Leak Detector Frequently Asked Questions

What is the principle of leak detector?

In the automatic leak detection using dry air as the medium, the test piece is pressurized and inflated to determine whether the gas filled body is leaking. The leaked gas can not be directly measured, but by the effect of the gas leakage, that is to say, when the workpiece and the compressed air source are cut off (pressure measurement method), if the gas leaks, the internal part of the workpiece Pressure is bound to change. What we want to measure is this pressure change. Or, when the workpiece or the compressed air supply is always connected (flow measurement method), if the gas is leaked, the interior of the workpiece will continue to pass through. The flow of this air flow is what we want to measure. Regardless of the pressure measurement method or flow measurement method, there are several corresponding different types of instruments for the user to choose.

What are the leak detection methods?

A. Pressure Measurement In today's industrial gas tightness detection, pressure detection is one of the most commonly used detection methods. When the test volume is small, the leakage rate can be set from 0.1 cc/min.

With the direct pressure detection method as the premise, the structural design of the test device can be made as compact as possible and the test system's own volume can be minimized as much as possible. As a result, higher operating reliability and greater test coverage can be achieved. The resolution of the test signal depends on the test pressure.

When the differential pressure method is adopted, because the resolution of the test signal is independent of the test pressure, a higher test accuracy can be obtained than the direct pressure test under a higher test pressure.

The pressure reduction method is used and the normal working conditions can be simulated under the overpressure condition of the measured workpiece.

Based on the pressure increase method and the partial pressure test method, the influence of the temperature change and the volume instability caused by the sealing jig or workpiece can be greatly suppressed, and the suppression effect is better than the pressure reduction method. When using the pressure rise method and working in the state of overpressure, the balance phase in the test process can be omitted. In addition, the test pressure is not limited by the pressure range of the measuring components. The reason is that they are independent of the test pressure.

B. Flow measurement method In the pressure measurement method described above, the larger the measured volume, the smaller the measurement signal becomes. In the flow method, the measurement signal is independent of the size of the measured volume. This is very convenient when correcting the system. The flow signal in the flow method can directly reflect the amount of gas leakage set for calibration.

In general, volumetric flow methods (such as pressure drop through a throttling element) can accomplish leak testing (small leak rate) and flow testing (high leak rate) in the same test system. For example, in the monitoring of the fuel system path, the instrument using the volumetric flow method is also equipped with a detection element (differential pressure sensor) to perform continuous leak detection on the system by pressure reduction method.

When using the mass flow method (thermometry), the test signal is not only independent of the size of the measurement volume, but also has nothing to do with the measurement pressure. The test signal will directly represent the amount of leakage in the standard unit of leak rate, cc/min, without having to calculate the leak rate (eg, pressure measurement method).

What problems should be noticed when selecting equipment suppliers?

The difference between manufacturer's direct supply and distributor's supply: The manufacturer has rich experience in leak detection, mature leak detection technology and related calibration equipment, and can provide perfect pre-sale and after-sales service according to your needs. Dealers only use profit as their ultimate goal. When they lose profits, it is difficult to provide perfect services for maintaining the brand. Dealers are generally non-professional technicians, and may not know the relationship between leakage and sealing. Perhaps you know more than him. Therefore, when selecting a supplier, it must be determined whether or not he has the ability to produce complete sets of equipment in order to reduce unnecessary workload (to find supporting equipment and busy) and funds, not to mention the problems of supporting equipment and equipment.

How to understand the quality of the selected product?

Products are generally constructed from various components. The performance and quality of components are the key to comprehensive product quality assurance. It is important to understand what kind of quality assurance the supplier's products provide. The full set of devices (electrical control system and integrated pneumatic control system) used in manufacturing good quality gas leak detectors must be supplied by well-known brands and provide quality written guarantees to ensure that pneumatic and electronic control systems are products that are thoroughly tempered by the research departments of large companies. . In addition, each instrument is qualified by the test center and issued a certificate before it leaves the factory, thus ensuring the quality of the product.

What is the application flexibility of the system?

The application flexibility of the system involves the detection mode, detection medium, measurement system, operation mode, automatic deviation correction function, and expansion attachments of the device.

1. The detection method will directly affect the detection results. Selecting the detection method suitable for the tested product will make the detection effect the best.

2. The detection medium is preferably clean air with low pollution cost.

3. The measurement system will automatically help you complete the volume conversion.

4. Automatic deviation correction can effectively improve the detection accuracy and efficiency.

5. Extend attachments can help you connect external devices such as computers to do data tracking analysis on the products under test.

Understand the resolution and accuracy in leak detection?

You may know that when you purchase leak detection equipment, resolution and accuracy are important factors. How to know the inspection capability of the equipment system requires understanding of the following issues:

1. A/D converter resolution does not represent system resolution. When choosing a device, you will encounter a propaganda with a resolution of 0.0001 psi, but did not tell you that this resolution will only appear when the range is very small, and you may not be able to use it. The resolution of the system should be given based on the instrument's range.

2. The highest precision does not equal the actual detection accuracy. The highest precision is often the result of an ideal condition when the comprehensive factors (such as temperature, pressure, etc.) are in the ideal state. In the actual test, comprehensive errors should be taken into consideration. The accuracy of the instrument should be integrated in the verification certificate to give an accuracy level that meets the national standards.

3. The detection rate is not fixed and varies according to the size of the DUT. If someone provides you with a test rate without knowing what you are checking, you should consider the product's credibility.

4. Detection sensitivity depends on the entire system, including parts and inspection specifications. If you encounter 0.01CC/min promotion, you should be skeptical that it may achieve this sensitivity under certain circumstances, but it is extremely difficult to achieve in the actual testing process.

5. The final test results You should believe in the assessment results of the certification department. Only the supplier who presents you with an authority certification certificate is truly trustworthy.

How to determine the comprehensive price?

The price of the equipment should not only be the price at the time of purchase, but should consider the purchase price, product quality assurance, product warranty, product energy consumption, investment in human resources, product installation costs and so on.