Function of the Steam Trap

To preserve the condensate seal. If steam blows through the outlet drain nozzle on the channel head, the rate of heat transfer will drop dramatically. 

To minimize condensate backup. If condensate fills up tubes, then those tubes are unavailable to condense steam. Thus, the rate of heat transfer will drop in proportion to the tubes filled with water. 

The steam trap is designed to pass liquids (H O) and retard the passage of vapor (steam). 

There are two problems with the use of the control scheme shown in Fig. 13.1. First, steam traps are mechanically unreliable. Second, as valve A closes, the pressure in the lower half of the channel head may briefly fall below the frequently unstable pressure in the condensate 

1 would ignore this problem if the steam pressure is 100 psig or more and the condensate collection header is 30 psig or less. For smaller steam flows, 5000 to 10,000 Ib/hr, 1 would use a steam trap. For larger steam flows, 1 would use a condensate pot and level control valve (LRC), as discussed in a following section. 

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