Greetings From SoundWater!
Today we discuss the “Searching Flow” message that appears during normal operation of your SoundWater ultrasonic flowmeter. Searching flow is a normal part of the measurement process, and occurs in three scenarios: (1) during startup, (2) at periodic “check up” intervals, and (3) when the ultrasonic signal is no longer detected. But what is actually happening during “searching flow”?
Figure 1. The “searching flow” message shown when the optimizing ultrasound transmission.
Searching flow is a mode in which your SoundWater flowmeter is looking for an ultrasonic signature. The flowmeter searches by emitting ultrasound (into the pipe and fluid) at different voltages and listening for an echo (the reflected ultrasound from inside the fluid) at the receiver. It is also tweaking the receiver, turning its “volume” up and down. It does all this in order to put enough energy into the pipe system so that you get the best measurement possible for the given fluid and pipe conditions. For example, if the measurement fluid becomes highly aerated, then the flowmeter will accommodate by increasing its transducer voltage to add more power into the system and continue measuring flow. Similarly, the receiving transducer may increase or decrease its gain (or volume) to optimize the incoming ultrasound signal. This is all necessary because fluid and pipe conditions vary between applications, and also with time. This is also a great feature of SoundWater flowmeters – they can accommodate to changing pipe and fluid conditions to provide the most accurate flow measurement possible!
This process of searching and optimizing the ultrasonic signal occurs every time the flowmeter is powered up, or after setting new pipe and liquid specifications. The whole process may take 5 to 10 seconds, and during this time a convenient message appears on your display indicating “searching flow.” If the flowmeter successfully detects the ultrasonic signal, and is able to measure flow, then the message disappears and measurement continues. However, if the flowmeter is unable to detect an ultrasonic signal, then it will continue to search until a signal is found. In this case, the flowmeter is telling you something important about your system!
If “searching flow” is shown on the screen continuously (more than 40 seconds), then the flowmeter is telling you that it cannot detect any ultrasonic signal. There are several reasons for this. One reason may be that the setup is incorrect, e.g., the pipe dimensions were entered incorrectly. Be sure to double check that your flowmeter setup accurately reflects the application (pipe dimensions). Another possibility is that the flowmeter’s transducers are not in direct contact with the pipe. Be sure to double check that sufficient coupling gel has been applied, that the transducers are pressed firmly against the pipe, and that the transducer spacing is correct. Remember, the flowmeter is telling you that it cannot detect the ultrasonic signal! So, look for things that might prevent ultrasound transmission; such as air, dried up coupling gel, flakey paint, or internal corrosion or fouling! Any of these things may significantly impede the transfer of ultrasound into the pipe and fluid thus preventing measurement.
So, be sure to pay attention to the “searching flow” message. It may be communicating something important about your piping system. In most cases, the searching process occurs only periodically and assures that you get the most accurate measurement possible – since the meter is able to dynamically adapt to changing conditions. In those occasions when searching occurs indefinitely, there may be something important to learn about your particular piping and fluid system. Remember to ask yourself “what about my piping and/or fluid system is preventing the transfer of ultrasound?”
As always, please feel free to contact SoundWater with your questions. We are here to support you.
Happy flow metering!
Jeff Peery, CEO
