Emerson Rosemount 3108, Быстрый старт

Страница: 13 / 40

Figure 4-2: Recommended Mounting Position
A. Transmitter is mounted vertically (maximum deviation of 3°).
B. 6° beam half angle.
C. 1.3 in./ft. (11 cm/m). Minimum of 12 in. (0.3 m).
Mounting from a conduit
The transmitters can be mounted from a conduit using the optional adaptor
accessory. See
Product Data Sheet for a list of all accessories and their part
numbers.
4.2 Open channel flow installations
Mount an ultrasonic transmitter over an area of clear liquid. Avoid mounting
the transmitter directly over any inlet stream. Never suspend the transmitter
by the cable.
The positioning is critical, and should be the correct distance upstream from
the flow structure as stated in the relevant standard for your country. For
example, in the ISO standards, the distance should be four to five times the
maximum height of the water (Hmax) for a thin plate weir, or three to four
times Hmax for a flume. For optimum accuracy, position the transmitter’s
front face at a height equal to the sum of the maximum flow depth plus the
transmitter deadband of 12.2 in. (300 mm) plus an extra 2 in. (50 mm).
It is important that the bottom reference of the transmitter should be
related to the datum of the primary measuring device (
Figure 4-4 ).
When setting the bottom reference on a ‘V’- notch weir, it is important the
true invert is used (
Figure 4-5 ) and not the meniscus level.
August 2019 Quick Start Guide
Quick Start Guide 13