INTRODUCTION
This document explains how to install small pipe transit time
ultrasonic transducers with a rail mounting. The transducers
can be installed vertically or horizontally. For horizontal
applications, install them on the side of the pipe.
The small pipe transducers have integrated transmitter and
receiver elements. A spacing slider is provided to adjust the
required spacing, based on pipe size and mounting method.
PRE-INSTALLATION
REQUIREMENTS
Program the Meter
Before installing the transducers, you must select the
optimum transmission mode, enter the site information, and
enter the fluid and pipe properties into the ultrasonic flow
meter. For detailed instructions, see the user manual for your
flow meter.
Select a Pipe Location for the Transducer
Select a location for the transducers on a section of pipe that
has at least 10 pipe diameters upstream of the transducers
and 5 pipe diameters downstream. See
configuration and transducer positioning” on page 2
For example, if a 2 in. pipe is being measured, the minimum
upstream pipe in front of the transducer should be 20 in.
and the minimum downstream pipe behind the transducer
should be at least 10 in.
Pipe runs shorter than the minimums may sometimes be
used with reduced accuracy. There is no way to determine
how much accuracy is sacrificed without doing in-field
testing. For installations where the 10/5 pipe diameters
rule cannot be followed, divide the total length of available
straight pipe into thirds and mount the rail with 2/3 of the
pipe upstream and 1/3 of the pipe downstream.
A full pipe is absolutely essential for making accurate flow
measurements. The flow meter cannot determine if the pipe
is full or not. If the pipe is partially full, the meter will
over-report the amount of flow by the percentage of the pipe
that is not filled with liquid or may not detect any flow.
Install the mounting system in an area where the transducers
will not be inadvertently bumped or disturbed.
Avoid installations on downward flowing pipes unless
adequate downstream head pressure is present to overcome
partial filling of—or cavitation in—the pipe.
YES
45°
45°
45°
45°
YES
TOP OF
PIPE
Figure 1: Transducer positioning
Transducers
Small Pipe Transit Time Transducers with Rail Mounting (DTTSU)
IND-UM-02647-EN-02 (March 2021)
Installation Guide