1418 design and installation of a visible element to the general emergency alarm on passenger ships

Guidelines for the design and installation of a visible element to the general emergency alarm on passenger ships

		dd-mm-yyyy = Entry into force
Document	MSC.1/Circ.1418	21-05-2012

1. The Maritime Safety Committee, at its ninetieth session (16 to 25 May 2012), with a view to providing guidance on the addition of a visual element to the general emergency alarm system on passenger ships, as required by SOLAS regulation III/6.4.2, and following a recommendation made by the Sub-Committee on Ship Design and Equipment, at its fifty-fifth session, and the Sub-Committee on Fire Protection, at its fifty-fifth session, approved the annexed Guidelines for the design and installation of a visible element to the general emergency alarm on passenger ships.
   
   
2. Member Governments are invited to use the annexed Guidelines from 21 May 2012 when applying the relevant provisions of SOLAS regulation III/6.4.2 and to bring them to the attention of all parties concerned.

Annex

Annex - Guidelines for a visual element to the general emergency alarm system on passenger ships

01 General

1 - General

This document provides guidance on the addition of a visual element to the general emergency alarm system on passenger ships, as required by SOLAS regulation III/6.4.2, for the purpose of alerting persons who are deaf or hard of hearing while minimizing the possibility of triggering seizures in persons who have photosensitive epilepsy.

02 Definitions

2 - Definitions

2.1Effective intensity is a measure of the brightness of a flashing light equivalent to the brightness of a steady-burning light as seen by a human observer. It is determined using specialized photometric equipment and reported in candela (cd).

2.2Field of view is the line of sight over any 135° sector from any location.

2.3Flash rate is the number of flashes per unit of time reported in Hertz (Hz).

2.4Illumination is the amount of light incident on a surface measured in lumens per square metre.

2.5Photosensitive epilepsy is a chronic neurological disorder characterized by recurrent seizures triggered by visual stimuli that form patterns in time or space, such as flashing lights, bold, regular patterns, or regular moving patterns.

2.6Polar diagram is a graph employing polar coordinates to show the variation in effective intensity as a function of direction from the visual signal device.

2.7Public accommodation spaces are those accommodation spaces for public use by passengers, such as public spaces, dining rooms, lounges, showrooms, public restrooms, corridors, lobbies, stairways, cinemas, gymnasiums, atriums, shops, and other similar spaces. It excludes cabins and associated balconies.

2.8Pulse duration is the time interval between initial and final points of 10 per cent of maximum intensity of the flash.

2.9Synchronized is appearing to occur at the same time as seen by a human observer.

2.10Visual signal is the element of the general emergency alarm conveyed by regular repeated flashes of light.

03 Principal characteristics

3 - Principal characteristics

3.1 The general emergency alarm system in all interior public accommodation spaces should have both a visual signal and an audible signal.

3.2 The visual signal should be integrated into the general emergency alarm system such that activation of the general emergency alarm results in the concurrent activation of both audible and visual signals without further action.

3.3 The device for producing the visual signal should have the same reliability and suitability for marine service as the other components of the general emergency alarm.

3.4 The visual signal should not interfere with the ability of the crew to safely navigate the ship at night.

3.5 The visual signal should be effective for alerting persons who are deaf or hard of hearing while minimizing the possibility of triggering seizures in passengers and crew who have photosensitive epilepsy. Visual signals with the following characteristics have been found to be acceptable¹:

1. the lamp should be a xenon strobe type or equivalent;
   
   
2. the colour should be clear or nominal white;
   
   
3. the effective intensity should not exceed 1,000 cd;
   
   
4. the flash rate should not exceed two flashes per second (2 Hz) nor be less than one flash every second (1 Hz) throughout the design voltage range of the device; and
   
   
5. the maximum pulse duration should be 0.2 s with a maximum duty cycle of 40%.
   
   

3.6 To be effective, the visual signal device should comply with Table 1. This can be verified from a polar diagram of intensity and angles determined in accordance with an international or a national standard acceptable to the Administration.²

3.7 All visual signal devices within a field of view should be synchronized. This includes strobes operated by separate systems. The field of view includes viewing from an adjacent space. However, it is not necessary to synchronize visual signal devices and other strobes located in an adjacent main vertical zone (MVZ) due to a field of view extending through a doorway or other opening in the MVZ boundary, provided that the combined flash rate of all devices and strobes in such field of view does not exceed 4 Hz.

3.8 For spaces equipped with the means of subdividing into smaller spaces (e.g. with movable bulkheads), the visual signal should be effective in each of the smaller spaces when so subdivided.

Table 1 – Minimum distribution of effective intensity
Ceiling-mounted device		Bulkhead-mounted device
Off-angle axis (degrees)	Minimum percentage of rated effective intensity	Vertical distribution (degrees)	Minimum percentage of rated effective intensity	Horizontal distribution (degrees)	Minimum percentage of rated effective intensity
0	100%	0	100%	0	100%
45	75%	30	90%	45	75%
90	25%	90	12%	90	25%

3.9 The visual signal should be designed and installed in such a manner to be quickly noticed by an alert person anywhere within the space. Either of the approaches in 4.1 or 4.2 or an equivalent standard acceptable to the Administration is suitable.

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¹These characteristics are the same as found in chapter 18 of NFPA 72-2010, National Fire Alarm and Signaling Code of the United States. Devices with similar characteristics are found in many commercial and public buildings in the United States.
²An example of such a standard is ANSI/UL 1971, Standard for Signaling Devices for the Hearing Impaired of the United States.

04 System design and arrangement

4 - System design and arrangement

4.1 Performance approach
A suitable performance requirement is complete coverage of a space with a minimum illumination of 0.4036 lumens/m2 as calculated at any point in the covered area, based on the use of the polar diagrams of the devices used.

4.2 Prescriptive approach

4.2.1 Visual signal devices should be located to provide complete coverage of the protected space.

4.2.1.1 The area of coverage of a bulkhead-mounted visual signal device is a rectangle with the device mounted halfway along one edge of the rectangle as shown in Figure 1. The maximum horizontal dimension (X) of the area of coverage for varying effective intensities is found in Table 2.

4.2.1.2 The area of coverage of a ceiling-mounted visual signal device is a square with the device located in the centre of the square as shown in Figure 1. The maximum horizontal dimension (X) of the area of coverage for varying effective intensities and lens heights is found in Table 3.

4.2.1.3 When the visual signal device is not mounted per 4.2.1.1 or 4.2.1.2, the maximum horizontal dimension (X) should be determined by doubling the distance from the device to the farthest edge of the area of coverage. The pertinent edge for a bulkhead-mounted device is the side edge, not the edge opposite the device.

Figure 1 – Area of coverage

 

Table 2 – Maximum dimension versus effective intensity
Maximum horizontal dimension (m)	Minimum effective intensity (cd)
6	15
8.5	30
9	33
10	41
11	50
12	59
13	69
14	80
15	92
16	104
17	118
18	132
19	147
20	162
21	179
22	197

 

Table 3 – Effective intensity of ceiling-mounted devices by maximum dimension and height of lens1

4.2.2 Bulkhead-mounted visual signal devices should be mounted on the bulkhead such that the entire lens is not less than 2,030 mm and not greater than 2,440 mm above the deck surface. For spaces with multiple levels, the mounting height should be determined above the nearest deck surface.

4.2.2.1 If the bulkhead-mounted visual signal devices cannot be mounted at least 2,030 mm above the deck due to low ceiling height, the devices should be mounted within 150 mm of the ceiling. The maximum horizontal dimension (X) should be reduced by twice the difference between the actual mounting height and 2,030 mm.

4.2.3 Ceiling-mounted visual signal devices may be mounted on or suspended from the ceiling. If ceiling heights exceed 10 m, ceiling-mounted visual signal devices should be suspended at or below 10 m.

4.2.4 For corridors less than 6 m in width, the following specification may be used instead of 4.2.1.

4.2.4.1 The minimum effective intensity of the visual signal device should be 15 cd.

4.2.4.2 Visual signal devices should be located not more than 4 m from the end of the corridor with a separation not greater than 30.5 m between devices.

4.2.4.3 If there is an interruption of the concentrated viewing path, such as a fire door, an elevation change, or any other obstruction, the area should be treated as a separate corridor.

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¹The effective intensities are based on providing at least 0.405 lumens/m² at the middle of the bottom edge of the coverage area, 0.246 lumens/m² at the bottom of the corners, and 0.243 lumens/m² at a height of 1.5 m in the corners by a visual alarm device with the minimum distribution of effective intensities of ANSI/UL 1971, Standard for Signaling Devices for the Hearing Impaired of the United States.

05 Testing requirements

5 - Testing requirements

5.1 After initial installation or modification, the system should be checked to verify proper operation including the following items:

1. that all visual signal devices operate upon activation of the general emergency alarm system; and 
   
   
2. that all visual signal devices are synchronized as specified in 3.7.
   
   

5.2 The periodic testing of visual signal devices as part of the general emergency alarm system should be included in the maintenance plan required by SOLAS regulation II-2/14.2.2.

• Informatietype: Internationaal
• Documentsoort: Circulaire niet in wetten.nl
• Toegangsrechten: Extern
• Identificatie: PUC_2013_14
• Versie: 1
• Datum beschikbaarheid: 10-06-2013
• Geldigheid van: 21-05-2012
• Wijzigingsdatum: 24-11-2016
• Titel: 1418 design and installation of a visible element to the general emergency alarm on passenger ships
• Organisatie: International Maritime Organization (IMO)
• Taal: Nederlands
• Thema: 1400 until 1499