Cone or in Indonesian known as temperature stake is one of combustion temperature gauges are relatively accurate. Cone made from a mixture of ceramic material with a composition as the glaze. The material is formed as a tall pyramid with three sides and is designed to soften and bend at a certain temperature. Each stake has a certain number (numbers 020 – number 15). Number 020 to a temperature of 600 ° C, up to number 15 to a temperature of 1431 o C.
The numbers correspond to the combustion temperature indicates at what temperature the stake will be curved or bent to touch the ground floor. The standard size for a large stake, height approximately 66 mm and for small stakes, high approximately 25 mm. Stake this temperature can only be used once. Once the temperature corresponding code number is achieved, then the stake would be warped and unusable.
Stake in order to function properly, it must be placed at the angle of 8 °, calculated from the axis perpendicular to the ground floor and placed in the furnace, placed near the hole reconnaissance (spy-hole) to be visible from outside the furnace. Because the stakes are made of ceramic material whose formulas tailored to the specific mature temperature, then the stake is considered a good temperature gauges, besides pyrometer.
To monitor the temperature of combustion, it is recommended to use a single series, consisting of three stakes sequential number, for example the number 5, 4, and 3 for ripe temperature of about 1150oC. The third stake arranged in rows with a tilt angle of 8 ° and placed in the furnace in such a way so that it can be seen through the spy hole. When the first stake (number 3) is bent and the tip almost touching the ground floor, then it means that the desired temperature is almost reached.
If the first stake (number 3) is bent and feet have touched the ground floor, and stick to two (number 4) is bent and the tip almost touching the ground floor, then it means that the desired temperature has been reached. Third stake (number 5) pursued in an upright at each end of the combustion. If a third stake (number 5) is also bent to touch the ground floor, it will pass through the fuel temperature should (overfiring).
Lower stakes used to determine that the combustion temperature to be reached, while a higher number used to prevent lest the temperature is too high. In everyday practice is often found that people only use a stake alone, which is certainly risky if the stake is not functioning properly.
Figure 32. Cone number 5 – Cone number 4 – Cone number 3
Stake was developed in Germany by a ceramics expert named Dr.Hermann Seger in 1886. At the beginning of this plate is used for combustion testing of flame-retardant materials. During its development he made a stake into several series, each given a number based on mature temperatures to be achieved, known as Seger stake. In addition to the stake Seger, developed also other stake-stake used in the ceramic industry, the stakes made by Eduard Orton Orton of America and stake staffordshire (ceramic industrial centers) in the United Kingdom that the three have little difference.
How it works stakes are as follows: upon contact with flames, heat effect first of all on the tip, then spread to the bottom; therefore, when mature point, the stake will be curved gently from top to bottom. Rate of temperature rise in the combustion velocity effect on employment stake, for example when the temperature reaches the combustion time mature too fast (fast firing) compared to the time it should be, it will be necessary a higher temperature to bend / bend stake.
The temperature rise per hour for each different stakes. According to Daniel Rhodes, increase of 20 ° C per hour is considered slow. Orton stake made for a temperature rise of between 60 ° C / h and 150 ° C / hour. When the high combustion temperature has been reached, (usually the color of dazzling white fire), stake in the furnace is hard to see. This can be overcome by mild air blowing into the furnace through the spy hole so that the stakes can be seen even if only in passing. This must be done very carefully.