This article was originally published on February 13, 2023, and updated on January 6, 2025.
The chemical industry manufactures a wide range of chemical and material products for industries that require durable and reliable measurement and monitoring technology for their production.
Accurate and dependable pressure and temperature measurement instruments are necessary to endure harsh chemical environments. However, incorrect use or failure of these instruments can result in serious outcomes such as equipment damage, employee injury, and environmental hazards. These are just a few reasons why it is essential to use instruments engineered to withstand the severe demands of chemical processing operations.
Ashcroft is a leader in pressure and temperature instrumentation since 1852. Read this article to learn about the factors to consider when selecting the best instruments for your chemical application. You will also get links to additional information in case you want to learn more.
5 factors for choosing pressure measurement instruments in chemical applications.
1. Critical process protection.
There are many considerations regarding application safety that impact the type of instruments you should choose. The following are a few common issues that may require special attention:
Acid leaks. This is a big concern in chemical processes that can lead to catastrophic safety issues such as equipment explosions, chemical spills, and fires, posing severe risks to both personnel and the environment.
One way to prevent acid leaks is to use an assembly, which offers an added layer of protection for your instruments and your process. Some assemblies, like the Ashcroft® Acid Leak Detection (ALD) assembly, have an added feature that alerts you when an acid leak occurs. It is designed with a special yellow coating that changes to red once it is exposed to acids with a pH of ≤ 3, providing a visual indication of a process media leak.
Extreme pressure and excessive vibration/pulsation. Instruments used in chemical facilities must meet specific standards to function effectively in challenging conditions. For instance, if overpressure occurs, it can cause a pressure gauge to fail and burst, propelling internal components forward. For that reason, you want to choose instruments that are equipped with safety features to prevent operator injury and minimize equipment damage in the event of failure.
Solid front gauges like the Ashcroft® 1279 Duragauge® Pressure Gauge incorporate a “solid” wall into the case structure that 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. Plus, the solid wall and blow-out back safety design serve to deflect escaping pressure, process media and fragmentary debris toward the back of the instrument and away from the operator. This helps keep your workers less susceptible to injury or worse. To learn more about the benefits of solid-front gauges, check out our blog.
Figure 1. Ashcroft® 1279 Duragauge® Pressure Gauge with Acid Leak Detection.
Limited lighting environments. If you need to read your pressure gauge in low-light conditions, using a retroreflective dial material like the Ashcroft DuraVis™ Gauge Dial can help. Unlike a reflective material that disperses light in different directions, DuraVis™ material reflects light back to the light source, making readability of your pressure measurements easier.
2. Instrument media compatibility.
The instrument's wetted materials must be compatible with your process media. If you are using the wrong materials, you may encounter instrument damage or failure. Ashcroft provides a Material Selector and Corrosion Guide to help ensure that you have the proper instrumentation for your application’s media.
Instrumentation may be limited in material availability for the components that come in contact with the process. In these instances, a diaphragm seal would be required. Diaphragm seals are available with a wide variety of materials and isolate instruments such as pressure gauges, pressure switches or pressure sensors from harsh media.
3. Instrument material traceability.
When selecting the appropriate instrument materials to use for chemical and petrochemical applications, it is important to confirm the materials not only meet the functional requirements of the process but also that the materials supplied do not deviate from the specified composition. The only way for an instrument manufacturer to provide unquestionable assurance that the instrument materials are what they are supposed to be is to have traceability documentation.
Material traceability involves maintaining comprehensive records that document the entire lifecycle of the materials used in your application, from their origin and manufacturing to their final form. This process certifies that the materials used in your application have records chronicling their creation and confirms that the materials meet the necessary quality and safety standards, reducing the risk of contamination or failure.
Two standards apply to this documentation: EN 10204 2.2 (referred to as a typical test report) and EN 10204 3.1 (referred to as an actual test report).
Another way to fact-check the material composition is with a positive material identification (PMI) report. PMI involves using special technology that can identify the metallic composition of a component.
Ashcroft offers this type of documentation for many of our products.
4. Instrument application requirements.
Selecting the correct instrument or configuration of instruments and accessories plays a critical role in your application operating safely and efficiently. From a macro perspective, selecting the correct type of instrument is important. For local pressure measurement, users can opt for mechanical or electronic (sensor-based) products. Each direction has its pros and cons, which is why you will often see both mechanical and electronic products on a local pressure reading installation.
From a micro perspective, it is important to select instruments with reasonable pressure ranges (not too high, not too low) and robust construction that can withstand the elements of the application (maximum pressure, maximum and/or minimum temperature, etc.).
5. Protection from harsh conditions.
It is not uncommon for instruments to be exposed to challenging, or even hazardous conditions. For safety considerations as well as product life and longevity, it is critical to protect the instrument from application challenges. ASME B40.100 standards guide lists several solutions to how best to protect the instrument from these conditions. In many cases, multiple accessories may be required to fully protect the instrument. Here are a few examples:
- For clogging concerns as well as pressure pulsations, a diaphragm seal in combination with a pressure snubber may be required.
- For pulsation, vibration, and pressure spikes, many people use a liquid fill to stabilize the pressure gauge needle and reduce the impact of these movements. Alternatives to liquid fill are direct-drive gauges that eliminate movement in harsh conditions and gauges that offer dampened movement technology, such as Ashcroft® PLUS!™ Performance.
Accessories such as pulsation dampeners, throttle screws, steel needle valves and diaphragm seals are also effective options in these situations. - For extreme temperatures, accessories such as a finned siphon can increase exposure to the ambient temperature for better heat dissipation and a capillary line can be used when instruments need to be removed from direct contact with the installation point due to elevated process temperature.
Ready to learn more?
Now that you know the factors to consider when choosing the right pressure and temperature measurement instruments, you can research the solution that’s best for your chemical or petrochemical application. Keeping these factors in mind can help you avoid problems, keep your process running with reliable and accurate measurements, and ensure the safety of your workers when exposed to extreme operating and environmental conditions.
If you want to learn more, here are a few more articles that may be of interest to you:
- Solid Front vs. Open Front Pressure Gauges
- Best Pressure Gauges for Ammonia Plant Applications
- Alternatives to Liquid-Filled Pressure Gauges for Vibration Protection
Feel free to contact us today to talk to one of our industry experts and get your questions answered. In the meantime, check out our guide to Pressure and Temperature Instrumentation for Chemical & Petrochemical Applications.