BS ISO 349:2020 pdf download.Hard coal — Audibert-Arnu dilatometer test.
5 Apparatus
5.1 Apparatus for preparing the coal pencil
5.1.1 Mould, polished internally, with accessories; see Figure b.1.
5.1.2 Gauge.
5.1.3 Ram, of which Figure B.2 shows an example.
5.1.4 Press, of which Figure B.3 shows an example.
5.2 Dilatonieter and accessories
5.2.1 Dilatometer tubes and pistons, see Figure 8.4.
5.3 Other apparatus
5.3.1 Electric furnace, example shown in Eigur B., consisting of a block of metal resistant to oxidation and of sufficiently high melting point. A suggested material is aluminium bronze. The metal block is pierced by at least two holes of 15 mm diameter by 350 mm deep to take the dilatometer tubes and one hole 320 mm deep to take a temperature-measuring device, which intends to keep the thermojunction of the thermocouple in the middle position of the inserted coal pencil with 60 mm. The block is heated by a metallic winding, suitably insulated. Control gear permits the use of any selected rate of heating up to 5 °C/min over a temperature range of 300 °C to 550 °C.
The furnace shall be constructed so that the temperature conditions are uniform in the dilatometer tubes placed in their normal position in each hole.
To verify this, heat the furnace at a rate of 5 °C/min. When the temperature reaches about 450 °C, make an exploration of the lower 180 mm of a dilatometer tube placed in the furnace, by comparing the readings on the normal temperature-measuring device and a thermometric probe placed in the tube. The difference between the probe temperatures and the mean temperature shown by the normal temperature-measuring device shall be less than
— ±2 °C in the lower 120 mm,
— ±5 °C from 120 to 180 mm.
This verification is not to be confused with the later calibration of the temperature-measuring device; it is intended to measure only the temperature variation along the tube.
5.3.2 Temperature-measuring device, consisting of a thermocouple accurate to 0,1 °C.
5.3.3 Cleaning equipment, consisting of the following:
5.3.3.1 Auger, diameter approximately 7,8 mm;
5.3.3.2 Brass wire brush, the diameter of which shall slightly exceed 8 mm;
5.3.3.3 Reamer, consisting of a steel bar of semi-circular section of diameter 7,95 mm.
The total length of each of the cleaning components shall be 400 mm.
5.5.2 Mould
Check the wear of the mould periodically with the gauge, which can also be used to check new moulds.
If, when the gauge is inserted in the larger orifice of the mould,
a) two lines can be seen on the gauge, the mould is too small and shall be reamed out;
b) one line can be seen, the mould is satisfactory;
c) no line can be seen, the mould is worn and shall be replaced.BS ISO 349 pdf download.