Support Article

DZR Components

What Is DZR?

DZR (Dezincification Resistant) or DR Brass is a type of brass used for manufacturing, which gives resistance to dezincification corrosion. Products that offer Dezincification Resistant properties will often be marked with the "DR" mark, as above.

What Is Dezincification?

Brass is a widely used metal alloy, made of copper and zinc. In certain circumstances, when exposed to particular combinations of pH and concentrations of chlorides it can experience a severe form of corrosion known as dezincification. This is where the zinc dissolves out of the brass, weaking and compromising the mechanical properties of the alloy.

In relation to HVAC applications, dezincification can result in system failure by causing leaks, blockages or even ruptures. It is therefore rightfully a major consideration when it comes to system design.

When Do I need to be concerned about Dezincification?

In the UK, it is mandatory for fittings that are going underground to be dezincification resistant.

Potable water is unlikely to cause dezincification, but if it is capable, or where distribution systems might introduce fluids that may cause dezincification, you should use DZR fittings. If you are unsure, advice can be sought from your local water authority to understand if you need to consider DZR components for your project.

Avoiding Dezincification at the point of manufacture

Raw Material at Flowflex Factory
Brass Raw Material waiting for production at Flowflex

Our job in this equation is to manufacture products that can offer DZR properties. In order to produce components that can resist dezincification, we have to use the right material.

Copper and Bronze are both immune to dezincification, however both have drawbacks when it comes to manufacturing. Brass is the most practical material for high volume production, and so to offer resistance to dezincification, we manufacture using a different grade of Brass.

DZR brass will typically be the CW602N, CW6265 or CW626N specification of brass rod, which has a lower zinc content than standard brass rod. Traditionally, <15% zinc content has been the accepted maximum limit for avoiding dezincification, however for stamping and machining brass we need zinc contents higher than this. Adding inhibitors to the brass allows it to have a higher zinc content, but still retain resistance to dezincification. We use DZR brass as per UK specifications which contains some Arsenic (0.02 – 0.15%) and Nickel (0% - 0.3%).

This material will follow all normal routes of manufacture, with extra steps involved for stress relief through heat treatment. Extra care also has to be taken that there is no cross-contamination between DZR and non-DZR brass.

Table: Composition of brass material used for manufacturing Flowflex products
Code Composition % (mass fraction) Density g/cm3
Element Cu Al As Fe Mn Ni Pb Sn Zn P Others
CW614N min 57.0 - - - - - 2.5 - Rem - - 8.4
max 59.0 0.05 - 0.3 - 0.3 3.5 0.3 - - 0.2
CW617N min 57.0 - - - - - 1.6 - Rem - - 8.4
max 59.0 0.05 - 0.3 - 0.3 2.5 0.3 - - 0.2
CW602N min 61.0 - 0.02 - - - 1.7 - Rem - - 8.4
max 63.0 0.05 0.15 0.1 0.1 0.3 2.8 0.1 - - 0.2
CW625N min 62.0 0.5 0.02 - - - 1.2 - Rem - - 8.4
max 64.0 0.7 0.15 0.3 0.1 0.2 1.6 0.3 - - 0.2
CW626N min 64.0 0.8 0.02 - - - 1.2 - Rem - - 8.4
max 66.0 1.0 0.15 0.3 0.1 0.2 1.7 0.3 - - 0.2
Figures are indicative only and not for reference

What does this mean for you?

If you require DZR components for your project, you will need to specify this with us when ordering. Flowflex Compression offers DZR components, in our Compression range, however as the corrosion resistance of DZR components can be compromised when heated in excess of 400°C, we only offer Bronze products in our Copper ranges.

Any Questions?

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