NZS5149 - the HVAC standard you probably don't know about, but should

By John Greaves (NZCE – mech), Senior Design Engineer, Black Diamond Technologies Ltd

The NZS5149 standard, dealing with refrigerant concentration in confined spaces, has been around since 2016. It’s important as it affects every new or altered DX system installed in NZ –but it is largely overlooked. If you are designing or installing DX HVAC systems YOU NEED TO KNOW ABOUT NZS5149. The consequences of getting it wrong are huge – maximum penalties of $500,000 and 2 years’ jail are possible.

Let’s start off by demystifying the standard a bit..........

NZS5149 is a safety and environmental standard that primarily deals with refrigerant leakage – and more precisely the risk of asphyxiation or fire that can result from any leak. The standard itself is around 200 pages long set out in four sections covering:

1. Definitions – describing terms, identifying refrigerants, classifying applications, explaining limits and describing mitigation. This is probably where you will spend most of your time trying to understand what is or isn’t required for any project.

2. Design & construction – requirements for piping, components and assemblye.g. pressure testing, tightening torques, inspections methods etc. Needed after you have decided what is required to meet the standard in section 1.

3. Installation site – specific requirements for applications such as machinery rooms and requirements for mitigation methods such as alarms or ventilation. Hopefully not too much time spent in here as this section as it means expense.

4. Operation maintenance & repairs – covers ongoing use of HVAC and mitigation systems to ensure correct performance. Also covers reclaim, disposal handling & storage of various refrigerants.

NZS5149 definitely is a tricky standard, but anyone working with DX air con or DX industrial plant should be using it regularly – I know I am.

Obviously wading through 200 pages of standards to work out what you need isn’t fun so I’ve distilled it down it to a few tips and

tricks that should help you at least get going in the right direction or know what other questions to ask. These are:

• What types of refrigerants to look out for

• What types of systems and applications to look out for

• Some quick guides to help determine if there is a problem or not

• What you can do if there is a problem So let’s get on and clear up some of these points.

Read the full article in the Industry Journal, August 2021 issue