PTS staging valves for chillers and heat pumps
11th December 2025
DENMARK: New from Danfoss are the PTS staging valves, which are designed to improve the performance and reliability of both oil and oil-free centrifugal chillers and heat pumps.
Part of the Danfoss Extended Oil-Free programme, these valves are said to offer extremely fast operation – within just five seconds – to prevent compressor surge and ensure stable system performance during both startup and shutdown.
The PTS valves are specially designed to prevent compressor surge, a common issue in centrifugal compressors caused by low pressure during startup. By reacting quickly to surge conditions, the PTS valves stabilise compressor pressure, reducing the risk of damage and extending system life. According to Danfoss, they could also function as load-balancing valves.
During startup, the PTS valves open rapidly within five seconds, connecting discharge to suction via the evaporator to build pressure before the discharge check valve opens. This prevents gas recirculation, protects the compressor from internal shock, and results in faster startup times and more efficient system performance.
At shutdown, the PTS valves quickly release pressure to protect compressor bearings and other components, helping to avoid shaft-bearing contact. During normal shutdown, the staging valve opens and the compressor speed slows down, ensuring smooth operation.
In the event of a fault or power loss, the discharge valve closes and the fast opening of the staging valve releases compressor pressure.
Suitable for all common refrigerants, including A2L, enhancing versatility, the valves are available in multiple sizes with KV values ranging from 18 to 38 to suit a range of system capacities.
They are compatible with Danfoss stepper valve drivers, including EKF, EKE 100, and Alsmart unit controllers, while being specifically optimised for use with Danfoss TGx and TTx Turbocor compressors.
