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By: Saurav Chattopadhyay on Sep 1, 2023 9:22:15 AM
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The Truth About CPVC Flammability

The building sector is becoming increasingly safety-conscious, and more people have started to take notice. 

This has been shown once again by transformative legislative action made by the government in the United Kingdom, which is to impose a mandatory height threshold of 18 metres for second staircases in all new residential structures. 

However, fire safety encompasses more than just construction itself. Investing in materials that are flame-resistant is particularly vital because of the long-lasting consequences of smoke inhalation as well as the devastation that may be caused by fires, which can result in great financial loss and damage to structures.

BlazeMaster® CPVC (chlorinated polyvinyl chloride,) is one such material that has achieved extensive usage as a fire safety solution due to its long-lasting strengths and cost-effective installation. Even the most labour-intensive projects benefit greatly from the exemplary flame retardant capabilities that BlazeMaster CPVC delivers.

In summary, BlazeMaster CPVC:
  • Is designed for 50 years of service life with a safety factor of 2
  • Will not sustain burning after the flame is removed
  • Limits smoke generation
  • Has the highest possible European Fire Classification Rating
  • Is approved for all light hazard applications


BlazeMaster CPVC holds the highest rating for flammability.

The European Fire Classification of Bs1d0, which is the maximum rating that can be achieved by a plastic material, has been awarded to BlazeMaster CPVC pipes and fittings.

Fire behaviour 'B' - Very low flammability, and no contribution to flashover.
Smoke development 's1'  - Low smoke development 
Flaming droplets 'd0'  - No burning droplets


In the event of a fire, BlazeMaster CPVC will not melt when installed per its listings. 

Because it is made of plastic, there is a common misconception that CPVC will melt and become ineffective in the event of a severe fire threat. 

CPVC is engineered by subjecting polyvinyl chloride (PVC) to a chlorination reaction. While PVC has an approximate total chlorine content of 57%, CPVC has an approximate total chlorine content of 67%. This extra chlorine is what gives CPVC its one-of-a-kind ability to withstand direct flame for extended periods of time.


It is not possible for BlazeMaster CPVC to remain burning in our environment.

CPVC has a Limiting Oxygen Index (LOI) of 60, which means that in order for a flame to be maintained, an atmosphere that contains at least 60% oxygen is required. As a result of the fact that the oxygen content of the earth's atmosphere is just 21%, the substance exhibits characteristics of being self-extinguishing and will cease burning the instant the flame is extinguished.


BlazeMaster CPVC has been listed by UL to UL1821. 

Underwriters Laboratories (UL), an essential authority within the industry that tests and certifies fire prevention goods, carried out an investigation to list BlazeMaster CPVC pipe and fittings to UL1821 which requires large scale fire tests for approval in exposed applications.



During the test, a fire with a peak temperature of 427°C in the flue came into direct contact with the joint and fitting of BlazeMaster CPVC piping. This caused the junction and fitting to become extremely hot. The sprinkler head began to operate after roughly one minute had passed since the beginning of the test, and it remained operational until a total of ten minutes had passed and was allowed to cool and then hydrostatically tested to 175 PSI with no ruptures or leaks. 

The BlazeMaster CPVC piping was subjected to burning, which resulted in the formation of a charred layer on the exterior of the pipe. This layer served as a thermal barrier that reduces the conduction of heat into the pipe. Water flowing through the piping system also cooled the inside of the pipe to further resist heat. Because of this, water is allowed to continue flowing through the pipe, combating the source of the fire.


Specifying fire sprinkler systems

More than ever before, modern building standards are dependent on outstanding levels of fire protection in order to remain in compliance with changing legislative mandates around the world.

We strongly recommend that individuals working in the construction business get themselves and their coworkers a copy of The Orange Book, which is the definitive specification guide. 

It not only provides a detailed explanation of what characteristics of BlazeMaster CPVC make it appropriate for fire safety, but it also makes it easy to access all of the necessary certifications, standards, and laws that pertain to your industry.

The Orange Book can be accessed immediately, free of charge through the Orange Book online portal