Meter Selection Guide

Correct specification of the appropriate meter is necessary to achieve desired accuracy and suitable data output, as well as to ensure safety in each application. While for most applications, the specification of the appropriate meter will be straightforward, using the specification process outlined below, for some applications there may be additional technical considerations which need to be assessed on a case-by-case basis. In all circumstances we recommend that you consult with Macnaught’s Technical Support Team to select the most appropriate meter for your needs The following steps are provided as general guidelines to assist with correct meter specification. However, to ensure accuracy of specification in relation to your application, we recommend seeking expert advice before making the final selection of the appropriate meter. Please note that Macnaught’s Technical Support Team is available free-of-charge to assist in the specification and identification of a suitable meter.

Flow Meter Size

Macnaught Positive Displacement Flow Meters are available in a range of sizes that are engineered to provide high accuracy across a wide turn down ratio. Figure 3 assists in interpreting your process flow rate, which is an important determinant to the accuracy of your meter. The size of meter should be selected for maximum coverage for your operating flow rates. As shown in Figure 4, the accuracy of the meter is optimal near the mid-range of the meter flow range. In some instances the required flow rates can fall across two meter options, e.g. if the required flow rate is 1 GPM both the MX09 & the MX12 are suitable, in such cases it is recommended to select the meter where the flow range is within the upper 50% of the meter’s flow range limits, i.e. the MX09 is preferred.

Macnaught standard ‘single point’ calibration is carried out at mid-flow range where the individual K-factor is assigned to the meter. Identifying the correct meter size for the operating flow rates will ensure the longevity of the meter and deliver optimal accuracy during its operation. For instances where operation is necessary outside the designated mid flow range of the meter, it is recommended that an optional ‘multi-point’ calibration is performed which will help ensure maximum accuracy is achieved. We recommend consulting Macnaught’s Technical Support Team before final selection.

Chemical Compatibility

o determine the most appropriate materials combination for each application it is essential that the wetted components of the meter assembly are confirmed for chemical compatibility. Macnaught meters are available in standard materials configurations, as shown on the quick reference table below (figure 5): common fluid types are listed and the recommended materials combination for each of them is indicated. For a more comprehensive chemical compatibility guide, please refer to Appendix E on page 79. The chemical compatibility guides referred to above are intended to provide general guidance on chemical compatibility. It is highly recommended that the data is checked on a case-by-case basis, as individual process variations in chemical concentration and temperatures from those of the reference data can influence compatibility. We advise seeking expert advice from Macnaught’s Technical Support Team to confirm the materials selection.