Posted on Leave a comment

Air Permeability Testing Resources

Air Permeability Testing Standards

ASTM C522 – Standard Test Method for Airflow Resistance of Acoustical Materials

ASTM D737 – Standard Test Method for Air Permeability of Textile Fabrics

ASTM D3574 – Standard Test Methods for Flexible Cellular Materials—Slab, Bonded, and Molded Urethane Foams

ASTM F778 – Standard Methods for Gas Flow Resistance Testing of Filtration Media

ASTM F2100 – Standard Specification for Performance of Materials Used in Medical Face Masks

EN 14683 – Medical face masks – Requirements and test methods

ISO 9237 – Textiles – Determination of the permeability of fabrics to air

MIL-M-36954 C – Military Specification – Mask, Surgical, Disposable

NIOSH TEB-APR-STP-0003 – Determination of Exhalation Resistance Test, Air-Purifying Respirators Standard Testing Procedure (STP)

NIOSH – TEB-APR-STP-0007 – Determination of Inhalation Resistance Test, Air-Purifying Respirators Standard Testing Procedure (STP)

Air Permeability Testing Procedures

Procedure for EN 14683:2019 Breathability Testing Using the Frazier Differential Pressure Air Permeability Tester – with the mass flow meter add-on unit installed

Procedure for EN 14683 Breathability Testing Using the Frazier Differential Pressure Air Permeability Tester in the standard configuration

Air Permeability Testing Terms

Air Permeability

Porosity

Air Permeability Testing Services

Frazier Air Permeability Testing Services

Air Permeability Tester Manufacturers

Frazier Differential Pressure Air Permeability Testers

Posted on Leave a comment

Procedure for EN 14683 Face Mask Breathability Testing Using the Frazier Differential Pressure Air Permeability Tester – in the standard configuration

The procedure described here is the procedure as described in pre-2019 versions of EN 14683.

The official configuration for EN 14683:2019 is: Procedure for EN 14683:2019 Breathability Testing Using the Frazier Differential Pressure Air Permeability Tester – with the mass flow meter add-on unit installed.

__________

Install the 25.0 mm dia (4.9 sq cm) bottom adapter plate (black rubber side down) over the standard 2.75″ diameter specimen opening.

Standard 2.75″ Diameter Specimen Opening
Bottom side of 25mm diameter Bottom Adapter Plate
Top side of 25mm diameter Bottom Adapter Plate
25mm diameter Bottom Adapter Plate installed in Standard 2.75″ diameter Specimen Opening

Install the 25.0 mm diameter (4.9 sq cm) Top Adapter Plate into the Specimen Clamp Ring in the Clamp Arm.

Top side of 25 mm dia Top Adapter Plate
Bottom side of 25 mm dia Top Adapter Plate
Fitting Top Adapter Plate into Specimen Clamp Ring
Lowering Clamp Arm

Use the Thumb Screws to secure the Top Adapter Plate into the Specimen Clamp Ring.

Securing Top Adapter Plate into Specimen Clamp Ring
Securing Top Adapter Plate into Specimen Clamp Ring

Place the face mask specimen over the 25 mm dia Bottom Adapter Plate.

Placing Face Mask specimen over 25mm diameter opening
Placing Face Mask specimen over 25mm diameter opening

Close Clamp Arm with 25 mm dia Top Adapter Plate

Specimen Clamp Arm closed over Face Mask specimen

Secure front of Clamp Arm with Permeability Tester Quick Clamp

Lifting Quick Clamp into closing position
Lowering handle to latch Quick toggle Clamp
Handle rotated out of the way

EN 14683:2019 Annex C specifies an airflow rate of 8 liters/min through a 25.0 mm dia Test Opening.

25.0 mm dia Test Opening = 4.9087 sq cm (0.00528 sq ft)

8 liters/min/4.9087 sq cm = 27.163 cu cm/sec/sq cm (53.470 cu ft/min/sq ft)

Look in the body of the 25.0 mm dia test opening calibration chart for manually operated tester (or make the correct entries in the Frazier Air Permeability software for the automated tester) and find the airflow of 27.2 in the cu cm/sec/sq cm chart or 53.5 in the cu ft/min/sq ft chart. Note the vertical manometer reading that corresponds with this airflow. Choose and install the correct nozzle size that corresponds with the vertical manometer reading. Interpolate between the whole numbers to 10ths of an inch for the vertical manometer.

Increase the vacuum pump (or push start button on the automated tester) until the vertical manometer reads the correct inch reading. Read the differential pressure (pressure drop) on the incline manometer (or automatically saved in the computer software database).

1 inch of water pressure = 248.84 Pascals.

Example:

delta P (Pa) = 1.2″ of water pressure x 248.84 Pascal = 298.61 Pa

__________

According to UNI EN 14683:2019:

The differential pressure (pressure drop) needs to be converted to Pascals/cm^2 for UNI EN 14683:2019 unit conformance.

Example:

delta P per sq cm (Pa/cm^2) = 298.61 Pa/4.9 cm^2 = 60.94 Pa/cm^2

__________

The Frazier Differential Pressure Air Permeability Measuring Instrument is manufactured by the Frazier Precision Instrument Company, Inc. located at 925 Sweeney Drive, Hagerstown, MD 27140 USA. frazierinstrument.com

__________

Posted on Leave a comment

Procedure for EN 14683-2019 Face Mask Breathability Testing Using the Frazier Differential Pressure Air Permeability Tester – with the mass flow meter add-on unit installed

The procedure described here is the procedure as described in 14683:2019 Annex C

Alternate procedure from previous versions of EN 14683: Procedure for EN 14683 Breathability Testing Using the Frazier Differential Pressure Air Permeability Tester in the standard configuration.

__________

Standard 2.75″ Diameter Specimen Opening

Install the 9″ diameter bottom seal plate over the bottom of the specimen opening.

9″ Diameter Bottom Seal Plate fits over 2.75″ dia Specimen Opening (red silicon rubber seal down)

Install the 25.0 mm dia (4.9 sq cm) bottom adapter plate into the bottom seal plate.

25.0 mm diameter Bottom Adapter Plate fits black rubber side down into Bottom Seal Plate.
25.0 mm diameter Bottom Adapter Plate fits black rubber side down into Bottom Seal Plate.

Specimen Seal Plate prevents edge leakage provided that the specimen is under 9″ in diameter.

25.0 mm diameter Bottom Adapter Plate fits black rubber side down into Bottom Seal Plate.

Place the mask specimen over the bottom seal plate.

Inside of cut mask specimen
Outside of cut mask specimen.
Face mask specimen placed over 25 mm diameter specimen opening.

Place the 25.0 mm diameter specimen opening adapter plate flat side down over the specimen with the holes aligned at 12 and 6 o’clock.

Bottom Side of 25.0 mm Diameter Top Adapter Plate
Top Side of 25.0 mm Diameter Top Adapter Plate
25.0 mm Diameter Top Adapter Plate over Bottom Seal Plate with the holes aligned at 12 and 6 o’clock.

Place the 9″ diameter Top Seal Plate with the Foam Gasket side down (with the holes aligned at 12 and 6 o’clock) over the Top 25mm Adapter Plate.

Bottom side of 9″ diameter Top Seal Plate
Top side of 9″ diameter Top Seal Plate
9″ diameter Top Seal Plate with the holes aligned at 12 and 6 o’clock.

Remove the standard round specimen clamp ring from the clamp arm (not shown) and install the Bottom Part of the Mass Flow Meter Air Intake Cone into the clamp arm.

Bottom part of the Mass Flow Meter Air Intake Cone installed into the clamp arm.

Lower the Clamp Arm and install thumbscrews through Bottom Part of the Air Intake Cone flange and through the Top Seal Plate into the threads of the Top Adapter Plate.

Attach manometer/pressure sensor vent tube onto the back of the bottom part of the Air Intake Cone.

Partially Lowered Arm with vent tube attached
Lowered Arm with vent tube attached

The Clamp Arm can now be raised and lowered to place and remove face mask specimens from the 25 mm dia test opening. Secure the Clamp Arm in front using the Quick Clamp.

Lowered Clamp Arm
Quick Clamp raised into position.
Quick Clamp Secured

Install the Top Part of the Air Intake Cone into the Bottom Part.

Inside view of Top Part of Mass Flow Meter Air Intake Cone
Top Part of Air Intake Cone sitting on Bottom Part of Air Intake Cone
Top Part being screwed into Bottom Part of Air Intake Cone
Top Part installed into Bottom Part

Install the Mass Flow Meter into the Top of the Air Intake Cone.

Installing Mass Flow Meter
Mass Flow Meter Installed

Face Mask Specimens can be placed and removed by securing and unsecuring the front Quick Clamp and carefully raising the Clamp Arm. Take care performing this operation with the Mass Flow Meter Installed.

__________

EN 14683:2019 Annex C specifies an airflow rate of 8 liters/min through a 25.0 mm dia Test Opening.

Increase the vacuum pump (or push start button on the automated tester) until the Mass Flow Meter reads 8.0 liters/min. Read the differential pressure (pressure drop) on the incline manometer (or automatically saved in the computer software database).

1 inch of water pressure = 248.84 Pascals.

Example:

delta P (Pa) = 1.2″ of water pressure x 248.84 Pascal = 298.61 Pa

__________

According to EN 14683:2019:

The differential pressure (pressure drop) needs to be converted to Pascals/cm^2 for EN 14683:2019 unit conformance.

Example:

delta P per sq cm (Pa/cm^2) = 298.61 Pa/4.9 cm^2 = 60.94 Pa/cm^2

__________

The Frazier Differential Pressure Air Permeability Measuring Instrument is manufactured by the Frazier Precision Instrument Company, Inc. located at 925 Sweeney Drive, Hagerstown, MD 27140 USA. frazierinstrument.com

Posted on Leave a comment

Testing Medical Face Mask Breathability with the Frazier Differential Pressure Air Permeability Tester using ASTM F2100-20

Medical face mask breathability as defined in ASTM F2100 (Standard Specification for Performance of Materials Used in Medical Face Masks) is based upon the EN 14683.

__________

ASTM F2100-20 Summary:

__________

6. Requirements

6.1 The properties of the medical face mask material shall conform to the specifications requirements in Table 1, as tested in accordance with Section 9.

6.1.1 Materials used in surgical masks shall comply with Level 1, Level 2, or Level 3 requirements.

__________

Table 1 Medical Face Mask Material Requirements by Performance Level

CharacteristicLevel 1 BarrierLevel 2 BarrierLevel 3 Barrier
Bacterial filtration efficiency, %> or = 95> or = 98> or = 98
Differential Pressure, mm of H2O/cm^2< 5.0< 6.0< 6.0
Sub-micron particulate filtration efficiency at 0.1 micron, %> or = 95> or = 98> or = 98
Resistance to penetration by synthetic blood, minimum pressure in mm Hg for pass result80120160
Flame spreadClass 1Class 1Class 1
Performance Requirement Levels of Medical Face Mask Materials

__________

9. Test Methods

9.2 Differential Pressure – Determine breathing resistance or differential pressure as directed in EN 14683:2019, Annex C.

__________

Note: Before performing these tests, make sure to read the entire ASTM F2100-20 and EN 14683:2019, Annex C documents which can be obtained from their respective authors.

Posted on Leave a comment

Air Permeability Testing Units

Airflow Units

1.0 Cubic Feet / Minute / Square Foot = 0.508 Cubic Centimeters / Second / Square Centimeter

1.0 Cubic Centimeters / Second / Square Centimeter = 1.96850 Cubic Feet / Minute / Square Foot

1.0 Liters / Minute / Square Centimeter = 32.80840 Cubic Feet / Minute / Square Foot

8.0 Liters / Minute / Square Centimeter = 262.46719 Cubic Feet / Minute / Square Foot

8.0 Liters / Minute / 4.90874 Square Centimeters = 53.46938 Cubic Feet / Minute / Square Foot (used for EN 14683, ASTM F2100)

8.0 Liters / Minute / 4.90874 Square Centimeters = 1.62975 Liters / Minute / Square Centimeter (used for EN 14683, ASTM F2100)

1.0 Cubic Feet / Minute / 4.0 Square Inches = 36.0 Cubic Feet / Minute / Square Foot (used for ASTM D3574 Test G)

1.0 Cubic Feet / Minute / Square Foot = 0.02778 Cubic Feet / Minute / 4.0 Square Inches (used for ASTM D3574 Test G)

Differential Pressure Units (Pressure Drop)

0.5 Inches of Water = 124.42 Pascals (used for ASTM D737)

1.0 Inches of Water = 248.84 Pascals

50.0 Pascals = 0.20074 Inches of Water (used for ISO 9237)

125.0 Pascals = 0.50184 Inches of Water

250.0 Pascals = 1.00369 Inches of Water (used for ISO 9237)

Posted on Leave a comment

Testing Medical Face Mask Breathability with the Frazier Differential Pressure Air Permeability Tester using EN 14683

The Frazier Differential Pressure Air Permeability Measuring Instrument is the ideal device for medical face mask breathability testing using the test methods and requirements published in EN 14683 (Annex C).

__________

Air Permeability/Breathability Testing Labs

__________

The Two Procedures for EN 14683 Breathability Testing Using the Frazier Differential Pressure Air Permeability Tester:

__________

Section 5.2.3 Breathability

When tested in accordance with Annex C, the differential pressure of the medical face mask shall conform to the value given for the relevant type in Table 1.

__________

Section 5.2.7 Summary of Performance Requirements

Table 1 – Performance requirements for medical face masks

TestType I *Type IIType IIR
Bacterial Filtration Efficiency (BFE), (%)> or = 95> or = 98> or = 98
Differential Pressure (Pa/cm^2)< 40< 40< 40
Splash Resistance Pressure (kPa)Not RequiredNot Required> or = 16.0
Microbial Cleanliness (cfu/g)< or = 30< or = 30< or = 30
*Type I medical face masks should only be used for patients and other persons to reduce the risk of spread of infections particularly in epidemic or pandemic situations. Type I masks are not intended for use by healthcare professionals in an operating room or in other medical settings with similar requirements.

__________

Annex C (normative)

Method for Determination of Breathability (Differential Pressure)

C.1 Principle

A device which measures the differential pressure required to draw air through a measured surface area at a constant air flow rate is used to measure the air exchange pressure of the medical face mask material, as show in Figure C.1. A water-filled (or digital) differential manometer is used to measure the differential pressure. A mass flow meter is used for measurement of the airflow. An electric vacuum pump draws air through the test apparatus and a needle valve is used to adjust the airflow rate.

__________

Figure C.1 – Test Apparatus for Measuring Differential Pressure

Differential Pressure Air Permeability Measuring Instrument for Breathability Testing in EN 14683:2019+AC Testing Standard

Figure Key

  1. Air Inlet
  2. Mass Flow Meter
  3. Lever for Mechanical Clamping
  4. System for Final Adjustment of the Pressure (either at the top or the bottom)
  5. System Ensuring Optimal Alignment of the 2 Parts of the Sample Holder
  6. Sample Holder with a Metal Sealing Mechanism
  7. Metallic Ring (3mm thick)
  8. Filter Material
  9. Differential Manometer or M1 and M2 Manometers
  10. Valve
  11. Vacuum Pump Including a Pressure Buffer Tank
  12. Mass Flow Meter for Checking Leaks (optional)

__________

Important Note:

According to EN 14683:2019:

The differential pressure (pressure drop) needs to be converted to Pascals/cm^2 for EN 14683:2019 unit conformance.

Example:

delta P per sq cm (Pa/cm^2) = 298.61 Pa/4.9 cm^2 = 60.94 Pa/cm^2

__________

Air Permeability Testing Units

__________