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PB-1 Flammability and Burning Characteristics

As a polyolefin, the flammability and burning characteristics of Polybutene-1 are akin to those of polyethylene and polypropylene materials. Independent testing in the USA reports that PB-1 resin conforms to the requirements of Underwriters Laboratories test UL94 HB classified material. PB-1 is classified according to Class IV.2 (normal flammability) in the recommendations of VKF (Association of Cantonal Fire Insurances in Switzerland).
 

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Flammability and Burning

Similar to other polyolefins, PB-1 is relatively difficult to ignite and is defined as combustible, but not regarded as highly flammable.

In common with most other organic polymers and materials used in manufacture and construction industries, Polybutene-1 will burn.

When Polybutene-1 pipe grade material is heated in air, melting will occur at ~ 127°C, and decomposition will commence at about 300°C with the release of volatile lower molecular weight hydrocarbons. A flame or radiant heat source can ignite these hydrocarbons.

Once ignition occurs, sufficient heat will be generated to continue the decomposition and provided enough oxygen is present, burning will continue even when the ignition source is removed. Burning is accompanied by the release of flaming molten droplets of polymer that could ignite other flammable material.

These comments can only be of a general nature, since the conditions in a real situation can never be fully predicted. They will depend on many factors, such as the location, the oxygen availability and the presence of other flammable materials.

Like many other organic materials such as wood, paper and cellulose, when Polybutene-1 burns, it gives off carbon dioxide and water as the main decomposition products, together with carbon monoxide and carbon (soot), as well as a considerable number of other, often irritant, decomposition and oxidation products in very low concentrations. These can include small amounts of certain noxious aldehydes such as formaldehyde and acrolein. These aldehydes are irritant and lachrymatory and therefore can cause the fumes to be irritant.

Being a polyolefin, the flammability and burning characteristics of Polybutene-1 are akin to those of polyethylene and polypropylene materials.


Flammability Performance

In conformance with fire protection standards

In an evaluation run by Springborn Laboratories Inc., a US private testing group in Enfield, Connecticut, samples of Polybutene-1 resin were found to conform to the requirements of Underwriters Laboratories test UL94 HB classified material.

Polybutene-1 is classified according to Class IV.2 (normal flammability) in the recommendations of VKF (Association of Cantonal Fire Insurances in Switzerland).

According to DIN 4102-1, Polybutene-1 belongs to Fire Protection Class B2. If fire protection measures are required for pipes >DN 50 in wall and ceiling ducts, then only allowable fire protection insulation (e.g. DOYMA pipe duct technology, MISSE insulation systems etc.) may be used.

The limiting oxygen index measured according to ASTM D2863-77 for Polybutene-1 is 17.5. Wherever Polybutene-1 pipe passes through a fire resistant wall, it must be sleeved in a suitable intumescent material.

The use of Polybutene-1 pipes and fittings in water pipe applications is approved by the statutory building and construction codes in most countries.


 

Polybutene is often referred to as Polybutene-1, Polybutylene, PB-1 or PB.

Polybutene is not sold by PBPSA members for use in pipe applications intended for use in North America, and those parties require their customers or distributors not to sell products made from Polybutene into pipe applications for North America.