Select a model that can handle the maximum working pressure of the steam system. For example, the FT3-015 has a maximum working pressure of 15 PSI. Consult capacity tables to properly size unit. Available in 3/4” through 2” NPT connections. Select these models for steam systems with maximum working pressure of 75 PSIG. The maximum operating pressure (PMO) rating of model selected must meet or exceed the maximum steam pressure or the trap may not open. For example; the FT-35-030 has a PMO of 30 psi. For drip applications, a 3/4” FT size is sufficient to exceed warm-up loads with a 2X safety factor. The condensate loads (lbs/hr) for process applications are normally calculated at the maximum steam pressure; then a safety margin is applied in order to select a trap with sufficient capacity at lower pressures. Reference full explanation of Safety Load Factors in Steam Traps Introduction section.
For Example:
Process application has a maximum steam inlet pressure of 50 psi, a maximum condensate load of 1,700 lbs/hr and is
discharging to a condensate return line with a possible back pressure of 10 psig. ΔP = 50-10 = 40 PSI
To select trap:
If the Safety Load Factor is chosen to be 2X max capacity at max differential pressure, then Trap should be selected based on
3,400 lbs/hr (1,700 x 2 = 3,400) at 40 PSI differential pressure with a PMO in excess of 50 PSIG
Selection:
FT77L-075-16-N, PMO=75 PSIG, 11/2” NPT with a condensate capacity of 3,750 lbs/hr at 40 PSI differential pressure.
