What are the uses of vent gas, nitrogen, purified compressed air, unpurified compressed air, and vented gases in a PID diagram?

Judging from your question, it seems you have been working in the chemical industry for only a short time; I’ll try to answer your questions accordingly. In a PID diagram, exhaust gas is used to maintain the operating pressure of equipment during normal production, and it allows for pressure relief when the equipment is shut down. Nitrogen in the PID diagram is also used to maintain the operating pressure of equipment, such as in reflux tanks; it can also serve as a nitrogen purge gas to prevent air from entering the system. It is used to displace toxic, harmful, or flammable gases within the system when the equipment is shut down, and it can also be used as a purge gas during the first start-up of the equipment, or as a gas for testing tightness. Purified air in the PID diagram, also known as instrument air, is used as the source of gas for all pneumatic valves. It can also be used to purge the system when equipment is introduced into it, and it can serve as a purge gas during the first start-up or for testing tightness. Unpurified air in the PID diagram, also known as industrial air, is used for operations such as purging the system when equipment is introduced, and it can also be used as a purge gas during the first start-up or for testing tightness. It can also be used for tasks like air cooling and soot blowing. As for exhaust gases in the PID diagram, there are many different types of such gases; their main purpose is to maintain system pressure, but they also have other functions. For example, PSA exhaust gases are used to purify hydrogen, while flare exhaust gases are used either for safety valve operation or emergency release. Some gases are released to balance pressures, and others are released during initial steam introduction, among other purposes

The answer is thorough! :victory: