Definition

1. Noun:
   • A unit of pressure: "Pounds per square inch" is a measurement unit that quantifies pressure or stress. It expresses the amount of force in pounds (lb) applied over an area of one square inch (in²).

Usage

• As a unit of measurement: "Pounds per square inch" is used in scientific, engineering, and industrial contexts to specify pressure levels. It is often abbreviated as psi.
  • The recommended tire pressure is 32 pounds per square inch.
  • This valve can withstand up to 150 pounds per square inch of pressure.

Advanced Usage

• "pounds per square inch absolute (psia)": Refers to pressure measured relative to a perfect vacuum (absolute zero pressure).

  • The absolute pressure inside the chamber is 14.7 psia at sea level.

• "pounds per square inch gauge (psig)": Refers to pressure measured relative to the ambient atmospheric pressure. Gauge pressure is what most common measuring devices (like tire gauges) display.

  • The compressor output is 100 psig.

Variants and Related Words

• psi: The standard abbreviation for "pounds per square inch."

  • The gas is stored at 2500 psi.

• ksi: An abbreviation for "kilopounds per square inch," equal to 1000 psi. Used for very high pressures, often in materials science.

  • The steel's yield strength is 50 ksi.

Synonyms

• Unit of pressure: A general term for any measurement of force per unit area.
• Pressure unit: A synonym emphasizing its function as a measure.

Related Phrases

• Pounds-force per square inch (lbf/in²): A more precise term that specifies the force is "pounds-force," which is technically correct in scientific contexts to distinguish force from mass.
  • The stress was calculated in pounds-force per square inch.

Noun

1. a unit of pressure