The sealing performance of the glove box is an important part of ensuring its normal operation. It can not only prevent the invasion of external gases and pollutants, protect the stability of the internal environment of the glove box, meet the experimental needs under specific atmospheric or anaerobic conditions, but also provide guarantees for the storage and handling of sensitive materials. In addition, good sealing performance ensures consistency in experimental conditions, thereby improving the accuracy and reproducibility of experimental results, which is particularly important for high-purity material processing and biological experiments. The following are several common methods for testing the sealing performance of glove boxes:
1. Positive pressure airtightness detection method: Inflate the inside of the glove box to the set positive pressure value, close the inflation valve, and start to maintain pressure. During the holding period, regularly monitor the pressure value inside the glove box. If the pressure continues to decrease, it indicates that there may be a leak inside the glove box.
2. Negative pressure sealing test: Seal the glove box and use a vacuum pump to evacuate the inside of the glove box to a certain negative pressure value. Monitor pressure changes during the pumping process and during the subsequent holding phase. If the pressure recovery rate is abnormal, it may indicate a leak in the glove box.
3. Volume quantitative sealing test: Inflate the glove box and record the volume change of gas during the inflation process. Evaluate the sealing performance of the glove box by comparing the changes in gas volume before and after inflation.
4. Oxygenation method: This method can only be used when a certain negative pressure is maintained in the sealed chamber. This method mainly involves determining the functional relationship between the increase in oxygen concentration inside a sealed chamber that has been purified with inert gas beforehand and time. The purpose of purifying the sealed chamber with inert gas in advance is to reduce the residual oxygen concentration in the chamber to a level compatible with the leakage rate to be measured. The hourly leakage rate of the sealed chamber can be calculated by measuring the change in oxygen concentration from the beginning to the end of the inspection.
5. Gas flow type sealing detection: Real time monitoring of the gas flow entering the glove box during inflation. If the gas flow rate increases abnormally, it may indicate insufficient sealing of the glove box.
6. Constant pressure method: The leakage rate is calculated by measuring the flow rate of the exhaust system that maintains the negative pressure inside the glove box isolated from the outside at a constant level.
7. Glove integrity testing: Before and after using gloves, use a glove leak detector for integrity testing. Usually, the pressure attenuation method is used to inflate the glove part of the glove box to a certain pressure, and then monitor whether the pressure drops. If the pressure drops beyond the allowable range, it indicates that the gloves may be damaged.
Each method has its own characteristics and application scope, and the choice of detection method can be determined based on the specific usage and environment of the glove box. In practical operation, a comprehensive judgment may also be made by combining visual inspection and other auxiliary means.
