Panametrics DigitalFlow GC868, Руководство для стартапов

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DigitalFlow™ GC868 Startup Guide (1 and 2-Channel) 1-2
Chapter 1. Installation
1.3.3 Transducer
Location
The Model GC868’s accuracy depends primarily on the location and alignment of
the transducers. In addition to accessibility, when planning for transducer location,
adhere to the following guidelines:
1. Locate the transducers so that there are at least 20 pipe diameters of straight,
undisturbed flow upstream and 10 pipe diameters of straight, undisturbed flow
downstream from the measurement point. To ensure undisturbed flow, avoid:
sources of turbulence in the gas such as valves, flanges, expansion joints, tees
and elbows; swirl; and dips or low spots in which condensed liquid may collect.
2. Because condensate or sediment at the bottom of the pipe may cause
attenuation of the ultrasonic signal, locate the transducers on either side of a
horizontal pipe, where possible. If limited pipe access necessitates top and
bottom-mounted transducers, shift the transducers to at least 10° off top center.
This will minimize the influence of any sediment or condensate traveling at the
lowest point in the pipe.
1.3.4 Cable Lengths
Locate the transducers as close as possible to the electronics console. Panametrics
supplies standard 10-ft (3 m) transducer cables to connect between the
transducers and the field mounted preamplifier. The connection from the
preamplifier to the electronics can be up to 500 ft (153 m) in length. If longer cables
are required, consult the factory for assistance.
1.3.5 Temperature and
Pressure
Transmitters
When installing temperature and/or pressure transmitters, locate them downstream
of the flowmeter transducers. These transmitters should be positioned no closer to
the flowmeter transducers than 2 pipe diameters and no further away from the
flowmeter transducers than 20 pipe diameters. The temperature measurement can
be made via contact RTD, but the pressure gauge must be tapped into the process
pipe.
Note: If you are using a 3-wire RTD for temperature measurement, the Model
GC868 requires an RTD input board. For monitoring pressure, the GC868
requires a 4-20 mA analog input board. If neither of these options are
installed, the GC868 can be programmed for static temperature and
pressure values.
1.3.6 Transducer Cables
When installing the transducer cables, always observe established standard
practices for the installation of electrical cables. Specifically, do not route transducer
cables alongside high amperage AC power lines or any other cables that could
cause electrical interference. Also, protect the transducer cables and connections
from the weather and corrosive atmospheres.
Note:
When using non-Panametrics cables to connect the flowmeter transducers
to the Model GC868 electronics console, the cables must have electrical
characteristics identical to the Panametrics cables. Type RG 62 A/U coaxial
cable should be used, and each cable must be the same length (within
±4 in. or 100 mm.).
ATTENTION EUROPEAN CUSTOMERS! In order to meet CE Mark
requirements, all cables must be installed as described in Appendix
A, CE Mark Compliance.