The chemical industry is the largest and most extensive application field for nitrogen equipment. Currently, the widely used applications include: Polyvinyl Chloride (PVC), with a purity of 99.5% and high flow rate. Polypropylene (PE), with a purity of 99.9% and high flow rate. The nitrogen application for this product is divided into two parts: one is for the loading and purging of activators and catalysts, requiring 99.9% nitrogen (small quantity), and the other is for the reactor, which uses 99.5% nitrogen in large quantities, though it is customary to use 99.9% purity.

Polyethylene and aniline, with a purity of 99.95%. For the petrochemical product aniline, nitrogen usage during catalyst regeneration is about four times the normal amount, but the usage cycle is short.

Maleic anhydride and ethanol, generally with a purity of 99.9%. Petrochemical product polyoxymethylene (currently, there are few domestic manufacturers, and demand is strong), with a purity of 99.9%.

Petroleum: Nitrogen can be used for purging pipelines and containers in the system, nitrogen filling, replacement, and leak testing of storage tanks, protection of flammable gases, as well as in diesel hydrogenation and catalytic reforming, with a general purity of 99.9%.

Phthalic anhydride: Purity of 99%.

Polyester: Upstream raw material PTA (purified terephthalic acid), actual usage purity is 95%, but generally 99% is used.

In the PTA production process, high-purity nitrogen is used for bubble purging to measure the liquid level of ethylene glycol in high-temperature and low-temperature reactors. After measuring the pressure difference between the high-pressure and low-pressure ends, a 4–20 mA standard signal is transmitted and then converted into liquid level height. High-purity nitrogen is also used to measure the pressure of vacuum systems and for backflushing filters in the PTA production process. Polyester chips generally have a purity ranging from 99% to 99.999% depending on the actual process, while downstream products such as filament and staple fiber have a purity of 99.9% to 99.999%.