Ensures stability of standard gases in cylinders
The secret of ensuring the stability of standard gases in cylinders
For gases with strong reactivity, such as nitric oxide and oxygen, the lower the concentration of standard gas, the greater the change in its composition will be. Therefore, we have made repeated studies on the reasons for the variation of nitric oxide standard gas or oxygen standard gas in high pressure vessels over time. The results show that, in addition to impurities such as water (vapor) in the raw gas (component gas and dilution gas), it is mainly caused by the reaction or adsorption of standard gas such as oxygen with the wall of the vessel. The secret to ensuring the stability of standard gases in cylinders lies in the container
Standard gas cylinder
In order to prevent the standard gas from contacting directly with the inner wall of the container, coating the inner walls of containers with substances that are difficult to react with and adsorb with standard gases, so as to keep the standard gas unchanged for a long time and maintain its concentration stably. The wax coating in the container can keep the standard gas stable for a long time.
A method of stabilizing the composition of nitric oxide standard gas and oxygen standard gas by filling them into high pressure wax-coated vessels. The coating is in gallo wax, cantley tree wax, wax, wax, paraffin wax, pure natural wax, wax and cabo, silicon carboxyl wax, Hector, wax, polyethylene wax, synthetic wax, select one or more of the following has been the use of standard gas preservation methods are: on the inner wall of the high pressure vessel, gold-plated, nickel and other metals, with fluorine resins such as plastic coating, high pressure gas container wall polishing, filling in advance is a high concentration of ammonia oxidation or oxygen adsorption equilibrium processing methods. However, the gold-plating method (raw material cost, equipment cost, labor cost) is high, and difficult to cover the base, easy to produce pores, so there is an error between containers. Secondly, in addition to the high production cost of plastic coating, gas is easy to adsorb on the plastic film, causing the concentration to change with time, and paint is easy to fall off from the inner wall of the high-pressure container. And the inner wall polishing and adsorption equilibrium treatment of the force method, so that the containers are easy to produce errors, using this treatment of the container filled with standard gas, its concentration at any time to read the change is much better than not treated, but it is difficult to get the barrier stable standard gas.
Customize calibration gas is the other name for it
On the contrary, the wax is heated and melted, and the liquid wax is evenly applied to the inner wall of the container. Because the coating is dense, it is difficult to produce pores and does not adsorb gases. In addition, the method has the advantages of simple processing, low price and small error between containers.