A mechanical pressure control is primarily controlled by what component?

A mechanical pressure control is primarily controlled by a pressure bellows. The pressure bellows is a device designed to respond to changes in pressure by expanding or contracting. This operation allows it to mechanically actuate other components within the pressure control system, such as switches or valves, to regulate pressure levels effectively.

The pressure bellows works on the principle of a flexible, sealed chamber that changes volume based on the pressure of the surrounding environment. When pressure increases, the bellows expands, which can then trigger a switch to turn equipment on or off, or adjust the position of a valve to maintain the desired system pressure.

While the other components listed are important in monitoring and controlling pressure in HVAC systems, they serve different functions. A pressure switch is used to make or break electrical circuits based on preset pressure thresholds but is ultimately actuated by the movement of components like bellows or diaphragms. A pressure gauge measures the pressure but does not control it; it simply provides readouts for the technician. A thermocouple, designed to measure temperature, operates independently of pressure measurement and control. Thus, the pressure bellows is specifically designed for mechanical pressure control applications, making it the most suitable choice in this context.