In the design and maintenance of medium-to-low temperature commercial refrigeration systems—such as walk-in blast freezers and cold chain logistics warehouses—R404A and R507 refrigerants are widely utilized due to their excellent low-temperature thermodynamic properties. However, as the evaporating temperature approaches -40℃, the pressure drop within the system increases and the vapor density thins. Traditional expansion valves often suffer from a "pressure-flow" mismatch, leading to severe superheat fluctuations (hunting) in the evaporator. This instability not only reduces heat transfer efficiency but also directly threatens the operational lifespan of the compressor.

Under extreme low-pressure operating conditions down to -40℃, systems charged with R404A or R507 demand exceptionally high sensitivity from the throttling mechanism. On one hand, lower evaporating pressures narrow the pressure differential (∆P) across the valve port, making conventional valves prone to insufficient refrigerant supply or transient overshooting. On the other hand, the pressure change rate of the charge medium inside the thermostatic bulb slows down at extremely low temperatures. If the internal mechanical friction or spring stiffness of the expansion valve is not optimized for these specific conditions, the valve needle action lags, failing to maintain a constant superheat relative to transient thermal loads.

To establish a stable equilibrium across a wide temperature range from -40℃ to +10℃, the TS2 (internal equalization) and TES2 (external equalization) series thermostatic expansion valves provided by Ningbo Brando Hardware Co., Ltd. address this industry pain point through precise, parameterized component design.

Dedicated Charge for Multi-Refrigerants: The TS2/TES2 series features a non-linear correction of the thermostatic bulb charge curve specifically for fluorinated refrigerants like R404A/R507, ensuring that the pressure response of the valve at low temperature zones aligns closely with the refrigerant's saturation pressure curve.

Interchangeable Orifice Assembly: Breaking the limitations of fixed-capacity valves, this series offers 8 finely graded orifice assemblies ranging from No. 0X to No. 6. For an R404A/R507 system, the rated capacity spans from 0.38 kW (Orifice 0X) to 9.1 kW (Orifice 6). This high-density capacity grading allows designers to achieve a near-perfect "capacity-to-load" match, avoiding frequent valve cycling caused by over-sizing.

In large-scale low-temperature cold rooms, evaporators feature long coil circuits, making the internal pressure drop non-negligible as the refrigerant flows through. If an internally equalized valve (TS2) is used, the pressure sensed underneath the valve diaphragm is the valve outlet pressure rather than the evaporator outlet pressure. This causes a miscalculation of the actual forces on the diaphragm, forcing the valve to close and resulting in insufficient liquid supply.

By implementing the TES2 valve equipped with a standard 1/4'' (6mm) external equalization connection, the system directly captures the actual pressure at the evaporator outlet. This configuration eliminates the negative interference of the evaporator's internal pressure drop on superheat control. Combined with the standard 1.5m highly flexible capillary tube, it ensures mechanical vibration resistance while achieving stable throttling flow control under extreme low temperatures down to -40℃, maintaining a constant cold room temperature.