Inverted Bucket Steam Trap – Models 401-SH & 501-SH

Inverted Bucket Steam Trap – Models 401-SH & 501-SH

Product Specifications

Model 401-SH 501-SH
Capacities To 770 lb/hr
(349 kg/hr)
950 lb/hr
(432 kg/hr)
Maximum Allowable Pressure 1,000 psig
(69 bar)
1540 psig
(105 bar)
Maximum Allowable Temperature 800°F
Body Material Carbon Steel
Stainless Steel
Maximum Operating Pressure 1000 psig
(69 bar)
1540 psig
(105 bar)
Connection Type Screwed,
Connection Size 1/2″ (15 mm)
3/4″ (20 mm)
1/2″ (15 mm)
3/4″ (20 mm)
Flow Direction Vertical Vertical

Inverted Bucket Steam Trap – Models 401-SH & 501-SH

Models 401-SH and 501-SH in carbon steel or stainless steel for vertical installation are made for overcoming the difficult combination of superheat and high pressure/low load service.

To survive this most severe steam service, Armstrong created an inverted bucket trap with a unique accumulation chamber. The chamber collects sufficient condensate to ensure full discharge cycles. A cup in the chamber floats up and down on the steam inlet tube, sealing it off as the condensate level rises.

At the same time as the chamber collects condensate, steam continues to flow under the bucket, making sure that the discharge valve closes tightly until the condensate rises into the trap body and the bucket falls down. The operation is on/off, no throttling or dribbling. In addition, you get all the familiar benefits of an inverted bucket steam trap.

  • Reliability. High resistance to wear, corrosion and water hammer with no gaskets.
  • Operation against back pressure. A unique leverage system multiplies the force provided by the bucket, to open the valve against system pressure.
  • Freedom from dirt problems. The mechanism is located at the top. No dirt can collect on the orifice. Small particles of dirt will be held in suspension until discharged by the full differential purging action.
  • Zero steam loss. The discharge orifice is surrounded by a water seal, which prevents live steam loss. Automatic air venting is provided by a small hole in the bucket.
  • Trouble-free operation. Inverted bucket traps require no adjustment. They do not allow condensate backup and are resistant to water hammer.


  • CE
  • CRN
  • EIL
  • IBR
  • NIBR