Drip leg|A drain for condensate in a steam line placed at a low point or change of direction in the line and used with a steam trap. Dry steam|The steam that exists after all the water has been vaporized into steam at its saturation temperature. Flash steam|Formed when hot condensate is released to a lower pressure and re-evaporated. Saturated steam|The pure or dry steam produced at the temperature that corresponds to the boiling temperature of water at the existing pressure. Trim|External controls and accessories attached to the boiler itself, such as sight glasses and water feeder controls. Turndown ratio|In steady systems, the ratio of downstream pressure to upstream pressure, usually applied to steam pressure-reducing valves. Water hammer|A condition that occurs when hot steam comes into contact with cooled condensate, builds pressure, and pushes the water through the line at high speeds, slamming into valves and other devices. Water hammer also occurs in domestic water systems. If the cause is not corrected, water hammer can damage the system; a banging noise in water pipes that occurs when the water supply solenoid valve on a humidifier abruptly shuts off water to the humidifier. Drip leg Dry steam Flash steam Saturated steam Trim Turndown ratio Water hammer