(1) The dry and wet temperature sensing element type humidity controller uses two temperature sensors placed at the same measurement point. It measures the relative humidity by detecting the temperature difference between the dry and wet sensing elements. These elements can be thermistors or even simple heating packs. As the temperature difference changes, it affects the resistance of the heating pack. This resistance change generates a voltage imbalance in a bridge circuit, which is then used to determine the relative humidity level accurately.
(2) Lithium chloride type electric humidity regulator
This type of regulator relies on the electrical properties of a lithium chloride coating that changes with air humidity. When the relative humidity increases, the moisture content in the coating rises, altering its conductivity. This change in current is amplified and used to control a solenoid valve responsible for spraying water. Once the set humidity level is reached, the signal relay opens, closing the solenoid valve and stopping the spray. If the humidity drops by 1% below the set value, the valve opens again, activating the humidifier to restore the desired level.
(3) Nylon (or hair) type pneumatic humidity transmitter
This system uses a natural material like nylon or human hair, which expands or contracts based on the relative humidity. A wetted element made from these materials is stretched under controlled tension, and the degree of elongation is directly related to the humidity level. This mechanical movement is converted into an output signal, typically through a lever or pressure mechanism, allowing the system to respond to humidity changes.
While these systems were once widely used, they tend to be complex and require regular maintenance. Over time, the sensitive components may degrade or lose their elasticity, leading to reduced accuracy. Due to these limitations, they are now less commonly used in modern applications. However, understanding their working principles remains important for historical and educational purposes.
Chloride Free Package The Special Plate For The Pipe
Chloride Free Package The Special Plate For The Pipe
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