The IP camera has performed the key role of monitoring and protecting user entities. But from time to time, IP cameras are used in special environments where extreme heat is present. This is where special housing is needed to protect these cameras.
That was the point raised by Kintronics in a recent technology note titled “How IP Camera Enclosures are Designed for High-Temperature Applications.”
Needless to say, IP cameras are tasked with the surveillance of end user entities. But there are also instances when they are needed at foundries or cement plants to monitor furnaces or other equipment where extreme heat is involved. In these circumstances, special enclosures are needed to protect the cameras against the heat.
“If you need to view the inside of a blast furnace or other extreme environments such as a rocket engine test, you will need to use a specially designed camera enclosure that protects the cameras,” the Kintronics note said. “This is not your normal 120°F (50°C) environment. The ambient temperature can reach over 752°F (400°C).”
Housing for cameras
According to the note, the enclosure, being the first level of defense in high-temperature environments, must survive the harsh environment and also provide thermal insulation that protects the camera. “They can’t be plastic or standard aluminum housings because this material can’t survive the extreme temperature. The housings are made from polished stainless steel. These enclosures have double chambers so that cooling air or liquid can be used to reduce the heat transfer from the ambient to the camera,” it said.
Further, given the environments in which the cameras are installed tend to be dirty and collect dust easily, a special mechanism is needed in the housing to clean the enclosure window. “A wiper with water won’t do the job in these high-temperature environments. The better enclosures include air barriers (or an air blade) that keep the front glass clean. The system uses an air compressor to reduce the maintenance required by preventing the formation of dust deposits on the glass,” the note said.
The enclosure window
The housing window is made from special material that not only has to survive the high temperatures, but also needs to resist thermal shock. Examples include Pyrex glass, quartz glass and tempered glass, and the glass to be used depends on the temperature of the site as well as the type of camera, according to the note.
“Tempered glass can be used if the temperature doesn’t exceed 260°C (500°F). Quartz glass is required if the temperature reaches 400°C (752°F). Thermal cameras require different glass because they have sensors that operate at a different wavelength than optical cameras. For example, they use Zinc-Selenium glass that can be used at a temperature of up to 200°C (392°F). This glass provides transmission of 7.5-14μm wavelengths,” it said. “Sapphire glass is used when you need to operate at up to 400°C (752°F). The glass is very clear and can pass wavelengths of .75μm to 4.5μm.”
Cooling, meanwhile, can be provided by air or water, according to the note. “Air cooling will allow operation at an ambient temperature of up to 80°C (176°F). Water cooling provides the highest temperature operation. The water needs to be relatively cool. The incoming water should not be hotter than 20°C (68°F),” it said.
It added that the rate of flow determines the maximum operating temperature. “For example, if the flow rate is 2l/min we can operate at up to 200°C (392°F), and the inside of the housing will be kept to a temperature of 2°C (89.6°F). If we increase the flow to 6.5l/m, we can operate at an ambient temperature of 400°C (752°F). In this case, the internal temperature can reach 44°C (111.2°F),” it said.
Source: William Pao, a&s International