This article was originally published on February 22, 2022, and updated on July 30, 2025.
In many systems, especially those involving high pressure or hazardous conditions, pressure gauge failure can have serious consequences, including operator injury and costly equipment damage.
Ashcroft has been a leading innovator in pressure measurement for over a century. We’ve engineered gauges to meet the most demanding safety and performance standards across industries, including oil & gas, chemical processing and power generation. It's our job to make sure customers make the most informed decisions when choosing instruments for their specific processes.
For instance, while we know there are plenty of applications where open-front pressure gauges are preferred, solid-front gauges have become a common choice for higher-risk operations. Read this article to learn the differences between solid and open front gauge cases and the benefits they each offer so you can decide which one is right for your application.
Choosing between solid-front and open-front pressure gauges
Your business depends on reliable, accurate and safe pressure measurements to keep operations running safely and efficiently. However, some systems, especially those involving high pressure or hazardous media, can experience gauge failure, causing serious injury to operators or expensive equipment damage. Before we go into too much detail, let's start with a quick review of both types of pressure gauge cases:
Open-front pressure gauge
Open-front instruments, like the Ashcroft® 8008S Pressure Gauge and the 8009 Pressure Gauge, offer a practical, economical and reliable solution for safe, routine applications. Typically, these smaller diameter gauges are used for more compact applications, are easier to install in tight spaces, and are available in a range of configurations.
This type of pressure gauge meets basic safety requirements and complies with industry standards. On the other hand, it lacks an internal solid barrier (or “baffle wall”) between the sensing element (typically a Bourdon tube) and the gauge dial. In an open-front design, all internal components are housed in a single chamber.
Solid-front pressure gauge
When the application involves high-risk, high-pressure, flammable, explosive or corrosive environments, such as those found in compressed gases, oxygen and hydrogen systems, solid-front cases offer an additional safety benefit over open-front designs. If a failure occurs, the resulting force can be extreme. Solid-front cases are specifically engineered to contain such failures, directing energy and hazardous materials away from the operator to reduce the risk of injury.
How do solid-front pressure gauges work?
Due to extreme process overpressure, excessive vibration/pulsation, fatigue, and/or incompatible process media, a pressure gauge system may rupture once it has been compromised. A solid-front option, which is available with the Ashcroft® 8008S Pressure Gauge and the 8009S Pressure Gauge, is engineered with safety features designed to mitigate damage and injury if a rupture does occur, including:
- A solid metal wall to isolate the pressure element from the front face
- A blow-out back panel to vent pressure and deflect fragment debris away from the operator
As you can see in Figure 1, the solid wall is situated immediately behind the indicating dial, allowing only the pointer shaft to protrude towards the front. All other system-related parts are contained (isolated) in the rearmost case section. This is especially critical for instrument installations in refineries, chemical facilities and process plants where there are specified standards.
Figure 1: Solid-front pressure gauge operation
Safety of solid-front gauges vs. open front gauges
There is no ASME standard test for cases, and no test to simulate a high-pressure gas rupture of the Bourdon tube or an explosion inside the tube. Most evaluations for this purpose simply introduce pressure into the case through the socket at a rate far slower than that which occurs during an explosive failure and therefore, will not truly demonstrate the advantages of a solid-front case.
That said, here are several ways to decide which gauge type is right for you. See Figure 2 for a quick comparison.
Figure 2: Solid front vs. open front comparison
Why pressure instruments fail
While many pressure gauge failures can be anticipated through careful system design and maintenance, not all are preventable. When a failure does occur, the construction of the gauge plays a critical role in determining the severity of the outcome.
Several factors can lead to gauge failure, including.
- Overpressure, caused by sudden spikes beyond the design limits. This is one of the most common reasons for failure.
- Excessive vibration can create mechanical fatigue over time, weakening internal components.
- Corrosive or incompatible media may degrade the sensing elements internally.
- Long-term process fatigue can lead to material wear and eventual rupture.
The most dangerous failures happen when the Bourdon tube breaks, especially in systems with gas. Gas can store a lot of energy, which may be released suddenly and violently if the tube bursts. Liquid systems are less risky because liquids do not compress, making ruptures less severe.
The volume and pressure within the system can also impact the severity of a rupture. Larger gas volumes contain more stored energy and result in more forceful failures. Similarly, tubes that rupture at higher pressures generate more intense case stress, particularly when gases are involved.
This is where solid front pressure gauges provide a distinct advantage. They are specifically engineered to reduce these risks, directing energy and debris away from the operator and limiting the potential for injury or equipment damage.
Ready to learn more?
There are many factors that go into selecting a pressure gauge for your application. Now that you know the differences between solid-front and open-front gauge designs, you are in a better position to make an informed choice. However, there is so much more information available. Here are a few related articles to check out:
- How To Identify Your Pressure Gauge and Get the Proper Replacement
- How Do I Select the Right Pressure Gauge Range?
- How Often Should I Check the Calibration of My Pressure Gauge?
You can also contact us to speak with one of our industry experts and get your pressure gauge questions answered. In the meantime, check out our pressure gauge selection tool, which is designed to make it easier for you to choose a gauge for your specific needs.
