Important Criteria When Choosing Pressure Gauges

Among the criteria for choosing pressure gauges, the pressure type is given top priority. In fact, gauge pressure measurement efficiently serves the purpose required in most processes. However, pressure gauges for absolute or differential pressure are considered in many industrial applications.

Differences between the three types of compression:

Gauge pressure

In gauge pressure, a barometer measures the difference between atmospheric pressure, also known as ambient pressure. This pressure varies with weather conditions and elevation above sea level. At sea level, it averages 1013.25 millibars. Since nearly all production points are exposed to the same air pressure, a gauge pressure measurement is usually sufficient for industrial applications.

Absolute pressure

Absolute pressure is always measured at zero, the pressure resulting from a complete vacuum. Therefore, it is always advisable to choose pressure gauges for this type of pressure when even the smallest change in atmospheric pressure can affect the process. Common applications for measuring absolute pressure are determining the vapor pressure of liquids, monitoring condensation pressures, and in distillation. Other examples of applications include vacuum pumps and food industry equipment.

Differential pressure

By differential pressure, we are talking about a type of pressure that determines—as the name suggests—the difference between two pressures. Therefore, differential pressure gauges have two process connections. They are used, for example, in monitoring filter and pump systems. Using this type of pressure, the fill level in a closed tank can also be determined—it is derived from the difference between the total pressure (liquid column + gas phase) and the gas phase pressure.

The Important Role of Pressure Gauges in Safe Filter Monitoring

Filter monitoring is a key function of differential pressure gauges, as the differential pressure increases as soon as the filter becomes clogged. These gauges then signal when the filter needs to be cleaned or replaced.

Thanks to its precise operation switch and display, the differential pressure gauge enables safe filter monitoring.

In the water industry, reverse osmosis is widely used to separate water from unwanted substances. Filter systems used operate with semi-permeable membranes.

To monitor filters, an international solution provider for treating drinking water, industrial water, and wastewater uses pressure gauges. These devices measure the pressure on both sides of the membrane.

Real-Time Intervention in the Filter

In addition to displaying the pressure differential on-site, the pressure gauge has a built-in precision switch. This switch sends a warning signal to the control center when a specified threshold value is reached. This enables the operator to arrange for timely filter cleaning or replacement. Thanks to the mechanical measurement principle, filter monitoring operates efficiently even in the event of a power outage.

Continuous Monitoring

Immediate filter intervention is essential for two reasons: First, it prevents potential water contamination. Second, the operator saves energy by continuously monitoring the filter. The dirtier the filter, the harder the pump has to work to achieve the required media flow.

Built-in Operating Pressure Indicator

The customer selected a suitable pressure gauge to monitor the filter for another reason: the built-in operating pressure indicator. This information is important for the plant manager because it enables him to draw conclusions about the pump’s performance. To obtain this information without using a comprehensive solution, it is preferable to set up an additional measuring site.

Additional Measurement Requirements

In addition to filter monitoring, differential pressure gauges are suitable for level and flow measurement tasks. Their various versions cover a wide range of applications.

Effective Use of Liquid-Filled Pressure Gauges

Liquid-filled pressure gauges can mitigate problems caused by vibrations and pressure pulsations, which are common in water treatment plants.

The fluid dampens these effects, protects internal components, and ensures accurate readings. However, it is important to ventilate these gauges after installation to maintain their accuracy under fluctuating temperature conditions.

Read also: Pressure Gauges in Water Treatment Plants

Training and Documentation

Training employees on proper meter handling and maintenance techniques significantly reduces the risk of contamination and meter failure.

Documenting cleaning procedures, maintenance activities, and test results creates a comprehensive maintenance record, which is critical for quality assurance and effective meter management.

Calibration and Verification

Regular calibration of pressure gauges is vital to maintaining measurement integrity and compliance with quality standards.

Facilities should establish a calibration and verification schedule that includes visual inspections for damage, routine cleaning, and adherence to storage procedures to prevent contamination and meter performance degradation.

Addressing Low Water Pressure Issues

Maintaining adequate water pressure is critical to the effectiveness of pressure gauges in treatment systems. Operators must monitor and control water pressure to prevent any drops that could impact system performance.

Implementing early warning systems can help identify pressure changes, allowing timely intervention to avoid major repairs and system downtime.

Summary of Critical Criteria for Selecting Pressure Gauges in Industrial Facilities

When selecting pressure gauges for water treatment plants and industrial facilities, a set of technical and operational criteria must be considered to ensure long-term efficiency, safety, and accuracy. This selection process is critical given the pivotal role pressure gauges play in monitoring processes and preventing failures.

First: Determine the Type of Pressure as a Primary Criteria

• The selection should begin by determining the type of pressure to be measured:
• Gauge (Relative) Pressure: Best suited for general applications where atmospheric changes are insignificant, noting that its accuracy decreases with altitude.
• Absolute Pressure: Essential for applications sensitive to atmospheric changes, such as distillation and condensation processes, as it provides an absolute reading relative to the vacuum.
• Differential Pressure: Ideal for monitoring filters and pumps and determining fluid levels in closed tanks.

Second: Design and Installation Criteria

Environmental Resistance:

• Choice of body material (316 stainless steel for corrosion resistance)
• Protection level: IP65 or higher for humid environments
• Operating temperature range suitable for the environment (-40°C to +85°C for harsh conditions)

Accuracy and Reliability:

• Accuracy of at least ±0.5% over the entire range
• Certified Calibration Certificates (ISO/IEC 17025)
• Shock and Vibration Resistance (IEC 60068-2-6)

Third: Functional Performance Criteria

• Measuring Range: Must exceed normal operating pressure by at least 25%
• User Interface: Clear and easy to read (digital displays or color indicators)
• Integration: Compatible with SCADA systems and industrial communication protocols

Fourth: Maintenance and Safety Considerations

• Calibration Intervals: Every 6-12 months depending on the intensity of use
• Maintenance: Design that allows for easy replacement of oil or mechanical parts
• Safety Features: Built-in pressure relief valves Excess

Fifth: Special Applications

For filter monitoring (especially in reverse osmosis systems), the importance of:

• Differential pressure gauges with electrical switches
• Early warning systems for high differential pressure
• Ability to operate during power outages

The final selection process should include a comprehensive assessment of the life-cycle cost (TCO). Oil-filled gauges, despite their higher cost, offer long-term savings through reduced breakdowns and maintenance.

By selecting a gauge based on these criteria, operators can ensure:

• Continuous measurement accuracy
• Reduced downtime
• Improved energy efficiency
• Compliance with industrial regulations
• Extended equipment life

Finally, the thoughtful selection of pressure gauges is an investment in the reliability of the entire facility, as an effective pressure monitoring system is the first line of defense against costly breakdowns and ensures continuity of operations in water treatment plants and critical industrial facilities.