Instrumentation
It also offers excellent turndown, linearity and repeatability. Now available in 60°C and 110°C temperature versions and a 30 bar higher pressure model, Atrato flowmeters use time-of- flight (TOF) ultrasonic technology that enables operation over very wide flow ranges (250:1) with excellent accuracy (better than ±1.0% of reading). The Atrato system uses the well
proven TOF measuring method, which is more reliable and accurate than Doppler shift measurement where reflected signals are required from irregularities in the liquid. The Atrato crystals are plain disks with a hole in the centre forming a washer, which are excited in such a way that they oscillate radially as opposed to the normal mode of excitement, which is across the thickness of the ceramic. This strong radial signal sends symmetrical pulses directly into the tube. Because of these annular ring
crystals the sound travelling down the pipe can be considered as a plain wave. The signal to noise ratio is described by Titan as remarkable, as there is
little background noise and high signal strengths. At times the signal to noise ratio is as high as 3,000:1. As the system is fully balanced at zero flows the two signals are identical and cancel each other out. This gives a very stable zero flow condition and is the basis of the flowmeters high ratio between minimum and maximum flows. As the flow increases these signals go out of phase and the system measures this phase shift to an accuracy equivalent to 250 picoseconds. In addition, the sound waves
travelling down the tube in the Atrato operating system are symmetrical, and as a result any changes in the fluid’s velocity profile across the pipe diameter will be averaged out by the signal as it passes from the transmitter to the receiver. It is therefore irrelevant whether the fluid is fully formed with turbulent flow or completely laminar with a classic parabolic profile. The company says that in practice this gives the Atrato an excellent immunity to Reynolds number changes and a good high viscosity performance. n
Smart meter verification diagnostic reports are also increasingly recognised by third-party regulatory agencies, enabling work practice changes that save money and improve worker and environmental safety.
Ultrasonic flowmeters perform without the contorted flow path and disadvantages of alternative designs.
When There’s No Room for Error
When it comes to measuring humidity in harsh manufacturing environments, you don’t want to cut corners. The Vaisala HUMICAP® Humidity and Temperature Transmitter Series HMT330 is an uncompromising transmitter you can depend on for years of trouble-free performance.
• Credibility that speaks for itself – close to 80,000 installations worldwide and counting
• 10-year warranty when annually calibrated • A wide range of options and configurations • Built for extreme environments • Support and service you can count on
Your customers choose the best. Why would you choose anything less?
www.vaisala.com/HMT330 sales@vaisala.com
CEN-TIA-G-HMT330 advert-Process Engineer Nov
2014.indd 1 For more information ✔ at
www.engineerlive.com/epe 26/08/14 15:17
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