What device is used to monitor the pressure in a refrigerant system?

The manifold gauge is the correct choice for monitoring the pressure in a refrigerant system because it is specifically designed to measure both the high and low pressure sides of the refrigeration system. This tool consists of two pressure gauges connected to hoses that can be attached to the service ports of the system, allowing for accurate readings of the refrigerant pressure.

Monitoring these pressures is crucial for assessing the overall health and efficiency of the system, diagnosing issues, and ensuring proper charging of refrigerant. The manifold gauge provides technicians with vital information about how well the refrigeration cycle is functioning and can indicate problems like blockages, low refrigerant levels, or issues with the compressor.

In contrast, the other devices mentioned serve different purposes. A thermostat controls the temperature in a system but does not measure refrigerant pressure. A compressometer is used to measure compression ratios in engines, not in refrigerant systems. A flow meter measures the flow rate of liquids or gases in pipes but does not provide information about pressure. Hence, the manifold gauge is uniquely suited for monitoring pressures in refrigerant systems.