PSIG vs PSI: A Clear – Cut Guide to Their Differences

In diverse industries, an array of pressure units are employed for measurements. A multifaceted scale proves invaluable in detecting even the most minuscule variations, and this is a key rationale behind the utilization of different units for pressure measurement. One realm where pressure measurement is ubiquitous is in pipeline systems. When dealing with pipelines and valves, pressure is an ever – present factor that demands a comprehensive understanding.

In the piping and related sectors, PSI, PSIG, and PSIA are among the most commonly used units. PSI stands for Pounds per Square Inch, PSIG for Pounds per Square Inch Gauge, and PSIA for PSI Absolute. Many individuals find themselves perplexed when considering the distinction between PSIG and PSI, as these two units share a similar nomenclature. However, it’s important to note that they are far from identical. Substantial differences exist between them, and meticulous care must be exercised when using these units for pressure measurement. tianyu valves

What is PSI?

PSI is a cornerstone unit in industrial pressure measurement. Instruments such as pressure gauges and sensors typically present pressure values in terms of PSI.

 

Here are the equivalences of 1 PSI:

0.068046 atmospheres

0.0689476 Bar

6894.76 Pascals

In the context of industrial valves and pressure measurement within pipelines, PSI serves as the standard unit. Specifically, it represents the pressure generated by a one – pound force of fluid acting on each square inch of the pipe’s interior surface.

PSI and PSIG are frequently confused and misused. However, once the meaning of PSIG is clearly grasped, the distinction between the two becomes much more apparent.

Where is it Used?

PSI finds extensive application across a broad spectrum of fields. It is predominantly used for measuring pneumatic and hydraulic pressures. Additionally, it plays a crucial role in water management systems, fire safety valving, and pipelining. This versatile unit is also employed in technical applications such as tire pressure measurement, testing and management operations, and wastewater management. Moreover, it is an essential unit within the valve manufacturing industry.

What is PSIG?

PSIG, or PSI gauge pressure, represents a relative pressure value. Gauge pressure, expressed in pounds per square inch gauge, is measured relative to ambient or atmospheric pressure. When calculating PSIG, the local atmospheric pressure is not factored into the value.

In simple terms, PSIG can be thought of as the pressure differential between the pressure inside a pipe and the atmospheric pressure outside. It is measured using gauges or similar instruments and is typically used when the pressure within a valve or pipeline exceeds atmospheric pressure.

One of the key characteristics of PSIG is that it measures solely gauge pressure. Generally speaking, gauge pressure refers to pressure measurements relative to atmospheric pressure, and PSIG is expressed in PSI units.

PSIG can also be related to PSIA (Absolute PSIA). Absolute pressure, or total pressure, encompasses the PSI value along with the atmospheric pressure. It’s important to note that PSIG is always lower than absolute pressure, and the relationship between them can be expressed as:

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

Comparing PSI and PSIG can be a source of confusion due to their superficial similarities. However, in practical applications, the differences between them become more evident. Without a clear understanding of these similarities and differences, it can be challenging to comprehend how instruments that use these units function.

Where is it Used?

PSIG is most commonly utilized in the transport and industrial valve industries. Its convenience makes it the unit of choice for measuring tire pressure, valve pressure, coolant pressure, and more. Since PSIG represents the internal pressure relative to the external atmospheric pressure, an emptied tire would have a PSIG value of -14.7 PSI.

This measurement is also widely used in HVAC and refrigeration systems. Given that gauge pressure often disregards local pressure variations, it is well – suited for these applications.

What is PSIG vs PSI – The Differences and their Meanings

When the topic of PSIG versus PSI arises, it is essential to consider their standard definitions and how they differ in practical applications. Here are the key distinctions between the two:

PSI	PSIG
A non – SI unit for measuring pressure.	A measure of gauge pressure.
Represents the pressure exerted on an object with a surface area of one square inch by a one – pound force.	Measures pressure relative to atmospheric pressure.
A standalone unit of measurement.	Measured in terms of PSI.
Widely used in the valve and pipeline industry, water management, and fire safety valving.	Commonly applied in the transport industry, especially for tire pressure measurement.
Can be converted into other units like Pascal and Bar.	As a relative pressure, it uses units such as PSI and Pascal for measurement.
Measured relative to a vacuum.	Measured relative to atmospheric pressure.

PSIG vs PSI and Valves

Valves have two primary types of pressure ratings: body pressure ratings and close – off pressure. The body pressure rating indicates the maximum pressure that a valve’s main body and stem can endure without leakage. The close – off pressure, on the other hand, is the highest pressure that a valve can maintain across its closing element (such as a ball or disc, depending on the valve type).

Both of these ratings are typically measured in PSI. For instance, WOG (water, oil, gas) is a common rating for industrial valves. A rating of 500 WOG indicates that the valve can withstand a body pressure of 500 PSI.

The pressure ratings of industrial valves are governed by various standards, including ISO and ASME. The ASME standard B16.34, for example, defines the pressure and temperature ratings appropriate for valves made from different materials.

Unveiling the Distinctions: PSIG vs PSI and Their Crucial Role in Valve Manufacturing

Whether in the valve manufacturing industry or any other sector, a clear understanding of the distinction between PSIG and PSI, as well as their roles in pressure measurement, is of utmost importance. By grasping the fundamental differences between these two units, one can gain deeper insights into how pressure ratings are applied to industrial valves. Industrial valve manufacturers must ensure that their products comply with established valve ratings and standards.

If you’re in search of a reliable and high – quality valve manufacturer, look no further than TianYu. With over a decade of experience in the field, TianYu specializes in manufacturing a wide range of industrial valves. We also offer customized solutions tailored to each client’s specific needs. Contact us today to have your custom valves designed and produced by our expert team.