How a steam trap works and how to choose one
The steam trap is the automatic valve that, in a steam system, discharges condensate and air while holding back steam. Choosing it well prevents water hammer, corrosion and energy waste. Here are the four main types.
Thermodynamic (disc)
It works on the velocity of flash steam: a single disc opens and closes cyclically. It is rugged, compact, handles high pressure and superheated steam and is frost-resistant. Ideal for main steam lines and high-pressure tracing.
Float (float & thermostatic)
A float modulates discharge continuously following the condensate level; a small thermostat vents air at start-up. It causes no waterlogging, so it is the best choice for heat exchangers and process where condensate load varies and full thermal output is needed.
Inverted bucket
An upturned bucket floats on steam and sinks with condensate, opening the valve. It is robust against dirt and water hammer and discharges intermittently. Good for fairly steady loads.
Balanced-pressure thermostatic
A temperature-sensitive element opens when condensate has sub-cooled a few degrees below saturation. Compact and an excellent air vent: suited to tracing, radiators and venting, where a little sensible heat can be recovered by holding the condensate.
How to choose, in short
- Steam line / high pressure → thermodynamic
- Exchanger / variable-load process → float
- Dirty environment, water hammer → inverted bucket
- Tracing, radiators, air venting → balanced-pressure thermostatic
The next step is sizing (PMO, PMA, TMO). For a guided selection, start from the selector or ask for support with a request for quotation.
Questions fréquentes
What is the difference between a thermodynamic and a float steam trap?
The thermodynamic is compact and rugged, handles high pressure and superheat with cyclic discharge; the float discharges continuously following the condensate level, with no waterlogging, ideal for exchangers and variable-load process.
Which steam trap prevents condensate waterlogging in exchangers?
The float (float & thermostatic) trap: it modulates discharge continuously, avoiding waterlogging, so the exchanger keeps full thermal output even at variable load.