Armstrong TT Series thermostatic steam traps are equipped with balanced pressure bellows or capsule-style elements. Designed for very low load condensate applications, these traps are constructed from durable materials, with specific models like the TTF-1, TTF-1R, and TT-2000 featuring 304-L stainless steel bodies. The thermostatic elements themselves utilize stainless steel and bronze components, including phosphor-bronze bellows caged entirely in stainless steel.

Thermostatic Operating Principle

The thermostatic steam trap operates based on the temperature differential between steam and subcooled condensate and air. Steam increases the pressure inside the thermostatic element, causing the trap to close. As condensate and non-condensable gases back up in the cooling leg, the temperature begins to drop. This cooling causes the thermostatic element to contract, opening the valve to discharge the accumulated fluids.

Application Note

The amount of condensate backing up ahead of the trap depends on load conditions, steam pressure, and piping size. It is important to note that an accumulation of non-condensable gases can occur behind the condensate backup.

Air Venting Capability

Thermostatic traps can also be effectively used to vent air from steam systems. When air accumulates and the temperature drops, the thermostatic air vent will automatically discharge air at temperatures slightly below steam temperature throughout the entire operating pressure range.

Model Specifications

Model	Nominal Size	Connection Type	Max Operating Pressure	Max Allowable Pressure	Capacity
TTF-1	15 mm (1/2"), 20 mm (3/4")	Threaded	20 barg (300 psig)	20 barg @ 232°C	1565 kg/hr (3450 lb/hr)
TTF-1R	15 mm (1/2"), 20 mm (3/4")	Threaded	20 barg (300 psig)	20 barg @ 232°C	1565 kg/hr (3450 lb/hr)
TT-2000	15 mm (1/2"), 20 mm (3/4"), 30 mm (1")	Threaded, Socket Weld, Flanged	20 barg (300 psig)	20 barg @ 232°C	1565 kg/hr (3450 lb/hr)

AE-2 Separator with TTF-1 / TTF-1R

The TTF-1 and TTF-1R thermostatic air vents are frequently utilized in conjunction with the AE-2 Separator.

Materials of Construction (AE-2 Assembly):

• Body Shell: ASTM A240 T304L
• Baffle Plate: ASTM A240 T304
• Connections: ASTM A479 T304 (3/4" NPT / DN20)
• Gasket: Copper Clad Non-Asbestos
• Thermostatic Air Vent: Stainless Steel and Bronze with phosphor-bronze bellows, entire unit caged in stainless steel

Dimensions and Weight (3/4" NPT Connections):

Dimension	With TTF-1R	With TTF-1
Body Diameter (A)	2.75" [69.8 mm]	2.75" [69.8 mm]
Overall Height (B)	11.78" [299.2 mm]	13.28" [337.4 mm]
Centerline to Outlet (C)	2.55" [64.8 mm]	N/A
Weight	2.50 lbs [1.1 kg]	2.50 lbs [1.1 kg]