The Use and Need for Penetration Sealing

In modern structures and buildings various specialised and technical installation services for power supply, computer and cable networks, transportation of water and sewage, and so on are installed as part of the build. Usually, these services penetrate fire separations in areas that are normally hidden away; above ceilings, through walls and other cavities. Because penetrations are usually hidden from plain view, it could be easy to forget them, but given they allow the flow of air and thus fire, it is particularly important that they are fitted with suitable fire safety protection that fulfills statutory and BCA fire safety requirements.

 

What is a penetration?

In fire stopping, a penetration refers to an opening, such as one made in a wall or floor assembly by the use of a cast-in-place sleeve. The purpose of penetrations is to accommodate the passage of technical installation services — mechanical, electrical or structural penetrant. A penetration may or may not have a firestop system included, though by Australian Law, they all should, for the purposes of preventing the spread of flame and fire. It is important to point out though, a penetration is not a penetrant and a penetration may have or may not include a penetrant or multiple penetrants (such as pipes, cables or similar).

 

Penetration seals

Fire stopping and penetration sealing compliance are identified under current building legislation as crucial elements in retaining the integrity of a building’s fire compartments. It is also a measure that maximises the amount of time available to enable people to escape from a building in the event of a fire.

 

Because poorly sealed penetrations have the potential to act as conduits, sealing systems are critical in forestalling the spread of smoke, heat and flame between fire compartments in areas where there are mechanical, electrical and general services.

 

Fire penetration sealing

As you will be well aware from our other blogs, fire stopping or fire rating is part of a building’s fire protection strategy. The aim of this strategy is to protect; inhabitants, lengthen structural integrity, and the infrastructure in general. It is also required to maximise the amount of time obtainable for people to escape from a building in the event of a fire.

 

To be effective, penetration seals and fire-stopping systems must be specified and installed in strict adherence with the manufacturer’s test, assessment and certification for each specific application and should be used as a tested system. It goes without saying that all fire-stopping systems need to be installed by a competent and certified contractor, in compliance with the manufacturer’s directions for application and product information sheets. Failure to do so renders warranties and insurance void.

 

Current Penetration seal systems can provide up to 4 hours of insulation against a cellulosic fire. To achieve this, there is an assortment of products that fully comply with international and Australian standards including:

 

Fire collars

Fire collars are designed to maintain the integrity and maintain the insulating rating of the fire-resistant element which has been penetrated by a building service. Collars are placed around the conduits in the penetration, so they contain all that passes through different spaces. When exposed to fire, these resistant collars – which contain intumescent within that expands under heat – expand, filling the space of the penetration, thus rendering it harder for flames, heat, smoke or gas to get through.

They are appropriate for installation in the various types of floors, walls and ceilings for which they have been tested.

There are various kinds of fire collars covering different applications and can range from; plastic pipes, copper pair coils, lagged copper pipes, electrical cables and other general building services.

 

Fire stop sealants

Where the penetration is small (say a single pipe through a wall or floor) fire stop sealants are more appropriate than a collar. Their purpose is to seal any small openings of up to 2-4 cm in diameter to prevent a fire from moving from one compartment to another in a building or structure. Like all passive fire products, they have a fire rating determined to be required to withstand the effects of a fire.

 

There are various kinds of fire sealants utilised depending on their individual properties ranging from; silicone, ablative or intumescent. They can be elastomeric which allows them expansion or movement capacity within a range of 25% – 50%.

 

Silicone Firestop Sealants are versatile and elastic, able to maintain stability in high & low temperatures. They are also impervious to; moisture, other chemicals and weathering. In contrast to other adhesives, silicone sealants must be given time to cure.

 

Ablative FireStop Sealants buy valuable time by absorbing the energy of a fire to protect what is underneath. They consume the heat energy from fire and release it as gases as they char to form insulation.

 

Intumescent Firestop Sealants are used predominantly around plastic pipes/materials penetrating through walls and floors. Due to heat exposure, the intumescent swell; increase in volume and decrease in density cutting off the space between the penetrant itself and the surrounding wall/slab.

 

Fire Barriers

Fire barriers are also known as ‘Ablative Coated Batt’ and are used to provide fire and acoustic barriers for areas that have voids made by penetration and passage of services in both drywall systems and masonry walls and floors.

 

These penetrating services may be; steel and copper pipes, PVC/HDPE/ABS cables regularly braced on ladders, trays or mechanical ducts. Most fire barriers are tested to provide up to 2 hours of fire resistance and heat insulation. In some extreme conditions or where required, some solutions can achieve up to 4 hours of fire resistance.

 

Fire Compounds

These are fast setting gypsum-based systems and can be used to provide a tight seal around service penetrations predominately in walls and floors. This is achieved through their design and the penetration area may require a higher rate of loading around it.

Intumescent Sealants

They are most commonly found in acrylic, silicone and graphite form. These sealants can adhere to most kinds of surfaces forming a non-hardening flexible seal. In turn, this provides an intumescent seal that provides fire resistance to walls, floors, fire-rated doors frames, glazing systems and other frameworks. They can be used to seal linear gaps in masonry walls to achieve suppression of up to 2 hours from smoke, toxic gases and fire.

 

Pipe Wraps & Collars

Wraps & collars are a simple and effective method of providing fire resistance wherein plastic pipework goes through what would otherwise be fire-resistant walls and floors. They will often consist of a coated steel sleeve with closed flexible graphite based intumescent liner that is securely fixed to a building or structure.

 

They are regularly composed of layers of graphite intumescent sheets sat within a polythene sheath. It could also be a flexible and adjustable roll that can be fitted to cater for various sizes of pipes up to 160-200mm in diameter.

 

Fire pillows

Designed to prevent the spread of fire in cases where cables and other non-combustible services penetrate fire compartment walls and floors, they are made of a sealed fabric pillow filled with a high expansion intumescent material.

 

The intumescent material reacts when exposed to extreme heat by producing a barrier of carbonaceous char. This char acts to provide an effective insulating plug and seal against flames and hot gases. Fire pillows are useful especially if it is necessary to create a temporary firestop or when the extent of service penetrations is not clear.

 

Passive Fire Barrier Curtains

Fire Curtains provide more flexibility and adaptability both to designers and on-site by making it possible for larger open plan areas to achieve regulations on fire compartmentation.

 

These systems can be fitted both vertically and horizontally affixed to steel, wood and between soffits and ceilings and act as an effective barrier. Since it comprises non-fibrous materials, it is easy for penetration services to go through and be sealed using combatable methodologies that enable the creation of an effective penetration seal.

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