PSIG Vs PSI: What Is the Difference

In this blog post, you’ll read:PSI, standing for Pounds per Square Inch, measures force over an area. PSIG, or Pounds per Square Inch Gauge, specifically measures pressure against atmospheric pressure, not including the atmosphere's pressure in its measurement. This distinction matters in fields like valve manufacturing, HVAC, and tire pressure, where knowing pressure relative to atmospheric conditions is key. Recognizing how PSI and PSIG differ enables professionals to accurately assess pressure, enhancing safety and efficiency in industrial operations and daily tasks.
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Many individuals become confused when comparing PSIG vs PSI because of the similar sounds of these two units. PSI and PSIG are both pressure measurement units but are not identical. PSI is a pressure unit defined as the force applied to a given area, meaning pounds per square inch. Because it is a gauge pressure, its psi measurement is about the pressure in the atmosphere.

PSIG is a unit of pressure called pounds per square inch gauge. It measures the force applied per unit area in the atmosphere. These devices have numerous distinctions, and users must take care when measuring pressure. This post will now evaluate the difference between PSI and PSIG.

What Is PSI?

Pressure gauge
Pressure gauge

Pressure results from the force applied to an object pressing against a specific area. PSI is a standard unit for measuring and expressing pressure in the US.

The PSI, which means Pound per Square Inch, is not the SI unit of pressure. Pascal is the SI unit for pressure. It is the pressure exerted on a 1 square meter area in response to a 1 Newton force. PSI refers to pounds of force per square inch of surface area.

In industrial settings, the PSI is a standard unit of pressure measurement. PSI is the pressure measurement unit on instruments such as gauges and sensors.

1 PSI is equal to:

  • 76 Pascals
  • 0689476 Bar
  • 068046 atmospheres

The standard pressure unit for industrial valves and pressure measurement is PSI. Measure the pressure of the fluid contained within a conduit or valve. PSI will represent the pressure generated by one pound of fluid force per square inch of tubing.

PSI and PSIG are often confused and applied incorrectly. Comparing PSIG versus psi is straightforward once you clarify the definition of PSIG.

Where is PSI Used?

PSI used
PSI used

Primary PSI applications include measuring hydraulic and pneumatic pressure. However, people also use it in other applications. Water management systems and fire safety valves are applications for this unit.

It serves technical objectives and measures in various environments. It is used for managing effluent, measuring and testing tire pressure, and managing. Also, this unit finds application in the valve manufacturing sector.

What is PSIG?

PSIG means PSI gauge pressure, which is the measured number of relative pressure. Compare the gauge pressure, measured in pounds per square inch gauge, to the pressure at sea level or in the atmosphere. The PSIG calculation excludes the inclusion of atmospheric pressure.

PSIG is the differential between a pipe’s internal and atmospheric pressure. Quantify it using a gauge or an analogous device. We measure PSIG when the pressure within a pipe or valve exceeds that of the atmosphere.

The PSIG unit exclusively gauges pressure, one of the most critical aspects to remember. The term “gauge pressure” denotes the process of quantifying pressure in the atmosphere. PSI units are used to quantify PSIG.

Furthermore, one may represent PSIG as Absolute PSIA or PSIA. Besides atmospheric pressure, absolute or total pressure refers to the pressure measurement in PSI. Constantly, PSIG is less than absolute pressure.

PSIG = PSIA – 1 atm (atm = atmospheric pressure)

Comparing PSI vs PSIG can be difficult because of the similarity between the two units. However, the distinction between the two becomes clear in valuable implementations. Understanding the similarities and differences between pressure measurement instruments in different units helps explain how they function.

PSIG gauge
PSIG gauge

Where is PSIG used?

The transport and industrial valve sectors use PSIG the most frequently. This unit helps measure tire and valve pressure, coolant pressure, etc. An exhausted tire has a 14.7 PSIA by the principle of internal pressure with atmospheric pressure psig

Additionally, this unit records pressure in HVAC and refrigeration systems. People disregard local pressure factors when using gauge pressure in such circumstances.

PSIG applications
PSIG applications

What Is the Difference Between PSI and PSIG: Comparison Chart

When the PSIG vs. PSI debate arises, it is crucial to consider the application-based distinctions between the two units’ standard definitions. There are several significant differences between psig and psi.

Gauge pressure measurement Non-SI units for pressure measurement
Pressure is measured in PSIG to atmospheric pressure. The pressure at which a one-pound force is applied to an object with a one-square-area surface area is denoted in PSI.
PSIG is measured in terms of PSI. PSI itself is a unit
It is frequently utilized in the transportation sector, particularly with tire pressure. It has wide applications in water management, valve and pipeline manufacturing, and fire safety valve industries.
PSIG is relative pressure, so it is measured in Pascal and PSI units. You can change PSI into different units like Bar and Pascal.

PSIG Vs. PSI and Valves

Body pressure and close-off pressure are the two primary categories of pressure ratings for valves. The body pressure Rating denotes the maximum achievable pressure on a valve’s main body and stems before leakage occurs. The close-off pressure indicates the maximum pressure that a disc or disk can maintain, depending on the type of valve.

These ratings are both expressed in PSI. A typical rating for industrial valves is WOG (water, oil, gas). A valve with a 500 WOG rating can handle a body pressure of 500 PSI.

ISO and ASME establish the pressure ratings for industrial valves. ASME standard B16.34 specifies the ideal pressure and temperature specifications for valves constructed from various materials.

PSIG Vs. PSI: Conclusion

Knowing the difference between PSIG and PSI and how they measure pressure is essential in valve manufacturing and other industries. Knowing the difference between psi and psig is vital to understanding industrial valve pressure ratings. Residential valve manufacturers must ensure their products conform to valve ratings and standards.

If you are searching for a manufacturer of high-quality valves, Plumberstar is your best choice. Plumberstar has an extensive 23-year tenure in the industry and focuses on producing various industrial valves. Additionally, we provide customization services to all our customers. Contact us immediately to have custom valves manufactured and designed by us.

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