The Armstrong 411G vertical installation inverted bucket steam trap offers smaller capacities at higher pressures. Designed for continuous drainage to prevent condensate backup, this forged carbon steel trap is highly resistant to water hammer and provides reliable performance in demanding industrial environments. For horizontal installation requirements, the related Model 421 offers similar performance characteristics.

Operating Principles and Features

A unique leverage system multiplies the force provided by the bucket to open the valve against system pressure. The mechanism is free-floating and has no fixed pivots to create wear or friction.

Because the mechanism is located at the top of the trap, no dirt can collect on the orifice. Small particles of dirt are held in suspension until discharged by the full differential purging action when the bucket sinks, pulling the valve off the seat. The discharge orifice is surrounded by a water seal, preventing live steam loss. Automatic air venting is provided by a small vent hole in the bucket.

TIP

Add suffix "CV" to the trap model number (e.g., 411G-CV) to specify an internal stainless steel check valve.

Materials of Construction

Component	Material
Body	ASTM A105 Forged Carbon Steel
Cap	Stainless Steel / ASTM A105
Internals	All Stainless Steel – 304
Valve and Seat	Titanium

Dimensions and Weights

Dimension / Feature	Screwed or SW (411G)	Flanged (411G-FW PN100*)
Pipe Connections	15 – 20 mm (1/2" - 3/4")	15 – 20 mm (1/2" - 3/4")
"A" Flange Diameter	-	160 mm
"B" & "C" Face-to-Face	224 mm	-
"BB" & "CC" Face-to-Face	-	298 – 304 mm
"G" Body Outside Diameter	103 mm	103 mm
"K" Center Outlet to Inlet	19 mm	19 mm
Number of Bolts	8	8
Weight	11.3 kg (25 lb)	14.4 – 15.4 kg (35 lb)

Note: Other flange sizes, ratings, and face-to-face dimensions are available on request. All models comply with Article 4.3 of the PED (2014/68/UE).

Pressure-Temperature Ratings

Maximum Operating Pressure	Max. Allowable Pressure @ -21 / +371°C	Max. Allowable Pressure @ 399°C	Max. Allowable Pressure @ 427°C
69 barg (1000 psig)	69 barg	65.5 barg	58 barg

WARNING

Maximum operating pressure to be marked on the nameplate will be determined by the actual orifice used. Maximum back pressure is 99% of inlet pressure. Traps with flanges may have different pressure-temperature ratings.

Capacity

Maintenance and Mechanism Adjustment

When performing internals maintenance, the mechanism should be adjusted carefully to ensure proper operation.

1. Remove the complete trap from the steam line.
2. Unscrew bolts and nuts and lift the cap.
3. Clean or replace the bucket or mechanism (valve and seat).
4. Adjustment: When correctly aligned, lever (B) can be moved sideways the same distance to the right as to the left. If guide pin (A) is not in the middle of the orifices, adjust by slightly hitting with a hammer.
5. Replace the gasket.
6. Put the cap back on the body and screw bolts and nuts.

DANGER

Equipment under pressure - Operating temperature > 100°C. Make sure the trap is cold and depressurized before handling!

Important Note

The type and material of the bolts must not be changed during reassembly.