Flowmeter tip of the month: Ensure meter accuracy
One of the easiest ways to ensure meter accuracy is to ensure that the meter is piped properly. Attention should be paid to the required upstream and downstream pipe requirements needed to ‘smooth’ out the flow profile. When laminar flow (Reynold’s Number < 2,000) is achieved, there are no disruptions and the maximum velocity is in the center of the pipe. This is a desirable profile. Partially open valves or improper alignment of flange gaskets can distort the flow profile causing turbulent flow (Reynold’s Number > 4,000). This will cause errors in the meter’s accuracy. Below are some guidelines on the minimum distances required to achieve the desired flow profile.
In the event that the recommended pipe lengths can’t be provided, there are devices that can assist in providing a favorable profile. Such devices include perforated plates and internal pipe tabs can reduce swirl and mimic a laminar flow profile.
Content provided by Spirax Sarco, originally published in Steam News Magazine.