helium mass spectrometer leak detector in fire equipment leak detection
1、 Causes of fire equipment cylinder leakage detection
Fire extinguisher belongs to special equipment, which is used in case of fire, so it is usually idle. However, there is 2.5 MPa in the cylinder containing fire extinguishing material Pressure, if there is leakage of the cylinder (at the weld and valve of the cylinder), especially when there is a small leakage, there will be a great hidden danger. Therefore, before leaving the factory, the manufacturer should carry out strict leak detection procedures to avoid the potential leakage during transportation or storage.
2、 Leak detection method for steel cylinder of fire fighting equipment
At present, many domestic steel cylinder manufacturers use the water detection method, that is, the fire cylinder is put on a certain pressure of about 2 MPa, and then the whole cylinder is put into the water tank to see whether there is bubble. However, this method can only detect the situation of large leakage. According to the calculation, the bubble diameter is? 2.26MM, and the leakage rate is about 1.0 x 10-4 when one bubble is emitted per minute It is difficult to realize the detection of small leakage.
With the increase of China's export volume and the improvement of customers' safety awareness, fire cylinder leak detection needs higher requirements, so now manufacturers have introduced helium mass spectrometer leak detector for leak detection; helium mass spectrometer leak detector is widely used in cylinder manufacturers, with positive pressure mode, and its working principle is as follows: the pressure of helium filling into the inspected workpiece is only 1.2 The air pressure is enough --- the suction gun is used to find the leakage point of the workpiece. Generally, in the positive pressure mode, the alarm value of the leak detector is set at 1.5 x 10-5 mbar.l/s. In the actual leak detection process, if the leakage rate of the workpiece to be inspected is greater than this value, the leakage alarm will be formed. If the leakage rate is less than this value, the cylinder sealing requirements are qualified.
3、 Description of leak detection form
Using helium mass spectrometer leak detector to detect fire cylinder is the most widely used detection method in the industry. A certain amount of helium is injected into the fire cylinder to make the pressure difference between the inside and outside of the cylinder. If there is leakage, the gas will leak out from the inside of the cylinder. Use helium mass spectrometer leak detector The suction gun moves slowly at the welding position and valve of the cylinder. If the suction gun inhales helium, an alarm will be generated, and the workpiece is confirmed to have leakage, so as to achieve the measurement effect.
4、 Application of fire equipment leak detection
Helium mass spectrometer leak detector It is widely used in modern industrial production, representing the advanced scientific and technological level, as well as the improvement of people's requirements for product quality. For example, the water immersion method was first used in China to detect the leakage of fire-fighting equipment. If the fire extinguisher is placed in the water, if there is no bubble, it is considered as qualified. This method is completely dependent on human observation, and it can not be used in case of small leakage The use of helium mass spectrometer leak detector can greatly reduce the risk of leakage, and even detect small leakage, and accelerate the production efficiency.
The positive pressure method of helium mass spectrometer leak detector is used. Firstly, helium is flushed into the fire extinguisher, and then it is placed in a closed chamber. The chamber is connected with the helium mass spectrometer leak detector. When working, the cavity is vacuumized first. After reaching a certain vacuum degree, the leak detection is started. The leakage rate is 10-5 mbar.l/s, which is regarded as qualified (the actual leakage is 2 ml. about 10-5 mbar. L / s) in 24 hours.