A gas leak detector is a device used to detect gas leaks, widely applied in industries such as petrochemicals, pharmaceuticals, food, and aerospace. Proper use of a gas leak detector can effectively ensure production safety and improve production efficiency. The following introduces the working principle, usage method, and solutions to red light faults of the leak detector. Working Principle of Vacuum Leak Detector The core of a vacuum leak tester is to create a low-pressure environment and use a highly sensitive pressure sensor to detect small leaks. During operation, the instrument first places the product to be tested in a closed test chamber, then removes the air from the chamber to create a vacuum environment. If there is a leak in the product, external air will flow into the test chamber, causing a change in internal pressure. When the highly sensitive sensor captures these tiny pressure changes, it can determine whether the tested product has a leak, and the leak rate can be obtained through relevant data processing. Working Principle of Microwave Leak Detector It performs scanning measurements by utilizing the characteristics of microwaves and the laws of electromagnetic wave attenuation. Its core components are a microwave detector and a microwave transmitting device. The detector detects signals radiated by microwave equipment, while the transmitting device emits microwave signals to the equipment being tested. When microwave radiation signals enter the detector, the detector converts these signals into electrical signals for amplification and processing. After calculation, the microwave radiation intensity value is obtained. By comparing the microwave radiation intensity values at different positions, the radiation leakage of the equipment can be determined. Usage Method of Leak Detector 1. Preparation Work Before using a gas leak detector, some preparations are required. First, check whether the gas leak detector is in normal working condition, including battery power and sensor status. Second, select an appropriate detection method and gas, and choose the suitable detection sensitivity and range according to the actual situation. 2. Detection Operation During the detection operation, follow these steps: (1) Turn on the gas leak detector and wait for the preheating time. (2) Bring the gas leak detector close to the area to be tested, keeping a certain distance. (3) Observe the display screen of the gas leak detector. If a gas leak is detected, it will issue sound and light signals for prompt. (4) Take corresponding measures for repair or treatment based on the detection results. 3. Precautions When using a gas leak detector, the following precautions should be noted: (1) Avoid sparks or static electricity during detection to prevent explosions or fires. (2) Avoid interference during detection, such as strong wind and strong light. (3) Calibrate the gas leak detector regularly to ensure the accuracy of detection results. Calibration of Air Micro-Leak Detector Zhejiang Province once drafted a local metrological technical specification *JJF1074 (Zhejiang) - 2012 Calibration Specification for Air Micro-Leak Detector* for leak detectors. Precision leak detectors require regular calibration of pressure and flow sensors. The instrument can achieve multi-point calibration, supporting up to 32 calibration points. Relevant settings include the number of points, i.e., the number of points used in the sensor calibration process. The value range must be from 2 to 32. Select points one by one, and users can define the points at the position where calibration occurs. The number of displayed points is determined by the number of points selected in the upper parameters. The linear limit is the limiting condition for calibration, which means the maximum allowable linear deviation for successful calibration. Since the core instruments for precision leak detector testing are pressure sensors and flow sensors, it is necessary to ensure the measurement accuracy of both sensors. For pressure sensor calibration, multi-point calibration should be implemented as much as possible to more accurately cover the pressure range of the sensor. During testing, connect the instrument's pressure sensor to the standard pressure sensor, record the corresponding table of indicated values between the tested pressure sensor and the standard pressure source one by one, and save it to the instrument's storage. As the flow sensor adopts a thermal mass flow sensor, there is a linear relationship between its instantaneous flow (flow rate) and the collected value. What Fault Does the Red Light of the Leak Detector Indicate? If the leak detector detects a gas other than air, the LED light bar starts to light up. More lights indicate a more serious leak. When the third red light or the second yellow light is on, the machine will emit a beeping alarm. The more LED lights are on, the faster the alarm sound will be. When the last yellow light or red light is on, the alarm sound will become continuous. Red light on: indicates a leak of helium or hydrogen. Yellow light on: indicates a leak of nitrogen, argon, or carbon dioxide. Move the probe away from the leak source, and the leak detector will automatically reset to zero. If the leak is serious and a large amount of gas enters the probe, the zero-resetting time will be extended by a few seconds. Do not perform the zero-resetting operation until the gas in the probe is completely exhausted, as this may cause a malfunction of the machine. After resetting to zero, move the probe near the leak source again and perform the same operation to reconfirm the detection result. During operation, ensure that both the gas inlet (Figure 1) and the gas outlet are unobstructed. The gas outlet is located at the connection between the probe and the machine. This device is designed to detect trace amounts of hydrogen from small leaks in non-flammable environments (such as indoor air in laboratories). The device is suitable for non-flammable atmospheres; if the concentration of flammable gas may be high enough to become explosive. Notes: 1. To turn off the alarm sound during leak detection, press and hold the zero-reset button for 2-3 seconds. After hearing a 1-second steady tone, release the button, and the alarm sound will be turned off. To turn on the alarm sound function again, press and hold the zero-reset button. The alarm sound function is always enabled when restarting. 2. The leak detector will turn off after 6 minutes of operation. This function prevents excessive battery consumption if the machine is accidentally left on. Source of the article: Instrumentation Users, Gas Alarm Official Website, Restek 2