Flow Meter Installation Guide

• It can be overwhelming when it comes time to install a flow meter with the many factors that need consideration to achieve effective flow measurement.
• The most critical consideration is following straight run requirements to ensure a well-developed flow profile for accurate flow metering.
• Consult the product manual and/or installation guide for recommendations or reach out to your distributor or manufacturer for installation assistance.

Flow meter installation can be intimidating. So, in this article, we will provide a few tips and tricks to make the process easier. Following these instructions will also help prevent measurement issues.

Considerations for Installing a Thermal Mass Flow Meter

Before flow meter installation, consult the product manual and other documentation to notate acceptable limits for the process gas temperature and the environmental temperature to which the transmitter electronics may be subjected. We recommend installing the flow meter at a location where the gas is dry or above the dew point temperature.

Operators must avoid installations which allow large droplets of water to condense out and to come in contact with the sensing element. Installations should also avoid applications with large quantities of gas-borne particulates as this might make the sensor dirty. In turn, a dirty sensor could affect the heat loss to the flowing gas and have a negative impact on the overall accuracy of the flow readings. Gas purge options may be available, if necessary.

Optimum flow meter installation requires sufficient straight run to allow a uniform, non-swirling, fully-developed flow profile within the flow conduit. Consult the manual and installation guide for each product to review minimum straight run requirements. Depending upon the specific location details, more or less straight run may be necessary to produce a satisfactory flow profile.

It is best to avoid installations which are immediately downstream of bends, abrupt cross-sectional area increases or decreases, fans, louvers, or other equipment in the line. These situations can cause non-uniform flow profiles and swirl which can result in signal errors. Problematic flow profiles require flow conditioning to improve meter performance. Consult the manufacturer, distributor, or an engineering firm for additional information and guidance for flow meter installation.

For more information on installing Inline Flow Meters specifically, you can refer to our article: Installing Flow Meters – Inline.

Or, for more information on installing Insertion Style, you can refer to our article: Insertion Flow Meter Installation.

Flow Meter Installation and Mounting Guidelines

Our Master-Touch thermal dispersion sensors require exposure to the flowing gas in the process pipe at a location that provides a uniform and consistent flow profile across the pipe diameter. Each flow meter is calibrated under tightly controlled conditions in an NIST-traceable facility. The factory calibrates our inline style flow meters with the sensors in a fixed position within the flow section.

EPI’s insertion flow meters are calibrated near the ISO Point-of-Average-Flow (.243r) positioning in the process line* with a fully-developed flow profile. However, anomalies in the actual flow profile or installations in non-circular ducts may require adjustments. Operators may need to modify the flow meter’s output signals or readings to achieve the best accuracy.

Furthermore, changes to the process gas composition, gas temperature, line pressure, etc. can affect the overall accuracy of the flow readings. However, in comparison with other flow measurement technologies, these effects are often minimal in thermal mass flow meters.

Master-Touch firmware supports two methods of in situ flow signal adjustments for superior accuracy:

• The C-Factor (Menu 811) adjusts the linearized microprocessor output by a uniform percentage of the readings. Operators should apply this simple adjustment before making any further adjustments.
• Point-Wise adjustments (Menu 750 PW-Curve Fit) provide greater flexibility. They allow adjustments in increments of 5% of the Full Scale, i.e., 10–15% or 65–70%. It is unlikely that more than two or three adjustments are necessary to achieve desirable results. However, we offer the option to apply those adjustments wherever along the Full Scale that you are able to capture the comparative values.