Panametrics DigitalFlow XGS868i, Руководство для стартапов, Страница: 11 / 86

DigitalFlow™ XGS868i Startup Guide 3
Chapter 1. Installation
1.3.2 Flowcell Location
The pipeline flowcell consists of the flow rate transducers and any pressure and/or temperature transducers
employed as part of the flow measurement system. Ideally, choose a section of pipe with unlimited access to the
flowcell; for example, a long stretch of pipe that is above ground. However, if the flowcell is to be mounted on an
underground pipe, dig a pit around the pipe to facilitate installation of the transducers.
1.3.3 Transducer Location
For a given fluid and pipe, the Model XGS868i’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 fluid such as valves, flanges, expansions and elbows; 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 the side of a horizontal pipe, when possible. If limited pipe access necessitates
top-mounted transducers and the sound beam path includes a reflection, shift the transducers to at least 10° off
top dead center. This will minimize the influence of any sediment on the reflected ultrasonic signals.
1.3.4 Cable Lengths
Locate the electronics enclosure as close as possible to the flowcell/transducers, preferably directly on the flowcell.
However, the factory can supply transducer cables up to 1,000 ft (300 m) in length for remote location of the
electronics enclosure. If longer cables are required, consult the factory for assistance.
1.3.5 Temperature and Pressure Transmitters
When installing temperature and/or pressure transmitters in the flowcell, locate them downstream of the
transducers. These transmitters should be positioned no closer to the Model XGS868i transducers than 2 pipe
diameters and no further away from the transducers than 20 pipe diameters.
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 flow rate transducers to the Model XGS868i electronics
enclosure, the cables must have electrical characteristics identical to the Panametrics cables. Type RG62
a/u coaxial cable should be used, and each cable must be the same length (within ±4 in.).