Here you can find answers about subjects concernng Air Duct panels, Laws, Installation info and more


What are composite panels?

Composite panels, commonly referred to as “sandwich” panels, have been frequently used, over the past 25 years, in both internal and external building construction, because of their added benefit of increased thermal efficiency.

It usually consists of two metal facings bonded to a central insulating core, to form a sandwich like panel. The result is a strong, highly insulated panel, which is installed on top of one another to quickly build a large construction with an increased thermal efficiency.


What are the benefits of such a panel ?

  • Being easy to maintain and clean
  • Gives off no smoke and no poisonous gas when exposing to fire
  • High thermal insulation properties, with thermal conductivity index 0.020w/mk
  • High strength to weight ratio, ts bending strenght reaches over 1Mpa
  • Easy to fabricate
  • Quick and easy to install
  • Redused the capacity of equipment of the central air conditioning system,so investment cost and operation costs decreased.
  • It saves over 20% on operating cost over a 30 year life.
  • Foamed with closed-cell structure, it’s water-proof and sound-insulated.

What are the dangers?

The main danger for composite panels rests with the type of insulation core.

Commonly there are 6 main types of insulated core:

  • Expanded Polystyrene (EPS)
  • Extruded Polystyrene (XPS) or Styrofoam (contains FR additives)
  • Polyurethane (PUR)
  • Polyisocyanurate (PIR)
  • Modified Phenolic Foam (MPHEN)
  • Mineral Wool (Rock or Glass Fibre)

These types can be split between Loss Prevention Certification Board (LPCB) approved cores and non-approved cores.


Which are the Non-Approved Cores ?

EPS and XPS. The reason both polystyrene types are non-approved is due to their highly combustible and burning properties. These types are known to produce molten droplets and toxic black smoke when exposed to fire and extreme heat, which is then radiated through the core, and can ignite the metal skin, causing rapid destruction of the premises. This core contains no fire resistance properties and has a 95% probability that it will cause the fire to spread.
PUR. As well has polystyrene, polyurethane will support combustion and is not insurance approved and very unsuitable for high-risk areas.


Which are the Approved Cores ?

LPS 1181 or 1208 approved PIR. This core has improved fire performance over non-approved PUR and PIR, although still not in high-risk applications such as cooking premises.
MPHEN. Phenolic Foam has improved fire resistance of up to 60 minutes and is approved to LSP 1181. This core is suitable for most risk applications.


What is the Danger of using non-approved cores ?

The main danger of using non-approved cores are their lack of fire protection and stability in emergency situations, especially when damaged. The lack of fire resistance properties that will aid the spread of fire are the main dangers. This can prove to be disastrous for businesses along with many insurers refusing to issue cover.


What are the Certifications needed ?

Assessing fire performance using time to ignition, heat release, spread of flame, smoke production rate and formation of flaming droplets/debris. Products are then classified under six Euroclasses. The six Euro classes, (compiled under EN 13 501-1), are as follows:

  1. Class (A): No contribution to fire
  2. Class (B): Very limited contribution to fire
  3. Class (C): Limited contribution to fire
  4. Class (D): Acceptable contribution to fire
  5. Class (E): Acceptable reaction to fire
  6. Class (F): No performance determined

Comparison of reaction to fire tests with current standards

Euro class Germany France UK
EN 13501-1 DIN 4102 NFP 92-501 BS 476 pts 6 & 7
A A M0 /
  A2 M0 Class 0
B B1 M1 Class 0
C B1 M1 Class 1
D B2 M2 Class 1
E B2 M3 Class 2
F B3 M3 Class 3

Euro class A is a very severe category primarily meant for non-combustible materials. It is unlikely, though not impossible, that composites will fall into this category. Here tests close to the existing tests are used to classify materials. These are the furnace test based on ISO 1182 and the calorimeter test based on ISO 1716. At the other end of the scale, for products of appreciable combustibility, (classes E and F), the materials are tested using a simple ignitability test for vertical specimens based on an existing small burner test. Materials within classes B, C and D are subjected to the Single Burning Item test.


Who is U.L.?

U.L. (Underwriters Laboratories) is an independent, not-for-profit product safety testing and certification organization, founded in 1894. Over the last century, Underwriters Laboratories has become the world’s best known independent product safety certification organization. Millions of products and their components are tested to UL’s rigorous safety standards.


Reasons to use UL Listed products ?

Experience the benefits of Third Party Certification
The UL listing is called a “Third Party Certification”. This certification provides an unbiased safety assurance to interested parties including the manufacturer, the specifier, and the consumer. UL’s field reps worldwide conduct periodic, unannounced on site inspections of UL-certified products in the manufacturer’s factory. The product is verified as being fully compliant with a set of rules governing the product. Another part of the agreement is traceable labels. Each product listed must have a label affixed to the product traceable to the manufacturer through Underwriters Laboratories.
Gain an advantage with Listed and Classified Products
They are not the same, in fact Classified products have been evaluated only for specific properties, a limited range of hazards, or suitability for use under limited conditions. If a product is Classified by UL, this can mean its testing meets the particular requirements for a single test with a published result, but has nothing to do with all the other tests that may form part of a Standard (i.e., UL 181).
Stand out with full UL Listing and Compliance


What is “Listed”?

A published list stating the product has been tested to and complies with the applicable Standard and maintains periodic inspection to assure production of the listed products are in accordance with the listing. Having UL Listing guarantees that the product fully complies with each and every one of UL’s requirements in the applicable Standard, and the manufacturer’s product can then bear the UL Mark.


Why UL 181 ?

UL 181 is a requirement applying to materials in the fabrication of air duct and air connector systems. The differences between an air duct and air connector lie in the testing they undergo by UL and as a result, the allowed uses by code.

Air Ducts are required to pass 15 various tests by UL as part of the listing process and some building codes further limit the run length. Air Ducts can be easily identified by a rectangular shaped UL label on the product.

Air Connectors only have to pass 12 tests by UL which do not include a flame penetration, puncture or impact test as part of the listing process. A connector is limited to shorter run lengths and can not pass through a wall, floor or ceiling. Certain building codes may also enforce additional limitations so checking the local code is important to ensure all compliances are being met. Air Connectors are identified by the round UL label displayed on the product.

Products falling within the Air Duct and Air Connector categories are also further classified as either Class 0 or Class 1. If designated as class 0 they will be made of all metal with a surface burning characteristic of zero. Class 1 designations have a flame spread index not exceeding 25 and smoke-developed index not exceeding 50


What is non-combustible product ?

‘non-combustible materials’ stand as:

‘…the highest level of reaction to fire performance.

Non-combustible materials include:

Any material which when tested to BS 476-11:1982 (2007) does not flame nor cause any rise in temperature on either the centre (specimen) or furnace thermocouples.
Products classified as non-combustible in tests following the procedures in BS 476-4:1970 (2007).
Any material classified as class A1 in accordance with BS EN 13501-1:2002 Fire classification of construction products and building elements. Classification using data from reaction to fire tests.


What will this mean for your insurance?

It is important to identify the location of any composite panels for insurance purposes. When looking for business insurance, quite often, non-approved composite panels will be the reason insurers refuse to quote on the risk.
This is especially important should you be looking to buy or lease new premises. For example, should you be needing new premises for food related activities, the wrong kind of composite panels should be a crucial part in your decision.
If you have non-approved composite panels, the replacement costs can be substantial.