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  4. Inverted Bucket Steam Traps

Inverted Bucket Steam Traps

Armstrong inverted bucket steam traps are the most reliable steam trap design available, providing efficient condensate drainage for virtually all types of steam equipment. With a free-floating stainless steel mechanism, continuous air venting at steam temperature, and proven resistance to water hammer, these traps deliver long service life and solid energy savings.

Learn more about Armstrong inverted bucket steam traps

How It Works

A unique leverage system multiplies the force provided by the bucket to open the valve against system pressure. The mechanism is free-floating with 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 are held in suspension until discharged by 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. A small vent hole in the bucket provides continuous automatic air and CO₂ venting at steam temperature. Inverted bucket traps drain continuously while discharging intermittently, allowing no condensate backup. All Armstrong cast iron inverted bucket steam traps are field-repairable for even bigger maintenance savings.

Armstrong Series Overview

SeriesBody MaterialInstallation Max PressureMax CapacityConnections
200ASTM A48 Cast IronVertical250 psig20,000 lb/hrScrewed ½″–2″
800ASTM A48 Cast IronHorizontal250 psig20,000 lb/hrScrewed NPT ½″–2½″
880ASTM A48 Cast IronHorizontal + Integral Strainer250 psig4,400 lb/hrScrewed NPT ½″–1¼″
300ASTM A105 Forged SteelVertical650 psig20,000 lb/hrScrewed, SW, Flanged ½″–2″
400Forged Chrome-Moly SteelVertical1,000 psig20,000 lb/hrScrewed, SW, Flanged
521ASTM A105 Forged SteelHorizontal650 psig20,000 lb/hrScrewed, SW, Flanged
1000ASTM A240 304L Stainless SteelVertical650 psig4,400 lb/hrScrewed NPT ½″–1″
1800ASTM A240 304L Stainless SteelHorizontal650 psig1,802 lb/hrScrewed NPT ½″–¾″
2000ASTM A240 304L Stainless Steel360° Connector650 psig1,300 lb/hrScrewed NPT ½″–¾″
5000Forged Chrome-Moly SteelVertical1,800 psig5,150 lb/hrSW, Flanged
6000Forged Chrome-Moly SteelVertical2,700 psig6,500 lb/hrSW, Flanged

Technical Resources

Educational Guides

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[D501855] 811 Cast Iron Inverted Bucket Steam Trap (1/2″ (15 mm), 15, 1/4")

811 Cast Iron Inverted Bucket Steam Trap

$ 263.22 $ 321.00
812 Cast Iron Inverted Bucket Steam Trap (1/2″ (15 mm), 15, 1/4")

812 Cast Iron Inverted Bucket Steam Trap

$ 500.00
883 Cast Iron Inverted Bucket Steam Trap (3/4″ (20 mm), 15, 1/4")

883 Cast Iron Inverted Bucket Steam Trap

$ 811.80
882 Cast Iron Inverted Bucket Steam Trap (1/2″ (15 mm), 15, 1/4")

882 Cast Iron Inverted Bucket Steam Trap

$ 505.12
[D501381] 881 Cast Iron Inverted Bucket Steam Trap (1/2″ (15 mm), 15, 1/4")

881 Cast Iron Inverted Bucket Steam Trap

$ 293.56
[C5297-67] 880 Cast Iron Inverted Bucket Steam Trap (1/2″ (15 mm), 20, 3/16")

880 Cast Iron Inverted Bucket Steam Trap

$ 227.14
[D500456] 816 Cast Iron Inverted Bucket Steam Trap (Screwed NPT, 2″ (50 mm), 15, 1-1/16")

816 Cast Iron Inverted Bucket Steam Trap

$ 2,899.52
815 Cast Iron Inverted Bucket Steam Trap (3/4″ (20 mm), 15, 1/4", ASTM A48 Class 30 Cast Iron)

815 Cast Iron Inverted Bucket Steam Trap

$ 1,351.36
814 Cast Iron Inverted Bucket Steam Trap (1″ (25 mm), 15, 1/4")

814 Cast Iron Inverted Bucket Steam Trap

$ 1,071.74
813 Cast Iron Inverted Bucket Steam Trap (3/4″ (20 mm), 15, 1/4")

813 Cast Iron Inverted Bucket Steam Trap

$ 708.48
[C5297-1] 800 Cast Iron Inverted Bucket Steam Trap (1/2″ (15 mm), 20, 3/16")

800 Cast Iron Inverted Bucket Steam Trap

$ 198.44
[D501330] 216 Cast Iron Inverted Bucket Steam Trap (1-1/2″ (40 mm), 15, 1/16")

216 Cast Iron Inverted Bucket Steam Trap

$ 1,907.32
215 Cast Iron Inverted Bucket Steam Trap (3/4″ (20 mm), 15, 1/4")

215 Cast Iron Inverted Bucket Steam Trap

$ 1,344.80
214 Cast Iron Inverted Bucket Steam Trap (1″ (25 mm), 15, 1/4")

214 Cast Iron Inverted Bucket Steam Trap

$ 1,103.72
213 Cast Iron Inverted Bucket Steam Trap (1/2″ (15 mm), 15, 1/4")

213 Cast Iron Inverted Bucket Steam Trap

$ 726.52
212 Cast Iron Inverted Bucket Steam Trap (1/2″ (15 mm), 15, 1/4")

212 Cast Iron Inverted Bucket Steam Trap

$ 433.78
[D503385] 211 Cast Iron Inverted Bucket Steam Trap (15, 1/4")

211 Cast Iron Inverted Bucket Steam Trap

$ 293.56
973 Steel Inverted Bucket Steam Trap (Screwed NPT, 1/2″ (15 mm), 15, 1/4")

973 Steel Inverted Bucket Steam Trap

$ 4,961.82
971 Steel Inverted Bucket Steam Trap

971 Steel Inverted Bucket Steam Trap

$ 2,717.48
521 Steel Inverted Bucket Steam Trap (Screwed NPT, 1/2″ (15 mm), 200, #38)

521 Steel Inverted Bucket Steam Trap

$ 3,193.08