1-6.Voltage supply

basic knowledge of Air Blow Heater

Once the compressed gas supply, ensure that the gas is ejected from the nozzle correctly.Add voltage until reaches the temperature the user required. This time, it takes several second to a few minute  to stabilize completely hot air temperature,  avoid excessive (overshoot),  please consider the time delay.

*Notes for overheat and not burn out.

The Air Blow Heater is safe when hot air temperature uses it under highest 1000 ℃.

However, when it is used  long time heating and extends the life used under 900 ℃.

A possibility of burnout if the temperature of the heating element exceeds 1200 ℃ becomes high.

When the user use the Air Blow Heater not built-in the heating element temperature sensor,  and used near a high temperature limit (highest 1000 ℃), please be sure to supervise heating element temperature.

Non-contact measuring methods, such as Pyrometer, are suitable.

Please visually monitored by a simplified red discoloration of the metal tube.

The highest temperature of air is near the end of the heating element.

It is cooled with a nozzle and a nozzle exit may show a low value.

Hot air is released into the air and lower the temperature rapidly, mixing the cool air.

As for the highest temperature (highest 1000 ℃) is not necessarily obtained by any cases or what kind of measuring method.

Therefore, if voltage which becomes the highest temperature based on the value measured at the nozzle exit is applied, it is possible the heating element may be burnout.

In the case of the hot air temperature sensor built-in type Air Blow Heater, even if it manages at hot air temperature, it can use comparatively safely.

1-6-1.How to adjust the voltage

The voltage from the power supply can be directly connected to the main line.

This time more than 15 ~ 20 L / min is always (Ex for 350w type) Please keep the gas flowing.

In many cases, it is not necessary to say that it is more convenient to have been able to adjust voltage.

A voltage regulator is used for adjustment of voltage.

The voltage regulators two types, one is winding wire type (product names such as Voltslider ,Slidac ), and another is semiconductor type (such as product names Varitap, SCRslider ).

The normal use we recommend the wire winding type.

The reason is that the supply voltage can be boosted to more robust.

In general, winding wire type can be adjusted from 0 to 130% of the supply voltage.

In contrast, semiconductor type (controlled by TRIAC and SCR) is about 0 to 95% adjustment range.

The advantage of semiconductor type is a light thing, and cheap to large electric power control , and the ease of automatic control.

The winding type is more safe unless these demands exist.

The semiconductor type needs cautions also for measurement of voltage.

An exact value is not shown depending on the kind of voltmeter.

 “True effective value type” of a digital type, “Moving-iron type”of a analog meter type, exact measurement is possible.

Applications are required to control very precise heating needs to stabilize the supply voltage.

In this case, please set up a regulated AC stabilized power supply before the voltage regulator.

Cost becomes high although it is ideal to stabilize voltage.

Often uses Air Blow Heater with temperature sensor, typically a constant temperature control system using a temperature controller and power controller.

Some of the thermo-controller Solid State Relays (SSR) ON-OFF controlling the heater.

SSR is controlled by a fast response should be aware of Air Blow Heater.

1-6-2.When the thermo-controller is used

The following cautions are required, to use the Air Blow Heater built-in temperature sensor and control hot air temperature by the thermo-controller.

1) When the air flow decreases extremely, although the temperature of a heating element is high, hot wind temperature is measured low.

If it controls by the value, the Air Blow Heater will be burnout.

When the thermo-controller is used, please consider to help ensure air flow is always the minimum required.(Monitored by flow switch, etc.)

2) Since the speed of response of a heating element is very fast,  the Air Blow Heater is required for the different consideration of the usual electric furnace control.

*A simple ON-OFF control is absolutely useless.

*Cycle control is possible in some cases.

In cycle control, cycle time should use the thing for 0.1 second.

Since the response of the heater is fast, the heater will flash in state cycle per 1 second.

Since a life falls remarkably if the heating element of the Air Blow Heater has an intense temperature change and flash, it become 1/100 or less.

When cycle control is surely performed a cycle for 1 second, the amount of control is lessened.

In this case, Voltage regulator is added to a thermo-controller.

If it uses on the conditions that ON state in the control cycle of a thermo-controller becomes long enough, and an OFF state almost becomes zero, most temperature changes of the heating element will be lost.

If possible, shorten the control cycle.

Most temperature controllers have more than one second control cycle, as Azbil SDC15, some models may include: 0.1 seconds.

If the control cycle is less than 0.1 seconds, almost no problem.

Even in this case, be careful of the PID value.

The speed of response is magnitude different in an electric furnace etc.(about hundreds times).

Although phase control is desirable for a hot wind heater, if it sees from a power supply side, it is not necessarily desirable load.

Moreover, there is also a problem of noise generating.

However, we recommend you that choose cycle control from now on since a thermo-controller with a short control cycle becomes easy to come to hand these days.

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