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SH/T 3005-2016 6.2.2 The selection of pressure gauges for use with special media and in special applications shall comply with the following provisions: a) For measuring acetylene, ammonia, and media containing ammonia, specialized pressure gauges shall be used； b) For the measurement of oxygen, an oxygen pressure gauge should be used ； c) For the measurement of hydrogen sulfide and sulfur-containing media, sulfur-resistant pressure gauges should be used ； 1. The key requirement for special pressure gauges used to measure acetylene or ammonia media is that the material in contact with the liquid in such gauges must not be copper. Under certain conditions, acetylene reacts with copper to form copper acetylide. Dry copper acetylide is highly sensitive to heat, friction, and impact, and can explode very easily. Under certain conditions, ammonia reacts with copper to form copper-ammonia complexes, which accelerates corrosion and may lead to leaks and other accidents. 2. Oxygen has strong oxidizing properties; in pure oxygen or oxygen-enriched environments, fats and oils can easily catch fire or even explode. Therefore, oxygen-specific pressure gauges must be thoroughly degreased and free of oil, and care must also be taken during installation, calibration, and use. 3. Hydrogen sulfide or sulfur-containing media, especially when the sulfur concentration is high and under other operating conditions (within the range that constitutes a hydrogen sulfide stress corrosion environment), exhibit a significantly enhanced corrosive capability. The difference between sulfur-resistant pressure gauges and ordinary pressure gauges also lies in the requirements for the material in contact with the liquid; for example, such material must meet the requirements of NACE MR0103. In current engineering projects, full-stainless-steel pressure gauges are commonly used for many applications, and their adaptability is quite good. For example, those applicable to the aforementioned acetylene-specific pressure gauges and ammonia-specific pressure gauges, as well as all-stainless-steel pressure gauges, can be used; selecting an appropriate material for the liquid contact surface along with meeting the relevant processing requirements will suffice, provided that the dial is labeled.