Breathing System Filters (BSF) Filtration Performance Test

As a category of air filtration products, BSF is mainly used in anesthetic machines and respiratory machines, and the importance of the product cannot be overstated. Therefore, it is necessary to test and take in charge of the quality of the product. In this article, we will introduce BSF testing from Relationship between standards, Requirements for aerosol, Particle counting method and photometric method, Test result comparison of particle counting method and photometric method etc.

1.Standards

1.1 Relationship between standards

ISO 23328-1 Breathing system filters for anaesthetic and respiratory use – Part 1: Salt test method to assess filtration performance is the standard which specified the test method of BSF. In China, YY/T 0753.1 is IDT ISO 23328-1.

As for the selection of test methods, Appendix C of the standard mentions: "The test method of NIOSH 42 CFR Part 84 is used as the basis for this test method."

NIOSH 42 CFR Part 84 relates to the test method for the filtration efficiency of respirators. In China, the corresponding standard is GB 2626.

1.2 Requirements for aerosol

ISO 23328-1 specifies using sodium chloride (NaCl) as the test aerosol, the following table compares the provisions of these three standards for NaCl aerosol and test flow.

Scince Purge 1406D (D-Plus) series automated filter tester is equipped with a generator that generates NaCl aerosols, and test the filter efficiency at MMAD 0.3μm, which meets standard requirements.

1.3 Requirements for aerosol detector

Understanding the specifications of the aerosol, then we take a look at the specifications for the aerosol detector.

The basis for the above three standards is NIOSH 42 CFR PART 84, the remaining two standards either the selection of aerosols, or the selection of detectors are referred to this standard. The sponsor of this standard is TSI, so TSI has an absolute advantage in this industry, it specified the photometer as detector, so GB 2626 and ISO 23328-1 also specified the photometer as detector. The ISO 23328-1 standard even directly incorporates TSI devices into the standard. Except for TSI, can other equipments test these products?

2.Testing equipment and test result comparison

2.1 Market share of tester in mask industry

There is a strong correlation between the three standards NIOSH 42 CFR PART 84, GB 2626, and ISO 23328-1. Therefore, let's take the fast growing mask (respirator) industry as an example and look at the market situation of mask filtration efficiency testing equipment. The current market share of mask testing instruments using counters as detectors is higher than that of the TSI 8130(A). In 2020, Chinese market, a conservative estimate of more than 2,000 counting method test rigs in the market.

On the one hand, TSI's equipment is expensive, with a one-time purchase cost of nearly $140,000 and subsequent annual maintenance costs (due to the high aerosol concentration of the photometric method, the photometer needs to be returned to the factory frequently for calibration and the filter needs to be replaced regularly), which many companies can hardly afford. On the other hand, a large number of test data show that the reliable counting method equipment also plays a significant role in the quality control of masks.

2.2 Particle counting method and photometric method

Particle counters are commonly used as detectors in China because particle counter products are more mature and widely used. In fact, particle counters are used more in the testing of filtration efficiency, especially in the field of air filtration, such as the testing of filter media and filter elements (both for general filters and HEPA/ULPA filters), and the detection of clean rooms (for cleanliness). Particle counters can distinguish the number of particles of different particle sizes, while photometers test the overall aerosol concentration, which cannot be evaluated for the distribution and filtration efficiency of different particle sizes. The concept that "a photometer test rig is more advanced than a particle counter test rig" is inherently limited and can be said to be a passive "popularization" concept.

2.3 Test result comparison of particle counting method and photometric method

The Scince Purge 1406D and 1802D series automatic filter testers use the particle counting method, and we have a large number of customers in both the filter material industry and mask industry. Some customers have both TSI 8130 and our testing equipment. Customer feedback is our filter testing equipment is easy to operate and maintain, and the test results can be compared to the TSI 8130.

Then, the same NIOSH 42 CFR PART 84-based breathing system filter (BSF) filtration performance test, in fact, using the counting method is also feasible.

3.Customer application cases

Our automatic filter tester has already been used in the breathing system filter industry.

In 2019, the British company Flexicare purchased a set of SC-FT-1406D automatic filter media tester for BSF products testing. It has been three and a half years so far, and is still in normal use.