Application of Hydrogen Leak Detection Technology in Refrigeration and Air Conditioning

1. Basic Principle of the Hydrogen Leak Detection Method

(1) The basic principle of the hydrogen leak detection method

The hydrogen leak detection method is a leak detection method using a mixture of 5% hydrogen and 95% nitrogen as the tracer gas, which is called the hydrogen-nitrogen mixture leak detection method, or the hydrogen leak detection method. The mixture of 5% hydrogen and 95% nitrogen is non-flammable (ISO10156 international standard), non-toxic and corrosive, and will not adversely affect equipment and the environment. Hydrogen has many unique advantages as a tracer element for leak detection.

The molecular weight of hydrogen is close to that of helium, and it is the smallest and lightest element of all chemical elements. It has good diffusivity, strong escape, and low adsorption and viscosity. Since hydrogen molecules move faster than other molecules, using safe low-concentration hydrogen as tracer gas can have faster response speed and better leak detection accuracy. The basic working principle is to use a specially developed hydrogen sensor, which only has a response signal to hydrogen and no response to other gases, which is a unique leak detection method. Once there is a signal response, it means that hydrogen gas enters the test piece through the leak hole, thereby indicating the position and size of the leak hole. At the same time, since the concentration of hydrogen in the general environment is very low, it will not cause false alarms due to background pollution.

(2) Main equipment of hydrogen leak detection method

Due to the above-mentioned properties of hydrogen, the sensitivity of the special hydrogen leak detector manufactured by the above working principle can reach the same level as that of helium detection.

(3) Process and method of hydrogen leak detection method

Engineering installation and maintenance providers can use hand-held nitrogen and hydrogen leak detectors (packages with gas cylinders/meter sets are available). When it is necessary to find the leak point of the system on site, the refrigerant is first emptied, and then the tracer gas of 5% hydrogen + 95% nitrogen is filled segment by segment, and a hand-held nitrogen-hydrogen leak detector is used to conduct a patrol leak detection. Because hydrogen is lighter than air, any leaked hydrogen can run up parts such as pipes and penetrate the insulation. Users can perform leak detection at the highest position of the part, which is much easier and more successful than other methods to find leaks.

2. Advantages of the Hydrogen Leak Detection Method

Whether it is in leak location or in leak testing applications, the hydrogen leak detection method has been widely used in various industries. The use of low-density safe hydrogen as a tracer gas for leak detection has many advantages over helium. It is very inexpensive and readily available from various gas suppliers. Today’s hydrogen-nitrogen mixed gas leak detection technology can detect leaks as low as 5*10-7mbar/s, which is equivalent to 0.1g/y, and its gas usage cost is only 1/10 to 1/20 of that of helium. At the same time, the helium leak detection method needs to add some auxiliary equipment, such as a helium recovery system.

3. Application and Prospect of Hydrogen Leak Detection Method in Refrigeration and Air Conditioning

Today, many refrigeration and air-conditioning customers around the world are using various types of hydrogen leak detectors. Hydrogen leak detectors have a very reliable sensitivity and measurement indication based on their unique technology in handling the background hydrogen concentration in the environment. Hydrogen leak detectors can bring you a more flexible leak detection solution that traditional leak detection cannot meet. For example, a customer can first use the pressure drop method to check for leaks and then use a hydrogen leak detector to find the location of the leak. Customers can also directly use the hydrogen leak detector for highly sensitive leak detection to avoid the influence of temperature changes on the pressure drop method leak detection. In modern leak detection methods, if the workpiece to be tested is not suitable for contact with water, there is an influence of temperature in the detection environment, or the workpiece to be tested is an elastic body that cannot be detected by the blister method and the pressure drop method, the hydrogen leak detection method is used. A cost-effective option.

In various leak detection applications, the emergence of the hydrogen leak detection method brings you greater opportunities to improve performance and efficiency. The hydrogen-nitrogen mixed gas leak detection method has been widely used in refrigeration, air conditioners, auto parts, engines, gearboxes, reducers, valves, pharmaceutical packaging, aircraft fuel tank oil circuits, and other seals or pipeline leak detection at home and abroad. The hydrogen leak detection method has high detection sensitivity, cost saving, and easy operation, which will be the development trend of leak detection technology in the future.