Vol.3 No.6 Subject: Flow Measurement News Date: 11-9-01 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 ******************************************* Choosing the Optimum Flow Measurement System Part I: Dirty and Contaminated Fluids This is the first in a series of newsletters looking at how to choose the optimum flow measurement system for various types of fluids. We start with one of the most common "problem" fluids, dirty and contaminated flows. It may seem obvious but, unless you have experience, always start by reviewing the application rather than deciding about the type of flowmeter you want first then trying to fit it to the application. Ask yourself the following questions about the fluid characteristics: What is the percentage solids in the flow, including the maximum percentage which the flowmeter may have to handle? What size are the solids? Naturally they must be able to pass through the flowmeter without clogging. Also consider the shape of the solids. Will the meter be handling tangling solids, such as tumbleweed or twine? These solids present particular difficulties for' in-stream' measurement methods, i.e. meters with measuring elements in the flow. Is the fluid abrasive or corrosive? This effects not only the choice of meter type but also the choice of construction materials. Once you have a good picture of the flow characteristics, compare the different types of flowmeter. The most common and least expensive choice for dirty and contaminated fluids is the propeller meter. These instruments come with various propeller designs, and in a wide range of construction materials. Pay close attention to the quality of construction, and if you are measuring abrasive flows, choose a meter that has a shield on the bearings. The bearings and gears are the most vulnerable parts of the propeller meter. The second favorite choice for dirty and contaminated fluids is the electromagnetic meter or magmeter, which uses a non-invasive measurement method. This makes the magmeter ideal for the toughest fluids, those containing tangling or large solids, as well as for applications in remote or hard-to-reach areas. Magmeters also have higher measurement accuracies of +/-0.5%, although this application rarely calls for accuracies higher than 2%. Both DP-type meters and rotameters tend not to be used for measuring dirty and contaminated fluids, unless particular circumstances, such as a tight-fit installation, dictate. Because they can accumulate solids in the meter, which affects performance and reading accuracy, except the V-Cone, the cone of which deflects the solids away from the reading element. Choosing the 'optimum' flow measurement system for dirty and contaminated fluid is a process of balancing the application requirements, your budget and the performance of various flowmeters. McCrometer manufactures a full line of quality propeller meters and magmeters, so for more information contact your McCrometer flowmeter expert at 951-652-6811 or visit our web-site www.mccrometer.com/testing. ******************************************* 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