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What are the types and test methods of airtight leak detectors on the market?
- 2019-09-06-

There are roughly 4 airtight leak detectors on the market. Each type of leak detector has its own characteristics. In addition, there are five test methods. Let's take a look at it.

(1) Negative pressure air tightness detector

The negative pressure air tightness detector is also called a vacuum air tightness detector. The product is extracted from the air, and the inside of the product is in a vacuum state. At the same time, the Heruis Precision Detector pays attention to whether the external gas will leak into the product to judge whether the product leaks or not.

(2) Multi-channel airtightness tester

With the improvement of the production efficiency of many manufacturers, one product inspection can no longer meet the needs of customers. The multi-channel airtightness tester has been popularized in the market, and multiple products are detected at the same time. This is currently on the market. The mainstream airtight detector detection method.

(3) Positive pressure air tightness detector

Through our precision pressure regulating valve, a certain pressure of compressed air is charged into the inside of the test product. At the same time, the gas change in the product is monitored in real time on the Herris precision detector, and the leakage of the product can be judged by paying attention to the change of the gas. Our positive pressure air tightness tester has three different pressure testers: low pressure, standard and high pressure.

(4) Flow tester

The test product was tested for leak tightness by means of instantaneous loss of flow. Divided into mass flow detection and body volume flow detection. (Generally used in pipeline blocking tests.)

The main principle is that the sensor directly detects the leakage rate of the product and displays it in real time, which can basically eliminate the time accumulation in the original pressure drop method leakage test. The test speed is fast, and the leak unit can be directly displayed, which is suitable for testing efficiency. The product.

Test method for airtight leak detector:

(1) Direct pressure method

The direct pressure method is to directly pressurize the compressed gas into the product through the pressure regulating valve. After the voltage is stabilized, the pressure sensor detects the pressure drop or the leakage amount in a period of time. Mainly used in some customers' tests for products with low sealing requirements.

(2) Quantitative test method

The closed product test method is suitable for testing products such as mobile phones, watches, cameras, and lights without air. The workpiece is placed in a sealed cavity, and the cavity needs to be a contoured cavity similar to the shape of the product (test cavity in the figure), so as to minimize the gap between the product under test and the inner wall of the cavity. The internal principle of the test instrument (D version) is to first open the inflation valve, and fill the compressed air with a fixed pressure into the reference volume inside the instrument. After the reference volume of the instrument is filled with a certain amount of pressure, the inflation valve When the test valve is opened, the pressure of the reference volume is released into the test chamber. If the product has a large leak, the pressure of the reference volume of the instrument will drop rapidly, and if it exceeds the limit value we set, it will alarm. If there is a small leak in the product, the air pressure of the reference cavity of the instrument will decrease slowly. After the pressure is maintained, the small leakage of the product during the test can be measured. Usually, 0. 1 cc/min can be measured. Accuracy (instrument display resolution is 0.01 cc / min).

(3) Mass flow method

It is mainly used in the engine block gearbox housing assembly test to reduce the influence of environmental factors such as temperature on the product. When inflating, simultaneously inflate the product end and the comparative cavity end at the same time, and stop the inflation after the voltage is stabilized. If there is a leak at the product end, the gas in the cavity will flow to the product end. At this time, the mass flow meter can be used to test the leak rate of the cavity end to the product end. Then calculate the leakage of the entire system by the following formula. This type of air tightness test method is often used in automated test equipment to test large product volume leaks.

(4) Mass flow method

The mass flow method performs gas tightness tests on products that are inherently leaky. Firstly, it is necessary to ensure that the pressure of the air inlet source exceeds the test pressure of the product; then the electronic pressure regulating valve automatically adjusts the pressure, and the adjusted pressure is the test pressure set in the parameter, and the gas flows through the flow sensor to the test product; The sensor is connected to a section of the test product for stress testing to verify that the pressure inside the test product meets the requirements, and feedback to the electronic pressure regulating valve in real time to continuously adjust the electronic pressure regulating valve. Because the flow rate of the product is relatively large during the airtightness test, the pressure inside the product will definitely decrease with time. The flow method test with real-time feedback can ensure that the pressure inside the test product does not follow the test time. The decrease, and the rate at which the gas flows through the flow sensor, is the flow of the product at the time of the pressure.

(5) Differential pressure test method

The differential pressure test method is based on the direct pressure test method, and a differential pressure sensor is added. The general differential pressure sensor has a range of 2000 Pa and a resolution of 0.05% or 0.005%. When inflating, the test valve group is opened, and the pressure at both ends of the differential pressure sensor is the same. When the voltage is stabilized, the test valve group is closed, the pressure on the right side of the differential pressure sensor is constant, and the other side is connected to the test workpiece, and there is leakage at the product end. The pressure drops. The differential pressure sensor compares the pressure at both ends to test for a small leak.

The test method of the airtight leak detector is more commonly used by the differential pressure test method. If you are interested in the tester, you can contact our customer service website for consultation, we will answer you one by one.