| Vol.3 No.5 Subject: Flow Measurement News Date: 10-9-01 From: McCrometer, "The Flow Measurement Specialists" ........ http://www.mccrometer.com ........ ******************************************* This newsletter is e-mailed by McCrometer monthly to subscribers worldwide. It consists of flow measurement information of interest for professionals in this field. For More information on our complete line of flowmeters go to: http://www.mccrometer.com ******************************************* Ask The Experts... How Different Flowmeter Types Display and Transmit Flow Data How is flow data presented by different flowmeters? Can it be easily transmitted to ancillary devices to control flow or trigger alarms? Here, we examine how different flowmeter types display data, and consider the electronic options for data transmission. Most flowmeter types use a register or dial to display flow data. Propeller meters, for example, are fitted with a mechanical register that advances a set amount per each propeller revolution to give the total flow through the meter. On newer models, the register is actually a small electronic device powered by the motion of the propeller. Propeller registers also provide a visual reference for flow rate with a "speed cup" rate indicator, which works much like the speedometer in a car. Other flowmeters provide flow data visually. Variable area meters, or rotameters, are typically clear with a "float" that bobs in the flow stream. How high the float rises in the meter correlates to the rate of flow through the meter. Even differential pressure meters, such as the V-Cone and orifice plate, can provide information visually by using a manometer. The difference in the heights of the manometer's fluid columns correlates to the difference between the high and low pressure ports, and so indicates flow rate. If you need to do more than view the flow data, electronic options are available on most types of flowmeters to transmit data to ancillary devices. Transmitters provide a 4-20 mA output that is proportional to the meter's signal. The signal can be used in various ways: sent to a chart recorder or data logger to determine flow over time; used to control valve openings and, therefore, flow through a piping system; or used to trigger alarms when flow rates get too high or too low. Some transmitters can have multiple outputs and perform some characterization for the meter. This includes accounting for non-linearities in the flowmeter's signal, the effects of gas expansion at different rates of flow, and the effects of flow temperature and pressure on the fluid. However you use the data from your flowmeter, it is useful to understand how different meter types display and transmit data. For more information, contact your McCrometer flowmeter expert at 951-652-6811 or visit our web-site www.mccrometer.com. ******************************************* Copyright 2001 McCrometer ******************************************* Know anyone looking for a steady dose of flow measurement information? ****************************************** To subscribe send e-mail to <mailto:news-request@mccrometer.com>news-request@mccrometer.com with a keyword SUBSCRIBE in the subject field. To unsubscribe, send e-mail to <mailto:news-request@mccrometer.com>news-request@mccrometer.com with a keyword REMOVE in the subject field. ******************************************* To subscribe or unsubscribe online, please go to our website at: http://www.mccrometer.com/subscribe.htm ******************************************* Distributed by McCrometer "The Flow Measurement Specialists" http://www.mccrometer.com |