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Characteristics of a Typical Hot Air Heater
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 PDF file for printing |
Hot air heater SAH series Fintech Fintech.co.jp
| HSH series models |
Measured models |
Data contents |
| 1 |
SAH100v-350w/10PH |
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Relationship of supply voltage - air flow rate -hot air temperature
Commonly used 100v-350w and 200v-440w types are described. |
| 2 |
SAH200v-440w/10AH |
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| 3 |
SAH200v-440w/10AH |
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Hot air outlet inner diameter and required supply pressure |
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Measurements of various heaters |
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Relationship of air flow rate and required pressure (without energization) |
| 5 |
SAH200v-440w/10AH)([dia]8) |
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Hot air temperature characteristics and air supply pressure
It is understood that the required pressure changes depending on the size of hot air outlet. |
| 6 |
SAH200v-440w/10BH/[dia]6 |
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SAH200v-440w/10BH/[dia]4 |
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| 8 |
SAH200v-440w/10BH/[dia]2 |
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| 9 |
SAH240v-1kw / 15AH ([dia]12) |
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Hot air temperature characteristics and air supply pressure
Data of 3412.14 BTU/hr (1 kW) class. 6 heating elements of type 10 “10*6PH” are arranged in parallel. Hence the required pressure is low. |
| 10 |
SAH200v-1200w/10*6PH/(R1/8) |
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| 11 |
SAH200v-1200w/10*6PH/(R1/8) |
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Temperature of the silicon bonding adhesive unit temperature |
| 12 |
SAH200v-1.2kw/15PH/(R1/8-R1/4)/+2S |
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Hot air temperature, supply pressure, and heating element temperature sensor |
| 13 |
SAH100v-700w/18BH/[dia]2/+S(R)
Heater with high temperature specification for silver soldering
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Hot air temperature, supply pressure, and heating element temperature |
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SAH220v-2kw/18PH/(R3/8)/+S
2 kW class typical model
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Hot air temperature, heating element temperature, and required air pressure |
| 15 |
SAH200v-6kw/15*6PH
20472.84 BTU/hr (6 kW) class typical model. Configured from 6 heating elements
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Hot air temperature, heating element temperature, required air pressure, and others |
| 16 |
Collection of various data |
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* Other data |
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* Collection of data in word format |
Accuracy of the Built-in Temperature Sensor
Hot air heaters consists of a model incorporating thermocouple, which allows hot air temperature to be monitored and controlled to a constant temperature using a temperature controller. However, temperature sensor (thermocouple) incorporated in hot air heaters do not have the required accuracy to be used as the reference temperature.
The temperature used as reference for heating should be measured with a separate accurate thermometer and use the temperature of built in sensor as the reference for operations. Therefore, when replacing the heater, reset using the standard thermometer and change the reference temperature for operations each time.
In other words, the built-in temperature sensor cannot be used as a temperature reference because the absolute value of the temperature is inaccurate, but reproducibility with the same heater is relatively good. Therefore its usefulness is sufficient as an operational standard.
The reason why the accuracy of the built-in temperature sensor is poor and cannot be used as a temperature reference is because the air flow state and temperature distribution inside the hot air heater is complex, and it is difficult to measure the average hot air temperature with the sensor installed inside the heater. In addition, the temperature measured changes considerably depending on the position of the sensor. The improvement is not much even if the sensor position accuracy is improved.
Service Life of the Built-in Temperature Sensor
Normally K thermocouple is used as a temperature sensor. Using a thermocouple of sufficient thickness may not be possible depending on the size of the heater. Wire with diameter of 0.039 in (ø1.0 mm) can be used for a metal case of ø0.5 in (ø13 mm) type and 0.019 in (ø0.5 mm) for metal case of ø0.314 in (ø8) type.
Since the structure is such that the temperature sensor passes through the center of the heating element, the sensor is exposed to almost the same temperature as the heating element. In many cases, there is no problem with the service life of the thermocouple but on using the SAH heater at very high temperatures, the service life of the built-in temperature sensor may be reduce. Specify R type (platinum type) built-in temperature sensor in such cases. The option code added to the model number is /+S(R).
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-1-
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Graph of hot air temperature and other characteristics with respect to supply voltage
Air is made to flow in hot air heater SAH 100v-350w type and hot air temperature and other parameters are measured for different supply voltages. This SAH 100v-350w type is the most standard model for 100 V.
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The minimum air flow rate of the SAH type hot air heater cannot be easily defined. The temperature of the heating element in this heater is 2012ºF (1100ºC) or less, and the main limitation is that the temperature of air inlet side metal case pipe is 302ºF (150ºC) or less.
That is, the flow rate satisfying the above limitation is the minimum flow rate with respect to the applied voltage.
For example, when 100 V is applied, it is limited by the heating element temperature, and the minimum flow rate is about 4.75 gal/min (18 L/min).
In case of 50 V, even though the heating element temperature is in safe range at 0.528 gal/min (2 L/min), the temperature of the metal pipe on the air inlet side reaches the danger zone of 446ºF (230ºC). Therefore, the minimum flow rate is limited, and the minimum flow rate is 0.79 to 1.05 gal/min (3 to 4 L/min).
Considering in the same way, the minimum flow rate at 30 V may be 0.52 gal/min (2 L/min).
However, there are some differences in the degree of heat dissipation to the surrounding environment and usage, and having a margin is preferable if possible.
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Graph of hot air temperature characteristics with respect to supply voltage
Air is made to flow in hot air heater SAH type and hot air temperature is measured for different supply voltages. This SAH 200v-440w type is the most standard model for 200 V.
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Relationship of the required supply voltage with respect to inner diameter of hot air outlet
The required supply pressure varies greatly depending on the air flow rate and hot air temperature and an accurate value cannot be provided. The value for airflow of 5.28 gal/min (20 L/min) when 200 V is applied to a typical model SAH200v-440w/10BH is given below. The inner diameter of the outlet is along the horizontal axis, and the required air supply pressure is along the vertical axis. The required pressure is equal to the pressure loss of the heater.
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Relationship of air flow rate and required pressure (without energization)
The relation between the air flow rate and the air supply pressure (= pressure loss) required to ensure that the air flows with the flow rate was obtained for the typical air heaters SAH200v-440w and SAH 240v-1kw.
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1.45 psi (10 kPa (kilo pascal)) is about 0.1 kgf/cm2 and it is about 0.1 atm (atmospheric pressure). 14.5 psi (100 kPa ) ≒ 1 kgf/cm2 ≒ 1 atm
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From the figure it is understood that the required supply pressure increases in direct proportion to almost square of the flow rate.
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Hot air temperature characteristics, and the relationship with the required air supply pressure
Air is made to flow at a predetermined flow rate in the typical air heater of type SAH200v-440w/10AH (straight outlet dia 0.314 in ([dia]8)), and the relationship between the air temperature with respect to the supply voltage and the required air supply pressure (= pressure loss) required to ensure that the air flows with the flow rate is determined.
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Model: SAH200v-440w/10AH (Hot air nozzle [dia] 0.314 in ([dia] 8 mm))
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Hot air temperature characteristics, and the relationship with the required air supply pressure
Air is made to flow at a predetermined flow rate in the typical air heater of type SAH200v-440w/10BH [dia]0.236 in ([dia]6) (hot air outlet [dia]0.236 in ([dia]6)), and the relationship between the air temperature with respect to the supply voltage and the required air supply pressure (= pressure loss) required to ensure that the air flows with the flow rate is determined.
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SAH200v-440w/10BH 0.236 in ([dia] 6 mm) (Hot air nozzle [dia] 0.236 in ([dia] 6 mm))
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Hot air temperature characteristics, and the relationship with the required air supply pressure
Air is made to flow at a predetermined flow rate in the typical air heater of type SAH200v-440w/10BH [dia]0.236 in ([dia]6) (hot air outlet [dia]0.236 in ([dia]6)), and the relationship between the air temperature with respect to the supply voltage and the required air supply pressure (= pressure loss) required to ensure that the air flows with the flow rate is determined.
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SAH200v-440w/10BH 0.236 in ([dia] 6 mm) (Hot air nozzle [dia] 0.236 in ([dia] 6 mm))
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-7-
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Hot air temperature characteristics, and the relationship with the required air supply pressure
Air is made to flow at a predetermined flow rate in the typical air heater of type SAH200v-440w/10BH [dia]0.157 in ([dia]4) (hot air outlet [dia]0.236 in ([dia]4)), and the relationship between the air temperature with respect to the supply voltage and the required air supply pressure (= pressure loss) required to ensure that the air flows with the flow rate is determined.
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SAH200v-440w/10BH [dia] 0.157 in ([dia] 4 mm) (Hot air nozzle [dia] 0.157 in ([dia] 4 mm))
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-8-
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Hot air temperature characteristics, and the relationship with the required air supply pressure
Air is made to flow at a predetermined flow rate in the typical air heater of type SAH200v-440w/10BH [dia]0.157 in ([dia]2) (hot air outlet [dia]0.078 in ([dia]2)), and the relationship between the air temperature with respect to the supply voltage and the required air supply pressure (= pressure loss) required to ensure that the air flows with the flow rate is determined.
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SAH200v-440w/10BH 0.078 in ([dia] 2 mm) (Hot air nozzle [dia] 0.078 in ([dia] 2 mm))
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-9-
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Hot air temperature characteristics, and the relationship with the required air supply pressure
Air is made to flow at a predetermined flow rate in the air heater of type SAH240v-1kW/15AG [dia]0.472 in ([dia]12) (hot air outlet [dia]0.472 in ([dia]12)) which is slightly larger than the standard type, and the relationship between the air temperature with respect to the supply voltage and the required air supply pressure (= pressure loss) required to ensure that the air flows with the flow rate is determined.
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Model: SAH240v-1kw/15AG (Hot air nozzle [dia] 0.472 in ([dia] 12 mm))
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The characteristic of SAH 240v-1 kw shows the curve in the graph for the low flow rate and high temperature range is S shaped because the heat loss is large as this model is not in a metal case.
If there is no heat loss, this curve is proportional to the square of the voltage.
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Hot air temperature characteristics, and the relationship with the required air supply pressure
Air is made to flow at a predetermined flow rate in the air heater of type SAH200v-1200w/10*PH (hot air outlet R 1/8) with a bundled structure of 6 heaters, and the relationship between the air temperature with respect to the supply voltage and the required air supply pressure (= pressure loss) required to ensure that the air flows with the flow rate is determined.
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Model: SAH200v-1200w/10*6PH (Hot air nozzle R1/8)
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The advantage of the structure bundled with 6 heaters is that the size (length) can be made small, and it also has an additional advantage that the supply air pressure is low.
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-11-
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The relationship of silicon adhesive unit temperature with the air flow rate and supply voltage.
Air is made to flow at a predetermined flow rate in the air heater of type SAH200v-1200w/10*PH (hot air outlet R 1/8) with a bundled structure of 6 heaters mentioned above, and the relationship of the internal temperature of the heater to the supply voltage (silicone adhesive part which has the least heat resistance of 356ºF (180ºC)) was determined.
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Model: SAH200v-1.2kw/10x6PH (Hot air nozzle R1/8)
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Temperature of the silicone adhesive part becomes too high when high temperature hot air with less air flow rate flows. Since this 200v-1.2kw is especially short design among the 6 bundle types, this increase is all the more.
If there is too little air, there is a danger of silicon adhesive getting ignited. Take care and ensure minimum flow rate for 6 bundle type.
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Hot air temperature characteristics, and indicated value of air supply pressure, and heating element temperature sensor
Air is made to flow at a predetermined flow rate in the air heater of type SAH200v-1.2kw/15PH (hot air outlet R 1/4), and the relationship between the air temperature with respect to the supply voltage and the required air supply pressure (= pressure loss) required to ensure that the air flows with the flow rate is determined. Further, the output temperature of the heating prevention sensor (heating element temperature sensor) is measured.
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Model: SAH200v-1.2kw/15PH/(R1/8-R1/4)/+2S
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If supply air stops or decreases due to some failure, the output temperature of the heating element temperature sensor rises more rapidly than the above value. If this can be detected, then damage to the heater from burning can be prevented even if there is air stop failure.
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Hot air temperature characteristics, heating element temperature, and required air pressure of high-temperature air heaters
Air is made to flow at a predetermined flow rate in the air heater of type SAH100v-700w/18PH (hot air outlet R 1/4), and the relationship between the air temperature with respect to the supply voltage and the required air supply pressure (= pressure loss) required to ensure that the air flows with the flow rate is determined. Further, the output temperature of the heating element is measured.
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SAH100v-700w/18BH/[dia]2/+S(R) special (Double flow nozzle, for high temperature)
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This heater is described as “Hot air heater for silver soldering”. Even if the heating element temperature is around 2102ºF (1150ºC), heater life is about a few thousand hours if a large diameter (around [dia]0.039 in ([dia]1.0 mm)) electric heating wire is used and hundreds of hours even with a thin electric heating wire [dia]0.019 in ([dia]0.5 mm)), and will be in the usable range even at hot air temperatures close to 1742ºF (950ºC).
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Characteristics of a typical hot air heater of 6824.28 BTU/hr (2 kW) class In addition to the hot air temperature characteristics, the heating element temperature and the required pressure of supply air is measured.
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Model: SAH220v-2kw/18PH/(R3/8)/+S
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Since this heater (18PH type) is of elongated length, the necessary pressure of air is high. When less air pressure loss is required, select type 29PH or 38PH that have bigger diameters. Air heater structure obtained by bundling 6 heater tubes further lowers pressure loss.
The approximate service life can be predicted from the heating element temperature. It is almost semi-permanent if it is below 2102ºF (1050ºC), about several thousand hours if it is about 1922ºF (1100ºC), and about 500 to 1000 hours if it is about 2102ºF (1150ºC). However, it is difficult to guarantee the service life as a manufacturer.
The bigger the heating wire diameter, the longer the life in general. Therefore, a high-power heater is advantageous, and even with the same power, low-voltage design and low surface load design are advantageous.
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Characteristics SAH200v-1200w/15*6PH.
Heater configured with 6 heating elements characterized by compactness and large output.
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Model: SAH200v-6kw/15*6PH/+2S
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