Digital vs. Mechanical Pressure Gauges

When it comes to selecting a pressure gauge for your application, understanding the differences between mechanical and digital options can help you make the right choice. Both have unique features and benefits that are best suited to different scenarios. 

In this Understanding the Basics series, you will get a high-level overview of the features, benefits and uses of these two pressure gauge options, including when to use one over the other and when to use both. Plus, you will receive recommendations for additional resources that can provide a deeper understanding of pressure gauges as a whole.  

The information in this article is based on more than 40 years of industry experience with temperature and pressure measurement, design, engineering, and product management, which includes 17 years working with Ashcroft - a leader in temperature and pressure instrumentation.

What does a pressure gauge do?

In a previous Understanding the Basics article, we provided an extensive overview of different types of mechanical (analog) pressure gauges and how they work. These instruments have been providing an efficient and reliable way to measure the pressure of liquids and gases in various industrial processes since the 1800s. They give operators valuable insights into processes that alert them to potential issues like pressure spikes (indicating a blockage), or pressure drops (signaling a leak) in the system. 

In the late 1900s, as technology advanced, digital pressure-sensing options became more accessible and offered a new way to deliver this critical data to system managers. Today, digital pressure gauges and mechanical pressure gauges each play an important role in commercial and industrial applications. Here are a few important highlights of both:

Features and benefits of digital pressure gauges

Digital gauge options have large, easy-to-read displays for quick, accurate and easy-to-read pressure readings. They operate on battery, loop power or DC power, allowing for continuous performance in different applications. Many digital gauges also include features like 4-20 mA output or switching capabilities for more versatility. Because digital gauges have no moving parts, there is no wear and tear from mechanical components, which enhances the instrument's durability and lifespan. 

The primary advantages of digital pressure gauges: 

• Higher accuracy and clarity: Digital displays reduce errors in reading, especially in low-light conditions or complex environments.
• Extended operating pressure: They can operate up to 100% of their full scale and withstand proof pressures up to 200%, providing added reliability.
• Enhanced functionality: With the inclusion of electronic outputs, digital gauges can connect with other monitoring systems and provide remote pressure readings.

Key considerations when choosing a digital option:

• Power dependence: Requires a reliable power source, which may limit use in remote or power-sensitive environments
• Higher initial cost: Although there are low-cost, low-quality options available online, high-quality digital gauges like those offered by Ashcroft, come with a higher upfront investment ($350 - $1,500) due to their advanced technology features and U.S.-based manufacturing.

Features and benefits of mechanical pressure gauges

Mechanical pressure gauges require no wires and no electrical power source to operate because they are powered by the process. That means the gauge will continue to provide pressure measurements in the event of a power outage and will work well in remote areas where the power supply is unavailable or unreliable.

The three primary aspects of a pressure gauge that make it functional:

• A flexible measuring element (tube). Made with an elastic material that moves when a change in pressure occurs.
• The movement. Converts the tube motion into a rotary motion to drive the pointer.
• The dial. Gives you a visual indication of the pressure measurement.  

Unlike the digital gauge that electronically displays the exact pressure measurement, reading a mechanical gauge requires more skill and ability to interpret the information on the dial and needle. 

The primary advantages of mechanical pressure gauges:

• No power source required: can provide important measurements to keep processes operating safely and effectively without electricity.
• Simple design: easy to install and maintain.
• Cost-effective: depending on the application, mechanical gauges are often more affordable than digital alternatives, ranging anywhere from $10 to $1,500. 

Key considerations when choosing a digital option:

• Overpressure limitations: Mechanical gauges typically operate best at up to 75% of their full scale and have a proof pressure of 130% max. Overpressure beyond these limits may lead to instrument damage.
• Durability challenges: The mechanical movement can wear out over time, especially when subjected to vibration or flow pulsations.

Figure 1: Mechanical vs. digital comparison.

Ready to learn more?

Now that you know the features, benefits and uses of digital and mechanical pressure gauges, you may want to deepen your knowledge on the subject a little further. Here are a few articles that can help: 

• How Much Do Mechanical Pressure Gauges Cost?
• 10-Steps to Choosing a Pressure Gauge
• What are the Advantages of Ashcroft Pressure Gauges?

At any time, feel free to contact one of our product experts with any questions you have.  In the meantime, check out our pressure gauge selection tool to help you find the best instrument for your needs.