combustible vapours or any abnormal condition in the hazard that is likely to produce fire.

Fire detection components shall be approved in accordance with the relevant part of EN 54 or EN 12094, whichever applies.

NOTE Detectors installed at the maximum approved spacing for fire alarm use can result in excessive delay in extinguishant release, especially where more than one detection device is required to be in alarm before automatic actuation results.

Automatic systems shall be controlled by automatic fire detection and actuation systems suitable for the system and hazard, and shall also be provided with a means of manual operation.

Electrically operated fire detection systems shall comply with the appropriate national standard. The electric power supply shall be independent of the supply for the hazard area, and shall include an emergency secondary power supply with automatic changeover in case the primary supply fails.

When two or more detectors are used, such as those for detecting smoke or flame, it is preferable for the system to operate only after signals from two detectors have been received.

Provision shall be made for manual operation of the fire fighting system by means of a control situated outside the protected space or adjacent to the main exit from the space.

In addition to any means of automatic operation, the system shall be provided with the following:

1. one or more means, remote from the containers, of manual operation;

2. a manual device for providing direct mechanical actuation of the system or an electrical manual release system in which the control equipment monitors for abnormal conditions in the power supply and provides a signal when the power source is inadequate.

Manual operation shall cause simultaneous operation of the appropriate automatically operated valves for extinguishant release and distribution.

NOTE 1 National standards may not require a manual release, or may require the release to operate via the pre­discharge alarms and time delay.

The manual operation device shall incorporate a double action or other safety device to restrict accidental operation. The device shall be provided with a means of preventing operation during maintenance of the system.

NOTE 2 The choice of the means of operation will depend upon the nature of the hazard to be protected. Automatic fire detection and alarm equipment will normally be provided on a manual system to indicate the presence of a fire.

Manual operating devices shall be approved in accordance with EN 12094-3.

Electric control equipment shall be used to supervise the detecting circuits, manual and automatic releasing circuits, signalling circuits, electrical actuating devices and associated wiring and, when required, cause actuation. The control equipment shall be capable of operation with the number and type of actuating devices utilized.

Electrical automatic control and delay devices shall be approved in accordance with EN 12094-1.

Where pneumatic control equipment is used, the lines shall be protected against crimping and mechanical damage. Where installations could be exposed to conditions that could lead to loss of integrity of the pneumatic lines, special precautions shall be taken to ensure that no loss of integrity will occur.

Non-electrical automatic control and delay devices shall be approved in accordance with EN 12094-2.

Pneumatic alarm devices shall be approved in accordance with EN 12094-12.

positive warning of impending discharge. The operation of the warning devices shall be continued after extinguishant discharge, until positive action has been taken to acknowledge the alarm and proceed with appropriate action.

Stop devices, where provided, shall be located within the protected area and shall be located near the means of egress for the area. The stop device shall be a type that requires constant manual force to inhibit system operation. Operation of the hold function shall result in both audible and distinct visual indication of system impairment. Operation of the stop device when the system is in the quiescent state shall result in a fault indication at the control unit. The stop device shall be clearly recognizable for the purpose intended.

Stop devices shall be approved in accordance with EN 12094-3.

6. Extinguishant

   1. General

This clause sets out the requirements for the specifications, system flow calculations and extinguishant concentrations. It shall be read in conjunction with the appropriate part of EN 15004 for the specific agent.

Specifications for gaseous fire-extinguishing systems shall be prepared under the supervision of a person fully experienced in the design of gaseous extinguishing systems and, where appropriate, with the advice of the authority. The specifications shall include all pertinent items necessary for the proper design of the system such as the designation of the authority, variances from the standard to be permitted by the authority, design criteria, system sequence of operations, the type and extent of the acceptance testing to be performed after installation of the system and owner training requirements. Extinguishant specifications are included in the various parts of EN 15004 for the specific agent.

Layout and system proposal documents shall be submitted for approval to the authority before installation or modification begins. The type of documentation required is specified in Annex A.

System flow calculations shall be carried out at a nominal extinguishant storage temperature of 20 °С, shall have been validated by an accredited approval authority by appropriate tests as for example described in this document, and shall be properly identified. The system design shall be within the manufacturer's specified limitations (see also Annex H).

NOTE 1 Variations from the nominal 20 °С storage temperature will affect flow conditions used in calculations.

NOTE 2 Pre-engineered systems do not require a flow calculation when used within approved limitations.

1. actual or equivalent pipe lengths from the container to each nozzle are all within 10 % of each other;

2. the discharge rate of each nozzle is equal (see Figure 1).

Allowance shall be made for the friction losses in pipes and in container valves, dip tubes, flexible connectors, selector valves, time delay devices and other equipment (e.g. pressure-reducing devices) within the flow line.

NOTE The flow of a liquefied gas has been demonstrated to be a two-phase phenomenon, the fluid consisting of a mixture of liquid and vapour, the proportions of which are dependent on pressure and temperature. The pressure drop is non-linear, with an increasing rate of pressure loss as the line pressure reduces by pipe friction.

The pressure drop shall be calculated using two-phase flow equations for liquefied gases and single-phase flow equations for non-liquefied gases.

NOTE These equations use friction factors and constants dependent on pressure and density obtained empirically. As the equations cannot be solved directly, a computer program is usually used to assist with the large number of iterative calculations in which pipe and nozzle sizes and if appropriate, size of pressure reducing devices, are selected within prescribed pressure losses.

Valves, fittings and check valves shall be rated for resistance coefficient or equivalent length in terms of pipe, or tubing sizes with which they will be used. The equivalent length of the cylinder valves shall be listed and shall include syphon tube (where fitted), valve, discharge head, flexible connector and check valve.

Dimensions in metres

NOTE Figures in bold in parentheses denote design nodes for calculations.

Figure 1—Typical balanced system

The piping length and nozzle and fitting orientation shall be in accordance with the manufacturer's approved manual to ensure proper system performance.

If the final installation varies from the prepared drawings and calculations, new as-installed drawings and calculations shall be prepared.

NOTE If turbulent flow is not maintained, separation of the liquid and gaseous phases will occur, which can lead to unpredictable flow characteristics.

Figure 2—Typical unbalanced system

All services within the protected enclosure (e.g. fuel and power supplies, heating appliances, paint spraying) that are likely to impair the performance of the extinguishing system should be shut down prior to, or simultaneously with, the discharge of the extinguishant.

CAUTION: It is recognized that the wood crib and polymeric sheet class A fire tests may not adequately indicate extinguishing concentrations suitable for the protection of certain plastic fuel hazards (e.g. electrical and electronic type hazards involving grouped power or data cables such as computer and control room under-floor voids, telecommunication facilities, etc.). An extinguishing concentration not less than that determined in accordance with 7.5.1.3, or not less than 95 % of that determined for heptane in accordance with 7.5.1.2, whichever is greater, should be used under certain conditions. These conditions may include:

1. cable bundles greater than 100 mm in diameter,

2. cable trays with a fill density greater than 20 % of the tray cross-section;

3. horizontal or vertical stacks of cable trays (closer than 250 mm);

4. equipment energized during the extinguishment period where the collective power consumption exceeds 5 kW.

If polymeric sheet fire test data are not available, an extinguishing concentration 95 % of that determined from the heptane fire test shall be used.

The safety factor of 1,3 relates to the increase of 30 % from the extinguishing concentration to the design concentration, which results in additional quantity of agent. Circumstances which may not be adequately covered by this factor (although in some cases they are covered by other requirements in this document) and which may need allowance for additional extinguishant (i.e. more than 30 %) are included but not limited to the following:

1. where leakage occurs from a non-tight enclosure. This is covered in this document by the requirement for a room integrity test and sealing of the enclosure to achieve a defined hold time;

2. where leakage occurs due to doors being opened during or immediately after discharge. This should be covered by operational protocols for individual risks;

3. where it is important to minimize the quantities of toxic or corrosive products of combustion from the fire;

4. where it is important to minimize the toxic or corrosive breakdown products from the extinguishant itself;

5. where excessive leakage occurs from an enclosure due to expansion of the extinguishant;

6. where hot surfaces, heated by fire or other means, may cause degradation of the extinguishing agent and hence reduce the efficiency of the agent;

7. where metal surfaces, heated by the fire, may act as an ignition source if not adequately cooled during agent discharge and hold time.

In practice, application of this document is likely to result in higher safety factors, for example by the application of gross volumes rather than net volumes and design of systems for minimum anticipated temperatures, rather than those that apply in real conditions.

WARNING: Under certain conditions, it may be dangerous to extinguish a burning gas jet. As a first measure, shut off the gas supply.

7.5.2 Inerting

Inerting concentrations shall be used where conditions for subsequent reflash or explosion could exist. These conditions exist when both:

1. the quantity of fuel permitted in the enclosure is sufficient to develop a concentration equal to or greater than one-half of the lower flammable limit throughout the enclosure; and

2. the volatility of the fuel before the fire is sufficient to reach the lower flammable limit in air (maximum ambient temperature or fuel temperature exceeds the closed cup flash point temperature) or the system response is not rapid enough to detect and extinguish the fire before the volatility of the fuel is increased to a dangerous level as a result of the fire.

The minimum design concentrations used to inert atmospheres involving flammable liquids and gases shall be determined by the test specified in Annex D, plus a safety factor of 10 %.

7.6 Total flooding quantity

The amount of extinguishant required to achieve the design concentration shall be calculated from Equations (1) or (2) as appropriate, or from the data in Table 3 of EN 15004-2:2008 and EN 15004-4:2008 to EN 15004­10:2008 and in Table 4 of EN 15004-3:2008.

In addition to these calculated concentration requirements, additional quantities of extinguishant may be required by national standards to compensate for any special conditions that would adversely affect the extinguishing efficiency (see 7.5.1), or if required by the physical characteristics of the extinguishant (see 7.9.1.2).

^<1) IjOO-cJv

where

Q is the total flooding quantity, in kilograms;

c is the design concentration in percent by volume;

V is the net volume of the hazard, in cubic metres (i.e. enclosed volume minus fixed structures impervious to extinguishant);

v is the specific volume, in cubic metres per kilogram: v = k_t+ k₂ x T

k_x, k, are constants specific to the extinguishant being used, supplied by the extinguishant manufacturer;

T is the minimum anticipated ambient temperature of the protected volume, in degrees Celsius.

Q is the total flooding quantity, in kilograms;

c is the design concentration, in percent by volume;

V is the net volume of hazard, in cubic metres (i.e. enclosed volume minus fixed structures impervious to extinguishant);

v is the specific volume, in cubic metres per kilogram: v = k_{+ k₂ x T

k_vk₂ are constants specific to the extinguishant being used, supplied by the extinguishant manufacturer;

T is the minimum anticipated temperature of the protected volume, in degrees Celsius.

NOTE For some purposes (e g. filling of containers) it may be convenient to express the flooding quantity as volume at given reference (standard) conditions. For those cases the total flooding quantity is equivalent to

Or = Q*vr

where

Q_r is the total flooding quantity, in cubic metres, expressed at ambient pressure (1,013 bar absolute) and T_R;

Q is the total flooding quantity, in kilograms;

v_R is the specific volume at reference temperature, in cubic metres per kilogram: v_R = k_}+ k₂ x t_r

k_vk₂ are constants specific to the extinguishant being used, supplied by the extinguishment manufacturer;

T_R is the reference temperature, in degrees Celsius.

The design quantity of the extinguishant shall be adjusted to compensate only for ambient pressures that vary more than 11 % (equivalent to approximately 1 000 m of elevation change) from standard sea level pressure (1,013 bar absolute). The ambient pressure is affected by changes in altitude, pressurization or depressurization of the protected enclosure, and weather-related barometric pressure changes. The extinguishant quantity is determined by multiplying the quantity determined in 7.6 by the ratio of the average ambient enclosure pressure to the standard sea level pressure. Correction factors for gaseous agents are shown in Table 5.

Table 5 — Correction factors