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

Series	Body Material	Installation	Max Pressure	Max Capacity	Connections
200	ASTM A48 Cast Iron	Vertical	250 psig	20,000 lb/hr	Screwed ½″–2″
800	ASTM A48 Cast Iron	Horizontal	250 psig	20,000 lb/hr	Screwed NPT ½″–2½″
880	ASTM A48 Cast Iron	Horizontal + Integral Strainer	250 psig	4,400 lb/hr	Screwed NPT ½″–1¼″
300	ASTM A105 Forged Steel	Vertical	650 psig	20,000 lb/hr	Screwed, SW, Flanged ½″–2″
400	Forged Chrome-Moly Steel	Vertical	1,000 psig	20,000 lb/hr	Screwed, SW, Flanged
521	ASTM A105 Forged Steel	Horizontal	650 psig	20,000 lb/hr	Screwed, SW, Flanged
1000	ASTM A240 304L Stainless Steel	Vertical	650 psig	4,400 lb/hr	Screwed NPT ½″–1″
1800	ASTM A240 304L Stainless Steel	Horizontal	650 psig	1,802 lb/hr	Screwed NPT ½″–¾″
2000	ASTM A240 304L Stainless Steel	360° Connector	650 psig	1,300 lb/hr	Screwed NPT ½″–¾″
5000	Forged Chrome-Moly Steel	Vertical	1,800 psig	5,150 lb/hr	SW, Flanged
6000	Forged Chrome-Moly Steel	Vertical	2,700 psig	6,500 lb/hr	SW, Flanged