The ST98 thermal mass flowmeter from Fluid Components International, when combined with the Vortab Insertion Panel (VIP) flow conditioner, provides an accurate, economical way to measure air/gas flow in sometimes challenging pipe configurations.
Flowmeters installed in the aeration systems of activated sludge wastewater treatment plants measure the airflow microorganisms need to thrive. Elbows, valves and shorter-than-optimum upstream straight-pipe runs create flow disturbances that can prevent meters from delivering precise readings on the air reaching the basin.
“Say you have an aeration system where large blowers are providing air to several basins through a network of progressively smaller-diameter pipes along with elbows and valves,” says Don Lundberg, product engineer for FCI/Vortab. “It’s critical to have the proper amount of air circulating through the aeration basin to sustain the microorganisms.
“Engineering wants to put flowmeters on the various lines, but unfortunately, due to space limitations, the pipe runs will come out of the ground or out of a manifold, then through a couple of 90-degree turns and valves that can leave under 10 diameters of straight run at any part of the process. That is inadequate for any flowmeter.”
Installed immediately after flow disturbances, the VIP flow conditioner neutralizes the disturbances, reducing the amount of straight-pipe run needed for accurate readings. Besides saving floor space, the flow conditioner can save hundreds of thousands of dollars in piping and retrofitting costs. It also has a very low pressure drop, potentially saving thousands of dollars in energy costs, according to Lundberg.
The thin, lightweight conditioner can be installed between flanges or welded in place. Made of 316L stainless steel, it is available for standard pipes from 2 to 40 inches. Other materials and larger sizes are available. The flow conditioner requires minimal maintenance. “Depending on the cleanliness of the process, it might require an occasional visual inspection,” Lundberg says. “If it’s a filtered environment, there would be no inspection requirements at all.”
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Able to operate over a wide flow range, the flowmeter has no moving parts. A thermal dispersion mass flow sensing element provides accuracy within 1 percent of reading and 0.5 percent of full scale and is reliable in harsh environments.
A two-way HART interface enables engineers to receive multiple process variables and configure the meter remotely. The insertion-style flowmeter can be installed without shutting down the process by using an NPT fitting, ball valve or hot tap. 800/854-1993; www.fluidcomponents.com.