Design Principles of Passive Fire Stopping Systems

Introduction

Turkish Language Association defines the term fire as "a large fire causing damage"[1]. Fire is a chemical reaction resulting from the combination of oxygen, a heat source, and fuel components. This chemical reaction causes the generation of heat, flames, gas, and smoke in the environment and spreads through buildings via convection, heat conduction, and radiation. Three fundamental measures are taken to protect buildings from fire. These are;  

1. Detection Systems (Smoke detection alarms, automatic doors, etc.)
2. Active Fire Suppression Systems (Sprinklers, fire extinguishers, etc.)
3. Passive Fire Protection Systems (Fire barriers, fire doors, etc.)

The systems mentioned above are complementary and must work integrated with one another. Detection systems and fire systems serve life safety by alerting building occupants during a fire through various electrical installations. Active fire suppression systems aim to extinguish the fire during a fire with the help of various mechanical installations. Finally, passive fire protection systems aim to prevent the fire from spreading within the building. In this study, the design principles of passive fire barrier systems, which are part of passive fire protection systems, will be examined in detail. At the same time, other passive fire protection measures used in fire compartmentation should be considered complementary and should not be overlooked. Fire Statistics and Areas of Application of Passive Fire Barriers Looking at various fire statistics worldwide, the importance of fire prevention measures is reinforced. Worldwide, on average, 3.8 million fires occur annually, resulting in approximately 45.4 thousand deaths[2]. Additionally, 75% of fire deaths result from smoke[3]. This statistic shows us the importance of controlling the smoke generated in a fire in the area where it occurs through passive fire prevention measures. In addition, smoke causes 47% of fire survivors to be unable to see beyond 3.5 meters. Finally, 57% of fire deaths do not occur in the fire's source volume[4]. In brief, most deaths occur not in the compartment where the fire originates, but in another compartment where the fire has spread and progressed. These mentioned statistics show us that lethal smoke in fire is as important as flames. Passive fire barrier systems are applied in various areas within buildings to prevent the spread of fire. During fire design, a "fire compartmentation plan" is created by considering all fire prevention systems together. The purpose of fire compartmentation of the building is:

• To protect occupants' exit routes.
• To ensure adequate structural stability.
• To increase the time required for firefighters to enter the building and rescue occupants.
• To contain the fire at its source.
• To prevent the passage of fire and smoke without damaging assets and equipment in other rooms.

A schematic representation of compartmentation performed horizontally and vertically is shown below. The walls marked in the figure are referred to in the literature as "fire walls".

Figure 1. Fire compartmentation representation

Passive fire barrier systems are used at points where the integrity of fire walls determined in fire compartmentation is compromised. When basic classification is performed, application areas are considered in 4 main categories.

1. Mechanical system penetrations
2. Electrical system penetrations
3. Joints and expansions
4. Facade connections

A schematic representation of application areas is shown below. Application areas may overlap with one another or may be in different areas. The important point here is the isolation of every point that compromises integrity.

Figure 2. Application areas of passive fire barrier systems

The statistics provided in this section show us that passive fire barrier systems are very important in minimizing loss of life and property, preventing risks after fire, and enabling the building to be returned to use quickly and easily. It has also been observed that passive fire barrier systems are applied across all mechanical, electrical, architectural, and structural disciplines and complement one another.

Regulations, Standards, and Design Principles

In our country, the "Regulation on Fire Protection of Buildings", published in the Official Gazette in 2007 and updated in 2015, contains the rules and design principles that must be followed regarding fire prevention measures[5]. The regulation's mandatory nature is emphasized in Article 5 with the statement: "If projects do not comply with the conditions stipulated in this Regulation in terms of fire safety, in addition to legal regulations, the building permit shall not be issued." When the Turkish fire regulation is examined specifically for passive fire barrier systems, Article 69 first catches the eye. This article is the only article in the regulation where the term "fire barrier products" appears. However, various sections and articles in the regulation state that fire walls must be isolated at least as much as wall resistance. The regulation, which does not address the standards and design principles of passive fire barrier products, refers to European and international standards in its relevant standards section. The table below specifies the international test standards and approvals for passive fire barrier systems. Table 1. International test standards for passive fire barrier systems

	European (Turkish) Standards	American Standards
System Penetrations	(TS) EN 1366-3	ASTM E 814 / UL 1479
Joints & Expansions	(TS) EN 1366-4	ASTM E 1966 / UL 2079
Facade Connections	(TS) EN 1364-3/4	ASTM E 2307

  Following tests conducted in accordance with these test standards, the fire performance of the system is evaluated and reported. Since test standards are non-harmonized test standards, relevant guidelines are required to report test results. In Europe, EOTA (European Organization for Technical Approvals), in the United States, UL (Underwriters Laboratories), and other third-party and independent organizations conduct and report tests. These tests are referred to as performance-based and all components in the system where passive fire barrier products are applied are specified and included in the test scope. The approval documents in which the performances in the test are evaluated are called ETA in Europe and UL approval in the United States. Fire resistance ratings of passive fire barrier systems vary. In fire resistance, integrity and insulation constitute the basic classifications. The table below shows the notation of European and American performance evaluations. Table 2. Sample fire resistance rating table for passive fire barrier systems

	European Performance Criteria	American Performance Criteria
Integrity (Flame and gas insulation)	E-120 à 120 minutes	F-4hr à 4 hours
Insulation (Thermal insulation)	EI-90 à 90 minutes	T-2hr à 2 hours

  The relevant resistance periods are determined for each "fire wall" based on fire scenarios and provide minimum adequacy for passive fire barrier systems. Design professionals who design passive fire prevention measures for buildings must use the information in this section in design principles. Passive fire barrier systems and products must be specified in architectural details, mechanical, and electrical system designs. Additionally, the design of passive fire barrier systems must comply with the relevant approval documentation. The following criteria should be considered for each detail, and design principles should be applied.[6]

1. Evaluation of base material characteristics
   1. What is the base material type? à Concrete, gypsum board, brick, etc.
   2. What is the base material thickness?
   3. What are the void sizes in the base material?
2. Evaluation of penetration details
   1. What material is penetrating? à Combustible pipe, metallic pipe, ventilation duct, insulated pipe, etc.
   2. What is the distance between penetrating materials?
3. Determination of fire resistance requirements à EI120, F-2hours, etc.
4. Determination of solution compliance with regulations and approval documentation
   1. Approval documentation (ETA, UL, etc.)
   2. All documentation for products (MSDS, LEED, Performance Declaration, etc.)
   3. Field application labeling
   4. Installer training certification
5. Consideration of mechanical system characteristics
   1. Material à PVC, PE, steel, copper, sheet metal, etc.
   2. Insulation à Armaflex, rock wool, mineral wool, etc.
   3. Dimensions à Pipe diameter, duct sizes
6. Consideration of fastening and connection elements
   1. Support spacing
   2. Fire resistance of fastening element
7. Determination of system additional characteristics
   1. Acoustics
   2. Thermal insulation
   3. Flexibility / Seismic performance
   4. Water insulation
   5. Explosion resistance
   6. Moisture and mold

Conclusion and Recommendations

In conclusion, passive fire barrier systems are one of the measures taken to protect buildings from fire. Detection, active suppression, and passive fire barrier systems, known as the three-legged stool, must work integrated with one another.   Detail approvals form the basis in the design principles of passive fire barrier systems, and these documents define the entire system (base material, penetrating material, application thicknesses, etc.). Particularly, when determining passive fire barrier systems, all project stakeholders must consider the design principles.   Tolga AYCI Technical Marketing Manager Hilti Turkey         REFERENCES

• TURKISH LANGUAGE ASSOCIATION, General Turkish Dictionary
• CTIF (International Association of Fire and Rescue Service), Report n. 21 - World Fire Statistics 2016.
• HALL, JR. JOHN R., NFPA Fire Analysis & Research, Quincy, MA. "Burns, Toxic Gases and other Hazards"
• NFPA Fire Protection Handbook, 18th Ed..
• Turkey Regulation on Fire Protection of Buildings, 2015
• HILTI, Passive Fire Barrier Applications Training, 2018
• HILTI, Passive Fire Barrier UL Approvals Library, 2018