Which device measures pressure differences?

Which device measures pressure differences?

• A. MPS
• B. Megnehelic gauge
• C. kPa
• D. NFPA 211

Answer: (B)

Measuring pressure differences needs a tool that compares two pressures and shows the difference. A Megnehelic gauge is a differential pressure device: it has two ports connected to the areas you want to compare, and the pressure difference causes a diaphragm to deflect. This motion moves a magnet and pointer to display the difference on a scale (often in inches of water). In dryer exhaust work, you use it to see how much pressure drops across a duct section, lint screen, or filter, which helps identify blockages or excessive restrictions. The other options don’t fit. One is a unit of pressure (kPa), not a measuring instrument. Another is a standard code (NFPA 211), not a device. The remaining item isn’t a differential pressure instrument. So the Megnehelic gauge is the correct device for measuring pressure differences.

Measuring pressure differences needs a tool that compares two pressures and shows the difference. A Megnehelic gauge is a differential pressure device: it has two ports connected to the areas you want to compare, and the pressure difference causes a diaphragm to deflect. This motion moves a magnet and pointer to display the difference on a scale (often in inches of water). In dryer exhaust work, you use it to see how much pressure drops across a duct section, lint screen, or filter, which helps identify blockages or excessive restrictions.

The other options don’t fit. One is a unit of pressure (kPa), not a measuring instrument. Another is a standard code (NFPA 211), not a device. The remaining item isn’t a differential pressure instrument. So the Megnehelic gauge is the correct device for measuring pressure differences.