AYO WX Frequently Asked Question

Why do we need to fit-test a tight-fitting PAPR in power-off mode?

Fit testing is a procedure used to determine how well a respirator “fits”—that is, whether the respirator forms a seal on the user’s face.

When a tight-fitting PAPR is fit-tested in power-on mode, as long as there is positive pressure in the mask, there will be no leak, thus it may appear the PAPR has a very good fit.

However, the issue with this practice is that it hides the bad fit or leak of the respirator such that when the air pressure drops to negative inside the mask, outside contaminants will be sucked right in.

Why can pressure in a PAPR be negative? Well, all PAPRs have their limit in producing air. Most PAPRs have a maximum flow of 200 – 220 L/min. However, when doing heavy work, such as on construction sites, if you are a big guy, the peak flow from breathing can easily exceed 250 L/min or even over 300 L/min. In this situation, a bad-fit PAPR cannot protect you well.

The negative pressure may not be present when doing the PortaCount fit testing, as the test protocol does not simulate heavy work.

The conclusion:

  • Tight-fitting PAPRs need to be tested in power-off mode to indicate a worse-case fit factor.
  • The power-on mode can be used to indicate a best-case fit factor.

Why loose-fitting PAPRs don't require fit testing but tight-fitting PAPR do?

The industry consensus on fit testing is that, Loose-fitting PAPRs don’t require fit testing, and tight-fitting PAPRs must be conducted fit testing.

But don’t draw the wrong conclusion that a loose-fitting PAPR is superior to a tight-fitting PAPR. Here is the truth:

  • Loose-fitting PAPR is only a simplified/crude version of PAPR at a cost of low protection factor and high battery consumption.
  • Loose-fitting PAPR only has an Applied Protection Factor (APF) of 25 while tight-fitting can be up to 1000.
  • The reason why loose-fitting PAPRs don’t require fit testing is simply because of its low APF rating and it is only suitable for non-critical protection.
  • If a loose-fitting PAPR goes through fit testing at Power Off mode, it will fail miserably.
  • If you can accept a low APF of 25 for a given job, you can generally use a tight-fitting PAPR as a loose-fitting PAPR without having to do a fit-testing, provided the tight-fitting PAPR has a minimum peak flow capacity of 170 L/min.

Why Breath-responsive PAPRs are Better

Traditional PAPRs run at a constant flow or blower speed, although they often offer 2 or 3 settings.

Key issues are:

  • Noisy at high flow setting.
  • Heavy and bulky, often it needs to be waist-mounted by a belt with a troublesome long hose connecting to the face mask.
  • Poor mobility, difficult to operate and maintain, thus their usability is quite limited.

Breath-responsive PAPRs solve these issues:

  • Quieter and more energy efficient.
  • Lighter and low-profile, often they can be worn on the face or around the head with no hose and belt.
  • Better mobility, easier to operate and maintain.

Challenge and outlook:

  • Breath-responsive technology is more advanced and technically difficult.
  • It requires a very low inertia fan running at a very high speed.
  • It requires high-tech motor technology, often a Brushless DC motor and Sensorless drive mechanism.
  • It requires intelligent control firmware to work effectively.
  • Only less than a handful of companies in the world can do it.
  • The prediction: Constant Flow PAPRs will be phased out in the next 10 years, Breath-responsive PAPRs are the brighter future.

What kind of respirator should be used for welding fume protection

The workplace exposure standard (WES) for welding fumes has been reduced from 5mg/m3 to 1mg/m3.
What does it mean for this significant reduction?

It means that breathing in welding fumes is more of a health hazard than we thought.

Welding fumes are carcinogenic, and if welding is part of your regular work, the safest approach is to always wear the best respirator available.

Here are some of the key points for consideration:

  • Welding fumes are accumulative in the lungs, try to reduce the exposure as much as practical.
  • The tightened 1mg/m3 does not mean it is a safe limit, it is only a legal maximum upper limit to be taken as a starting point.
  • Disposable mask is only for a temporary and less critical application, not recommended for your long-term work health related to welding fumes.
  • Non-powered reusable respirators are not ideal: often filter cartridges are fitted on the front of the mask, hindering welding helmets. Besides, being a negative pressure mask, it is prone to facial leaks.
  • Loose-fitting PAPR with a waist-mount power unit and a long hose to the integrated welding helmet appear as a common image of good protection gear for welding. But good welding respiratory protection doesn’t have to be bulky, heavy, troublesome, and overly expensive. Besides, being an old technology, a loose-fitting PAPR offers only 2-3 times better protection than a disposable respirator.
  • In most cases, the best option is a breath-responsive tight-fitting PAPR P3, with features including low profile, high mobility, easiness of use, and affordable cost.
  • PAPR P3 AYO WX-Welding is one such respirator that excels, and it is now available.