Cold Storage Expansion Valves: Main Types

Cold storage expansion valves are primarily classified by degree of automation and operating principle. The most commonly used are thermostatic expansion valves and electronic expansion valves.

Common Types of Cold Storage Expansion Valves

Thermostatic Expansion Valve (TXV) — Most Common
It uses a sensing bulb to detect the superheat at the evaporator outlet and automatically adjusts the opening. It is a purely mechanical device requiring no electrical power. It is further divided into:

• Internally Equalized: Senses the evaporator inlet pressure through an internal passage. Suitable for small cold rooms with short piping and low pressure drop.

• Externally Equalized: Senses the evaporator outlet pressure via an external equalizer line. Suitable for long coil runs, multiple parallel circuits, or systems with high pressure drop, preventing insufficient liquid feed caused by resistance.

Electronic Expansion Valve (EEV) — Smart/Intelligent Type
Driven by a stepper motor and precisely controlled by a microprocessor. It offers a wide调节 range and extremely fast response. Ideal for high-precision temperature control or variable-frequency cold storage systems.

Manual Expansion Valve — Commissioning/Standby
Controlled entirely by manually turning the valve stem. Simple in structure. Rarely used as the main throttling device; mostly found in ammonia systems, experimental setups, or bypass/standby applications.

Float Expansion Valve — For Flooded Systems Only
Controls liquid level by buoyancy. Used only for flooded evaporators with a free liquid surface or intercoolers; it cannot be used for dry-expansion evaporators.

Selection Guide

In cold storage design, if it is a typical small-to-medium Freon system with stable operating conditions, a thermostatic expansion valve is the most cost-effective choice. If precise temperature control is required or the system load varies significantly, an electronic expansion valve should be considered.