BS EN ISO 4823 pdf free download
BS EN ISO 4823:2015 pdf free download.Dentistry Elastomeric impression and bite registration materials.
7.2.1.2 Material delivery system, for delivering a volume of (0,5 ± 0,02) ml of the material onto the base plate (see EigurtLA.1).
7.2.1.3 Polyethylene sheets, wrinkle-free, approximately 60 mm by 60 mm and 0,035 mm thick (one per specimen).
7.2.1.4 Polyethylene sheet discs, approximately 10 mm in diameter and 0,035 mm thick (two per specimen).
7.2.1.5 Elastomeric plug, for forming the floor of the test increment-containing cavity.
7.2.1.6 Test apparatus, for applying a force of (14,71 ± 0,01) N (see Figure Al). The mass of the glass loading plate shall be included as part of the test load.
NOTE The dial indicator illustrated as a part of the test instrument in Figure Al plays no part in the consistency test.
7.2.1.7 Linear measuring instrument, accurate to 0,5 mm, for measuring diameters of the test specimen disc (2.13).
7.2.1.8 Timing device (6.16).
7.2.2 Advance preparation steps
Accomplish the following steps beFore beginning any of the test procedures:
— adjust the test apparatus (7.2.1.6) so that the contact surface of the loading shaft foot can descend within 5 mm of the top surface of the apparatus base;
— cover the top surface of the base plate (7.2.1.1) with a polyethylene sheet (7.2.1.3);
NOTE A thin film of silicon grease applied to the bottom ofthe loading plate will secure the polyethylene sheet covering in place, as required for the test.
— use the depth-gauge end of the plunger (see Figure A.1) to push the elastomeric plug (7.2.1.5) into the tapered end of the dispensing tube to the depth allowed by the stop;
— use the depth-gauge end of the plunger to seat two of the polyethylene sheet discs (7.2.1.4) to cover the cavity floor formed by the plug.
7.2.3 Specimen preparation and test procedure (3 specimens)
Accomplish the following steps within 25 s after the completion of mixing:
— slightly overfill the cavity in the dispensing tube (see Figure A.1) with the mixed material and strike off the excess to form the test increment;
— push the increment-extruding end of the plunger against the elastomeric plug to expel the test increment, along with one or both of the polyethylene discs, onto the centre of the base plate. Do not attempt to separate the discs from the test increment;
— centre the increment on the base of the test apparatus (7.2.1.6) directly under the elevated loading- shaft foot;
— place and hold the glass loading plate centred and in contact with the shaft foot;
— allow the (14,71 ± 0,01) N load to descend slowly onto the increment.
NOTE To obtain a more uniformly circular specimen disc, keep the glass plates as parallel as possible during loading and keep rotation of the plates to a minimum.
Allow the total load to rest on the specimen-forming assembly for 5 s. Lift the foot of the loading shaft from contact with the loading plate and allow the assembly to remain at room temperature for at least 15 mm. Separate the loading plate from the assembly so as to leave the specimen on the base plate. Use the measuring instrument (7.2.1.7) to make two diametral measurements of the specimen, one across the major diameter of the disc and one across the minor diameter. Report the average of the two measurements as the diameter to be considered when determining whether the specimen complies with the diameter requirement specified in Table 1.
7.2.4 Pass/fail determination and expression of results See 6.4 and 6.5.
7.3 Working-time
NOTE There are two working time test apparatus required depending on the type of material being evaluated. Type 0 materials are tested using a weight loading device and types 1. 2, and 3 are evaluated using the displacement rheometer described under Z3..3.
7.3.1 Apparatus and materials applicable to the Type 0 materials
7.3.1.1 Specimen forming ring mould, (40,0 ± 0,2) mm ID. 48 mm O.D and (9,0 ± 0,1) mm in height.
7.3.1.2 Flat glass or polymeric specimen forming base plate, approximately 50 mm by 50 mm and about 6 mm thick
7.3.1.3 Mould release agent, such as silicone grease that will not react with the material being tested.
7.3.1.4 Clay or soft wax, capable of being moulded so as to fix the ring mould (73.1.1) to the base plate (7.3.1.2).
7.3.1.5 Timing device, such as a stop watch.BS EN ISO 4823 pdf download.
