Tracking flow from the outside

Tracking flow from the outside

TTFM 6.1 from Greyline Instruments

Accurately measuring flow rate is paramount to keeping a water treatment plant running normal. While electronic measurement devices come in many different forms, the ability to measure flow rates from outside the pipe provides ease and efficiency. The TTFM 6.1 transit time flowmeter from Greyline Instruments is designed specifically for that.

The flowmeter can be used to accurately measure the flow rate of relatively clean, nonaerated liquids like potable water, raw water, cooling water, de-ionized or reverse-osmosis water, oils and chemicals in full pipes. Ultrasonic transducers mount on the outside of a pipe without shutting down flow. The flow rate is then displayed on the large, backlit display, along with total volume, signal strength, relay status, and other diagnostic values. Use the built-in control relays as flow alarms or volume totalization. Connect the isolated 4-20mA output to PLCs or controllers. A 128 MB data logger is standard and is capable of capturing up to 26 million data points. Optional MODBUS RTU via RS-485 is available for connection to automation systems.

“The previous generation transit-time meter from us had a very easy-to-understand programming menu and structure, and we’ve maintained that with this unit and then built upon it by adding advanced diagnostics which help confirm good installation or help diagnose potential install errors,” says product manager Ken Elander. “We’ve also further enhanced the ease-of-use through hardware and firmware changes, which allows the product to work in more difficult applications.”

Standard features of the unit include a pair of SE16B ultrasonic transducers that clamp on to 2- to 48-inch pipes. It comes with a pair of 25-foot tri-axial sensor cables with BNC connectors that can measure flow rate from 0.07 to 40 feet per second. Installation is easy, as the unit comes with stainless steel transducer mounting brackets and clamps, an alignment bar, and silicone coupling compound kit. The electronics are enclosed in a watertight polyester and polycarbonate IP66-rated box ideal for outdoor installation.

The unit works on a wide range of pipe materials, including carbon steel, stainless steel, ductile iron, concrete lined ductile iron, cast iron, PVC, PVDF, fiberglass, copper, brass, aluminum, and pipes with bonded liners including epoxy, rubber, and Teflon. It operates by measuring the “transit time” or “time of flight” for ultrasonic sound pulses transmitted from one transducer to another. Depending on the mounting configuration, the signal may cross the pipe once, twice or four times. To measure flow, the transit time is compared between ultrasonic signals travelling upstream and downstream. 888-473-9546;


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