Construction and System Software of Two-zone Thermal Shock Test Chamber

2025-01-16

Construction and System Software of Two-zone Thermal Shock Test Chamber

Construction of Two-zone Thermal Shock Test Chamber:

1, Construction mode of environmental test chamber:

Environmental test chamber is composed of a high temperature test chamber located at the upper end, a low temperature test chamber located below, a freezer cabinet located at the back and a home appliance control chamber (system software) located on the right. In this way, the shell occupies a small area, compact structure, beautiful appearance design, the freezer unit is placed in a separate generator chamber body, in order to reduce the vibration and noise of the freezer unit operation on the environmental test chamber harm, in addition to the installation and maintenance of the generator set, the household appliance operation panel is placed on the right panel of the environmental test chamber to facilitate the operation of the actual operation;

2, Shell surface raw materials: cold-rolled plate, surface electrostatic powder spraying solution;

3, The shell cavity raw materials: imported stainless steel plate (SUS304);

4, Thermal insulation material: heat resistant hard plastic polyamine ester foam + foam glass plate;

5, The door: single door, equipped with double silicone rubber sealing and sealing rubber strip heating equipment, under the self-limiting temperature heating zone, to avoid the experiment essence and frost;

6, Test rack: move up and down left and right sliding type stainless steel plate test rack. The pneumatic double-effect cylinder shows a stable and symmetrical driving force. The positioning device of the test rack uses an electromagnetic field triggered limit switch;

7, Cable wire installation hole: the upper end of the test rack and the top of the high temperature test chamber is provided with a telescopic cable threading tube.

Air conditioning system software of two-zone thermal shock test chamber:

1, Gas control method: forced circulation system natural ventilation, balanced temperature control method (BTC). The method refers to the refrigeration unit in the continuous operation of the condition, the automatic control system according to the temperature point set according to the PID automatic and operational output results to manipulate the electric heater's heart output, the ultimate UI will exceed this stable balance.

2, Gas circulation system equipment: embedded central air conditioning room, air supply mode channel and stainless steel plate short-axis exhaust fan, the application of refrigeration unit and kinetic energy adjustment system software, according to the exhaust fan to carry out a reasonable heat exchanger, more than the purpose of maintaining temperature change. According to the improved air flow of the gas, the total gas flow and the working capacity of the heat exchanger with the electric heater and the surface cooler are improved.

3, Evaporative cooling method: fin type air heat exchanger.

4. Gas heating method: select nickel-chromium wire electric heater.

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Definition and Use of Temperature Cycling Test Chamber

2025-01-16

Definition and Use of Temperature Cycling Test Chamber

Temperature cycling test chamber is a kind of laboratory equipment widely used in various industries, its main function is to cycle the product within a certain temperature range to simulate the operation of the product in different temperature environments. The equipment is an important tool to realize product reliability testing, quality control and product performance evaluation.

The temperature cycling test chamber is widely used and can be used for testing in various fields, such as aerospace, automotive, electronics, electric power, medical and other fields. In the aerospace sector, temperature cycle test chambers are used to test the performance of aircraft components at extreme temperatures to ensure their reliability in extreme environments. In the automotive field, the temperature cycle test chamber is used to test the performance of automotive components under different temperature and humidity conditions to ensure that the car can operate normally in a variety of environments. In the field of electronics and power, temperature cycling test chambers are used to test the performance and reliability of electronic equipment under different temperature conditions to ensure that the equipment can operate stably for a long time. In the medical field, temperature cycling test chambers are used to test the performance and reliability of medical equipment under different temperature and humidity conditions to ensure the normal operation of the equipment.

The working principle of the temperature cycling test chamber is to carry out the cycling test by controlling the temperature and humidity in the chamber. The device has a variety of temperature control modes, such as constant temperature control, programmed temperature control, programmed temperature control, etc., which can be selected according to needs. During the test process, the temperature cycling test chamber will place the product in different temperature environments for testing to simulate the use of the product in different environments. After the test is completed, users can improve and upgrade the product according to the test results to improve the reliability and performance of the product.

In short, the temperature cycling test chamber is a laboratory equipment widely used in various industries, and its main function is to cycle the product within a certain temperature range to simulate the operation of the product in different temperature environments. The equipment can be used for testing in various fields, such as aerospace, automotive, electronics, power, medical and other fields, and is an important tool to achieve product reliability testing, quality control and product performance evaluation.

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Environmental Test Chambers-Reliability Tests

2025-01-16

Environmental Test Chambers-Reliability Tests

Environmental resistance test:

Temperature cycle test, temperature and humidity resistance test, impact test

Durability test:

High and low temperature preservation test, continuous switch operation test, continuous action test

Temperature cycle:

a. No boot test: 60℃/6 hours ← Rising and cooling for 30 minutes →-10℃/6 hours, 2cycle

b. Boot test: 60℃/4 hours ← Rising and cooling 30 minutes →0℃/6 hours, 2cycle, power supply without packaging and load

Temperature and humidity test:

No power test: 60℃/95%R.H./48 hours

Boot test: 60℃/95%R.H./24 hours/no packaging power supply load

Impact test: impact distance 3m, slope 15 degrees, six sides

Humidity test: 40℃/90%R.H./8 hours ←→25℃/65%R.H./16 hours, 10cycle)

High and low temperature preservation test: 60℃/95%R.H./72 hours →10℃/72 hours

Continuous switch action test:Complete the switch within one second, shut down for at least three seconds, 2000 times, 45℃/80%R.H.

Continuous action test: 40℃/85%R.H./72 hours/power on

High And Low Temperature Test Chamber

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Heat Dissipation Method of Thermal Shock Test Chamber Refrigeration Unit

2025-01-16

Heat Dissipation Method of Thermal Shock Test Chamber Refrigeration Unit

Generally speaking, thermal shock test chamber is divided into two refrigeration methods: air-cooled and water-cooled. The accuracy of the test results not only depends on the excellent process quality of the equipment itself, but also is closely related to the cooling efficiency of the refrigeration unit. So what factors affect the heat dissipation efficiency?

In short, the air-cooled type has the greatest impact on its heat dissipation efficiency or environmental factors. For water-cooled refrigeration units, the key factor is the water tower configured as a fixed equipment, the following is the method of improving the heat dissipation efficiency of different cooling methods.

Firstly, air-cooled thermal shock test chamber：

Reason: Because the heat dissipation of the air-cooled refrigeration unit mainly relies on the electronic fan to dissipate a large amount of heat through the fin. If the environment is very dusty, the equipment is affected by the wind, a lot of dust will adhere to the fan and fins. Although less dust does not have any effect on the air-cooled refrigeration unit, when the dust on the fins continues to increase, it will directly affect the heat dissipation effect of the air-cooled refrigeration unit, resulting in poor heat dissipation effect and the corresponding cooling capacity.

1, The user should provide a relatively clean use environment for the air-cooled refrigeration unit (smooth ventilation is the best), and try to stay away from the harm of all kinds of dust. This will extend the frequency of inefficient operation of air-cooled refrigeration units because there is more dust in the environment, and give the unit equipment a safe and stable operation environment.

2, Keep the equipment clean and tidy, and clean the fins regularly. Can be washed with wind and tap water, if the environment is harsh, the dust impurities on the fins are more oil, then rinse with tap water first, and then spray on cleaning dust, after 10 minutes or so, and then repeatedly rinse with tap water. After using the air-cooled refrigeration unit for a period of time, it is necessary to carry out a comprehensive cleaning for the environment and the machinery and equipment.

Secondly, water-cooled thermal shock test chamber：

Reason: Since most of the water tower is installed outside, it needs to withstand strong light radiation, higher temperature, and fast water evaporation, which is easy to cause insufficient water flow in the cooling water circulation, and finally cause poor cooling effect and even high pressure alarm.

1, Timely water supply.

2, Check whether the water supply valve is abnormal.

3, Check the running status of the water tower, if abnormal, it needs to be adjusted to normal state in time.

4, Clean the pipeline filter.

5, Keep the water source clean.

The main policy to improve the heat dissipation efficiency of the air-cooled thermal shock test chamber is to place the chiller outdoors, avoid direct sunlight as far as possible, and make a protective shed for the equipment if conditions exist. If it must be placed indoors, it is better to put it next to the window to maintain good ventilation, or install an air pipe to draw hot air to the outside.

three-zone thermal shock test chamber

#Hot And Cold Temperature Test Equipment #Hot And Cold Extreme Temperature Impact Test Chamber #Intelligentized Thermal Chamber #Two Boxes Basket Type Thermal Shock Test Chamber #Thermal Shock Rapid Temperature Change Chamber #Industrial Three-Zone Thermal Shock Test Chamber

Industrial Computer Reliability Test Solutions

2025-01-16

Industrial Computer Reliability Test Solutions

Industrial computers can be divided into three categories according to their application attributes:

(1) Board class: includes Single Board Computer (SBC), Embedded board (Embedded Board), Black Plane, PC/104 module.

(2) Subsystem class: includes single-board computers, boards, chassis, power supplies and other peripherals combined into operational subsystems, such as industrial servers and workstations.

(3) System integration solutions: refers to a set of systems developed for a professional field, including the required software and hardware and surrounding, such as automatic teller machines (ATMs). The application of industrial computers widely covers ATM, POS, medical electronic equipment, game machines, gambling equipment, etc. The multi-field industry makes industrial computers must be able to withstand the use of sunlight, high and low temperature, wet and other environments, so the relevant reliability test is the focus of various manufacturers in the research and development test.

Common reliability tests for industrial computers:

Wide temperature test

Wide temperature range: according to the actual application environment can be divided into four categories:

1, Outdoor: especially for the extreme low temperature or high temperature areas, such as northern Europe and desert countries, the temperature range can be from -50 to 70°C.

2, Confined Spaces: for example, where a heat source is generated, such as near a boiler, the high temperature range is about 70°C3. Mobile equipment: such as vehicle equipment, the high temperature can be 90°C4 depending on the car area. Special harsh environment: such as aerospace equipment, oil drilling equipment.

Aging stress test

Aging stress test: The temperature range is from -40°C to 85°C, and the temperature variation rate is 10 °C per minute for cyclic testing

Constant temperature and humidity machine - standard type

The purpose of the machine is to simulate the product under the combined conditions of temperature and humidity in the climate environment (high and low temperature operation & storage, temperature cycle, high temperature and high humidity, low temperature and low humidity, dew test... Etc.), to detect whether the adaptability and characteristics of the product itself have changed. ※ Must meet the requirements of international standards (IEC, JIS, GB, MIL...) To achieve international consistency of measurement procedures (including test procedures, conditions, methods)

Test item: Wide temperature test

Thermal shock machine - stress screening testing machine

Temperature cycling stress screening is the product in the design strength limit, the use of temperature acceleration technology (in the upper and lower extremal temperature of the cycle, the product produces alternating expansion and contraction) to change the external environmental stress, so that the product produces thermal stress and strain, By accelerating the stress to make the potential defects in the product emerge [potential parts material defects, process defects, process defects], in order to avoid the product in the use process, the test of environmental stress sometimes lead to failure, causing unnecessary losses, for improving the product delivery yield and reducing the number of repair has a significant effect, in addition, the stress screen itself is a process stage process. Rather than a reliability test, stress screening is a 100% procedure performed on the product.

Test item: Aging stress test

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Influence of Capillary Length of High and Low Temperature Test Chamber on Parameters of Refrigeration System

2025-01-16

Influence of Capillary Length of High and Low Temperature Test Chamber on Parameters of Refrigeration System

1. Influence on suction and exhaust temperature and pressure

With the same charge amount, the shorter the capillary, the larger the refrigerant flow rate, so the suction temperature and exhaust temperature will decrease; Similarly, when the capillary is constant, the larger the charge amount is, the larger the refrigerant flow rate is, and the suction temperature and exhaust temperature also decrease.

However, with the increase of flow, the inspiratory pressure also rises. For the exhaust pressure, the shorter the capillary is, the smaller the filling amount is. When the capillary length is constant, the higher the charge amount is, the higher it is.

2. Influence on condensing temperature and pressure

When the refrigerant charge is constant, the shorter the capillary tube is, the condensation temperature and pressure decrease.

When the capillary length is constant, the higher the charge amount, the higher the condensing temperature and pressure.

3. Influence on evaporation temperature and pressure

The shorter the capillary, the greater the evaporation temperature and pressure.

When the capillary length is constant, the higher the charge amount, the higher the evaporation temperature and pressure.

4. the influence of supercooling and superheat

When the refrigerant charge is constant, the longer the capillary is, the higher the supercooling degree and the superheat degree are.

When the capillary length is constant, the higher the charge amount, the greater the supercooling degree and the smaller the superheat degree.

5. Influence on cooling capacity, power consumption and performance coefficient EER

When the refrigerant charge is constant, the longer the capillary length, the smaller the power consumption, but the cooling capacity is also smaller, the EER is smaller.

When the charge amount increases to a certain extent, because of the influence of heat exchange temperature difference, the cooling capacity increases, and the EER also increases.

6. Design points of capillary system

(1) On the high pressure side, the reservoir is generally not used, in fact, whether the reservoir is used does not depend on what kind of throttling device, but depends on whether the operation of the entire system is needed, such as heat pump system, shutdown pump system.

(2) In the suction tube, it is best to use a gas-liquid separator.

Because when the capillary system is shut down, the high and low pressure side will balance and the evaporator will accumulate refrigerant liquid, the gas-liquid separator can prevent liquid shock and refrigerant migration.

(3) The high pressure side can accommodate all the refrigerant charged, which is to prevent the capillary blockage when the damage to the high pressure piping system and compressor.

(4) In the high load condition of the evaporator, because the capillary system can be fed back to the condenser side, the condenser should take into account whether the condensing pressure will be too high under this condition, so it is necessary to increase the condensing heat transfer area.

(5) The pipe between the condenser outlet and the capillary inlet should not accumulate refrigerant liquid.

One is that when the compressor is shut down, this part of the refrigerant liquid will evaporate because of the pressure drop, flow into the evaporator and condense, thus bringing some heat to the refrigeration space, which may have an impact on the closed space of the refrigerator, for the air conditioning, this part of the heat can be ignored;

Another is that this will delay the time of the balance of the high and low voltage side, which may cause problems when the low torque compressor starts again, which can generally be solved by increasing the delay in the control (in fact, this is also good for reducing the impact of the starting current on other electrical appliances or the grid).

(6) The capillary inlet must be filtered to prevent clogging, especially the HFC refrigerant used now, which is required to add a dryer in design.

(7) Before the refrigerant enters the capillary, it is best to have a certain degree of undercooling, which can be added to the evaporator by adding a section of undercooling tube, or generating heat exchange with the suction tube, so that the gas flash in the capillary is minimal, thereby increasing the cooling capacity and ensuring the refrigerant flow.

However, it should be noted that at low temperature conditions, the undercooling may be too large because there is a little return liquid in the suction tube, which increases the capillary flow rate, and in turn increases the undercooling degree, which may eventually cause the return liquid.

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Maintenance Method of High and Low Temperature Test Chamber

2025-01-16

Maintenance Method of High and Low Temperature Test Chamber

There are three common types of high and low temperature test chamber controllers: software failure, system failure and hardware failure.

1, Software failure:

Software failure mainly refers to the controller failure of the high and low temperature test chamber, including the internal parameters, the control point IS control and output signal of the solenoid valve on and off.

2, System failure:

System failure refers to the initial design problems of the refrigeration system, including the leakage of refrigerant caused by high and low temperature test chamber does not cool down, and refrigerant leakage is often due to transport and high and low temperature test chamber operation jitter or refrigeration copper pipe welding process is not fine and other reasons caused.

3, Hardware failure:

Hardware failure may lead to non-cooling hardware compressor, solenoid valve and other refrigeration components.

Then the user can listen and touch to roughly understand what is the hardware high and low temperature test chamber damage, if it is a compressor failure, the compressor sound will be abnormal or do not work does not start or the compressor itself temperature is much higher than usual temperature, and the solenoid valve failure and other refrigeration components failure users are not too good to master.

In addition, the damage of the controller and the damage of the electronic parts of the control refrigeration system may also cause the phenomenon of non-cooling and non-cooling of the high and low temperature test chamber.

Scientific principle of heating and cooling of high and low temperature test chamber:

The high and low temperature test chamber has the functions of heating, cooling, humidification and dehumidification, and can detect the product's high temperature resistance, low temperature resistance and humidity resistance. How is the temperature in the high and low temperature test chamber controlled?

The heating device is the key link to control whether the high and low temperature test chamber is heated up. The controller outputs voltage to the relay when it gets the heating instruction. The high and low temperature test chamber is about 3-12 volts of direct current added to the solid state relay. The AC end of the high and low temperature test chamber is equivalent to a wire connection, and the contactor is also drawn at the same time. Heat up the constant temperature and humidity test chamber.

Cooling is an important part of the high and low temperature test chamber, which directly affects the determination of a high and low temperature and performance, including compressor, condenser, throttling device, evaporator four major components, compressor is the heart of the refrigeration system, it inhales low temperature and low pressure gas, into high temperature and high pressure gas, through condensation into a liquid to release heat, through the fan to take away heat, Therefore, the test chamber is the reason of hot air, and then become low pressure liquid through throttling, and then become low temperature and low pressure gas through the evaporator back to the compressor, the refrigerant in the evaporator to absorb the heat of the high and low temperature chamber to complete the gasification process and absorb heat, to achieve the purpose of refrigeration, to complete the high and low temperature test chamber cooling process.

High and low temperature chamber temperature and cooling rate test procedure:

In the adjustable range of the temperature of the test chamber, the lowest nominal temperature was selected as the lowest cooling temperature, and the highest nominal temperature was selected as the highest heating temperature.

Open the cold source, so that the test chamber from room temperature to the lowest cooling temperature, stable for at least 3 hours, rise to the highest heating temperature, stable for at least 3 hours and then to the lowest cooling temperature, during the heating and cooling, record once a minute, until the end of the test process.

The principle of high and low temperature test chamber heating and cooling is so, the realization of its function is completed by the setting of the control system, understanding the principle of heating and cooling, in the use of high and low temperature test chamber must be more handy.

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Setting and Maintenance of Constant Temperature and Humidity Test Chamber

2025-01-16

Setting and Maintenance of Constant Temperature and Humidity Test Chamber

Constant temperature and humidity test chamber is a relatively precise test equipment. In order to ensure the smooth completion of each test process, the power supply of the connected equipment must be stable at around 380V to ensure that the compressor will not be damaged. In addition, you must ensure the personal safety of the personnel who receive the power, so please understand the specific operation methods before wiring.

Constant temperature and humidity test chamber adjust or replace the connected power supply. After checking that the voltage of the power supply to be connected is correct, connect the neutral terminal to the neutral terminal in the distribution chamber. Ensure that the neutral line is connected, otherwise it may cause the equipment of the constant temperature and humidity test chamber to fail to work normally or burn electrical components.

After confirming that the neutral wire is connected, connect the 3 ∮ wire to the three terminals under the main switch of the distribution chamber in the constant temperature and humidity test chamber, and tighten the screws. We need to connect the ground wire, which is connected in the same way as other power cables, and directly to the ground terminal of the distribution chamber. In the process of connecting each power cord, everyone must ensure that the different colors of the power cord can be correctly identified to avoid connection errors and normal testing.

Maintenance of constant temperature and humidity test chamber:

1, Clean the water circulation system: clean the water filter, replace the filter, check the operation of the pump, including the operation of the water flow switch, adjust the water circulation flow and test operation.

2, Check all electrical wiring and electrical components to ensure reliable operation and good contact.

3, Replace the fresh air filter.

4, Refrigeration system cleaning: replace the refrigeration oil, clean the oil filter.

5, Check the vulnerable parts of the refrigeration system: check the sealing condition of the compressor and connecting parts, and replace all filters.

6, Refrigeration system leakage inspection: check all the connecting parts of the refrigeration system and the connecting parts of the valve plate are leaked and tightened.

7, According to the working conditions to supplement refrigerant: check whether the need to supplement the system refrigerant to ensure effective cooling capacity.

8, Comprehensive system operation: check whether the operating components are in good condition.

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Solution to Thermal Shock Test chamber Refrigeration System Blocking

2025-01-16

Solution to Thermal Shock Test chamber Refrigeration System Blocking

Thermal shock test chamber is generally composed of compressor, air conditioning evaporator, cooler and pipe system software. Refrigeration system blockage generally has two kinds of dirty blockage and ice blockage, and oil blockage is relatively rare.

1. Dirty and blocked

When the compressor of thermal shock test chamber is damaged, and there is waste in the refrigeration system, this waste is very easy to block in the capillary or filter device, which is called dirty plugging. Dirty blockage is because there is residue in the refrigeration system (oxygenated skin, copper chips, welding through), when it is circulated with the refrigerant system, it causes blockage at the capillary or filter device.

Dirty blockage removal method: remove the capillary tube, filter device, cooler, air conditioning evaporator with gas cutting, disassemble the carbon molecular sieve in the capillary tube and filter device, clean the cooler and air conditioning evaporator, carry out dry, vacuum packaging, welding, and fill with refrigerant.

2. Ice jam

Ice blockage is caused by water entering the refrigeration system of thermal shock test chamber. Due to its own with a certain amount of moisture, coupled with the maintenance or refrigerant in the whole process of taking time processing regulations are not tight, so that water and gas into the system software. Under the ultra-high pressure effect of the compressor, the refrigerant is changed from a liquid to a vapor state, so that the water is passed into the narrow and long capillary tubes with the refrigerant circulation system. When the moisture content of each kilogram of refrigerant exceeds 20mg, the filter device is saturated with water, and the water can not be filtered out. When the temperature of the capillary inlet and outlet is 0 ° C, the water is converted from the refrigerant and becomes ice, resulting in ice blocking.

Dirty blocking and ice blocking are divided into full and half blocked, the common fault condition is that the air conditioning evaporator is not frosting or frosting is not full, the temperature behind the cooler is high, and the hand drying filter or capillary entrance feels that the temperature is basically the same as the indoor temperature, sometimes less than the indoor temperature, and a lot of steam is sprayed out of the cutting process pipe. After the ice jam occurs, the friction resistance of the compressor exhaust pipe increases, resulting in the compressor overtemperature, the overload protector is working, and the compressor stops running. After about 25 minutes, a part of the ice jam melts, the compressor temperature decreases, the contact point of the temperature controller and the overload protector is closed, and the compressor starts the refrigerator. Therefore, the ice blockage has regularity, and the air conditioning evaporator can see regular frosting and defrosting conditions.

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The Measuring Principle of Hygrometer in High and Low Temperature Test Chamber

2025-01-16

The Measuring Principle of Hygrometer in High and Low Temperature Test Chamber

Temperature and humidity is the percentage of the amount of water vapor (vapor pressure) contained in a gas (usually air) and the amount of saturated water vapor (saturated vapor pressure) in the same case as the air, expressed in RH%. Humidity long ago had a close relationship with life, but it was difficult to quantify it. The expression of humidity is humidity, relative humidity, dew point, ratio of moisture to dry gas (weight or volume), and so on.

Humidity measurement method hygrograph humidity measurement from the principle of the division of twenty or thirty. But humidity measurement is always one of the difficult problems in the world measurement field. A seemingly simple quantity value, in depth, involves quite complex physico-chemical theoretical analysis and calculation, beginners may ignore many factors that must be paid attention to in humidity measurement, thus affecting the reasonable use of sensors.

Common humidity measurement methods are: dew point method, wet and dry bulb method and electronic sensor method, dynamic method (double pressure method, double temperature method, shunt method), static method (saturated salt method, sulfuric acid method)

1, Dew point method hygrograph: is to measure the temperature when the wet air reaches saturation, is a direct result of thermodynamics, high accuracy, wide measurement range. Precision dew point instrument for measurement can reach ±0.2°C or even higher accuracy. However, the cold mirror dew-point meter with modern optoelectric principle is expensive and often used with standard humidity generators.

2, Wet and dry bulb hygrometer: this is a wet measurement method invented in the 18th century. It has a long history and is widely used. Wet and dry bulb method is an indirect method, which converts the humidity value from the wet and dry bulb equation, and this equation is conditional: that is, the wind speed near the wet bulb must reach more than 2.5m/s. The common wet and dry bulb thermometer simplifies this condition, so its accuracy is only 5~7%RH, and the wet and dry bulb does not belong to the static method, do not simply think that improving the measurement accuracy of the two thermometers is equal to improving the measurement accuracy of the hygrometer.

3, Electronic humidity sensor method hygrometer: electronic humidity sensor products and humidity measurement belong to the industry that rose in the 1990s in recent years, at home and abroad in the field of humidity sensor research and development has made great progress. Humidity sensors are developing rapidly from simple humidity sensors to integrated, intelligent, multi-parameter detection, creating favorable conditions for the development of a new generation of humidity measurement and control systems, and also raising humidity measurement technology to a new level.

4, Double pressure method, double temperature hygrometer: is based on the thermodynamic P, V, T balance principle, the balance time is longer, shunt method is based on the precise mixing of moisture and dry air. Due to the use of modern measurement and control means, these devices can be quite precise, but because of the complex equipment, expensive, time-consuming operation, mainly used as standard measurement, its measurement accuracy can reach ±2%RH or more.

5, Static method of saturated salt hygrometer: is a common method in humidity measurement, simple and easy. However, the saturated salt method has strict requirements for the balance of liquid and gas two phases, and high requirements for the stability of ambient temperature. It requires a long time to balance, and low humidity points require even longer. Especially when the humidity difference between the indoor and the bottle is large, it needs to be balanced for 6 to 8 hours each time it is opened.

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