This valve uses a plunger to open and close a fluid passage. Which valve is referred to?

The valve that uses a plunger to open and close a fluid passage is the solenoid valve. This type of valve operates electrically, utilizing a solenoid, which is essentially an electromagnet. When the solenoid is energized, it creates a magnetic field that moves the plunger, directly controlling the flow of fluid through the valve.

Solenoid valves are commonly used in HVAC systems to manage the flow of refrigerants, water, and other fluids due to their quick response time and reliability. They can act as on/off valves and are essential for automatic control in systems, allowing for precise regulation without manual intervention.

In contrast, the other types of valves mentioned have different operational mechanisms. A four-way valve is typically used to control the direction of the flow of a fluid, particularly in refrigeration and heat pump applications, but it doesn’t utilize a plunger for operation. A thermostatic expansion valve regulates refrigerant flow based on temperature but relies on thermal principles rather than a mechanical plunger. A bleed valve is a type of valve used primarily to release trapped air or gas but also does not use a plunger for operation.