Selecting the best respirator for the task at hand

It can be challenging for workers to wear negative pressure respirators during the entire duration of a work shift. When a person’s work rate increases, their breathing rate increases. Subsequently, the user would experience an increased resistance on both inhalation and exhalation when wearing the respirator.

Another option for workers is to use PAPRs (powered air purifying respirators), which are battery-powered fan units that draw contaminated air through the filter and deliver clean air to the facepiece worn by the user. However, different manufacturers have different flow rates. Some flow rates are greater than others and it may be therefore difficult to select the most appropriate PAPR for the task.

Focusing on these two types of respiratory protection, it can be difficult to confidently choose which will achieve optimal respiratory protection and minimise added respiratory workload for the user.

Safety Equipment Australia’s engineering team first developed a data logger in-house in the 1990s. With the technology available at the time, a first prototype was created that measured the pressure inside the mask which can be converted to flow. The objective was to develop a device to measure the data whilst the respirator is worn and analyse it to assist in selecting respirators with inhalation and exhalation resistance that are suitable for the task. Another objective was to also determine if PAPRs supplied sufficient airflow.

With the ongoing support of mining and metal processing end users from the development stage to gathering real data testing, it was clear that a more refined version of the data logger was needed to assist end users who are required to wear respiratory protection. With today’s technology, an inconspicuous and portable version of the data logger was created using updated software and components, achieving an advanced tool to assist with the selection of respiratory protection equipment.

In 2021, the SE-RDA Respiratory Data Analyser was finally released. This portable instrument measures and logs the air pressure inside a respirator and calibrated filters while fitted to a person. The device can be used on location during normal work, continuously recording each individual breath at a rate of 50 samples per second for up to 12 hours. The recorded data is then downloaded onto the software, which in turn is converted into flow rate. As a result, the information can be used in the selection of an appropriate respirator for the work at hand for all industry types.

The SE-RDA device comes with software for use on windows PC, measuring all tasks performed during a shift — including minute volumes (averaged over entire shift or selected intervals), total volume breathed, peak inhalation flow rates and the total amount of time the respirator is worn.

Key features of the SR-RDA:

• Captures multiple breathing parameters in real time.
• Can be used to measure human breathing during any activity, even when breathing protection is not normally worn.
• Monitoring can be done on negative-pressure air-filtering respiratory protection devices (RPD), as well as PAPRs and SCBA (self-contained breathing apparatus).
• Does not affect breathing resistance or interfere with the airflow through the mask.
   

The SE-RDA software enables OH&S professionals to quantify:

• Minute volumes (averaged over an entire shift or selected periods).
• Total volume breathed.
• Peak inhalation flowrates for all tasks performed during the period.
• Breathing resistance (BR) and work of breathing (WoB) for various types of RPD.
• ISO Work Rate classification (W1–W4) and how the work rate varies over the period.
• The amount of time the respirator is worn during the shift.