Site Considerations; Electronics Console Location; Flowcell Location; Transducer Location - GE DigitalFlow DF868 Startup Manual

Chapter 1. Installation

1.3 Site Considerations

Because the relative physical locations of the flowcell and the Model DF868 electronics console are important, use the
guidelines given in this section to plan the Model DF868 system installation.

1.3.1 Electronics Console Location

The standard Model DF868 electronics enclosure is a Type-4X weather-resistant, dust-tight, indoor/outdoor type.
Typically, the electronics console is mounted in a meter shed. When choosing a mounting site, make sure that the
location permits easy access to the console for programming, testing, and servicing.
Note: For compliance with the European Union's Low Voltage Directive (73/23/EEC), this unit requires an external
power disconnect device such as a switch or circuit breaker. The disconnect device must be marked as such,
clearly visible, directly accessible, and located within 1.8 m (6 ft) of the Model DF868.

1.3.2 Flowcell Location

The pipeline flowcell consists of the flow transducers and any temperature transducers employed as part of the
flowmeter system. Ideally, choose a section of pipe with unlimited access as the flowcell, such as a long stretch of pipe
that is above ground. However, if the flowcell is 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 DF868'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 10 pipe diameters of straight, undisturbed flow upstream and 5 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.
2. Because sediment at the bottom of the pipe and gas at the top 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
center. This will minimize the influence of any sediment or gas on the reflected ultrasonic signals.

1.3.4 Cable Lengths

Locate the flowcell/transducers as close as possible to the electronics console. The factory supplies transducer cables
up to 1,000 ft (306 m) in length. If longer cables are required, consult the factory for assistance.

1.3.5 Temperature Transmitters

When installing temperature transmitters in the flowcell, locate them downstream of the flow transducers. These
transmitters should be positioned no closer to the flow transducers than 2 pipe diameters and no further away from the
flow transducers than 20 pipe diameters.
2 DigitalFlow™ Multipurpose Ultrasonic Liquid Flowmeter Startup Guide (1- and 2-Channel)