The SV family of flow sensors is designed to reliably detect the flow rate of water-based media. It includes outputs for both flow rate and medium temperature.
Flow rate of cooling water supply and return lines is critical in many applications, but instruments can be expensive. What if you could monitor flow rate in more of your supply and return lines?
The vortex flow meter technology provides good accuracy at an affordable price.
The vortex flow principle is a proven method for measuring flow of water based liquids. Behind a blunt body integrated in a measuring pipe, the flowing liquid generates vortices that are detected by a piezoceramic sensor. Since the cross section of the pipe is known, the number of vortices determines the flow rate, independent of the liquid's pressure and temperature fluctuations. This technology enables a simple, low cost and easily manufactured flow meter.
Q. What are the medium limitations?
A. The specified accuracy can only be achieved when the medium is 95% water.
Q. What is affected if the medium is less than 95% water?
A. First, accuracy will be affected based on the kinematic viscosity, ν, of the medium. For 1 < ν < 4 cSt, accuracy is 3% of full range. For 4 < ν < 14 cSt, accuracy is 4% of full range.
Second, because it is more difficult to form vortices in viscous media, a higher minimum flow rate is required. The chart below shows this effect. Example shown: for kinematic viscosity of 6 cSt, minimum flow rate is 10 lpm.
Q. How do I determine kinematic viscosity for water / glycol mixtures?
A. If you do not know the kinematic viscosity for your mixture, use the chart below based on concentration and temperature. Example shown: For 40% glycol / water mixture at 20 °C, kinematic viscosity is 4 cSt.
Q. What is the effect of solids in the medium?
A. Small quantities of solids do not influence the measurement. Of course, the size and quantity must be such that the meter is not mechanically damaged.
Q. Do changes in medium pressure or temperature affect the measurement of the meter?
A. No, so long as the pressure and temperature remain within the specified values.
Q. Is a frequency output the same thing as a pulse output for totalizing?
A. No. For totalizing applications, a pulse output is required. A 24 VDC signal is sent every time a specified volume (e.g., 0.1 gallons, 1 ml, etc.) flows through the meter regardless of the flow rate. A frequency output provides a digital signal directly relatable to the flow rate. This digital signal can be further evaluated with counters, PLCs, etc. Frequency outputs are often used for mechanical flow meters like turbine meters. The rotational motion of the turbine, which turns according to the flow rate, is detected and converted into frequency signal.
For meters with totalizing function, please refer to the SM and SU families.