Oil-Free Shut-Off Valve for Turbocor Systems

Danfoss has introduced the OFB range, a tight oil-free shut-off ball valve designed specifically for oil-free chillers and heat pumps equipped with Turbocor^® compressors, addressing refrigerant migration risks and serviceability challenges in high-performance HVAC applications.

Addressing suction-side risks in oil-free systems
Oil-free compressor architectures rely on precise flow conditions and strict control of refrigerant behavior during standstill and start-up. In applications such as data centers and advanced HVAC installations, uncontrolled refrigerant liquid migration on the suction side can compromise compressor protection and system availability.

The OFB valve is intended to function both as a service valve and, when motorized, as an anti-refrigerant migration valve. Installed on the suction side, it provides isolation and migration prevention without introducing measurable pressure losses that could affect compressor efficiency.

Three-in-One functional design
The OFB incorporates a three-in-one configuration combining a smooth suction-cone transition, a tight shut-off isolation ball valve, and full motorization capability. The suction-cone geometry is designed to maintain high inlet flow quality with negligible pressure drop, supporting stable compressor operation.

When equipped with an actuator, the tight shut-off ball valve prevents refrigerant migration during shutdown and start-up phases, while also enabling safe system isolation for service and maintenance.

Compatibility and modularity
The OFB series is designed as a fully modular solution compatible with all Danfoss Turbocor^® TGx and TTx compressors. It is available with 12 inlet flange options in 3”, 4”, and 5” sizes, supporting both new installations and retrofits.

Multiple global connection standards are supported, including ANSI, ASTM, DIN, and EN, allowing integration across different regional system designs. The valve is rated for operating temperatures from –40 °C to +100 °C, covering a wide range of climatic and application conditions.

Actuation and mechanical durability
To complete the assembly, the OFB can be supplied with compact MQT electrical actuators featuring brushless motor technology and a 10-second response time. The valve’s low breakaway torque enables the use of smaller, energy-efficient actuators, reducing mechanical stress on the system.

A reinforced stem sealing system with guide bearings and top-mounted support is designed to prevent misalignment and limit wear under continuous operation. The combined valve–actuator assembly has been endurance-tested for 100,000 cycles, supporting long service life in mission-critical applications.

Context within the EXO program
The OFB valve expands Danfoss’ EXO – Extended Oil-Free portfolio, which focuses on improving reliability and protection in oil-free HVAC systems. By integrating flow optimization, isolation, and motorized control into a single component, the OFB addresses a critical interface point in oil-free compressor systems, particularly where uptime and efficiency are essential.

For system designers and operators, the introduction of OFB reflects a broader trend toward tighter integration and protection of oil-free technologies as their adoption increases in demanding environments such as data centers and high-efficiency commercial buildings.