Which instrument is last in the options for measuring low-pressure regulator outlet pressure?

• A. Digital Manometer
• B. Bourdon Gauge
• C. Pressure Gauge
• D. Water Manometer

Answer: (D)

Measuring very small regulator outlet pressures benefits from tools that are both sensitive and practical to use in the field. A water manometer excels in accuracy at ultra-low pressures because the pressure is directly balanced by a column of water; the height difference translates straight into pressure with little need for complex calibration. But its practicality in real-world testing is limited: you need a stable setup, a sealed manometer with water, careful leveling, and it can be bulky or slow to read, making it less convenient for quick field checks. In contrast, a digital manometer gives a clear numeric readout and is portable, a Bourdon gauge is rugged and quick for low to moderate pressures, and a standard pressure gauge is familiar and straightforward to use, though it may not offer the finest resolution for very low pressures. Because of these practicality factors, the water manometer is the least preferred option in typical field testing, placing it last among the choices.