A specimen medical face mask is supported on an apparatus. A volume of synthetic blood is sprayed horizontally at the specimen mask to simulate the scenario of a mask being splashed by a punctured blood vessel. The volume of fluid, distance to impact, orifice size and fluid velocity are defined in this method and intended to be consistent with this health care scenario.
Any evidence of synthetic blood penetration on the side of the medical face mask contacting the wearer’s face constitutes failure. Results are reported as “pass/fail”.
Specimen medical face masks are evaluated at a total of three different velocities corresponding to human blood pressures of 10,6 kPa, 16,0 kPa, and 21,3 kPa. Test results are reported at each velocity and the medical face mask is rated at the highest corresponding blood pressure for which medical face mask specimens demonstrate an acceptable quality limit of 4,0.
NOTE This test method differs from ISO 16603 by dispensing a stream of 2 ml of synthetic blood against the target area of a complete medical mask specimen whereas ISO 16603 involves the continuous contact of a specimen of protective clothing with synthetic blood over the period of an hour. The exposure time of 1 min in ISO 16603 is at a hydrostatic pressure of 13,8 kPa. ISO 16603 is used for preliminary evaluation of protective clothing penetration resistance to synthetic blood in conjunction with ISO 16604, which uses a microbiological challenge. Both procedures are intended for assessment of protective clothing that has the potential to contact blood or other body fluids for extended periods of time, and under pressure.
1 Equipment
1.1 Test apparatus, capable of affixing the specimen medical face mask and dispensing synthetic blood at the target area of the specimen and consisting of a specimen-holding fixture, a fluid reservoir, a pneumatic-controlled valve and valve controller to dispense a specified volume of synthetic blood through a small-diameter canula in a controlled amount of time, and a valve control switch as shown in Figure 1.
Dimensions for the test apparatus are provided in Figure 2. A parts list for the test apparatus is given in Annex A. Alternative designs are permitted as long as the same operational characteristics are achieved.
Dimensions for the specimen-holding fixture are provided in Figure 3. It should be convex and apply only enough pressure to gently stretch the specimen while holding it firmly in place 300 mm from the tip of the canula on the valve. Metal clips or an elastic cuff may be used to hold the specimen against the fixture provided they remain away from the target area and do not damage the specimen.
NOTE The specimen-holding fixture illustrated in Figures 2 and 3 consists of a platform on which is mounted an open-ended transparent plastic box. The platform is fitted with a vertical ring clamp used to hold the pneumatic valve. The front of the box has a hole cut in it to fit the convex mounting fixture on the outer door where the specimens are positioned. The outer door is closed with the specimen in position and the specimen is held between the wall of the box and the door. The door is held closed by magnetic strips along the top of the box and the door. A hole is cut through the centre of the convex specimen-mounting fixture and the door to allow the test operator to visually note if any fluid penetrates to the inside layer of the specimen medical face mask.
1.2 Air-pressure source, capable of providing air at a gage pressure of (700 ± 25) kPa.
1.3 Graduated cylinder, calibrated and graduated to measure liquid with a precision of 0,1 ml.
NOTE A 10 ml graduated cylinder with an expanded lip has been found to be a convenient size.
1.4 Balance, calibrated and with a precision of at least 0,01 g.
1.5 Temperature/humidity recorder, capable of monitoring the ambient temperature (to ± 0,5 °C) and humidity (to ± 1 %) during testing.
1.6 Controlled temperature and humidity chamber or space, capable of maintaining the specified temperature and humidity conditions for preconditioning of specimens.
1.7 Targeting plate, a recommended addition to the test apparatus, consisting of a plate with a 0,5 cm hole as shown in Figures 3 and 4, which can be positioned so that the hole is centred approximately 1 cm in front of the specimen mask, between the mask and the canula, such that the fluid stream passing through the hole impacts the centre of the specimen mask. The targeting plate blocks the high pressure leading edge of the stream and allows only the steady-state stream to impact the mask, thus increasing the accuracy and repeatability of the velocity of the stream which impacts the specimen masks. Subclause 7.3 should be used for setting the test pressure when using the targeting plate.
The splatter of fluid hitting the targeting plate can be contained by using a disposable plastic cup with the appropriately sized hole punched in the bottom as the targeting plate. The cup is mounted horizontally with the opening facing the nozzle by any convenient method. The cup in Figure 4 is supported by a sheet of lexan. The cup fits in a hole in the lexan that is the diameter of the base of the cup. The lexan is set in a notched stand to hold it upright. A second cup placed below the lip of the targeting cup can be used to collect the run-off.
2 Reagents
2.1 Synthetic blood, prepared as described in Annex B.
NOTE Because the synthetic blood readily stains clothing, wear a laboratory coat or similar cover during testing. Wear a face shield or use a fixed shield if standing behind the test specimen for observing its performance.
2.2 Isopropanol, of laboratory grade, for cleaning the canula and surfaces contacted by the synthetic blood.
