Packaging for terminally-sterilized medical devices
BS 6256:2021 pdf free.Packaging for terminally-sterilized medical devices – Method for determination of methylene blue particulate penetration.
The layout of the apparatus is illustrated in Figure 1 and Figure 2.
The atomizer, working under a constant pressure and flow of compressed air, disperses a solution of methylene blue into a mist at a uniform rate. The mist passes into the evaporation tube (E) where it is diluted to a total volume of 30 dm3/min by dry air entering at (B). The droplets of solution evaporate before reaching the control cock (C), leaving a residue of solid particles of methylene blue. When the control cock (C) is in the test position, the test cloud passes to the test circuit which contains the sample under test and the filter paper.
When the control cock is turned to the central or air position, the cloud is diverted to the by-pass circuit and at the same time air is drawn through the test circuit. In the off position of the control cock, the cloud remains diverted to the by-pass circuit, but there is no flow through the test circuit. The rates of flow in the circuits are adjusted to 30 dm3/min by means of the air valves V2 and V3.
To test a sample, the control cock is first turned to the off position and the sample and filter paper are inserted into their respective holders. The test cloud is then passed to the sample for a predetermined time, following which air is passed for a further period of 2 s in order to sweep out the residual cloud from the test circuit. The control cock is then turned to off and the filter paper removed. Finally, the test stain is developed with steam and the penetration assessed by comparing the stain with the standard stains.
6.1.1 Fill the atomizer with a 1% methylenc blue solution up to a level 6 mm below that of the spray orifice:
approximately 500 ml of solution are required.
6.1.2 After a maximum of 8 h operation, discard the methylene blue solution and replace with a fresh 1% solution of methylene blue.
NOTE The methyk’ne blue solution in the atomizer with the standard nozzle is consumed at a rate of approximately 10 ml per hour This loss is due in part to the atomization of the solution and in part to the evaporation of water from the main bulk of the liquid. The concentration of the solution in the reservoir therefore increases steadily during the operation of the apparatus The volume of the reservoir is chosen so that the change in concentration, and loss of volume, of the solution during a period of 8 h operation or less will not cause an appreciable change in the concentration of the test cloud.
6.2 Start-up instructions
6.2.1 Start up the apparatus as follows.
a) Turn the control cock (C) to OFF.
b) Switch on the suction pump.
c) Close and clamp the unloaded test piece holder (T).
d) Clamp the unloaded test paper holder (F) firmly closed.
e) Turn the control cock (C) to TESt
f) Adjust the air valve (Vi) to give a flow of 30 dm3/min through the bypass circuit.
g) Turn the control cock (C) to OFF.
h) Adjust control valve (VJ to give a flow of 30 drn’/min through the test circuit.
I) Turn on the compressed air to the atomizer and adjust the needle valve (V1) until the pressure gauge (D) registers 205 kPa. The ball in the compressed air tlownieter (M1) should now rise to the calibration mark. If the air flow is insufficient, turn off the compressed air and clear the atomizer jets.
NOTE I Steps e) to h) establish the nominal air valve settings to give the required flow rates in subsequent operations Minor adjustments only from these settings can be made.
NOTE 2 For details of maintenance, see Clause 8.
6.2.2 Maintain the air pressure at a constant of 205 kPa. The air pressure is not to be increased to bring the air flow up to the correct value.
6.3 Preparation of standard stains
Prepare the standard stains as follows.
a] Close and clamp the unloaded test piece holder.
b) Clamp a short piece of filter paper in the test paper holder.
c) Turn the control cock (C) to TEST for 20 s. During this period check, and adjust if necessary, the air valve (V2) in the test circuit to give a flow rate of 30 dm/min.
d) Turn the control cock (C) to OFF.
e) Unclamp the test paper holder and discard the piece of filter paper.
f) Insert and damp in the test paper holder the end of a 300 mm length of filter paper.
g) Turn the control cock (C) to TESt hold for 1 s and then turn to OFF,
h) Unclamp the test paper holder, move the strip 25 mm to one side and reclamp.
I) Repeat steps g) and h) but for 2 s duration.
j) Repeat the sequence, increasing the duration of the run by I son each up to 10 s.
k) Remove the filter strip and expose it to a jet of steam until the intensity of the stains is fully developed.
NOTE Thss filter strip, with 10 stains of increasing intensity, Is the standard test strip against which the test stains are compared. The I second stain is equivalent to a 2.5% penetration when the test is run for 40 s. Successive stains represent increments of a 2.5% penetration so that the 10 second stain corresponds to a 25% penetration.
6.4 Preparation of test stains
6.4.1 Prepare the test stains as follows:
a) cut two test pieces from the specimen to be tested, each 400 mm x 400 mm, and condition them in accordance with 13S EN 20187 for not less than 24 h. Carry out the remainder of the test within 10 mins of removal of the test pieces from the conditioning atmosphere;
b) turn the control cock (C) to OFF;
c) clamp a test piece into its holder such that the wire side is challenged by the test cloud;
d) clamp a short length of filter paper into the test paper holder;
e) turn the control cock (C) to TEST and after 10 s to OFF. During this period, check, and, if necessary, adjust the flow rate of the test circuit to 30 dm/minute;
1) discard the piece of filter paper and replace with a fresh piece;
g) turn the control cock (C) to TEST and after 40 s turn to OFF;
h) remove the test piece and the piece of filter paper. Develop the stain on the filter paper using a jet of steam; and
i) repeat steps c) to h) using the other test piece and testing the other side of the specimen.
6.4.2 Under the identical lighting conditions, compare the test stains with the standard stains and visually match them.BS 6256 pdf free download.Packaging for terminally-sterilized medical devices