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Fan vs Pump Air Sampling Methods: What are the Differences?

<p>Fan vs Pump Air Sampling Methods: What are the Differences?</p>

Article Details

Last Updated

06 May 2022

Published

04 May 2022

Category

Outdoor

At Aeroqual, we’ve been in the business of developing cutting-edge air quality monitoring equipment for over twenty years. Having deployed both active fan and pump sampling technology across a range of air monitoring systems, our engineers are closely familiar with the pros and cons of each method. So, how do you know which type of sampling technology is right for you? Is there a significant difference between the two? And if so, how can you use that knowledge to obtain the best possible outcome for your project?

An introduction to the pump sampling method

The pump sampling method works by using an air sampling pump to actively pull ambient air from the surrounding environment into the device. This method is ideal for maintaining a steady flow should a pressure drop occur, or when a sample needs to be drawn through a system with narrow tubing. When faced with an obstruction or sudden pressure differential, a pump sampling system will continue to function as normal.

However, pump sampling is not without its drawbacks. An air sampling pump consumes significantly more power than fan sampling technology. It also tends to be heavier, impacting portability and comfort. When using the commonly found diaphragm pump, a degree of pulsation is likely to occur during flow. This pulsation can potentially disrupt the measurement process, affecting the data accuracy in some cases. In summary, pump-based sampling offers excellent static pressure performance and flow reliability. However, high power consumption, increased weight and noise, and flow pulsation can prove challenging for trying to capture accurate results on the go.

Fan sampling types – axial vs centrifugal

Fan sampling technology is comprised of two distinct types. Axial fans (otherwise known as windmill fans) offer a tremendous flow rate. These fans are well-suited to moving large amounts of air, with lower power consumption than pump-based technology and zero pulsation. The issue with using axial fans is that a sudden pressure drop is likely to result in performance issues. This makes axial fans less suitable than other methods in certain outdoor environments, with these types of monitoring systems better deployed in more controlled conditions.

Splitting the difference between the axial fan and the pump sampling method is the centrifugal fan. Also known as the radial fan or blower-type fan, the centrifugal fan can actively move considerable amounts of air while also maintaining flow in the event of a pressure drop, constriction, or obstruction. Lightweight, with less power consumption than air sampling pumps, the centrifugal fan generates zero pulsation, for a smooth flow. This type of fan also has the advantage of being somewhat self-cleaning, in that airborne dust is simply flicked out by the rotors in the direction of the exhaust. This helps ensure that the centrifugal fan airflow is not as affected by the particle content of the air as the axial fan method.

Choosing the right sampling method

Given the option of these three sampling types, how do you know which method is best suited to you? The answer lies in which factors are most important for your project (while minimizing the impact of any potential drawbacks). For projects in variable outdoor environments, the pump sampling method can help provide a reliable flow no matter the conditions. However, a comparative lack of portability and potential accuracy issues (caused by pulsation) make fan sampling a more attractive option in most cases. While axial fans may struggle to withstand a sudden pressure drop, centrifugal fans offer the best of both worlds.

In generating zero pulsation, centrifugal fans help the user record accurate measurements, producing trustworthy, defensible data. A typically lightweight build makes for increased comfort and portability. A ‘self-cleaning’ design and the ability to maintain flow in the event of obstruction are ideal for sampling in dusty or changeable outdoor environments (along with indoor areas). It’s these reasons, along with a high level of durability and overall balanced performance, that make centrifugal fan sampling our method of choice in designing Aeroqual Ranger – the ultimate connected handheld solution.

Aeroqual

Designing the ultimate connected handheld solution

Aeroqual Ranger is our cloud-connected portable monitoring solution for industrial and occupational hygienists and environmental health and safety professionals. Ranger delivers remote data access and highly accurate measurements on a range of outdoor pollutants, in a flexible, lightweight design.

Ranger helps reduce on-site visits and eliminate data loss via automatic alerts and our Ranger Cloud software. Backed by a sampling method that best complements these goals, Ranger delivers actionable insights and increases operational efficiency, saving you time and money on your next monitoring project.

Want to find out more?

If you have any questions about air sampling, Aeroqual Ranger, or anything else you like to know more about, don’t hesitate to get in touch!

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