The Armstrong A3 Cast Iron Float and Thermostatic Steam Trap is part of the B & BI Series, combining high performance and long service life with economy for heating applications. Built with an ASTM A48 Class 30 cast iron body rated to 125 psig at 353°F (8.5 barg at 178°C), the A3 provides continuous condensate drainage with high air-venting capacity — essential for efficient heating system operation.
The thermostatic air vent element is charged to provide compensated response to the pressure-temperature curve of steam at any pressure from less than 20″ (500 mm) Hg vacuum to 30 psig (2 bar). This makes the A3 particularly well-suited for vacuum return heating systems where continuous drainage and rapid air venting are required for system efficiency.
Key Features
- Continuous condensate drainage — no condensate backup
- High air-venting capacity via thermostatic element
- ASTM A48 Class 30 cast iron body
- Maximum operating pressure of 30 psig (2 bar)
- Capacity up to 1,410 lb/hr (640 kg/hr)
- Operates from vacuum to 30 psig
- Horizontal flow direction
Applications
Ideal for heating service including radiators, unit heaters, heat exchangers, and other HVAC equipment where continuous condensate drainage with high air-venting capacity is required. The vacuum-capable design makes it well-suited for systems with vacuum return lines. Available with screwed connections in 3/4″ (20 mm) size.
