Hot air blower
A hot air blower , also known as a hot air blower or hot air gun , is a power tool that can be used to heat the work area in a targeted manner. A fan sucks in ambient air , heats it with a heating element and blows hot air out through an outlet pipe.
The structure is similar to a hair dryer . The air flow rate can typically be set between 150 and 500 liters / min and the temperature from 50 to 600 ° C. Many devices can be fitted with differently shaped outlet nozzles to direct the flow of hot air.
commitment
One advantage of the hot air blower over an open flame such as that of a blowtorch is that it can be easily adjusted to lower temperatures. Combustible materials can be processed more easily without igniting them.
Usage examples for hot air guns:
- Deformation of plastics (e.g. for shrinking heat shrink tubing )
- Application and removal of adhesive films made of plastics or with polymeric adhesive layers
- Ver welding of plastics (so-called hot gas welding , see also joining plastics )
- Removal of lacquer or paint layers
- dry
- Accelerating or stimulating chemical curing: e.g. B. of baking enamel
- Hot air sterilization
- Soldering and desoldering, for example of electrical components
- Thawing or defrosting
- Ignition of combustible materials; Low-smoke heating of charcoal
- Uncapping of honeycombs
Simple hot air blowers only allow a rough temperature and air volume setting. Heating coils can be switched on in stages. Overheating of the device is prevented by overheating protection . Half the power reduction is sometimes achieved by connecting a diode in series, so that only one half cycle of the AC mains voltage is used.
Electronics -Heißluftgebläse regulate the temperature of the discharged air by means of a placed in the stream of hot air temperature sensor . The control electronics can maintain a certain target temperature relatively precisely, even if nozzles or obstacles in the air flow greatly reduce the amount of air.
As an alternative to purely electrically operated devices, gas burners are also offered, the flame of which is shielded to such an extent that hot air escapes at a predictable temperature.
Space heating
Hot air blowers for room heating deliver significantly higher air throughput at a moderate maximum temperature. They are used to warm (fairly) closed rooms, for example to prevent water pipes or hardening concrete and plaster from freezing on building sites, to dry walls or their paintwork, to enable indoor craftsmen to work when the outside temperature is higher than the winter cold. Vehicles, mobile homes and marquees are also heated with it. Electrical energy is relatively expensive, the delivery capacity is limited: from a household socket often with 10 amps × 230 volts = 2,300 watts , per house or construction site perhaps with 3 × 25 A × 400 V ( three-phase current in a triangle) = 30 kW. Therefore, for the sake of simplicity, heating outputs of up to 2 kW are usually realized electrically as radiators or fan heaters, rather historically: Spirit and gasoline stoves with outputs of 2 to 5 kW, however, often as gas radiators with combustion of a propane-air mixture on a flame arrester and possibly catalytically active, perfused ceramic honeycomb wall. Kebap grill walls combine three to five such elements, each 130 mm × 90 mm, each with a maximum output of 3.5 kW.
Higher outputs of typically 10 to 30 kW are implemented as hot air blowers (also because of the shape: heating cannon ) with an electric motor blower and heating oil or heating gas combustion. The fan causes a large-scale air vortex in the hall via the fast-flowing horizontal air ejection, which ideally mixes and - gradually - heats all the air in the room.
Oil is cheaper than gas, but it smells, the CO 2 promotes plant growth in a greenhouse , but puts a strain on the respiration of animals and humans. Butane - propane - methane ( natural gas ) deliver less and less CO 2 per heating output, but more water vapor, which condenses on cold tent walls, for example. Parking heaters for vehicles (2.5 to 35 kW) may also be operated with gasoline from the vehicle tank and have their own exhaust gas discharge; not all of them heat the air without going through the engine cooling system.
With hot air generators from 20 kW, the flame and heating air are increasingly kept separate. Since the exhaust gas is discharged into the open via a chimney, heating oil can be used on the one hand without polluting the room air, and on the other hand, more heat can be used through the condensation of the water vapor content of the exhaust gas. Supply and exhaust air hoses with nozzles smooth the transition to mobile, containerized heating and air conditioning systems.
