Inverted Bucket Steam Trap - Models 411G & 421 | Armstrong | Americas

Inverted Bucket Steam Trap – Models 411G & 421

Inverted Bucket Steam Trap – Models 411G & 421

Product Specifications

Model 411G 421
Capacities 1300 lb/hr (590 kg/hr) 1300 lb/hr (590 kg/hr)
Maximum Allowable Pressure 1000 psig (69 bar) 1000 psig (69 bar)
Maximum Allowable Temperature 700°F (371°C) 700°F (371°C)
Body Material ASTM A105 Forged Steel ASTM A105 Forged Steel
Maximum Operating Pressure 1000 psig (69 bar) 1000 psig (69 bar)
Connection Type Screwed, Socketweld, Flanged Screwed, Socketweld, Flanged
Connection Size 1/2″ (15 mm), 3/4″ (20 mm) 1/2″ (15 mm), 3/4″ (20 mm)
Flow Direction Vertical Horizontal

Inverted Bucket Steam Trap – Models 411G & 421

Models 411G and 421 in forged chrome-moly steel inverted bucket traps for vertical installation with a choice of screwed, socket weld or flanged connections.

The Model 411G is for vertical installation, and offers smaller capacities at higher pressures. The Model 421 adds the convenience and savings of inline repairability, and is designed to meet today’s energy-management requirements efficiently and economically over a long, trouble -free service life.

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, which prevents live steam loss. Automatic air venting is provided by a small vent hole in the bucket.

Inverted bucket traps drain continuously, although discharging intermittently, allowing no condensate backup. They are also resistant to water hammer.


  • IBR
  • NIBR
  • PED