Gas Fitter Practice Test

Which instrument is used to check the pressure drop across an indoor coil?

1. A velometer

2. An inclined manometer

3. An anemometer

4. A psychrometer

The correct answer is: An inclined manometer

The inclined manometer is the correct instrument for checking the pressure drop across an indoor coil. It is designed to measure the pressure in a system by providing precise readings in a visual format, typically using a glass tube filled with liquid. When connected to the system at two points, it can indicate the difference in pressure, which is essential for determining the efficiency of the coil in a heating or cooling circuit. In contrast, while other instruments may measure different parameters, they are not suited for pressure drop measurement. A velometer is primarily used to measure the velocity of air flow, which does not provide the specifics needed for pressure drop analysis. An anemometer is also focused on measuring air speed, making it irrelevant for assessing pressure differentials. Lastly, a psychrometer measures humidity and temperature, which does not correlate with pressure readings. Each of these tools serves its specific purpose, but for pressure drop evaluations, the inclined manometer is the appropriate choice.