Appendix C
A-60
INSTALLING THE TRANSDUCERS
This chapter covers the procedures for installing the transducers. It covers guidelines for
selecting a measurement site (Section 4.1) and describes the procedures for spacing and
mounting the transducers (Section 4.2). Three different mounting methods are described:
the V method, Z method, and W method (Section 4.4).
4.1 Measurement Site Selection
Prior to installing the transducers, a proper site must be selected to ensure accurate
measurement. Examples of site recommendations are illustrated in Figure 4-1.
Use the following guidelines when selecting the transducer site:
!
Choose a section of pipe which is always full of liquid, such as a vertical pipe with
up flow or a full horizontal pipe.
!
The site should have a straight run equivalent to at least 10 pipe diameters upstream
and 5 pipe diameters downstream from any elbows, tees, throttling valves, orifices,
reduced sections, or other flow disturbances.
!
After a pump, control valve, or double piping bend, up to 30 diameters of straight run
may be required upstream from the flowmeter for greater accuracy. A distance of
5 diameters downstream is usually sufficient under all circumstances.
!
On horizontal pipes, always mount the transducers on the sides of the pipe, in the
3 o'clock or 9 o'clock positions. (This avoids sediment along the bottom of the pipe and
gas bubbles or air pockets along the top of the pipe, which can cause signal loss.)
!
Ensure that the pipe skin temperature is within the transducer temperature rating. The
transducers are rated for -40 to +300°F (-40 to +150°C), at 77°F (25°C) ambient
temperature. Higher ranges are available with optional high temperature transducer
blocks (Section 4.5).
!
If possible, select a section of pipe where the inside is free from excessive corrosion or
scaling. Such conditions can make accurate measurement difficult or impossible.
If any or all of the above guidelines cannot be followed completely, it is still possible to
obtain meaningful flow measurements, often with little or no loss of accuracy.
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