CFM or m³/hr — how to compare machines

Negative air machines get quoted both ways and it makes comparison shopping harder than it needs to be. They are the same number in different units: 1 CFM = 1.699 m³/hr. This machine is 2000 CFM, which is 3400 m³/hr.

Two things worth checking when you compare against another unit. First, whether the figure quoted is free air or airflow with filters fitted — a number measured with nothing in the filter track is not the number you will get on site. Second, whether it is the maximum or a rounded-down working figure. We quote the machine's rated maximum with the filter train installed.

Built for containment work

Set up inside an enclosure and duct the exhaust outside, and the HSS3300 pulls the containment negative, so air moves into the work area, never out of it. That is the whole principle behind asbestos enclosures and silica-generating fit-out work, and it is the difference between dust staying in the room and dust ending up in the rest of the building.

Run it as a recirculating scrubber instead and it simply cleans the air in place, dropping airborne particulate in occupied areas, during demolition, or after a strip-out. Both modes, one machine, no accessories to buy.

Buy or keep hiring?

Typical hire of a similar unit runs around $650 a week. At that rate the HSS3300 pays for itself in a few weeks of use, and every week after that is margin instead of cost. If you are running containments more than one month a year, owning wins.

Replacement filters

We stock the 24" x 24" H13 HEPA and the matching pre-filter, so the machine does not sit idle waiting on a part. Filters are the running cost of a containment programme — order spares with the machine and keep a set on the truck.

More features

• Two-Stage Filter Train pre-filter catches the bulk, HEPA catches what matters, and the pre-filter protects your HEPA spend
• Two-Speed Operation dial airflow to the containment instead of running flat out
• Roto-Moulded Seamless Housing no seams to leak, no panels to crack, no rust
• Positive-Lock Filter Retention filters cannot shift in transit or under load
• Moulded-In Stacking Grooves nest up to three units for transport and storage
• 8-Point Motor and Cage Mounting holds alignment through the kind of handling site equipment actually gets
• Ducted Inlet and Outlet 315mm outlet takes lay-flat or rigid duct for exhaust outside the containment

• Model: HSS3300 (240V)
• Airflow: 2000 CFM — 3400 m³/hr (56.7 m³/min)
• Motor power: 1000 W
• Supply: 240 V / 50 Hz, 10 A
• Fan speed: 2400 RPM
• Speed settings: Two (high / low)
• Filtration: Two stage — pre-filter + H13 HEPA, rated 99.97%
• HEPA size: 24" x 24" (610 x 610 mm) standard
• Outlet: 315 mm dia. duct connection
• Housing: Roto-moulded polyethylene, seamless
• Controls: Power switch, 10 A circuit breaker, differential pressure gauge, power supply receptacle
• Mobility: Four casters, moulded lifting handles both sides
• Stacking: Up to 3 units
• Dimensions: 1020 x 740 x 800 mm
• Weight: 70 kg
• Colour: Black

Silica dust and the new NSW rules

Since 1 September 2024 the NSW WHS (Crystalline Silica Substances) Regulation has required PCBUs to control silica processing, document a silica risk control plan, carry out air monitoring, provide health monitoring and train workers on the risk. Engineering controls sit at the top of that hierarchy — above PPE — and a HEPA negative air machine is one of the few controls that works on the airborne fraction rather than at the tool.

Confirm the specific control measures your risk assessment requires. This machine is equipment, not advice.

• 1 x HSS3300 negative air machine
• 1 x H13 HEPA filter (installed)
• 1 x pre-filter (installed)
• Four caster wheels
• Operation and maintenance manual

Will it run on a normal site power outlet?

Yes, 240 V, 10 A, standard plug. No three-phase required.

Can I use it for asbestos removal?

It is the class of equipment used for that work, filtered to H13 HEPA. Whether it satisfies the requirements of your specific removal control plan is a decision for your licensed removalist and your risk assessment.

How many do I need for my containment?

Depends on enclosure volume and the air changes per hour your control plan calls for. Send us the dimensions and we will run the numbers with you.

Do you supply ducting?

Yes, 315 mm lay-flat and rigid duct available separately, ask for a quote.