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　　There are many types of high-purity gases, but which ones are harmful to the human body? When it comes to high-purity gases, let's talk about common gases first. We are all very familiar with oxygen, but is it harmful to the human body? The normal oxygen content of high-purity gas in the air is 21%. When the oxygen content exceeds 40%, it will cause oxygen poisoning.

　　Nitrogen is harmful to the human body and can cause suffocation due to excessive inhalation. Argon is as harmful as nitrogen, and so is carbon dioxide. Ammonia is corrosive and toxic, and its harm to the human body is chronic poisoning due to inhalation. Excessive inhalation of hydrogen and helium can cause suffocation.

　　High-purity gas Let's talk about the harm that corrosive or toxic gases can cause to the human body. In fact, the concept of high-purity gas is that it cannot cause harm. This is not a big deal. It's just to express purity. Let's first talk about the smelly sulfur dioxide. The corrosive smell is unpleasant. Inhaling it will cause mild poisoning to the human body. Nitric oxide is corrosive and inhaling it will damage the respiratory system.

　　Hydrogen sulfide is corrosive and highly toxic, and inhalation of a powerful neurotoxin can cause chronic poisoning and acute poisoning. You see, harmful gases can cause harm to people. Of course, good high-purity gases will not cause any harm to people. So, what are the design points of high-purity gas pipelines?

　　(1) For gases with different characteristics, independent supply areas should be planned. Generally, consideration should be given to strengthening the centralized management of corrosive/toxic, flammable, inert and similar gases. Explosion-proof walls and leakage areas should be specially planned for the flammable gas area. If there is insufficient space, consideration can be given to placing the inert gas in the toxic/corrosive area.

　　(2) Pipeline design should consider the transportation distance. The longer the distance, the higher the cost and risk. Generally speaking, the reasonable design flow rate is 20ml/S, combustible gas is less than 10ml/S, and toxic/corrosive gas is less than 8ml/S. In terms of usage design, the pressure at the use point and the pipeline should be considered.

　　(3) According to the distribution of gas equipment, the pipeline network of high-purity gas cannot be too large or too long. Use unclosed circular pipes to continuously discharge a small amount of gas from the end of the system to ensure that high-purity gas always flows in the pipeline network and no "dead space" will occur to cause high-purity gas contamination.

　　(4) The "dead space" of stagnant gas in the pipe should be reduced, and blind pipes should not be installed. Cleaning control devices, multi-valve control devices, control of the opening and closing sequence of each valve, and blowing systems should be installed between the special gas tanks and equipment.

　　(5) For equipment with different requirements for high-purity gas purity, a graded high-purity gas delivery system should be used. A water supply delivery system can also be used, but a terminal gas purification device can be installed near the gas equipment with higher purity.