When it comes to pressure management, PSI is one of the most popular abbreviations. In fact, even people who aren’t part of the technology or transportation industry are familiar with the term.
But if you work in the fleet management industry, PSI is not the only abbreviation you’ll need to know about.
There are other nuances of pressure management in the form of PSIG and PSIA.
In the sections below, we offer an in-depth overview of PSI vs PSIG vs PSIA, explaining what each one means and why it matters.
Here’s everything you need to know.
What is PSI?
Let’s start with the basics.
PSI is perhaps one of the most popular of them all.
It stands for Pounds per Square Inch – a unit of pressure that measures the force exerted on one square inch of surface area referring to gas or liquid.
It’s the most common unit used to measure tire pressure, hydraulic systems, and various other applications in fleet management.
For this article, we’ll use this abbreviation in relation to air in a tire.
However, PSI can be further categorized into PSIG and PSIA, each serving different purposes.
What is PSIG?
Let’s explore the difference between PSI and PSIG.
PSIG stands for Pounds per Square Inch Gauge and can also be referred to as Gauge Pressure.
This measurement is relative to the ambient atmospheric pressure.
Essentially, PSIG is the pressure read on a gauge, which ignores the atmospheric pressure acting on the surface. This is the pressure you typically see when you check your vehicle’s tire pressure with a handheld gauge.
In most cases, the suggested tire pressure for vehicles is generally close to 32 PSIG.
However, external factors like barometric pressure and ambient temperature can influence the apparent inflation of the tires despite the constant number of air molecules inside them.
In many industrial settings, gauge pressure is the standard metric, particularly in engine testing environments. These settings assess oil, fuel line, and coolant pressures on original equipment manufacturer (OEM) prototypes for automobiles, trucks, construction machinery, and aircraft.
Why does all of this matter for your fleet?
Accurate tire pressure readings are essential for safety and fuel efficiency. Underinflated or overinflated tires can lead to increased wear, blowouts, and poor fuel economy.
For vehicles with hydraulic systems, understanding PSIG also helps ensure these systems operate within safe and efficient parameters, preventing leaks and potential system failures.
What is PSIA?
But what about PSIA?
PSIA stands for Pounds per Square Inch Absolute and is often referred to as Absolute Pressure.
Unlike PSIG, PSIA accounts for atmospheric pressure, providing a total pressure measurement. At sea level, atmospheric pressure is approximately 14.7 PSI, so a reading of 0 PSIA would mean a complete vacuum.
For fleets operating in varying altitudes, understanding PSIA is crucial. Atmospheric pressure changes with altitude, and PSIA helps adjust measurements to ensure consistent performance and safety across different regions.
Accurate PSIA readings are also vital for optimizing engine performance, especially for turbocharged or supercharged engines that rely on precise pressure measurements to function efficiently.
Applications of PSI, PSG, and PSIA in fleet management
Now that we’ve laid out the foundations, it’s key to understand how these abbreviations apply to fleet management.
Modern fleet vehicles often come equipped with TPMS, which typically measure PSIG. These systems alert drivers to significant changes in tire pressure, helping to prevent accidents and reduce maintenance costs.
For those utilizing hydraulic lifts, cranes, or other equipment, understanding the difference between PSIG and PSIA ensures these systems are operating safely. Regular monitoring can prevent costly breakdowns and extend the lifespan of the equipment.
Not to mention that advanced diagnostics tools measure PSIA to provide a comprehensive understanding of engine performance. For fleet managers, this means better maintenance scheduling, improved fuel efficiency, and reduced downtime.
PSI, PSG, and PSIA: Which One Should You Use?
As a vehicle fleet manager, understanding and using the correct pressure measurements is essential for maintaining your fleet’s efficiency and safety.
Overall, PSI is the most widely used option of all three in the transportation industry.
At the same time, PSIG measures pressure relative to the ambient atmospheric pressure and is what most tire pressure gauges read. PSIG is, therefore, crucial for tire maintenance and hydraulic systems, ensuring optimal tire pressure and safe hydraulic operation.
On the other hand, PSIA is particularly useful for fleets operating at varying altitudes, as noted above. It’s also valuable for advanced engine diagnostics, especially for turbocharged or supercharged engines requiring precise pressure measurements.
Oftentimes, fleets and heavy-duty repair shops are not as informed about PSIA, with the exception of cases where isolating pressure in a system is essential.
Conclusion
Understanding PSI, PSIG, and PSIA is more than just a technicality.
It’s about optimizing your fleet’s performance and safety.
Incorrect pressure readings can lead to vehicle inefficiencies, increased fuel consumption, and heightened risk of accidents.
By grasping the differences and applications of these pressure measurements, fleet managers can make informed decisions, ensuring their vehicles are running at peak performance.
