How to Optimize Water & Wastewater Monitoring Instruments

This article was originally published on May 3, 2021, and was updated on August 21, 2024.

Pressure instruments play a crucial role in ensuring the ideal conditions for water and wastewater systems across various sectors. If you are a design engineer, systems integrator, or plant operator, you understand that choosing the correct instrumentation is essential for the efficient, reliable and safe operation of your systems.

With a legacy dating back to 1852, Ashcroft has been at the forefront of creating quality pressure measuring and monitoring instruments that are widely used in water and wastewater facilities worldwide.

This article offers several effective strategies to enhance the performance of instrumentation in various water and wastewater applications in industrial, commercial, and residential settings. Whether you are responsible for monitoring pressure, temperature, or flow in a water treatment facility or ensuring the safety of your potable water system, these insights will assist you in achieving your desired outcomes.

When you are finished reading, you will also be directed to additional resources to help deepen your knowledge of these applications and the instrumentation that can help your water and wastewater systems run efficiently. 

8 Ways to optimize instrument performance in water and wastewater applications.

1.     Minimize pressure pulsations.

Instruments installed near pump systems tend to be exposed to surges of pressure that continuously fluctuate the sensing elements of the instrument. When this happens, the needle on the pressure gauge twitches up and down the scale keeping internal components in motion, causing inaccurate readings and premature wear and tear on the mechanical parts of the pressure gauge.

To mitigate the effects of pulsation, the industry often employs flow restrictors as a solution. For example, Ashcroft® pulsation dampeners, pressure snubbers,  throttle valves, throttle screws and capillary lines are all designed to help protect instruments from pulsation.

2.     Protect against excessive vibration.

Pointer flutter, abrasive chattering and grinding of the internal components can also cause poor readability. To prevent instrument damage from occurring:

• • • Mechanical pressure gauges can be protected by dampening methods such as liquid filling the case or selecting the Ashcroft® PLUS!^™ Performance option.
      
      
    • Mechanical pressure switches must rely on capillaries to be safely removed from the source of vibration.
      
      
    • Sensor-based products like the Ashcroft® 2074 series digital gauges are mostly resistant to vibration. Any readability effect on digital gauges caused by pulsation or vibration on these instruments can be dampened by slowing the response time of the gauge. 

3.     Use an overpressure option.

Pressure spikes and surges (such as water hammer) can increase pressure conditions beyond the maximum allowable working pressure of the instrument. This can cause irreparable damage because mechanical pressure gauges are vulnerable to pressure spikes.

Pressure gauges have layers of protection against pressure spikes ranging from internal stop pins that help prevent overextending the segment gear of a pressure gauge to pressure limiting valves (PLV) designed to shut off at a specific pressure. Alternatively, using an overpressure range option like the XRA option on the T6500 pressure gauge can provide added protection against pressure spikes.

4.     Insulate instruments from temperature effects.

The most common temperature concern in water/wastewater is excessively cold temperatures. Instruments installed outdoors can be exposed to extremely low temperatures in certain parts of the world. If not properly insulated, water in the pipes can freeze and cause either temporary performance issues or permanent damage to the internal components.

While water/wastewater applications typically do not encounter elevated temperatures, occasional steam service applications may require the use of a coil siphon to insulate instruments from hot steam.

5.     Prevent clogging.

Wastewater operations involve the handling of particulate-laden materials (i.e., sludge). The particulate matter in the process media can accumulate inside of instruments, affecting their operation and performance. Worst case: clogging will cause the instrument to fail.

One of the more effective means of protection against clogging is the use of isolation rings. Isolation rings are installed in line with the pipe, sandwiched between two flanges. Not only does the design eliminate dead legs, but the sensing element is typically made of a flexible yet durable material that can withstand the abuse of heavy solids moving through the pipe.

6.     Eliminate corrosion.

Many water and wastewater operations involve corrosive chemicals that may not be compatible with the wetted materials of an instrument. The industry famously uses diaphragm seals, which can be constructed from a large variety of materials. A diaphragm seal manufacturer should be able to provide resources and direction on what materials are compatible with your process, i.e., the Ashcroft material selection guide.

7.     Ensure displacement.

To ensure the proper functionality of instruments when using a standard diaphragm seal, it is important to confirm sufficient displacement for operation. Pressure ranges below 30 psi and pressure switch set points under 10 psi can pose challenges. In these instances, seals with elastomeric materials (that provide more flex) or metal diaphragms with large diameters (which have larger surface areas) can amplify the displacement and help operate instruments designed for lower pressures.

However, this dynamic adds constraints on available materials and may have limited solutions for meeting the material requirements. It is important to consider this dynamic when designing system pressures for new installations. Refer to the Ashcroft® Complete Guide to Pressure Instrument Assembly to learn more. 

8.     When appropriate, choose products that are NSF/ANSI/CAN 61-certified for public safety.

Instruments used in potable water systems play a critical role in maintaining the quality of water to protect public health. That's why potable water systems must only use components that meet the requirements of NSF/ANSI/CAN 61. 

Ashcroft offers many instruments with NSF/ANSI/CAN 61 certification for use in potable water applications. These certifications verify that our products meet the stringent health effects requirements for drinking water system components and underscore Ashcroft’s commitment to product safety, quality, and public health.

Want to know more?

After learning all the ways you can protect your pressure monitoring instruments in water and wastewater applications, we understand you may still have questions. As a next step, here are a few additional resources that may be of interest to you:  

• Isolation Ring Assemblies for the Water/Wastewater Industry that are Accurate and Reliable
• Why Use a Flushing Connection on a Diaphragm Seal?
• Best Practices for Installing Flanged Diaphragm Seals
• When to Use a Welded Instrument Assembly
• Understanding NSF/ANSI/CAN 61 Approvals for Pressure Instruments

Of course, you can also contact us directly to speak to a product expert who can answer your questions. In the meantime, download our Pressure and Temperature Instrumentation for Water and Wastewater Applications guide: