If your application can experience overpressure, your pressure gauge needs to withstand those negative effects. Pressure line spikes and “water hammer” may introduce pressure beyond the operating range of the instrument and cause damage.
How can you protect your pressure gauge from the impacts of overpressure?
This article will discuss some of the options available for overpressure protection to keep your application running, even in harsh environments.
T6500 Pressure Gauge with XRA Overpressure Protection
Why is an overpressure protection option so important? Because it shields the instrument against overpressure buildup in the system, and it can withstand overpressure up to four times the measurement portion of the range.
Ashcroft’s T6500 pressure gauge with option XRA is an excellent fit for process and industrial applications, particularly those where pressure spikes or overpressure beyond the measurement portion of pressure ranges can occur. For example, the opening or closing of a valve, pipeline overpressure, faulty regulators, process components (compressor, reciprocating pumps) and other factors can also contribute to this.
Water hammer, also known as a hydraulic transient, is a common culprit of sudden surges in pressure. You’ll often see an additional external pressure limiting valve (PLV) used to mitigate it, but with the T6500’s overpressure protection option, the PLV may not be necessary. We’ve developed a product that makes this process less complex, and it also means fewer potential leak paths along with cost savings – and there’s a clearly-defined overpressure range on the gauge’s dial.
So, how does the overpressure protection work? First, the overpressure mechanism restricts motion of the Bourdon tube beyond the measurement of the gauge dial range. In restricting that motion, the natural spring rate of the Bourdon tube with relation to pressure is altered and allows the system to see high pressures that would otherwise damage the gauge.
There’s also unique dial artwork designed to identify two pressure regions; the first is the “measurement range,” which features the typical graduation and figure pattern seen on the standard T6500. Also, there’s a red band beyond the full-scale range with the word “overpressure” clearly displayed on the dial. This portion of the scale allows for pressures up to 400% of the gauge range.
The accuracy class of the measurement portion of the scale is ±1.0%. This section is the pressure region, which the gauge should typically operate. The second is the “overpressure range,” which is a simple visual indicator that the process pressure has exceeded the maximum working pressure intended for this instrument.
The final figure shown in this region is the maximum overpressure value that can be seen by the gauge. The proper range for your application should be selected similarly to a conventional pressure gauge, where the operating pressure should read mid-scale.
Figure 1: Ashcroft T6500 Pressure Gauge with Option XRA
To choose the correct pressure gauge range for your process, you will need to consider the standard operating pressure of the gauge and the potential pressure spikes that may occur in the process.
1209 Pressure Gauge with XRA Overpressure Protection
Another effective pressure gauge with protection from overpressure is Ashcroft’s new option XRA for the 1209 pressure gauge. This 4 ½-in. stainless steel, solid front pressure gauge now offers option XRA to accommodate up to 417% overpressure without damaging the gauge.
In applications where pressure spikes, surges and water hammer are a possibility, option XRA reduces the need for an external pressure limiting valve while extending gauge capacity. The 1209 is also available with optional liquid fill or the patented PLUS!™ Performance option to dampen shock, vibration and pulsation.
The XRA feature restricts the motion of the Bourdon tube once the specified full-scale pressure value has been attained. As a result, instrument capacity is enhanced to withstand up to 417% overpressure without incurring damage and reduces the need for an external pressure limiting valve. This is especially useful for applications where pressure spikes, surges and water hammer are a concern.
Figure 2: Ashcroft 1209 Pressure Gauge with Option XRA
This gauge consists of a 316L stainless steel case, ring and wetted parts to resist corrosion from the environment and the process media. It’s ideal for use in:
- Offshore oil rigs
- Chemical and petrochemical plants
- Machine equipment
- Food and beverage industry
- Pulp and paper
- Power plants
We don’t like to pressure you, but we have more information.
Now that you better understand what makes the best pressure gauges to use in situations that see overpressure, you can choose the best solution for your application. Ashcroft’s XRA option for the T6500 and 1209 pressure gauges can help protect your gauge from the effects of overpressure.
If you want to learn more about pressure gauges, here are some other articles to read:
- How Do I Select the Right Pressure Gauge Range?
- Choosing the Right Pressure Gauge Dial Size
- Solid Front vs. Open Front Pressure Gauges
- Selecting the Right Pressure Gauge for Ultra-High-Pressure Applications
- Product Review: T6500 Ultra-High-Pressure Gauge
Reach out today to talk to one of our industry experts and get all your pressure gauge questions answered. In the meantime, check out our pressure gauge selection tool to help you find the best instrument for your needs. 