Intek 111D - Manual (Page 7)

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MAN114 REV C.wpd
tube transducer, whether flanged or not, must not be used to pull other piping together or to
make up angular mismatch of fittings. The transducer junction box (if supplied) should never
be rotated for any reason.
The 1 '
16
" tube transducers may be sleeved with a
c" tube for added support. Connection
should always be made to the 1 '
16
" tube, as there is no assured seal between the flow tube and
the
c” support sleeve.
Some tube transducers have an integrally mounted cable; do not pull on this cable, or attempt
to remove the fitting where the cable enters the sensor shell.
Fluid temperatures other than ambient require special attention. Thermal gradients from one
end of the transducer to the other, as well as along the radius of the connection pipe, are
undesirable. Therefore, effective insulation should be installed around the inlet and outlet
straight line runs. Gradients which may exist in the line further up stream can be removed if
an insulated elbow is installed in the line prior to entering the straight line portion of the
plumbing. Metallic support braces for the sensor or adjoining plumbing can act as a heat sink
and cause operational problems in high temperature applications. The support braces should
be thermally isolated from the line to avoid large heat conduction effects.
If the transducer is for use above 300°F, it will have a side arm and connector box, where the
internal high temperature wiring is connected to the lower temperature transducer cable. Free
air should be allowed to flow around the side arm and connector box to keep the box cool.
The side arm can be insulated up to one third of its length from the transducer body.
In these applications, proper thermal control is vital to accurate meter performance. Non-
uniform heat tracing, relay on/off temperature controllers and oscillating proportional type
control should always be avoided. Steam trace lines with good pressure regulation or properly
tuned proportional temperature control systems are effective in maintaining uniform fluid
temperature. A box around the sensor and inlet tubing is highly recommended for operating
temperatures higher than room ambient. Allow enough inlet tubing inside the box to allow
the fluid temperature to become the same temperature as the surrounding air. Separately
control the box air temperature at the same temperature as the incoming fluid temperature
to minimize thermally induced indication errors.
Flow stream conditioning must also be considered to maximize meter performance. Avoid
upstream protrusions and short distance straight runs. Flow pulsations, such as those created
by metering pumps, may cause the instrument to differ from the factory calibration.
Furthermore, if the flow is varied by stroke and by pump speed adjustment, the indication will
most likely be non-repeatable. If you are using a pump of this type, it is recommended that
a pulsation dampening device be used to provide smooth continuous flow. A second choice
would require readjustment of the instrument calibration (cal) potentiometer after installation
(See SECTION 4.2).
For liquid measurement systems using high pressure gas to force flow, the effects of the
absorbed gas must be considered. In these cases, sudden pressure drops up stream of the
sensor such as line size expansions, control valves, and pressure dropping regulators must be
avoided. Sudden pressure drops can cause the absorbed gas to release into the liquid, making