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There are four groups of housings classified according to environmental conditions in which they should properly work, ensuring desired level of protection:
- Environment class I (indoor) - closed rooms, temp. 5 to 40
- Environment class II (indoor, general) - closed rooms not heated continuously, temp. -10 to 40
- Environment class III (outdoor shaded places) - outer conditions not fully depending on weather conditions, temp. -25 to 500 C, humidity to 85 - 95%,
- Environment class IV (outdoor, general) - temp. -25 to 600 C, humidity to 85 - 95%,
PN-EN-50130-5 (Alarm systems - Environmental tests.)
In order to ensure proper work conditions for the protected devices, housings may be equipped with heaters, fans, cooling systems etc., depending on specific environment.
In CCTV systems, the components most vulnerable to environmental conditions are cameras. Most of them can work in temperature range from -10 to 50 o and relative humidity of the air reaching 90% (without condensation). If these requirements are not met, we should use special housings that will ensure operating conditions suggested by the manufacturer(s) of the camera and lens. It is highly important for proper camera work to keep such conditions that won't allow to mist over the surface of the lens (dew point). This is the role of heaters with thermostats, sometimes supported in more expensive models by fans.
Housings often have IP ratings. Furthermore, they should provide good vandal resistance, but easy access to the camera and lens - for maintenance purposes. They should ensure optimal working conditions taking into account internal temperature increase caused by the heat generated by the camera.
IP rating describes the resistance against penetration of solid objects (the first number) and against liquids (the second number). Camera housings are usually rated as IP 65 or IP66, which means that they are fully dust-resistant and partially waterproof. Environments with high humidity will require to use housings/cameras marked IP67 or IP68; the latter ones can even work underwater.
IP rating describes the resistance against penetration of solid objects (the first number) and against liquids (the second number). Camera housings are usually rated as IP 65 or IP66, which means that they are fully dust-resistant and partially waterproof. Environments with high humidity will require to use housings/cameras marked IP67 or IP68; the latter ones can even work underwater.
According to temperature maintenance, housings can be divided into several groups:
- Equipped with heater and thermostat; the heater is usually mounted in the front of housing, on the bottom by glass window. Its main job, besides maintenance of adequate temperature, is protection against freezing and condensation of water (especially on lens surface, what would cause significant distortion of image)
- Air-cooled housings with natural convection ventilation, used in places with low temperature differences, e.g. shaded rooms. In other cases, due to overheating possibility, air-cooled housings with forced ventilation and heater are employed, e.g. cameras on south side of a building===
- Air-cooled housings with forced circulation and compressor; they are required in localizations with high temperature differences, e.g. observation of technological processes
- Water-cooled housings working in extremely very high temperatures e.g. in steelworks.
It is worth to note that mounting a camera in small housing may allow to keep sufficiently stable temperature even without additional heater, due to the heat generated by the camera itself. In turn, a camera in hermetic housing (i.e. adapted for work in very dusty or humid rooms) may even without a heater reach temperature higher than allowed; in this case use of cooling measures is essential. The most important role of a heater and thermostat is ensuring right and stable temperature - elimination of step changes of work conditions of camera and lens. Protection against freezing and condensation of water is one of the basic requirements for any CCTV system.
Housing heater M5614
Special housings.
In flammable environment we should definitely use special housings adapted to work in zones at risk of explosion; they are expensive, but they ensure adequate security level. Prices of these housings may exceed a few hundred times camera prices. They simply must fulfill strict security norms.
In flammable environment we should definitely use special housings adapted to work in zones at risk of explosion; they are expensive, but they ensure adequate security level. Prices of these housings may exceed a few hundred times camera prices. They simply must fulfill strict security norms.
Explosion-proof housing of Videotec company.
Keeping housing glass from getting dirty may require to use a wiper and washer. In some cases such special housings, e.g. with wipers, are employed for cameras mounted very high (e.g. on poles), where any access would be very troublesome, or when images from a camera must definitely be available even during variable atmospheric conditions - rain or snow.
There are also housings designated to use in the risk of vandalism; they are made of transparent polycarbonates and durable alloys. Usually they have dome form adapted for attaching to a ceiling or boom.
Housing sizes.
Camera housings have various sizes. The smallest i.e. M5430,M5434 are designated to encapsulate camera modules with PCB size around 32x32mm placed inside. This housings don't have heater - the heat generated by working camera allows to keep temperature stable enough for operation in their typical applications. We should be aware of possible distortion of images in the case of high differences or quick changes of temperature, due to possibility of misting over. Important part of installation work is proper sealing of the hole made for taking out wires (improper sealing is the commonest reason of bad work or damage).
Camera housings have various sizes. The smallest i.e. M5430,M5434 are designated to encapsulate camera modules with PCB size around 32x32mm placed inside. This housings don't have heater - the heat generated by working camera allows to keep temperature stable enough for operation in their typical applications. We should be aware of possible distortion of images in the case of high differences or quick changes of temperature, due to possibility of misting over. Important part of installation work is proper sealing of the hole made for taking out wires (improper sealing is the commonest reason of bad work or damage).
Ease of assembling.
Another issue, beside camera housing size, on which we should pay attention during its selection, is ease of assemblage and durability. Seemingly unimportant matter, however during installation of a large number of cameras such solutions as:
Another issue, beside camera housing size, on which we should pay attention during its selection, is ease of assemblage and durability. Seemingly unimportant matter, however during installation of a large number of cameras such solutions as:
- Way of opening: "turning aside" or "upwards" - considerably making easier to set lens sharpness, assembling of additional elements, wires;
- Adequate housing security - use of screws requiring special key;
- Availability of a large number of brackets that allow installing the housing not only on walls but also on ceilings, on poles etc,
Significantly help to shorten installation time and make camera's installation optimal. There are also used housings designated for concrete applications, e.g. underwater. Most of manufacturers offer full sets: camera with lens, housing, wires (optionally with IR lamp). Installers needn't worry about tightness of bushings then.
The camera in vandal proof housing - M10748
We should always remember to leave enough free space inside camera's housing for cables and additional devices as heaters, devices securing video line, power supplies or modulators. In the case of using twisted-pair cables (or other special cables) as transmission carrier, adequate transmitting devices are also installed in housings.
During installation of a camera it is important to remember about separation the zero voltage supply rail of the camera and analogical rail or chassis of the housing.
