Which devices are recommended for actual field testing to measure the exact pressure drop?

• A. Pitot tubes and flow meters
• B. Thermometers
• C. Anemometers
• D. Hydrometers

Answer: (A)

Measuring exact pressure drop in field tests relies on data about how much water is moving and the pressures in the flowing stream. A Pitot tube provides velocity pressure, which, when used with the appropriate static pressure reading, helps determine the flow velocity in the line. A flow meter gives a direct measure of the actual flow rate. Together, these tools let you relate the observed flow to the pressures acting in the system, so you can calculate the exact pressure loss across a hose, fitting, or valve under real operating conditions.

The other instruments don’t directly provide the needed information for pressure drop: thermometers measure temperature, anemometers measure air speed rather than liquid flow, and hydrometers measure liquid density. They don’t yield the data necessary to determine pressure differences in a firefighting hydraulic setup.