Accurate and precise pipeline meter measurements are critical key components that can result in substantial losses to your company.  Most company owners focus most of their time on identifying measurement errors caused by obstructions upstream or near the flowmeter, as they can cause errors that range beyond 50%,  and overlook errors caused by pulsation. Measurement errors from pulsation may actually have a larger impact on the system than you'd think.

Pulsation can interfere with the flow through capped lines and cause large differences in the measured throughput between series meters. If you have a background in pipeline engineering, you can easily eliminate meter errors caused by pulsation yourself. Here are 3 easy solutions.

Assessing Square-Root Error and Calibrating the System as Necessary

One of the easiest ways to determine whether there is a metering problem associated with pulsation is to compare the measured square-root error with the expected square-root error of the system. The measurements of the system may be inaccurate if the variables used to compute flow is inaccurate. At times, while pulsation is not the primary culprit, the computer analog and system is simply not calibrated properly to account for the variables present in the actual work environment. You can easily get these measurements from the computer software. 

If the square-root error measured and the square-root error variable inputted into the system is not within the same range, the measured input and output will exhibit a relatively large difference. In this situation, that installation pulsation control device is not necessary. Instead, the system simply needs to be calibrated to match the actual variables presented in the pipeline system.

Reducing Sound Pressure and Noise

High noise levels and sound pressure can end up damaging the metering equipment, like the regulators, control valves, control valve accessories and more. The vibrations coupled with the damage may amplify pulsation and its effects, so you want to keep the workplace as quiet as possible. Measure noise levels periodically to assess whether noise levels need to be reduced. A maximum noise level has yet to be recommended for the workplace in general; however, some equipment should only operate below a certain noise level. For example, regulator noise should always be below 110dBA. To reduce sound pressure and noise to quiet the effects of pulsation, you can:

• install heavier wall pipes that are less prone to vibrations;
• install insulation;
• bury quiet equipment like regulators; and,
• install noise attenuating trims or silencers on particularly loud equipment.

Installing Pulsation Control Devices

If the pulsation within the pipeline itself is rather large and replacing the pipes will be too expensive, you can opt to install pulsation control devices along the flow line. There are several different types of pulsation control devices that you can choose from: dynamic variable orifices (DVO), tuneable side branch absorbers (TSBA) or performance augmentation networks (PAN). Each type of device possesses unique properties catered to specific pipeline system features.

For example, DVOs are inexpensive and effective; however, they restrict gas streams of the pipelines, which results in narrow frequency ranges. On the other hand, TSBAs track compressor speed, and do not restrict gas flow. These systems are generally most recommended for pipeline systems that rely on reciprocating compressors. The type of pulsation control device that is best for your system will depend on many factors, such as the type of parts that are installed upstream and downstream the flowmeter. 

Conclusion

Measurement errors introduced by pulsation are fairly common in metering pipeline systems, and errors caused by pulsation are often overlooked, as pulsation is not normally measured or assessed regularly. By eliminating errors caused by pulsation, the system will become a lot more accurate and precise. This will reduce overall loss due to meter misreadings. If you need assistance, contact companies like Industrial Measurement & Control.