How to choose a gas sampling bag？
2024-01-25 11:50:15
The correct selection of gas sampling bags can better measure the actual value of the sample being measured, reduce economic costs, improve efficiency, and reduce errors. Let's take a look at the advantages and disadvantages of gas sampling bags made of different materials.
The sampling bag is mainly composed of a membrane and a valve: the part in contact with the gas is also a membrane and a valve. Currently, three materials are commonly used: aluminum foil composite membrane, Teflon (polytetrafluoroethylene) membrane, and Tedlar (polyfluoroethylene); the more common valves in China are: Teflon (polytetrafluoroethylene) Switch valve, Teflon nozzle without switch, polypropylene (PP) material valve, ABS material valve, metal valve or nozzle. From the perspective of membrane material stability, Teflon and Tedlar materials are recognized as acid and alkali-resistant and corrosion-resistant materials. Their physical and chemical properties are relatively stable. Then from the perspective of membrane materials, these two The sampling bag made of this material has the lowest background value. In addition, the sampling bag must be equipped with a valve. Of course, it is better to use a Teflon valve, because in the design of Teflon valves at home and abroad, the sealing ring generally does not come into contact with the gas sample. The conclusion is that the sampling bag made of Teflon membrane + Teflon valve; or Tedlar membrane + Teflon valve has the lowest background. Teflon membrane, Tedlar membrane and Teflon valve are perfect match, but they are expensive.
Some domestic manufacturers have replaced Teflon valves with ABS valves or PP valves. In this way, there is a problem that the materials of the ABS and PP valves themselves will contaminate the gas sampling bags. Usually these two valves have sealing rings inside, and the sealing rings are usually made of nitrile material. These materials will come into contact with the gas in the gas sampling bag, and will more or less affect the background value of the empty bag.
Gas sampling bags made of aluminum foil composite films are usually called aluminum foil gas sampling bags. Some people also call them aluminum foil gas collection bags or sampling bags. This kind of bag is suitable for ordinary gases, not very corrosive gases, and has good detection capabilities for gases. It is used for ordinary sampling analysis with low accuracy. Because the materials that the gas sample comes into contact with are not materials with high chemical stability. For example, the inner layer of the aluminum foil composite film is PE. This material is definitely not corrosion-resistant. PE and aluminum foil are bonded by glue. The valves are made of PP or ABS materials. There are certainly volatiles. Aluminum foil composite film, PP valve or ABS valve, the cost of these three raw materials is very cheap compared to the above combination, so the overall price of aluminum foil gas sampling bag is cheap. Because of this, there are generally no aluminum foil gas sampling bags equipped with Teflon valves. Because Teflon valves are relatively expensive, even if they are good, they cannot play their role in aluminum foil gas sampling bags.
The advantage of metal valves is high temperature resistance, which corresponds to aluminum foil sampling bags. If equipped with metal valves, you should consider the high temperature advantages of metal valves. However, the aluminum foil composite film is not resistant to high temperatures. What is generally used in China is not a metal valve, but a metal nozzle, which is an old-fashioned bicycle tire air nozzle. The air nozzle is a straight-through gas connector without a switch function. Valves made of PP and ABS materials are equipped with switches, and some also have sampling holes, which can be used for needle sampling, and are cheap. Therefore, the best combination for aluminum foil gas sampling bags is PP and ABS valves.
Procurement of laboratory instruments is a tedious and complicated task. If you find the wrong instrument, you will often be overwhelmed by the purchase of laboratory instruments. kedun Biotechnology Co., Ltd. has always maintained good cooperative relations with large domestic and foreign chemical companies and instrument equipment suppliers, and has become a special dealer for many manufacturers. Choosing kedun can make the procurement of laboratory instruments simple and complicated, and effectively improve the quality of laboratory equipment procurement. Procurement efficiency.
The sampling bag is mainly composed of a membrane and a valve: the part in contact with the gas is also a membrane and a valve. Currently, three materials are commonly used: aluminum foil composite membrane, Teflon (polytetrafluoroethylene) membrane, and Tedlar (polyfluoroethylene); the more common valves in China are: Teflon (polytetrafluoroethylene) Switch valve, Teflon nozzle without switch, polypropylene (PP) material valve, ABS material valve, metal valve or nozzle. From the perspective of membrane material stability, Teflon and Tedlar materials are recognized as acid and alkali-resistant and corrosion-resistant materials. Their physical and chemical properties are relatively stable. Then from the perspective of membrane materials, these two The sampling bag made of this material has the lowest background value. In addition, the sampling bag must be equipped with a valve. Of course, it is better to use a Teflon valve, because in the design of Teflon valves at home and abroad, the sealing ring generally does not come into contact with the gas sample. The conclusion is that the sampling bag made of Teflon membrane + Teflon valve; or Tedlar membrane + Teflon valve has the lowest background. Teflon membrane, Tedlar membrane and Teflon valve are perfect match, but they are expensive.
Some domestic manufacturers have replaced Teflon valves with ABS valves or PP valves. In this way, there is a problem that the materials of the ABS and PP valves themselves will contaminate the gas sampling bags. Usually these two valves have sealing rings inside, and the sealing rings are usually made of nitrile material. These materials will come into contact with the gas in the gas sampling bag, and will more or less affect the background value of the empty bag.
Gas sampling bags made of aluminum foil composite films are usually called aluminum foil gas sampling bags. Some people also call them aluminum foil gas collection bags or sampling bags. This kind of bag is suitable for ordinary gases, not very corrosive gases, and has good detection capabilities for gases. It is used for ordinary sampling analysis with low accuracy. Because the materials that the gas sample comes into contact with are not materials with high chemical stability. For example, the inner layer of the aluminum foil composite film is PE. This material is definitely not corrosion-resistant. PE and aluminum foil are bonded by glue. The valves are made of PP or ABS materials. There are certainly volatiles. Aluminum foil composite film, PP valve or ABS valve, the cost of these three raw materials is very cheap compared to the above combination, so the overall price of aluminum foil gas sampling bag is cheap. Because of this, there are generally no aluminum foil gas sampling bags equipped with Teflon valves. Because Teflon valves are relatively expensive, even if they are good, they cannot play their role in aluminum foil gas sampling bags.
The advantage of metal valves is high temperature resistance, which corresponds to aluminum foil sampling bags. If equipped with metal valves, you should consider the high temperature advantages of metal valves. However, the aluminum foil composite film is not resistant to high temperatures. What is generally used in China is not a metal valve, but a metal nozzle, which is an old-fashioned bicycle tire air nozzle. The air nozzle is a straight-through gas connector without a switch function. Valves made of PP and ABS materials are equipped with switches, and some also have sampling holes, which can be used for needle sampling, and are cheap. Therefore, the best combination for aluminum foil gas sampling bags is PP and ABS valves.
Procurement of laboratory instruments is a tedious and complicated task. If you find the wrong instrument, you will often be overwhelmed by the purchase of laboratory instruments. kedun Biotechnology Co., Ltd. has always maintained good cooperative relations with large domestic and foreign chemical companies and instrument equipment suppliers, and has become a special dealer for many manufacturers. Choosing kedun can make the procurement of laboratory instruments simple and complicated, and effectively improve the quality of laboratory equipment procurement. Procurement efficiency.
