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Fire/Safety Curtain Research

Fire/Safety Curtain Research

It is common belief in the UK that Safety [Fire] Curtains have to be exhibited to the audience at every performance. Read on for Mike’s research demonstrating why this is not true.

The Safety [Fire] Curtain separates the stage from the auditorium and is intended to slow or stop a fire starting in one of the two areas from reaching the other area. In the early 20th century Safety/Fire Curtains were commonly skinned with asbestos fiber-based material due to its fire-resistant properties. As the health hazards surrounding asbestos fibers have become better understood during the latter part of the 20th century, these potentially life-saving fire curtains have become something of a problem for theatres to deal with.

In 1935, the UK Her Majesty’s Stationery Office (HMSO) published a book aimed at providing UK-wide theatres guidance on theatre safety. At the time, and still to this day, regulations around Fire/Safety Curtains are the responsibility of the local fire authority. This is why you might see a production in London’s West End where the Safety Curtain is never demonstrated to the audience. HMSO got as close as they possibly could to laying down the rules, and many local authorities adopted them. Read on for the detail from the 1935 publication.

Manual of Safety Requirements in Theatres and Other Places of Public Entertainment was first published by Her Majesty’s Stationery Office (HMSO) in 1935 and reprinted in 1949. An online version is available on the HathiTrust website Link opens in new window (availability may be restricted by country in avoidance of potential copyright reasons).

 

MANUAL OF SAFETY REQUIREMENTS IN THEATRES AND OTHER PLACES OF PUBLIC ENTERTAINMENT

Issued by the Home Office, 1934 (Reprinted 1949)

PART V

PROSCENIUM WALL. FIRE RESISTING CURTAIN AND DRENCHER OVER CURTAIN. ROOF VENTS, SPRINKLERS AND VALANCES.

There is no doubt that where a stage and scenery is employed the most dangerous area will be on or about the stage and every precaution must be taken to provide a measure of fire separation between the audience and the stage which will function till clearance can be effected, and so to arrange the ventilation as to give prompt and certain vent to smoke, flame, and hot gases from a fire arising on or about the stage otherwise than through the proscenium opening. Fire separation can be provided by means of a fire-resisting proscenium wall and fire-resisting curtains with drenchers over; ventilation by roof vents which will ensure that there is a ready means of escape for fire, smoke and hot gases through the stage roof. The Ring Theatre fire in Vienna in 1881 led to experiments being carried out by the Austrian Society of Engineers in 1885 and by the Austrian Government in 1895. A model approximating one-third linear dimensions (or 1/27th cubical content) was used and some very remarkable results were obtained. In one experiment the roof vents were tightly closed, and within 20 seconds of the scenery on the stage being well alight pressure rose to 5 inches of water and the curtain was blown into the auditorium. This explained why the gas lights in the Ring Theatre had been extinguished, because pressure of gas at the jets would never be more than 3 lbs. With the roof vents open, no pressure was produced in the auditorium and the draught from auditorium to stage was sufficient to bulge the curtain towards the stage.

It will be seen from definition (10) on page 6 that the term “scenery” does not include metal or asbestos scenery or hangings consisting of certain materials of the weights therein mentioned.

Where no scenery other than the above is used on the stage, it is not suggested that the provisions of this Part of the Manual should be applied. Where any other form of scenery is used, however, this Part should be rigidly applied.

The provision of at least a fire-resisting wall, some form of roof vent and a curtain with fire-resistance equivalent to that of a heavy wool curtain, with a system of drenchers to keep it wet for a short period, is the minimum compatible with safety and it is strongly recommended that these safeguards be provided in all buildings seating over 400 persons even if only occasionally used. This will probably involve structural alterations which may be somewhat costly, and it is suggested that notice be given to owners of such buildings that alterations to enable the building to comply with these requirements should be completed, within a period of, say, one year in the case of places regularly used and two years in places occasionally used. The method suggested for determining whether a particular place is used “regularly” or “occasionally” for purposes of this Manual is set out in definition (4) on page 6 and, for purposes of the application of this Part of the Manual, it is felt that account should be taken only of those performances which consist of stage plays and entertainments of that nature. In addition, it will be observed from the various tables of requirements which follow in this Part that exemption from the provisions considered therein is suggested for places used “occasionally and exceptionally only on not more than twelve days in any one year”.

Until such safeguards as are here suggested are provided, there is much to recommend the procedure adopted in some cities where a trained fire brigade exists. In those cities, a member of the fire brigade is on duty on the stage during all performances. The fireman’s time is paid for by the owner or licensee of the premises. The presence of a trained man will ensure that fire appliances are got to work promptly and efficiently and, in the absence of the safeguards provided by a reliable cut off between the stage and the auditorium, it is essential that the fire should be held in its earlier stages. Appliances available for use by this man should include at least a Mark 3 hand-pump but, if the requirements of this Manual as regards fire appliances are adhered to, such an appliance will be available wherever a stage and scenery is employed in a building seating over 400 persons.

In addition to the stage itself, there are other places, such as scene docks, workshops and stores, in which material of a combustible nature is present and which therefore constitute definite risks. These places are included in the expression “the stage risk” and steps should be taken by way of adequate fire separation, sprinkler protection, etc., to isolate from the rest of the stage risk any outbreak of fire which may occur in these parts of the building. It is realised that in many old buildings the provision of fire- resisting walls and so on for these portions of the building may be impracticable, but this provision should certainly be made in new buildings.

Proscenium Wall.

In new buildings and in buildings with a stage area exceeding 600 square feet, the proscenium wall should be of the highest possible class; for smaller stages and buildings occasionally used, something simpler and less expensive might be allowed, and it is suggested that three different classes of proscenium wall be provided for different types of building and user, as follows:—

57. - (a) In premises seating over 400 persons, in which scenery is employed (unless they are so used occasionally and exceptionally only and on not more than twelve days in any one year), the stage shall be...

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At the Iroquois Theatre, Chicago, at Edinburgh, and at Madrid, the curtain failed to come down all the way and was of little value. Reference is made to the cause of failure in a later paragraph.

It is advised that curtains of varying degrees of fire-resistance be provided for different classes of buildings, as set out in the table below.

A general Requirement is recommended in the following terms:–

58. In premises seating over 400 persons in which scenery is employed (unless they are so used occasionally and exceptionally only and on not more than twelve days in any one year), the proscenium opening shall be fitted with a fire curtain as in table below:—

Class of building and user. Grade of curtain required.
1. In new buildings seating over 400 persons. A = Rigid one-piece curtain complying with Requirements 59 to 65.
2. Existing buildings regularly used with stage area over 600 square feet. B = Rigid two-piece curtain complying with Requirements 59 to 65.
3. Existing buildings regularly used with stage area less than 600 square feet. C = Rigid three-piece curtain complying with Requirements 59 to 65.
4. Existing buildings occasionally used seating over 1,000 persons. D = Roller asbestos curtain complying with Requirements 60 to 65.
5. Existing buildings occasionally used seating over 700 but not more than 1,000 persons. E = Roller or festooning asbestos curtain complying with Requirements 60 to 65.
6. Existing buildings occasionally used seating over 400 but not more than 700 persons. F=Heavy wool curtain complying with the specification on page 50 and having at least 18 inches overlap if parted in centre and 18 inches overlap over proscenium arch.

The following constructional Requirements should be applied in respect of rigid safety curtains:—

59. Where a rigid curtain of the one, two, or three-piece type is required (see Figure 10):—
(a) The framework shall be of steel and shall be covered on the stage side with hydraulically flattened steel sheets of not less than 16 S.W.G. and on the auditorium side with wire woven asbestos cloth with or without a covering of similar steel sheets. The framework shall be so arranged as to form as far as possible a rigid structure, and the steel sheets shall be securely bolted to the framework along each edge, and to any bracing.
(b) Steel guides of such a form as to overlap both sides of the edge of the curtain, securely fixed to the wall and fully protected with teak not less than 1 1/2 inches finished thickness or other incombustible materials at least 2 inches in thickness, shall be provided for the vertical edges of the curtain. Such guides shall lap over the stage side of the moving portion of the curtain for a distance equal to its thickness. The side play allowed shall not exceed 1/2 inch.
(c) At least two counterweights shall be provided. They shall be attached by means of steel ropes to two or more independent fittings placed symmetrically at a suitable distance apart at the upper edge of the curtain. The counterweights shall run in rigid guides continued to the floor of the stage basement, unless terminated by sufficient cantilever stops securely built into the walls of the building, and shall be protected by hard wood not less than 1 3/4 inches finished thickness, metal or other incombustible material continuously from their lowest position to at least 6 feet above the fly level.
(d) The weight of the curtain in relation to the counterweights shall be such as to allow sufficient bias to ensure that the curtain will start its descent and will overcome the effects of wind pressure during descent.
(e) (i) The raising of the curtain shall be effected by hand or power gear which shall be so guarded as to prevent misuse or personal injury.
(ii) The hauling ropes shall be of steel and shall be attached to the centre of the curtain, and the strength of such ropes and the rope connected to the air buffer or brake referred to in the following paragraph shall be sufficient to withstand the stresses due to the action of the brake.
(iii). The sheaves of pulleys over which the ropes for counterweights or for raising the curtain pass shall have a diameter not less than 35 times the diameter of the ropes employed. (iv) Permanent stops shall be provided to prevent the curtain being overwound when being raised.
(f) A dash-pot, air buffer or other similar device shall be fitted which shall come into action during the descent of the curtain in such a way as to slow down its descent and allow it to come to rest upon the stage with- out shock. Where an air brake is provided the rope therefrom shall work in conjunction with the main raising gear in such a manner that over- running of the main lifting cables shall be avoided.
(g) A smoke-stop formed by an asbestos roll having a diameter not less Smoke-stops. than half that of the thickness, of the curtain shall be provided so as to form a reasonably smoke-tight seal between the curtain and the stage (see Figure 11). A smoke-stop at the top of the curtain when lowered shall be formed by an angle or channel bar resting on a projecting ledge with a soft asbestos pad between or by a vertical fin on the curtain top bedding into a bath of sand fixed to the proscenium wall on the stage side.
Diagram of a smoke-stop
(h) If it is desired that the height of the working opening should be Fixed Valance. less than that of the proscenium opening, a fixed valance may be provided. Such valance shall consist of a suitable steel framework covered on one side with wire woven asbestos cloth with a covering of hydraulically flattened steel sheets of not less than 16 S.W.G. and shall be constructed in all other respects as the moving portion of the fire curtain. It shall not exceed 6 feet in depth at any point and the lap over the moving portion when such portion is in its lowest position shall not be less than 18 inches.

In addition to the foregoing, there are certain other Requirements which apply to safety curtains generally whether or not they are of the rigid type :—

60. Where the use of asbestos fabric is required for fire curtains, it shall be be of a quality suitable for the type of curtain in use. (See specification on page 49.)
61. The lap of the curtain over the brickwork of the proscenium opening shall be at least 18 inches at the upper and each vertical edge when the curtain is in its lowest position, and the upper and lower edges shall be so arranged as to form reasonably smoke-tight joints.
62. The average speed of descent of the curtain shall be not less than one foot per second: descent. provided that the curtain shall in all cases completely close the proscenium opening within 30 seconds.
63. - (a) Rigid curtains shall be provided with releasing gear which can be operated from at least two positions one of which shall be near the principal stage exit or near the stage door-keeper’s office and the other at stage level on working side. Where staff are not usually present on the stage this latter release position may be on auditorium side of the proscenium arch.
(b) Roller or festooning asbestos curtains and heavy wool curtains may have one release position at stage level, working side. Where staff are not usually present on the stage, release position may be on auditorium side of the proscenium arch.
(c) The position and purpose of the releasing gear shall be indicated by a permanent fixed notice.
64. The raising and releasing gear and all moving parts shall be efficiently protected in order to remove the possibility of accidental interference with the descent of the curtain.
65. Where a rigid fire curtain, or an asbestos curtain of the roller or festooning type, is provided the words “SAFETY CURTAIN” shall be painted in lettering complying with Condition 132 and not less than twelve inches in height on the auditorium side of the curtain and within the lower third of its depth.
66. The safety curtain shall be lowered once during each performance, in the presence of the audience.

The Manual of safety requirements in theatres and other places of public entertainment’s Requirement and Condition suggested for adoption No. 66 is the rule which was, and still is, largely adopted by all local authorities throughout the UK, and from which the general understanding that this is a UK-wide rule comes from.

In a newspaper article recounting the tale of the gruesome fire Link opens in new window which claimed the life of The Great Lafayette on the stage of what is now the Edinburgh Festival Theatre, it was stated that as a result of the tragedy “The Lafayette Bill brought in the lowering and raising of the safety curtain at every performance to ensure it is fully working and will do its job in the event of an incident”. Thus far no evidence has been offered to support this claim, and it is not supported at a UK national level by Hansard, the official report of all Parliamentary debates. It may be that the Lafayette Bill was local to Edinburgh.


Failure of the fire-resisting curtain occurred at Edinburgh, where there was some hesitation in lowering the curtain because a spotlight and its operator had not moved out of the way. An ordinary drop curtain was lowered, but this was carried inwards by the draught from the auditorium to the stage and jambed the safety curtain by blocking the guides. At the Iroquois Theatre a swinging spot-light bracket stopped the descent of the curtain. At Madrid ambiguous orders were given and again the subsequent lowering of the fire-resisting curtain was impeded by a drop curtain.

67. No scenery or apparatus of any kind shall be so arranged as to interfere with the descent of the safety curtain.
68. - (a) In case of fire, the safety curtain must be lowered at once, and its descent once started must not be stopped, otherwise it may not restart. No drop curtain is to be lowered in place of the safety curtain.
(b) A notice to this affect must be displayed at all curtain release positions, together with the notice required in Requirement 63 (c).

At the Palace Theatre, New York, in 1932, before the fire-proof curtain could be lowered or the automatic roof vents had opened, a draught from the stage towards the auditorium caused the fire to pass below the curtain, and this set fire to a cloth valance curtain on the auditorium side of the proscenium opening. Although the fire-resisting curtain, roof vents, drenchers and sprinklers all functioned perfectly and the fire was extinguished with very little damage, the burning valance curtain caused a stampede towards the exits and, though these were ample, several people were injured.

69. There shall be no valance curtain of combustible material, whether or not rendered flame-resisting, above the proscenium opening.

Drenchers over Curtain.

The function of these drenchers is two-fold. In curtains of the rigid type they will prevent distortion of the metal framing of the curtain and also serve to keep the asbestos damp. In the non-rigid types of curtain they will keep the asbestos or wool thoroughly damp, for a period at any rate, and this will increase the weight of the curtain and make it less liable to belly out in one direction or the other. A drencher head is shown in Figure 12.

Diagram of a drencher head
70. - (a) In premises seating over 400 persons in which scenery is employed (unless they are so used occasionally and exceptionally only and on not more than twelve days in any one year), drencher heads for delivering water on to the stage side of the fire curtain shall be provided at approximately eight-foot intervals (see Figure 10).
(b) Drenchers shall be operated by trip valves. Any stop-valve controlling the supply of water thereto shall be locked or fixed in the open position.
(c) Release gear shall be provided as in table below:—

Class of building and user. Number and arrangement of Release positions.
New buildings seating over 400 persons

Existing buildings regularly used and seating over 400 persons.

Existing buildings occasionally used and seating over 1,000 persons.
A = Two release positions, one at working side stage level and the other near the principal stage exit or stage door-keeper’s office. Where staff are not usually present on the stage, release position may be on auditorium side of proscenium arch instead of working side stage level.
Existing buildings occasionally used and seating over 400 but not more than 1,000 persons. B = One release position working side stage level. Where staff are not usually present on the stage, release position may be on auditorium side of proscenium arch instead of working side stage level.

(d) Connection shall be to a constant and efficient water supply. Where it is not possible to provide such a supply, or if the conditions are such that the opening of hydrants on or about the stage or on outside fire mains may impair the supply to the drencher system, an overhead tank holding at least 7 minutes supply for the system shall be provided. (See Note below.)
(e) Apparatus for testing the supply to the drencher installation shall be provided (e.g., a pressure-gauge or a bib-cock situated, in either case, between the stop-cock and the trip valve).

Stage Roof Vents.

The importance of a stage roof vent for safeguarding the audience cannot be over emphasised; the Austrian experiments proved this conclusively. At Exeter, where there was no roof vent, persons in the gallery were quickly stifled and lost their lives. Comparison of two similar fires is interesting in this respect. At the Iroquois Theatre, Chicago, the roof vents were installed but work on them was not complete and they were boarded up; there was also an exhaust fan working behind the gallery seating. At Edinburgh very light roof construction and light glazing acted as a roof vent and gave passage to the fire almost at once. In both cases there was an intense fire on the stage and the fire-resisting curtain had failed to come down all the way. At Chicago many of those in the gallery were killed before they even left their seats, while at Edinburgh conditions in the auditorium were never dangerous and hardly even unpleasant for at least four minutes.

71.—(a) In premises seating over 400 persons in which scenery is em- ployed (unless they are so used occasionally and exceptionally only and on not more than twelve days in any one year), stage roof or side vents, opening direct to the open air, shall be provided as set out in the following table:—

Class of building and user. Type of vent required.
New buildings seating over 400 persons. A = of the roof type, see Figure 13 (i.e., windows in stage wall are not adequate). To have an area equal to one-sixth of the stage area.
Existing buildings regularly used with stage area over 600 square feet. B = Of the roof type, see Figure 13. TO have an area equal to one-eighth of the stage area.
Existing buildings regularly used with stage area under 600 square feet.

Existing buildings occasionally used seating over 1,000 persons.

Existing buildings occasionally used seating over 700 but not more than 1,000 persons.
C = Side lights (e.g., windows in the stage wall) permitted, see Figure 14; they must be bottom- or centre-hung and have an area equal to one-eighth that of the stage.
Existing buildings occasionally used seating over 400 but not more than 700 persons. D = Sidelights permitted, see Figure 14. Area not less than one-tenth of stage area.

(b) In buildings regularly used the opening of such stage roof or side vents or the lowering of the safety curtain must stop or reverse any exhaust fans operating on the auditorium side of the proscenium arch.
(c) Stage roof vents shall be as near as possible to the centre of the stage and above the highest part; side vents shall be as high as possible.
(d) The openings in such vents shall be closed by valves, louvres or shutters. These shall be of the “counterbalanced shutter” type, the “inclined falling sash” type, or the “counterbalanced skylight” type. They shall be capable of being opened automatically by the fusing of suitable links and by the cutting, releasing or burning of a cord, such cord shall come down near to the safety curtain release position on the stage.
(e) The links and cord shall hold the valves, louvres or shutters closed against a force of at least thirty pounds excess counterweight tending to force them open. Fusible links must be placed within the ventilator opening, above the roof line and well clear of the water from any sprinkler or drencher head.

Tests carried out in the U.S.A. proved that any wire netting below roof vents is soon choked up by pieces of light material carried by the up-current of air, and this might restrict the upward passage of fire, smoke and hot gases.

(f) Wire netting shall not be permitted anywhere in or immediately below the vents; provided that suitable wire netting may be fixed immediately inside the glass of the vent openings and arranged to open therewith.

Sprinklers.

72. In new buildings seating over 400 persons in which a stage is pro- vided and scenery is employed (unless the building is so used occasionally and exceptionally only and on not more than twelve days in any one year), sprinklers shall be provided for the whole of the stage risk including scene dock, workshop, basement, dressing-rooms, property store and band room. If the grid is of incombustible material the sprinklers shall be below the grid; otherwise they must be provided both above and below the grid. If adequate pressure and volume of water is not available a pressure tank, gravity tank or booster pump shall be provided.

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