Armstrong International D503157 Air and Gas Vent

The Armstrong International D503157 Air and Gas Vent is a high-performance Series 21AR Cast Iron Fixed Pivot Ball Float designed for the efficient removal of air and gases from pressurized liquid systems. Engineered with a 1/2" NPT connection and a precision 5/64" orifice, this unit is built to manage a maximum operating pressure of 133 PSI. It is technically identical to the 21-AR-1/2-133 model, providing a robust solution for preventing air binding in HVAC systems, hydronic heating, and compressed air applications. The cast iron construction ensures long-term industrial durability, while the free-floating lever mechanism facilitates a positive shut-off that prevents liquid loss. By maintaining optimal airflow management, the D503157 improves system efficiency and protects equipment from the corrosive effects of trapped oxygen and the performance-dampening impact of gas pockets.

• Enhanced System Efficiency: Automatically purges air to prevent air binding and ensure smooth liquid circulation.
• Pressure Resilience: Specifically rated for 133 PSI differential pressure, making it ideal for high-static environments.
• Durable Cast Iron Housing: Provides superior strength and resistance to mechanical stress in industrial settings.
• Versatile Compatibility: Standard 1/2" NPT inlet and outlet connections allow for easy integration into existing piping.
• Reliable Float Mechanism: The fixed pivot ball float ensures consistent operation without the risk of the linkage sticking.

How do I know if my air vent is clogged?
If your system experiences reduced flow or if the vent fails to discharge air, the 5/64" orifice may be blocked by debris. Periodic inspection of the internal mechanism and flushing the unit can restore proper function.

Can the D503157 be used on steam lines?
No, the Armstrong Series 21AR is specifically designed for air and gas venting from liquid systems. For steam service, an inverted bucket or thermostatic air vent is required.

What happens if system pressure exceeds 133 PSI?
Exceeding the rated 133 PSI differential pressure may cause the vent to lock in the closed position, as the internal float buoyancy cannot overcome the high pressure acting on the valve seat.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.

This item is not eligible for free shipping.