Dust can quickly become a serious issue on civil construction sites, quarries, forestry operations and roading projects. Beyond reducing visibility and creating an unpleasant working environment, certain types of airborne dust can present genuine health risks to workers.
WorkSafe New Zealand identifies effective dust control as an important part of workplace health and safety. Where dust cannot be eliminated, businesses need to consider appropriate controls to minimise exposure. Water suppression is one of the engineering controls that can be used to help keep dust from becoming airborne.
For businesses operating in demanding environments, choosing the right dust suppression unit in NZ therefore isn't simply about finding a water tank and pump. Tank capacity, pump performance, build quality, vehicle compatibility, controls and ongoing reliability can all affect how useful the equipment is in day-to-day operation.
If you're comparing dust suppression units for an upcoming project or adding another unit to your fleet, here are the main factors worth considering before you buy.
1. Start With the Right Tank Capacity
One of the first decisions is how much water you need to carry.
A tank that's too small may require frequent refilling, adding unnecessary downtime throughout the working day. On the other hand, selecting a larger unit than your vehicle or operation requires can add unnecessary weight and cost.
Think about the size of the site, how frequently dust suppression will be required, available water sources and the carrying capacity of the vehicle.
Promax offers dust suppression units in a wide range of capacities, from compact options through to 15,000-litre units for larger operations.
For example, smaller units may be suitable where manoeuvrability and flexibility are priorities, while higher-capacity systems can make more sense for large civil, quarrying, forestry or roading projects where substantial areas need regular water application.
The right capacity isn't automatically the largest one available. It's the size that provides sufficient operating time while remaining appropriate for the vehicle and job.
2. Check the Pump Performance
A tank holds the water, but the pump determines how effectively you can use it.
Pump reliability and flow rate are therefore important considerations when comparing dust suppression equipment.
You need enough flow for the spray configuration you're planning to use, while also considering whether the pump will cope with the demands of regular site operation.
For example, Promax slip-on dust suppression units can feature a Honda GX160 semi-trash water pump with a flow rate of up to 1,000 litres per minute and a maximum head of 28 metres.
Depending on the application, petrol, diesel and hydraulic pump configurations may also be available.
Before purchasing, ask the supplier what pump is included, what its flow rate is, what maintenance it requires and whether alternative pump configurations are available for your application.
A good tank paired with an unsuitable pump can limit the effectiveness of the entire system.
3. Consider How the Water Is Distributed
Effective dust suppression isn't simply about putting as much water as possible onto the ground.
How that water is distributed matters.
Look closely at the spray system provided with the unit. Adjustable spray nozzles can give operators greater control over where water is applied and how wide an area is covered.
Depending on the unit and application, useful features may include rear spray bars, front spray bars, adjustable spray nozzles and dribble bars.
Some applications may also benefit from a water cannon where more targeted or longer-range application is required.
Promax, for example, offers an optional Sidewinder water cannon with radio remote control on its dust suppression systems.
Think about the actual conditions your team encounters. A quarry may have different requirements from a civil roading contractor, and a forestry operation may need a different configuration again.
The system should suit the job rather than forcing the job to fit the equipment.
4. Don't Overlook Tank Stability and Baffling
Water moves, and thousands of litres of water can create substantial forces when a vehicle accelerates, brakes or changes direction.
For mobile water tanks, controlling this movement is an important consideration.
Look for a tank designed specifically for transport applications and check what baffling system is used.
Promax dust suppression units use the Promax Ball Baffle System, designed to reduce the movement of water inside the tank during transport.
This is an important detail that can easily be overlooked when buyers focus only on capacity and price.
When comparing units, ask how the tank manages liquid movement and whether the overall system has been designed for the type of mobile application you're planning.
5. Look at the Build Quality
Dust suppression equipment can have a demanding working life.
Civil sites, forestry operations and quarries aren't gentle environments. Equipment can be exposed to vibration, water, mud, dust and changing weather conditions, so durability should be high on the purchasing checklist.
Look beyond the tank itself and inspect the supporting structure, pipework, fittings and mounting system.
Promax slip-on units, for example, use galvanised steel pipework and a heavy-duty galvanised steel skid-mount frame.
Galvanised components can be particularly valuable for equipment regularly exposed to water and outdoor working conditions.
Build quality also affects downtime. Saving money on the initial purchase isn't necessarily a saving if fittings, pipework or structural components require frequent repairs later.
For equipment expected to work regularly, total lifetime value is usually more important than the lowest upfront price.
6. Slip-On or Chassis-Mounted DSU?
Another important decision is how permanently you want the dust suppression system attached to the vehicle.
A slip-on dust suppression unit can provide flexibility because the unit is mounted on a skid frame. This can be useful for businesses that want to use a vehicle for different applications at different times.
A chassis-mounted dust suppression unit, by comparison, is installed directly onto the truck chassis and can be a better option for vehicles dedicated primarily to water delivery and dust suppression.
Promax's chassis-mounted dust suppression systems are available in capacities from 5,000 to 15,000 litres, with petrol, diesel or hydraulic-driven pump options, front and rear spray bars, high-flow washdown hose and in-cab controls.
Think about how frequently the vehicle will be used for dust suppression. If it's a dedicated dust truck, a permanent chassis-mounted solution may make sense. If you need more flexibility across your fleet, a slip-on configuration may be more practical.
7. Make Sure the Unit Matches Your Vehicle
A dust suppression unit needs to work safely with the vehicle carrying it.
Water is heavy. One litre of water weighs approximately one kilogram, meaning the water alone in a 10,000-litre tank is around 10 tonnes before you account for the tank, frame, pump, pipework and other equipment.
Vehicle payload and configuration therefore need careful consideration.
Check the dimensions and empty weight of the unit as well as its water capacity.
For example, Promax lists its 5,000L dust suppression unit at approximately 3,800mm long, 2,000mm wide and 1,500mm high, with an empty weight of around 500kg. The larger 10,000L unit is approximately 4,800mm long, 2,250mm wide and 1,950mm high, with an empty weight of around 950kg.
These figures demonstrate why vehicle compatibility needs to be assessed properly rather than simply choosing a unit based on tank volume.
8. Consider Operator Controls and Ease of Use
A dust suppression system may be used repeatedly throughout a working day, so ease of operation matters.
Features that allow operators to control water application efficiently can reduce unnecessary stopping and make the system easier to integrate into normal site operations.
In-cab controls are particularly useful because they allow spray functions to be operated without the driver repeatedly leaving the vehicle.
Promax units include options for in-cab control of spray functions, while adjustable rear sprays provide further control over water distribution.
Other practical features worth considering include water-level sight glasses, hose reels, easy-to-access filling points and suitable suction systems.
These may seem like relatively small details when comparing specification sheets, but they can make a noticeable difference during everyday use.
9. Think About How and Where You'll Refill
Water availability can have a major impact on dust suppression productivity.
If your unit constantly needs to travel long distances to refill, the time lost can quickly add up.
Before purchasing, think about the water sources normally available on your sites and check whether the unit can accommodate them.
Some Promax dust suppression units include suction systems that allow filling from alternative water sources, subject to the suitability and permitted use of that source. Camlock connections can also support bulk water transfer and filling.
The faster and easier it is to refill your tank, the less time your equipment spends away from its primary task.
10. Consider Washdown and Multi-Purpose Use
Depending on your operation, a dust suppression unit may be useful for more than spraying haul roads.
A hose and reel can provide additional flexibility for washing equipment or targeted water application around the site.
Promax slip-on units can include a 30-metre hose reel, while chassis-mounted configurations can include a high-flow washdown hose and reel.
When comparing units, think about whether these additional functions would be useful for your crews.
Equipment that can perform several practical site tasks may provide better overall utilisation than a system designed for only one narrow purpose.
11. Understand Your Dust-Control Responsibilities
Purchasing a dust suppression unit shouldn't be treated as a substitute for assessing workplace dust risks.
WorkSafe NZ states that PCBUs have a duty to eliminate risks where reasonably practicable and, where this isn't possible, minimise them using appropriate control measures.
Respirable crystalline silica is a particular concern in industries including construction, quarrying and roading. WorkSafe notes that water spray and misting systems can be used as part of controlling silica dust and keeping dust out of the air.
For more information, read the official WorkSafe NZ guidance on silica dust in the workplace, or our article on why dust control matters more than ever.
The appropriate controls will depend on the specific hazards and work being undertaken, so a dust suppression unit should form part of a wider, site-specific dust-management approach.
12. Compare More Than the Purchase Price
Price matters, but it shouldn't be the only factor when comparing dust suppression units in New Zealand.
Consider what you're receiving for the investment.
Look at tank construction, pump quality, pipework, spray configuration, mounting system, controls, warranty and the availability of replacement components and technical support.
Downtime also has a cost. If an inexpensive unit regularly needs repairs or isn't capable of meeting site demands, any upfront saving can quickly disappear.
Promax designs, manufactures and supports its dust suppression units in New Zealand and offers custom configurations for different civil, forestry and roading requirements.
Promax also provides a 10-year pro-rata warranty on its tanks and frames, giving buyers additional long-term support.
Questions to Ask Before Buying a Dust Suppression Unit
Before making your final decision, ask the supplier:
- What tank capacity is appropriate for my vehicle and application?
- What is the empty weight of the complete unit?
- What pump is fitted and what flow rate does it provide?
- What spray configuration is included?
- Can the spray system be controlled from inside the cab?
- What baffling system is used?
- What are the filling options?
- Is a hose reel included?
- Can the unit be customised?
- What warranty and after-sales support are provided?
- Are replacement components readily available in New Zealand?
A knowledgeable supplier should be able to discuss your actual operating requirements rather than simply recommending the biggest or most expensive unit.
Choosing the Right Dust Suppression Unit in NZ
The best dust suppression unit is one that fits your vehicle, operating environment and daily water requirements while providing reliable performance over the long term.
Tank capacity is important, but it's only one part of the decision. Pump performance, baffling, spray coverage, construction, vehicle compatibility, operator controls, refill options and after-sales support can all affect how well the equipment performs once it reaches the worksite.
Promax offers a range of New Zealand-designed and manufactured dust suppression units, including slip-on and chassis-mounted configurations for civil construction, forestry, quarrying and roading applications.
If you're comparing options for your fleet or an upcoming project, explore the Promax Dust Suppression Units range or contact the Promax team to discuss the capacity and configuration best suited to your operation.