How to Optimize Water & Wastewater Monitoring Instruments

To ensure the highest quality of water for use across many essential industrial, commercial, and residential sectors, you need the right tool for the job. From material processing and waste management to personal use, a steady supply of application-appropriate water is essential. 

But how do you know if your water quality is sufficient?

Pressure and temperature instruments used for measurement and monitoring can help water and wastewater companies achieve and maintain the system conditions they need to keep their water treatment and distribution operations running efficiently, reliably, and safely. 

When working with design engineers, systems integrators or plant operators, it is important to select the right instrumentation for the application. Otherwise, they may encounter problems that can lead to operation stoppage, damaged equipment or worse — injuries.

At Ashcroft, we have been producing the highest quality pressure and temperature instruments since 1852, and they are a familiar sight in many water and wastewater treatment facilities around the globe.

Below, we highlight ways you can optimize the performance of your instrumentation for water and wastewater applications. 

8 Ways to Optimize Instrument Performance for Monitoring Water & Wastewater Applications

1.      Minimize Pressure Pulsations

Instruments installed near pump systems tend to be exposed to pressure pulsations, which are surges of pressure that continuously fluctuate the sensing elements of the instrument. You can see this in a pressure gauge as the needle twitches up and down the scale keeping internal components in motion.

Not only does this make getting a reading nearly impossible, but it can also cause premature wear and tear on the mechanical components of the pressure gauge. The industry commonly uses flow restrictors to minimize the impacts of pulsation. Pulsation dampeners, pressure snubbers, throttle valves, throttle screws and a capillary line can all help protect instruments from pulsation.

2.      Protect Against Vibration

Excessive vibration can also affect instruments. Pointer flutter and abrasive chattering and grinding of the internal components can cause poor readability. Mechanical pressure gauges can be protected by dampening methods such as liquid filling the case or selecting PLUS!^™ Performance option.

 Other mechanical products such as pressure switches must rely on capillary to be safely removed from the source of vibration. Digital products (pressure gauges or transmitters) are mostly impervious to vibration, at least from a readability standpoint. Any readability effect on digital gauges caused by pulsation or vibration 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 from Temperature Effects

Instrumentation must be protected against both ambient and process temperatures that are above and below the specified limits. Outside of the occasional steam service, it is uncommon for water/wastewater applications to have elevated temperatures.

Instruments that are on steam service should use a coil siphon to insulate the instrument from the hot steam.

The more 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.

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

When using a diaphragm seal, it is important to ensure there is enough displacement to operate the instruments. Pressure spans lower than 30 psi, as well as pressure switch set points lower than 10 psi, can be very difficult to operate on a traditional diaphragm seal.

In these instances, seals with elastomeric materials (that provide more flex) or, alternatively, 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 min/max guide for more information on diaphragm seal assemblies.

8.      Configure the Assembly Properly

When configuring an assembly with one or more instruments on a diaphragm seal: 

1. 1. 1. Use manufacturers that are involved with both diaphragm seals and instrumentation. Ideally, every instrument would be made from the same manufacturer as the diaphragm seal. This would ensure assemblies are built within known parameters of the instrument. For example, at Ashcroft, the seal assemblers know the limits of the instruments on specific seals/material configurations.
         
         
      2. The assembly should be calibrated and (for pressure switches) factory set as a complete assembly. Calibrating instruments and switches prior to assembling to a diaphragm seal will likely result in an accuracy issue when retested, especially at the low pressures typical of water and wastewater applications.
         
         
      3. Limit the volume of system fill (fill fluid above the diaphragm seal). If the fill fluid volume is low:
         - Your instruments can be more responsive.
         - Temperature fluctuation will have less of an effect on your instruments.
         
         Using low-volume fittings, which have an intentionally small bore, can help reduce total fill volume. Also, using multifunction instruments can be a very effective strategy. For example, instead of using a pressure gauge and a switch, you can install a switch with a pressure-indicating display or a digital gauge with local indication and switching capability.

Selecting the Right Pressure & Temperature Instrumentation to Monitor & Control Water & Wastewater

Pressure and temperature measurements are an integral part of the treatment process because they help to keep water flowing safely and reliably throughout the system. With such an important job, instrumentation should be properly specified for each application.

• Water storage. Ashcroft SL17 is a submersible level transmitter that is designed specifically for use in aquifers, reservoirs and tanks. It has a rugged design that features an IP68/NEMA 6P watertight housing, all 316 stainless steel construction, and vented polyurethane-jacketed cable. These features ensure the instrument provides accurate and reliable results throughout its expected service life. 
• Chemical feed systems. Ashcroft 1259, 1279, 1009, 1209, T5500, and T6500 pressure gauges are suitable for continuous monitoring of input and output pressures in chemical feed systems. They come in a variety of wetted materials to ensure compatibility with many process media. A diaphragm seal can be added to isolate valuable instruments from highly aggressive media. 
• Filter systems. Ashcroft 1132, 1133, and F5509 differential pressure gauges can be used for local filter pressure readings. We also offer GC52 DP transmitters for remote signaling and D4 pressure switches for automatic shutdown capabilities. If multiple functions are needed, we can construct a custom assembly with all necessary instruments.
• Pipe systems. By adding isolation rings, such as Ashcroft 80 (wafer), 81 (bolt thru), and 82 (threaded), to instruments, we can eliminate particulate traps that can lead to clogging in particulate-laden processes. 
• Pump systems. Mechanical pressure gauges and pressure switches are commonly used for monitoring and controlling locally at the pump. Pump applications can create conditions that (if left unprotected) can reduce the life expectancy of mechanical instruments. The addition of an Ashcroft 80, 81, or 82 isolation ring, a type 201 diaphragm seal with a flush port, or flush-mounted seal to instrumentation can help prevent clogging in pump systems. 

We don't want to pressure you, but we have more information.

Instruments play a critical role in maintaining the quality of water to protect public health, so it is essential that you make the right selections for your specific requirements.  Otherwise, there is a risk of inaccurate measurement data or failure during use.

While it can be challenging to determine which instrument solution is right for your application, the experts at Ashcroft are here to help. 

 With extensive application-specific knowledge and skills, Ashcroft specializes in the design and manufacture of high-quality pressure and temperature instruments for a wide range of water and wastewater systems. We are fully committed to helping customers find the best instrumentation for their needs. Whether you need a standard instrument or a custom instrument assembly, we’ve got you covered. 

To learn more about our products and services, please contact us today.

You can also read some related articles:

• 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

For detailed information about water and wastewater instrument applications, download our guide for  “Pressure and Temperature Instrumentation for Water and Wastewater Applications”: