Ensuring a proper respirator fit is essential for workplace safety, particularly in industries where airborne contaminants pose a risk. The TSI PortaCount Pro fit test system is widely used for quantitative fit testing, but some users have concerns about moisture buildup in the sample tubes and its potential impact on test accuracy.
How the TSI PortaCount Pro Fit Test System Works
The TSI PortaCount Pro respirator fit test system includes a pair of sample tubes, the blue one samples ambient air and the clear tube attaches to the respirator and samples from inside it. A valve inside the PortaCount Pro fit tester switches from one tube to the other according to a programmed sequence.
Potential Causes of Excess Moisture in Sample Tubes
Moisture buildup in sample tubes can occur for several reasons:
- Temperature Differences: Warm breath condensing on colder tube walls can cause moisture accumulation.
- High Humidity Environments: Testing in humid conditions increases the likelihood of moisture buildup.
- Repeated Testing: Conducting multiple fit tests back-to-back without changing or drying the sample tubes can lead to excess moisture retention.
Moisture Buildup in Sample Tubes
Typically, after several uses, the first few inches of the twin-tube can become fogged with moisture, as the test subject's warm breath condenses in contact to the cold walls of the tube.
TSI's Answer: Can Moisture Affect Fit Test Results?
Occasionally, our customers ask if the moisture build-up in the sample tube might affect the tests or expose employees to harm based on moisture exhaled during previous fit tests.
Here's how TSI answers the first question, per their Fit Testing Frequently Asked Questions:
"Exhaled moisture droplets have little effect on the PortaCount® Respirator Fit Tester for two reasons. One is that there are not enough of them to make a difference and the other is that large droplets either evaporate or impact with the walls of the sample tube before they reach the PortaCount fit tester. If a body-generated droplet were to be counted by the PortaCount fit tester, the result would be a fit factor that is lower than it should be. There is no possibility of overstating the fit factor."
Common Misconceptions About Moisture & Fit Testing
There are a few common misconceptions regarding moisture in sample tubes:
- Moisture can lead to false positives: In reality, excess moisture does not increase fit factor readings. If anything, it can lead to lower fit factors.
- Moisture buildup makes fit tests unreliable: While excessive moisture can be problematic, following proper maintenance practices ensures accurate testing.
TSI's Application Note: Hygienic Security & the PortaCount Respirator Fit Tester
As to the concerns over employee exposure, TSI has issued an application note: Hygienic Security and the PortaCount Respirator Fit Tester. In it, TSI states that air drawn into the PortaCount twin-tube always travels from the test respirator toward the fit tester or is stopped. It isn't possible for the respirator wearer to inhale with sufficient force to reverse the air flow direction [to expose themselves to moisture from a previous test].
The application note does suggest having multiple twin tubes available during testing, so you can swap them out between uses and avoid moisture buildup.
Best Practices for Maintaining Fit Test Sample Tubes
To ensure accurate fit test results and minimize moisture buildup, consider these best practices:
- Rotate sample tubes: Keep multiple tubes on hand and swap them between tests.
- Store tubes properly: Keep them in a dry location to prevent moisture accumulation.
- Monitor environmental conditions: Conduct tests in controlled environments with minimal humidity when possible.
How to Reduce Moisture Buildup in Fit Test Sample Tubes
If you don't have multiple tubes available, however, you can rinse the tubes with Isopropyl alcohol, then shake or spin the tube to remove the excess. The alcohol will absorb the moisture and dry quickly and will help keep your sample tubes clean between tests.
Want to Learn More About Respirator Fit Testing?
Read my other posts about respirator fit testing and learn more about the TSI PortaCount Pro quantitative respirator fit test system at RaecoRents.com
