Polybutylene Pipe Sizing: AS/NZS 2642 vs AS 5082

In light of recent developments in the New Zealand plumbing industry, understanding the differences between various standards and sizing conventions is key to making informed decisions that benefit both installers and end users. Two common standards used in Polybutylene (PB) piping systems are AS/NZS 2642 and AS 5082 sizing, each with unique attributes that impact performance, installation, and long-term reliability.

What is AS/NZS 2642?

The AS/NZS 2642 product standard for polybutylene pipes and fittings has been in place since 1984. This standard was specifically developed for PB plumbing systems, specifying pipes internal diameter and wall thickness. Its specifications have been relied upon for decades and match the pipe sizing of many homes already plumbed under this standard.

AS 5082 Metric Sizing: A Newer Alternative

Metric-sized PB systems, a more recent entry into the market, follow a different approach by focusing on the pipe's thickness. The AS 5082 standard was developed specifically for pipes to be used with electrofusion fittings as these fittings require thicker walls for proper installations. While this may seem like a minor difference, it has significant implications for how pipes perform under pressure, and how easily they integrate with existing systems. As metric size pipes have significantly thicker walls, this results in a bulkier, heavier, more cumbersome product with a need for a whole new range of fittings, pipe clips and tools to connect pipework.

Wall Thickness and Performance

AS/NZS 2642 plumbing systems, such as the LEAP WaterLink Plumbing System, feature thinner walls without compromising strength, thanks to the precision of the standard. These pipes have for decades met and exceeded the pressure requirements of both residential and commercial projects. This results in a more efficient, lighter system that can be installed quickly and with less material wastage when compared to the more expensive AS 5082 pipes and fittings.

AS 5082 pipe systems, although having a higher-pressure rating because of its relatively thicker walls, may have a lower flow rate due to a smaller internal bore for corresponding sized AS/NZS 2642 pipes.  This will potentially make pipework designs more complex and installations more labour-intensive and costly.

Choosing the Right System for Your Projects

When deciding between AS/NZS 2642 and AS 5082 PB systems, it's important to consider both the technical specifications and the practical implications of installation. AS/NZS 2642 offers the advantage of a thinner, lighter pipe without compromising on performance, making it ideal for cost effective, faster, and more efficient installations. On the other hand, AS 5082 sized systems, while unnecessarily stronger, will be more expensive due to their thicker walls, lower flow rates, as well as heavier pipe and fittings.

Understanding these differences can help you choose the right pipe and fitting sizes to ensure your plumbing projects meet both your expectations and the needs of your clients, all the while staying compliant with industry standards.