H-Class vs M-Class Vacuums: Which One Does Your Job Legally Need?
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Most of the arguments we hear on this come down to one thing. Someone has an M-Class extractor on the truck, they've got a bit of asbestos cleanup in front of them, and they want to know if it will do.
It won't. Here's why, and here's where the line actually sits.
What is the difference between an M-Class and an H-Class vacuum?
The classes come from the dust classification in AS/NZS 60335.2.69 (the Australian/New Zealand adoption of IEC 60335-2-69, Household and similar electrical appliances — Safety — Particular requirements for wet and dry vacuum cleaners, including power brush, for commercial use). It sets three hazard classes.
| L-Class | M-Class | H-Class | |
|---|---|---|---|
| Minimum filtration efficiency | 99% | 99.9% | 99.995% |
| Maximum filter penetration | 1% | 0.1% | 0.005% |
| Dust exposure standard it's built for | above 1 mg/m³ | 0.1 mg/m³ and above | below 0.1 mg/m³, and carcinogens |
| Typical dust | plaster, soil, limestone | timber, concrete, most silica, MDF | asbestos, mould spores, lead, engineered stone |
| Legal for asbestos in Australia | No | No | Yes |
| Airflow alarm required | No | Yes | Yes |
| Sealed/dust-free bag disposal | No | Yes | Yes, plus a sealed filter |
The gap between 99.9% and 99.995% sounds like rounding. It isn't. M-Class lets fifty times more dust back into the room than H-Class does. On a dust where a single fibre matters, that is the whole argument.
The other difference is what happens outside the filter. An H-Class machine has to keep the dust contained through the whole cycle — sealed bag, sealed filter, closed disposal. An M-Class machine has a bag system, but the filter itself isn't treated as contaminated waste. On an asbestos job, the filter is contaminated waste.
Does the law actually require H-Class for asbestos work in Australia?
Yes, in practice.
The approved Code of Practice How to Safely Remove Asbestos — the Safe Work Australia model Code, adopted as an approved code in NSW by SafeWork NSW — states that asbestos vacuum cleaners should comply with the Class H requirements in AS/NZS 60335.2.69, or equivalent. It also says a HEPA-filtered H-Class industrial vacuum should be used wherever reasonably practicable.
Two things about how a Code of Practice works. It isn't the regulation itself — the duty comes from the WHS Regulation. But under the WHS Act an approved Code of Practice is admissible in proceedings, and an inspector or a court will treat it as evidence of what is reasonably practicable. If you used an M-Class machine on asbestos, "the code says H-Class" is the first sentence of the prosecution.
So: not "H-Class is a nice idea". H-Class, or you explain yourself.
Can I use an M-Class vacuum for silica dust instead?
This is the one place M-Class is genuinely in play, and it depends on the material.
For general construction dust — concrete cutting, brick, block, render — on-tool extraction into an M-Class or H-Class vacuum is the standard control. WorkSafe Victoria guidance points at Class M or H for crystalline silica work, and recommends H where reasonably practicable.
For engineered stone, the answer moved. A prohibition on engineered stone is in place, and the controlled processing, removal and disposal work that is still permitted sits under a much tighter control set, with H-Class extraction part of that picture. The detail differs by jurisdiction and by the type of work, so check the current SafeWork NSW position for your work.
Our honest read for a mixed-trade operator: buy H-Class once. An H-Class machine legally covers L, M and H dust. An M-Class machine covers L and M only. If you own one hazardous-dust vacuum, owning the wrong one costs you a second purchase the first time asbestos turns up.
What should I look for when buying an H-Class vacuum?
Beyond the class marking, four things matter on site.
A real airflow alarm. M and H machines must warn the operator when airflow drops below the safe threshold (20 m/s at the hose). On a Nilfisk ATTIX 751-0H ($3,637.70) that's the FlowSensor with an audible warning. If the alarm is going, you're not filtering properly.
Bag-in / bag-out disposal. You should never open a contaminated machine. The Numatic HZ370 ($1,870.00) uses HepaFlo sealed bags with an H13 filter to EN 1822 — the bag seals shut before it leaves the drum. Same principle on the larger Numatic HZD570 dual motor ($3,135.00) when you need more air.
Filter cleaning that doesn't need opening. Fine asbestos debris blinds a filter fast, and suction drops off. Automatic filter cleaning — InfiniClean on the Nilfisk VHS 42 30L ($1,938.42) — pulses the filter clear without breaking containment. On a long strip-out this is the difference between one machine and three.
Enough machine for the volume. A 15 L cartridge is fine for cleanup after a bonded sheet removal. A 70 L stainless drum, or a Husqvarna DE 110 H ($2,797.00) rigged as a pre-separator system, is what you want behind a grinder or on friable work.
How often does an H-Class vacuum need to be tested?
More often than most operators do it.
Accepted industry practice, and a manufacturer requirement on most H-Class machines, is a DOP test (dispersed oil particulate) at least every 12 months, plus after any filter change or repair. The DOP test checks the whole filtration system — the HEPA element and the seals around it — to confirm it is still holding at 99.995%. A filter that is intact but seated badly fails the test, and you would never know by looking.
Between DOP tests, inspect for filter damage, seal condition and correct suction, and keep the records. If an inspector asks, "when was it last tested" is a question with only one good answer.
What will get you pulled up on site?
The predictable ones:
- Using the H-Class machine on wet material or slurry. The code is explicit — don't. Wet asbestos wrecks the filter and you can't decontaminate it.
- Brush attachments. Fibres lodge in the bristles and can't be cleaned out.
- Using the asbestos vacuum for general site cleanup. Once it's an asbestos vacuum, it's an asbestos vacuum.
- Storing it uncovered. Between jobs it should be sealed, labelled, and kept away from general plant.
FAQ
Is an M-Class vacuum ever legal for asbestos removal in Australia?
No. The model Code of Practice specifies Class H to AS/NZS 60335.2.69 for asbestos. M-Class is for medium-hazard dusts and does not meet that standard.
Can I just put a HEPA filter in my M-Class vacuum?
No. The class rating covers the whole machine — seals, bag system, alarm and disposal path — not just the filter element. A retrofitted filter does not make an M-Class machine H-Class, and it can't be certified as one.
Is H-Class the same as HEPA?
Not quite. HEPA (H13 or H14 to EN 1822) describes the filter element. H-Class to AS/NZS 60335.2.69 describes the certified performance of the complete appliance. Every H-Class asbestos vacuum has a HEPA filter, but a HEPA filter alone doesn't make an H-Class vacuum.
Do I need an H-Class vacuum for unlicensed asbestos work under 10 square metres?
Yes. The licence threshold and the equipment standard are separate things. Removing 10 m² or less of non-friable asbestos may not need a Class B licence, but you still owe the same duty to control exposure, and that means H-Class.
What do I do with an H-Class vacuum after friable asbestos work?
Decontaminate it inside the enclosure before it comes out, seal the inlet, and wrap it. If it can't be properly decontaminated, it's disposed of as asbestos waste. Bag it, don't hose it.
How much should I budget?
Working H-Class machines start around $1,870 for a 15 L Numatic HZ370 and run to roughly $3,600 for a 70 L Nilfisk ATTIX 751-0H. Add DOP testing and consumables — bags and filters are an ongoing cost, not a one-off.
Deconsafe Solutions supplies H-Class vacuums, negative pressure units and decontamination equipment to asbestos removalists across Australia. We're the only Deconta dealer in the country, and we also stock Nilfisk, Numatic and Husqvarna. Prices above are current at time of writing.