The material of gas delivery hoses directly determines their adaptability, safety, and service life. Different materials have significant differences in core properties such as chemical compatibility, temperature resistance, pressure resistance, and permeability, which in turn affect their application scope. Specific impacts can be explored from the following dimensions:
1、 Chemical compatibility: determining the compatible gas type
The chemical reaction risk between the material and the transported gas is the primary consideration for selection:
Rubber (natural rubber, nitrile rubber): Natural rubber has good alkali resistance, but is easily corroded by organic solvents (such as gasoline, toluene), and is only suitable for inert gases such as air and nitrogen; Nitrile rubber is resistant to oil and organic solvents, and can transport hydrocarbon gases such as propane and butane. However, it is not resistant to strong oxidizing gases such as chlorine and ozone, and is prone to aging and cracking.
Plastic materials (polyethylene, polytetrafluoroethylene PTFE): Polyethylene is acid and alkali resistant, but has poor resistance to strong oxidizing gases (such as concentrated nitric acid volatile gas), making it suitable for transporting low-pressure inert gases; PTFE (Teflon) has strong chemical stability, resistance to strong acids, alkalis, and oxidants, and can transport corrosive gases such as fluorine, chlorine, and hydrogen fluoride. It is a core choice in the chemical and semiconductor industries.
Metals (stainless steel, copper): Stainless steel (316L) has better corrosion resistance than ordinary steel and can transport oxygen, hydrogen, etc., but it is prone to stress corrosion when in contact with sulfur-containing gases (such as hydrogen sulfide); Copper material is prone to react with ammonia to form copper ammonia complexes. It is strictly prohibited to use it for ammonia transportation, otherwise it may cause corrosion of the pipe wall and gas pollution.
2、 Temperature resistance: limited application environment temperature range
The difference in temperature resistance upper and lower limits of different materials determines whether they can adapt to high and low temperature scenarios:
Low temperature scenario: Ordinary rubber is prone to hardening and cracking below -20 ℃, making it unsuitable for gas transportation in cold chain environments; And EPDM rubber can withstand low temperatures up to -50 ℃, while PTFE can withstand low temperatures up to -200 ℃, which can meet the requirements of low-temperature gas transportation assisted by liquid nitrogen (such as low-temperature nitrogen).
High temperature scenario: Polyethylene is prone to softening and deformation above 80 ℃, and is only suitable for ambient temperature gases; Silicone rubber has a temperature resistance limit of about 200 ℃ and can be used for sampling high-temperature exhaust gases in the engine compartment; PTFE can withstand temperatures up to 260 ℃ and is suitable for transporting high-temperature gases (such as steam and hot nitrogen at 180 ℃) in chemical reaction vessels.
3、 Pressure resistance: affects the applicable pressure level
The mechanical strength of the material determines the pressure resistance of the hose, which is directly related to the safety of high-pressure scenarios
Low pressure scenario (<0.6MPa): PVC material hoses are lightweight and cost-effective, but have poor pressure resistance and are only suitable for laboratory low-pressure gases (such as inert gas blowing in fume hoods); Rubber hoses (such as EPDM) can withstand a pressure of up to 1.0MPa and can be used for low-pressure transportation of civilian gas (such as natural gas).
High pressure scenario (>1.0MPa): Plastic hoses (such as PTFE) need to be paired with woven reinforcement layers (such as glass fiber, stainless steel wire), with a pressure resistance of over 10MPa, suitable for industrial transportation of high-pressure hydrogen and oxygen; Pure metal hoses (such as stainless steel corrugated pipes) can withstand a maximum pressure of 30MPa and can be used for high-pressure process gas transportation in petrochemicals, but attention should be paid to avoiding frequent bending that can cause metal fatigue.
4、 Permeability and cleanliness: related to gas purity requirements
The gas permeability and surface cleanliness of materials are crucial for the application of high-purity and high-purity gases
High purity gas scenario (such as electronic specialty gas for semiconductors): Ordinary rubber hoses have strong permeability, which can easily cause external impurities (such as air and moisture) to infiltrate, or gas (such as helium) inside the tube to leak, affecting gas purity; PTFE hoses have extremely low permeability and smooth inner walls without adsorption, which can avoid gas contamination by impurities on the pipe wall and meet the requirement of "99.9999% purity" in chip manufacturing.
Food and pharmaceutical scenarios: Silicone rubber hoses are non-toxic, odorless, and can be sterilized at high temperatures (121 ℃ high-pressure steam), suitable for transporting food grade carbon dioxide (such as carbonated beverage inflation) and medical oxygen; PVC hoses may release plasticizers and are strictly prohibited from being used for transporting gases that come into contact with food.
In summary, the selection of materials for gas transmission hoses should be based on the matching of "gas transmission characteristics (corrosiveness, purity), application environment (temperature, pressure), and safety requirements (no leakage, no pollution)". Incorrect selection may lead to hose damage, gas leakage, and even safety accidents, which need to be accurately judged based on specific scenarios.