Fire Resistant Elevator Doors

Abstract

Elevator systems in use today are designed and produced to meet various requirements for their intended use. Fire-resistant lift landing doors has become mandatory after shifting from 95/16/EC to 2014/33/EU. In terms of compliance with the norms, there are regulations in each country that match international standards. For manufacturing fire-resistant lift doors, TS EN 81-58 and the Regulation on the Protection of Buildings from Fire are taken into account in Turkey. This paper includes general information about fire resistant lift doors produced within the scope of fire protection of the buildings and fire tests applied on these doors.

1. Introduction

Elevator systems should be installed in a way that minimizes fires that may occur during the design, construction, operation, maintenance and use of all kinds of structures, buildings and facilities used by public institutions and organizations, private organizations and real persons, and by applying the procedures and principles of the measures, organization, training and supervision to be taken before and during the fire, in order to ensure that any fire that may arise is extinguished with minimum loss of life and property.^[1]

While the regulations on fire adjustment studies that contribute to increasing performance in fire tests of elevator doors bring many strict rules, the test results in comparison with the expected performance criteria are documented.

2. General features of fire-resistant landing doors

Fire-resistant doors not only prevent the spread of smoke and flame to entrances, stairs and other places, they also ensure the safety of occupants and help maintaining the structural integrity of the building.

Fire-resistant landing doors are products that meet rules specified for protecting the buildings against fire. Therefore, fire doors should be designed and manufactured to resist fire so occupants can be safely evacuated from the building and meet criteria, such as flame resistance and smoke integrity.

For the doors to be considered as fire-resistant, they should be designed and manufactured with three-quarters of the fire resistance of the wall surrounding the door. With a wall that resists fire for 4 hours, the door should resist the blaze for 3 hours while with a wall that resists fire for 2 hours, a door that resists fire for 1.5 hours, etc. The doors can have higher resistance.

In terms of resistance criterion, there are three types of fire-resistance criteria: integrity, insulation and radiation. “E” represents integrity, “I” represents insulation and “W” represents radiation resistance.

In EN 81-58, these performance criteria are explained as follows:

Integrity (E): Integrity, which is the main criterion for judging the performance of the lift landing doors, indicates the leakage rate of the door opening does not exceed 3 m³/min. Sustained flaming is flaming for more than 10 s while integrity shall be considered to have been lost by the occurrence of sustained flaming. For the landing door, integrity indicates the total time in minutes it continues to maintain its separation function when two of the following three conditions are not met:^[2]

End of,

1. Flaming, which ignites the cotton pad applied in accordance with Article 10.4.5.2, or
2. Flaming, which enters the clearance gauge as specified in Article 10.4.5.3, or
3. Ongoing flaming

According to EN 13501-2, the integrity assessment is made by considering the following three situations:^[3]

1. Cracks or openings exceeding the given dimensions,
2. Ignition of the cotton pad
3. Sustained flaming on the exposed side.

Thermal Insulation (I): In order to save people and animals living in the buildings, and to save goods, the building materials should be preferred based on whether they ignite or how long they resist fire. When making a decision, the size and the height of the building is taken into account because the dimensions of the building is important in fire fighting and rescue efforts.^[4]

• Inorganic materials: glass wool, rock wool
• Organic materials: polystyrene, polyurethane, rubber, polyethylene

Glass wool, which is used in fire-resistant doors, is produced in our country. Its raw material is basalt stone. It is used as firestop with heat and sound insulation in buildings, vehicles, fixtures and industry. Its upper limit for resistance heat without binder is 750° C (1,000° C temporarily) while it is 650° C with organic binder (bakelite).

“I” criteria of landing doors are also related to spread of fire in the building. Insulation material used in landing doors decrease the impact of fire up to a certain temperature, and also prevents the spread of fire.

Construction materials can catch fire through contact with flame or heating up to a certain temperature. Coating doors with insulation material prevents the transfer of heat or flame to other floors, and temporarily restricts fire in the floor where it broke out while giving people the necessary time to safely evacuate the building.

It indicates the total time in minutes that the landing door specimen sustains its fire separation function during the test without being exposed to these two conditions:

1. A mean temperature rise on the unexposed face limited to 140° C above the initial mean temperature
2. The maximum temperature rise at any point limited to 180° C above the initial mean temperature

Accordingly, when such temperatures are experienced, the thermal insulation criterion “I” is not met.

As it is evident from the above statements, temperature changes are observed by attaching thermocouples to the unexposed face of the specimen.

EN 13501-2 states that the classification of integrity should be made if the component is also classified for thermal insulation. Where a component is classified in terms of both integrity “E” and insulation “I,” the integrity value should be determined by the first of these three criteria not met.

Where an element is classified both for integrity “E” and insulation “I,” the value of integrity is that determined by whichever of the three aspects fails first.

Where an element is classified without an insulation “I” classification, the value of integrity is that determined by the time to failure of only the cracks/openings or sustained flaming aspects, whichever fails first.

Radiation (W): According to EN 13501-2, Radiation “W” is the ability of the element of construction to withstand fire exposure on one side only. Accordingly, the probability of the transmission of fire as a result of significant radiated heat, either through the element or from its unexposed surface to adjacent materials, decreases. The element may also need to protect people in the vicinity.

An element that satisfies the thermal insulation criterion “I, “I1” or “l2,” is also deemed to satisfy the “W” requirement for the same period. Failure of integrity under the “cracks or openings in excess of given dimensions” or the “sustained flaming at unexposed side” criteria means automatic failure of the radiation criterion.

Elements for which the radiation criterion is evaluated shall be identified by the addition of a “W” to the classification. For such elements, the classification shall be given by the time for which the maximum value of radiation, measured as specified in the test standard, does not exceed a value of 15 kW/m².

The fulltime history of the radiation shall be given in the classification report.

3. Binding directives, norms and standarts

For designing and manufacturing fire-resistant doors, certain rules should be followed. Standards and directives where these rules are specified both define the manufacturing and application issues and the required features of the materials that will be used. In our country, Regulation on Fire Protection of Buildings should be considered.

The provision in the second paragraph of Article 62 of the above mentioned Regulation stating, “Elevator pit and the machine room shall be made of non-flammable materials that are resistant to fire for at least 60 minutes”; the provision, “Elevator doors must be fire resistant and smoke-proof for at least 30 minutes, while they shall be fire resistant and smoke-proof for at least 60 minutes in buildings higher than 51.5 m” in its seventh paragraph; the provision, “Landing doors, where they have to contribute to the protection of the building against fire, including those with glass parts, must be suitably resistant to fire in terms of their integrity and their properties with regard to insulation and the transmission of heat” in Annex 1 of 2014/33/EU Lift Directive have been interpreted as all elevator landing doors must be fire-resistant, whether they contribute protecting the building from fire or not, in accordance with the Regulation on the Protection of Buildings from Fire, prepared by the Ministry of Environment and Urbanization.

International norms and directives regarding fire resistant landing doors are:

1. 2014/33/EU — Lift Directive 2014: It entered into force in Europe on April 20, 2016, 95/16/EC directive.
2. EN 81-58:2003 — Safety rules for the construction and installation of lifts — Examination and Tests, Part 58: Landing doors fire resistance test: It specifies the method of test for determining the fire resistance of lift landing doors that may be exposed to a fire from the landing side.
3. EN 1363-1 — Fire resistance- Tests, Part 1: General requirements: It specifies the general principles for determining the fire resistance of various elements of construction when subjected to standard fire exposure conditions.
4. EN 1363-2 — Fire resistance tests, Part 2: Alternative and additional procedures: It specifies alternative heating conditions and other procedures that may need to be adopted under special circumstances
5. EN 81-20/-50 — Safety rules for the construction and installation of lifts, Lifts for the transport of persons and goods, Part 20: Passenger and goods passenger lifts: EN 81- 1:1998+A3:2009 and EN 81-2:1998+A3:2009 Standards that are the most important references regarding elevators in all European countries and almost all over the world, and defines the safety rules for the construction and installation of elevators, are replaced with EN 81-20 Safety rules for the construction and installation of lifts, Lifts for the transport of persons and goods-Part 20: Passenger and goods passenger lifts, which became obligatory as of September 2017.
6. EN 1364-1 — Fire resistance tests for non-loadbearing elements, Part 1: Walls: Specifies fire resistance of non-loadbearing walls.
7. EN 1634-1 — Fire resistance tests for door and shutter assemblies, Part 1: Fire doors and shutters: It specifies fire resistance tests for doors.
8. EN 1634-2 — Fire resistance and smoke control tests for door, shutter and openable window assemblies and elements of building hardware. Fire resistance characterization test for elements of building hardware: It specifies fire resistance criteria for building hardware.
9. EN 1365-1 — Fire resistance tests for loadbearing elements. “Walls”: It specifies the general qualifications of loadbearing walls.
10. EN 1365-2 — Fire resistance tests for loadbearing elements. “Floors and roofs”: It specifies a method for determining the fire resistance of floor constructions without cavities or with unventilated cavities; roof constructions, with or without cavities (ventilated or unventilated); floor and roof constructions incorporating glazing with fire exposure from the underside.
11. EN 1366-3 — Fire resistance tests for service installations. “Penetration seals”:  It specifies the criteria for fire resistance of building hardware and elements.
12. EN 1366-4-A1 — Fire resistance tests for service installations. “Linear joint seals”:  It specifies the fire resistance of linear joint seals based on their intended end use.
13. EN 1366-1 — Fire resistance tests for service installations. “Ventilation ducts”:  It specifies a method for determining the fire resistance of vertical and horizontal ventilation ducts, including access panels.
14. EN 1366-2 — Fire resistance tests for non-loadbearing installations, Part 2: “Fire dampers”: It specifies a method for determining the fire resistance of fire dampers installed in fire separating elements designed to withstand heat and the passage of fire, smoke and gases at high temperature.
15. EN 13501-3+ A1 — Fire classification of construction products and building elements. Classification using data from fire resistance tests on products and elements used in building service installations: “Fire-resisting ducts and fire dampers”: It specifies the procedure for classification of the resistance to fire performance of construction products and building elements used as components of building service installations.
16. EN 12101-1 — Smoke and heat control systems. “Specification for smoke barriers”: It specifies the technical specifications for smoke barriers.
17. EN 13501-2 + A1 – Fire classification of construction products and building elements, Part 2: “Classification using data from fire resistance tests, excluding ventilation services”:  It specifies the procedure for classification of data from fire resistance tests.
18. BS 476-22-1987 — Fire tests on building materials and structures, Part 22: “Methods for determination of the fire resistance”: It specifies the test method for fire resistant doors.

4. Fire resistance tests on landing doors

Fire resistance tests are carried out to measure fire resistance of elevator landing doors by exposing a specimen, which carries the same features with the original door, to certain temperatures determined by the standards.

Main requirements for the tests in line with the 1st, 2nd and 3rd parts of TS EN 1363 are:

• A custom engineered test furnace working with liquid or gas fuel,
• A fire-resistant test frame in order to accommodate the test specimen,
• Thermocouples that will be used for temperature measurement inside the furnace and on the exposed and unexposed sides of the specimen,
• A thermocouple that will be used in order to determine ambient temperature near the specimen before and during the test,
• A measurement and recording device conforming to standards in order to measure the pressure in the furnace,
• A measurement device that measures deviation at least once per minute,
• A canopy that collects the leaked gases on the unexposed side,
• a suction fan that draws gases through a duct provided with a system for measuring the volume flow.

Before the tests, a full detailed specification of the test specimen should be provided by the test sponsor prior to its installation at the laboratory. This specification will be examined in the laboratory to conduct a detailed examination of the specimen and to agree the accuracy of the information supplied. Additional assembly or assembly parts may be needed, if the specimen encounters permanent damage due to detailed examination. Prior to the test, the clearances between the moving components and the fixed parts of the door assembly are measured and recorded, and the door is checked for functionality by opening and closing.^[5]

When a test specimen is attached to a sealed furnace chamber, like being attached to the well, the accuracy of gas measurement system is checked and flow measurement is verified.  On satisfactory completion of this check, the exhaust fan remains in operation and the furnace is ignited.

Furnace temperature and pressure should be kept under control as specified in the Standards, in order to fully simulate the conditions occurring after flaming,

At the commencement of the test, heat of all thermocouples — except moving thermocouples — are measured and recorded, and the intervals between recordings should not exceed 1 minute.

Observations shall be made of the general behavior of the door specimen during the course of the test with notes made concerning deformation, opening of the gaps, melting or softening of materials, charring of surface finishes, etc. If quantities of smoke are emitted from the unexposed face, this shall be noted, although the test is not designed to evaluate the hazard. The time of the occurrence of flaming, data from the flow measuring instrumentation and gas concentration in the furnace, face temperature of the unexposed side, radiation from this face and door deformation should be recorded.

Tests are carried out during the time required based on the resistance classes or until if the specimen is in a condition that is no longer satisfying any of the performance criteria.^[2]

After the test, a detailed test report, including all technical features and data recorded during the test, about the tested specimen is prepared. The report includes the performance evaluation on the fire resistance. The performance of the specimen is determined based on the basis of its ability to remain in place as a fire barrier, its ability to control the leakage of hot gases to the lift well and to satisfy any additional criteria for thermal insulation and radiation that may be specified. Transient peaks in the observed leakage rate curve can be ignored if they are due to fluctuations in the measuring chain or the presence of combustible materials like paint or coatings that melt due to heat, but this increase should not occur as a result of increasing gaps or further dislocations in the specimen.^[5]

Test report should include the leakage rate through the door during the course of the test, the time and duration of the occurrence of flaming; the deformation of the door, as a function of time; radiation emission when measured, as a function of time; unexposed face temperature curves when measured, as a function of time; and the classification of the door and the field of application of this classification.^[2]

Test results are considered to be applicable to doors of sizes different from those of the test specimens, all other constructional details being the same, within the following limitations:

Without correction to be applied on the measured leakage rate:

1. A similar door of lower height than the tested specimen;
2. A similar door with a door opening or an opening width in the wall equal to the one tested within a range of ± 30%.

After correcting the measured leakage rate as a function of the increase in height, as specified in the Standards:

• A similar door with increased height up to 15%.^[5]

5. Conclusion

Fire resistance of a door is determined with a fire-resistance test and its assessment. A fire-resistance test is directly an ignition process where the door specimen is attached to a proper frame and tested. Fire resistance of the doors are determined by placing the properly designed door specimens into frames with certain dimensions and placed in the furnace, which is controlled in accordance with time, temperature and pressure values specified in the Standards. These applications can then be documented in specific reports and released to the market within the frame of accreditation rules.