Schneider Electric (Barber Colman) AT-529 Restrictor Kit

The Schneider Electric (Barber Colman) AT-529 Restrictor Kit is a critical component for maintaining the operational integrity of all bleed bulb type pneumatic thermostats. This kit is specifically engineered for full compatibility with Barber Colman TK-2000, TK-3000, and TK-4000 series pneumatic room controllers. In a pneumatic control loop, the restrictor serves as the fixed orifice required to create the pressure drop necessary for the branch line signal. Without a precision-calibrated pneumatic restrictor, bleed-type stats cannot accurately modulate the branch pressure, leading to erratic damper or valve positioning. This HVAC restrictor kit ensures that the air supply to the sensing element is maintained at a consistent flow rate, which is paramount for high-accuracy temperature regulation in commercial facilities. As a veteran-grade replacement HVAC part, the AT-529 allows for the restoration of factory-spec air bleed rates, eliminating common calibration drift issues caused by oil-clogged or debris-narrowed original orifices.

• Universal Compatibility: Seamlessly integrates with Schneider Electric pneumatic controls, including the legacy Barber Colman TK-2, TK-3, and TK-4 lines.
• Precision Air Regulation: Restores factory-calibrated bleed rates to ensure linear signal response across the entire branch pressure range.
• Enhanced System Reliability: Replacing fouled restrictors prevents hunting and stabilizes the control loop, reducing wear on downstream actuators.
• Durable Construction: Designed to withstand the continuous pressure fluctuations inherent in industrial HVAC control systems.

If the supply pressure is correct but the branch pressure stays pegged or doesn't move, a clogged or missing AT-529 restrictor is often the culprit. Proper bleed-type operation requires this fixed restriction to create the signal differential.

This kit is specifically optimized for all bleed bulb types. Utilizing it on non-compatible non-bleed systems may result in improper pressure regulation and is not recommended for master/sub-master setups unless specified.

In systems without high-efficiency air drying and filtration, these small orifices can accumulate oil aerosol and moisture. We recommend checking restrictor flow during every seasonal calibration cycle to ensure peak performance.

This item is not eligible for free shipping.

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.