JPH0133953Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a flame detection fiber used to detect combustion and ignition of a pilot flame in combustion appliances such as gas baths, gas water heaters, and kerosene stoves. It is extremely important to check whether the combustion equipment is burning, whether the pilot flame is ignited, etc. from the viewpoint of preventing fires and poisoning accidents due to incomplete combustion. The pilot flame of combustion equipment is generally housed inside the combustion equipment to prevent it from being extinguished by wind, and a glass window is provided so that it can be seen from the outside. However, the drawback is that the glass windows get dirty over time, making it difficult to see the pilot fire inside. Additionally, depending on the combustion equipment, the combustion part or pilot flame may be located in a location that cannot be seen directly, or may be located far away and cannot be confirmed with the naked eye. In order to solve the above-mentioned difficulties, this invention emits light when one longitudinal end is inserted into the combustion flame or pilot flame of a combustion device, and the light is transmitted to the other longitudinal end and is used to prevent the combustion flame or pilot flame from entering the combustion equipment. The object of the present invention is to provide an optical fiber that can reliably detect Optical fibers come in various compositions, and most optical fibers soften at temperatures below 1000°C and cannot be used in flames, but silica-based optical fibers can withstand high temperatures of over 1000°C. However, silica-based optical fiber
It does not emit light unless the temperature exceeds 1200℃, and at the air combustion temperature of city gas, the temperature is too low to emit light. Therefore, in the present invention, a luminescent material 3 made of a metal oxide that emits light when heated and that can withstand the softening point temperature of the silica optical fiber is attached to the longitudinal end 2 of the silica optical fiber 1. As the luminescent material 3, carbol or a metal oxide such as Fe, Ni, Cu, etc. is used.The color tone of the luminescent material 3 varies depending on the temperature of the flame, and changes from red to yellow to white as the temperature increases. There are various ways to attach the luminescent material 3 to the silica-based optical fiber 1, but the point is that the luminescent material 3 can be attached in any way as long as it is not removed from the tip of the silica-based optical fiber in the measurement atmosphere. It's okay. For example, a substance that reacts and changes in quality in a flame, such as carbon, may be sealed in the tip 2 of the silica-based optical fiber 1, or a silica-based glass 4 containing components of the luminescent material 3 may be sealed at the tip of the silica-based optical fiber 1. 2
You can weld it to. The following optical fiber was manufactured as an example of the optical fiber of the present invention. Approximately 50mm of the cladding from the tip of a 2m long plastic clad fiber (PCF) was peeled off, a thin layer of soot made by flame hydrolysis reaction (which should not peel off even when immersed in water) was applied to 5mm of the tip, and nitric acid was applied. After immersing it in nickel (10% aqueous solution) for about 10 seconds, it was ignited with an oxyhydrogen flame to turn the soot containing Ni into transparent glass. At this time, nickel nitrate reacted with an oxyhydrogen flame and became an oxide of nickel oxide. After that, when I put this tip into the pilot flame of an instantaneous water heater, I was able to discern a clear red light from the other end of the same fiber. In response to this, when we peeled off the 50mm cladding from the tip of a plastic clad fiber (PCF) and put that tip into the pilot flame, a dark red light was seen at the other end 2m away for the first 30 minutes. But then it disappeared. This is thought to be due to the carbonized residue left behind when the cladding was peeled off, which temporarily emitted light, but burned out over time. Also, when a normal multi-component fiber was placed in a pilot flame, it softened in about 5 minutes and no flame could be detected. As described above, the present invention uses quartz-based optical fiber, so it has a high heat resistance, and therefore does not soften, deform, or become soft even when placed in a clean combustion flame such as city gas, propane gas, or oil stove. Transmittance does not decrease due to alteration. Furthermore, the emissivity of metal oxides is about 10 times higher than that of the oxidized surface, as is clear from the comparison of the polished surface and the oxidized surface in Table 1 (Source: Written by Akira Takagi, All About Infrared Applications: Nationwide Publishing) Therefore, the optical fiber of the present invention, in which the luminescent material 3 made of metal oxide is provided at the tip of the silica-based optical fiber 1, emits light even at low temperatures, and can reliably detect not only combustion flames but also low-temperature pilot flames. Furthermore, by using the optical fiber of this invention, it is now possible to easily see flames in places that were previously difficult to see, and in particular, it is possible to easily see flames in places that are difficult to see.In particular, it is possible to easily see flames in places such as outdoor gas water heaters, etc., while staying indoors. This is convenient because you can check the details. Further, in the present invention, since the luminescent material 3 is enclosed or welded to the longitudinal end of the quartz-based optical fiber, there is no possibility that the luminescent material 3 will fall off during use, and flame detection can be performed reliably. 【table】

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams showing different examples of the present invention. 1 is a silica-based optical fiber, and 2 is the tip of the silica-based optical fiber. 3 is a luminescent material.

Claims (1)

[Claims for Utility Model Registration] (1) A luminescent material made of a metal oxide that emits light when heated and that is resistant to the softening point temperature of the silica optical fiber is attached to the longitudinal tip of the silica optical fiber. flame detection fiber. (2) The flame detection fiber according to claim 1, which is obtained by sealing a luminescent material into the tip of a silica-based optical fiber. (3) The flame detection fiber according to claim 1, which is a utility model, and is obtained by welding quartz glass containing a luminescent component to the tip of a quartz optical fiber.