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Ventilation duct insulation

 

In order to protect the ventilation system from condensing steam, fire or to dampen noises caused by the flowing air, various types of insulation are used.

The terms for installing insulation are set in the Regulation by the Ministry of Infrastructure “on the required technical conditions for buildings and their location”. Polish Journal of Laws 08.201.1238 . As stated in the Regulation, when the ventilation system leads through unheated rooms, it is susceptible to energy loss and should be insulated with a fire retardant material.  

Due to the difference in temperatures between the ventilation duct and the room in which it is placed, water often condenses on the duct surface. Insulation allows to prevent this phenomenon. In order to avoid water condensation on the duct surface, it is required to insulate them so that the insulation surface temperature is similar to ambient temperature. The efficiency of this type of insulation is decided by the appropriate thickness of the insulating layer. Another factor influencing the proper operation of the insulation layer is the assembly. The installation should be completely sealed. To install the anti-condensation insulation layer, we use self-adhesive pins and weld pins. Part of the insulation is fitted with an adhesive surface which allows it to stick directly to the duct surface Despite this, for ducts with larger diameters, we recommend to use additional pins or bind the ducts with TKS-N round nylon bands.

The air flow inside the duct as well as the running ventilator fan causes vibration and noise. Additionally, the air flow through elbows and T-sections causes additional sound. To reduce the noise, we use silencers or insulation installed on the external surface of the ventilation duct.

Silencers consist of an external casing, the ventilation duct, in which the noise absorbing material is placed - usually rock wool, secured with a perforated section.

An additional component to consider for the ventilation system installation is proper fire protection. The terms for duct fire resistance are set in the Regulation by the Ministry of Infrastructure “on the required technical conditions for buildings and their location”.  The regulation states that the desmoking ventilation systems should conform the the fire retardancy class of the ceiling.

Section 6 of the Regulation, Ventilation and air conditioning, contains the following stipulation in § 147. 1.:  Ventilation and air conditioning should ensure sufficient quality of indoor environment, including air exchange, air cleanness, temperature, moisture, relative humidity, air flow speed, observing separate requirements and specifications as in the Polish Norms for ventilation systems as well as fire safety regulations and acoustic standards as stipulated in the Regulation.

According to the Regulation, in § 267. 1.: “Ventilation ducts should be made of inflammable materials, while flammable thermal and acoustic insulation sections as well as other flammable coating of the ventilation duct are allowed only on the external side so as to prevent fire propagation.”

Insulation solutions intended for use in high temperatures as materials and systems which limit the distribution of heat to the surrounding area while in direct contact with hot flames, gases, liquids, materials and other media.
Types of high-temperature insulations depend on the material used in their manufacturing as well as on the intended use.

An example of a material with high fire retardancy properties is rock wool.  High melting temperature of rock wool fibers means that is inflammable, which ensures a high level of fire safety.

When selecting an insulation system, keep in mind the following parameters: low heat conductivity, inflammability, high fire retardancy - which means low smoke and burning drop emission during a fire scenario.

Due to different requirements as to insulation installations, there are several insulation materials available.

The basic insulation component is mineral wool - rock or fiberglass.

Rock wool is based on minerals such a: basalt, gabbro, dolomite or limestone aggregate or bricks. The minerals are melted in volcanic temperatures and made into fibers. The individual fibers are glued together with a special resin to form specific products - boards, mats, covering.  

Fiberglass wool is made of quartz sand and cullet. It is used to make board panels and mats in which the fibers are placed laterally to the surface, however this means more binding agent has to be used.

Both rock and glass wool features very low heat transfer coefficient, which guarantees very high level of thermal insulation.

Both types of wool also feature high acoustic absorbing capacity, low dynamic rigidity and effective dampening of internal acoustic energy. This means both materials are perfect for acoustic insulation of the ventilation system.

Wool insulation offers high fire retardancy. Rock wool preserves its characteristics in up to 1000°C. Glass wool can withstand temperatures up to 600-700°C. However, these heat resistance figure apply only to the fibers. The binding agent can withstand temperatures up to 250°C. The more binding agent, the less resistant the wool to high temperatures, this means rock wool is more effective in desmoking installations. Rock wool insulation is perfect for installations which, for example, spread the heat from a fireplace.

A major advantage of both glass and rock wool is its hygroscopicity and absorbability.
Rock wool is also highly resistant to mechanical damage.  Glass wool does not have as much density, which means it is not recommended in sections which are to withstand lots of strain. However, glass wool is more flexible, which means similar packaging can fit as much as three times the amount of glass wool than would be possible for rock wool. Additionally, glass wool is lighter than rock wool. Due to higher fiber flexibility, it adapts better to uneven surfaces. Rockwool is much more rigid and has a tendency to separate.

Rock wool is often used in all types of thermal insulation systems, including systems resistant to strain and deformation. Glass wool can be used whenever a large amount of strain is not expected. It is perfect as a filling.

Possible carriers for the insulation include: fleece and aluminum foil. The carriers secure the insulation material. Aluminum tape is used to seal and install insulation secured with fleece.

Insulation systems can also be secured with fleece made of unwoven cloth. Depending on fleece density and structure, it can be cleaned or not.

Rubber mats and coating is used to insulate ventilation systems.  This type of insulation is made of synthetic rubber. Rubber mats are available with an adhesive layer which enables easy and quick installation.  Due to the elasticity, rubber insulation can be adapted to fit almost any shape of the duct or fitting to be insulated. Rubber ensures protection from steam condensation and effectively dampens vibration and noise. Rubber mats, due to low heat transfer coefficient, improve the energy efficiency of the installation.

URSA AIR ducts also offer very good insulation properties.  URSA AIR ZERO A2 panels are made of glass wool to build ventilation ducts which are thermally and acoustically insulated.

URSA AIR ZERO A2 are made of mineral wool, covered with fiberglass fabric on one side and a glass and aluminum mesh on the other.

The mesh ensures durability and stability, the aluminum foil acts as a steam insulation layer. The mineral wool which constitutes the basic component of URSA AIR ensures very good thermal and acoustic insulation as well as offers antibacterial protection. Thermal resistance of the panels is 0,75 m2K/W, fire retardancy class, on the other hand, is A2-s1, d0.

In order for the insulation to be effective, it needs to be properly fixed. Some of the insulation mats are fitted with an adhesive layer which enables quick and easy installation.  To install the insulation on the duct surface, we use - apart from regular adhesive -  adhesive and welded pins.

Adhesive pins are used to install the thermal insulation on a smooth surface of a ventilation duct, utilizing a self-adhesive layer of foam which ensures durable fastening and no damage to the coating. Welded pins are used to fasten the thermal insulation to smooth ventilation duct surface. They are welded by means of manual transformer welders with adequate power which ensures  durable fastening and no damage to the coating surface.

Insulation tightness is guaranteed by the use of sealing tape. TALE sealing tape is made of 30 micron thick aluminum. The fiberglass mesh ensures high tear resistance. Its structure allows it to be used to connect technical installations with aluminum coating.

When installing the insulation on the surface of the duct it is important to keep in mind that all insulated surfaces are to be clean, dry and degreased. Optimum temperature for installation is between 5 °C and 35 °C.

Properly selected and installed insulation allows to minimize heat losses in the ventilation system, prevents water condensation, and in the event of fire will not contribute to fire propagation.



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VENTILATION DUCT INSULATION
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