Seametrics TX100-200-SERIES User Manual

Page 4

INSTALLATION

Page 2

Fair (unacceptable if air is

present)

Fair (unacceptable if fluid

contains sediment)

Best

Immersion.

The TX100/200-Series standard sensors are

not designed for continuous underwater operation. If your
meter may experience occasional temporary immersion, as
in a flooded vault, a unit modified for immersion should be
specified (Option -40).

x Dia.

FLOW

An insertion flow sensor measures the velocity of flow at one
point in the pipe; flow rate and total can be inferred from this
one point. Accuracy is decreased by any factor which makes
the flow at the measured point unrepresentative of the entire
flow stream. This includes distorted flow patterns caused by
upstream fittings too close to the sensor. The worst offenders
are fittings that increase the flow on one side of the pipe, such
as partially-opened gate or butterfly valves. Fluid moving in a
pipe does not flow at the same velocity. Toward the center of
the pipe, fluid moves faster than at the wall, and the relation-
ship between the two changes as overall flow rate increases.
This change in the “velocity profile” can result in non-linearity,
which means that the K-factor (see page 7) that is correct for
one flow rate may be incorrect for another. Recommended
depth settings (see page 6) have been carefully chosen to
minimize this source of error, and should be followed carefully,
especially in the smaller pipe sizes.

Piping.

For best results, the TX sensor should be in-

stalled with at least ten diameters of straight pipe
upstream and five downstream. Certain extreme situations
such as partially-opened valves are particularly difficult and
may require more straight diameters upstream. See Straight
Pipe and Full Pipe recommendations on following pages.

Positioning the Meter.

Horizontal is the preferred instal-

lation orientation, since it improves low-flow performance
slightly and avoids problems with trapped air. Bottom, top,
and vertical pipe installaations are all acceptable if required
by the piping layout.

CAUTION: These water meters are

not recommended for installation

downstream of the boiler feedwater

pump where installation fault may

expose the meter to boiler pressure

and temperature. Maximum recom-

mended temperature is 200ºF.