BS 6256:2021 pdf free download – Packaging for terminally-sterilized medical devices一Method for determination of methylene blue particulate penetration.
5.6 Rotary suction pump.
5.7 Air drier.
6 Procedure
6.1 Preliminary
6.1.1 Fill the atomizer with a 1% methylene 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 methylene 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 (V2) to give a flow of 30 dm3/min through the bypass circuit.
g) Turn the control cock (C) to OFF.
h) Adjust control valve (V3) to give a flow of 30 dm3/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 flowmeter (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 dm3/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 clamp 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 OFE.
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 1 son eachupto 10 s.
k) Remove the filter strip and expose it to a jet of steam until the intensity of the stains is
fully developed.