Extra‑large air separation equipment consists of air compression system, large‑scale air pre‑cooling system, super‑large molecular‑sieve purification system, air booster system, booster turbo‑expander system, as well as super‑large rectification system and heat‑exchange system. Owing to the large dimension of supporting unit equipment and high requirements for manufacturing processes, type‑selection of matching valves is particularly critical, which has a direct bearing on production safety, system regulation performance, output quality and investment cost.