Which substance does a steam trap primarily discharge from steam lines and equipment?

A steam trap primarily discharges water and condensate from steam lines and equipment. The primary function of a steam trap is to remove condensate – which is the water formed when steam cools – from the system while preventing the escape of steam. This mechanism is crucial in maintaining the efficiency of steam systems; if condensate is not effectively removed, it can lead to water hammer, reduced heat transfer, and inefficiencies in heating processes.

When steam is used in equipment, it condenses into water as it loses heat. The steam trap ensures this condensate is continuously drained while allowing live steam to remain within the system. By effectively balancing the discharge of condensate and the retention of steam, steam traps contribute to the overall operational efficiency and safety of steam systems.

Other substances like air and oil are not the primary focus of a steam trap. While some steam traps might also be designed to handle air venting or prevent oil from entering the system, their main purpose is centered on the management of water and condensate. Therefore, the answer focuses correctly on the essential role of the steam trap in discharging water and condensate.