Dwyer FLMG - Manual (Page 6)

Page 3
EQUALIZATION AND GROUNDING
Metal Pipe Installations. To equalize the electrical potential
of the fluid, the FLMG meter, and the surrounding pipe, secure
the flange plates (factory-installed on the equalization lug) to
both pipe flanges at one of the bolt holes, as shown below.
Be sure the lockwasher fits between the pipe flange and the
flange plate.
Equalization Diagram
Equalization Lug
Meter
Flange Pipe
Flange
Bolt
Run wire from equalization lug to both pipe flanges;
secure flange plates under bolt heads as shown.
Meter Flange
Pipe Flange
Flange Plate
Lockwasher
WARNING: ELECTRICAL SHOCK HAZARD When
the meter is externally AC powered, the piping sys-
tem must be grounded to meet national and local
electrical safety codes. Failure to do so can result
in electrocution.
Plastic Pipe Installations. When the FLMG is installed in a
plastic piping system, it is not necessary to use the equaliza-
tion straps, but very important to ground the meter to avoid
electrical shock hazard and electrostatic interference with
meter function.
INSTALLATION
Positioning the Meter. These meters can be installed
horizontally, vertically, and in any radial position.
Straight Pipe Recommendations. As with most flow
meters, the FLMG requires some straight pipe before and
after the meter for best accuracy. However, the ability of
electromagnetic meters to average the flow across the entire
pipe allows for shorter straight pipe recommendations than
most mechanical meters (see page 4).
Full Pipe Recommendations. All magmeters require a
method for determining that the pipe is empty, to prevent false
reading. This meter is designed to go to zero reading if one
or more electrodes is exposed. For highest accuracy, install
the meter so that the pipe will be full when there is flow. If air
bubbles may be present in the pipe or sludge accumulation
is an issue, rotate the meter by one flange hole to position
the control housing at a 45˚ angle (see diagrams on page 5).
Fittings. The FLMG flanges have standard ANSI 150 lb drilling
and mate with any other ANSI 150 lb flange.
Calibration. The FLMG is factory-calibrated and will not require
any form of field calibration.
Caution: These flow sensors are not recommended
where installation fault may expose the flow sen-
sor to boiler pressure and temperature. Maximum
recommended temperature is 130˚ F.
INSTALLATION and GROUNDING
Caution: In chemical injection ap-
plications, install chemical injection
point downstream of magmeter, or far
enough upstream to allow complete
mixing of fluids before the meter.
Chemical Injection. When any magmeter, by any manufac-
turer, is used in a chemical injection application, the chemical
injection point must be placed downstream of the magme-
ter OR far enough upstream for complete mixing to occur
before the fluid reaches the meter
. When unmixed chemical
alternates with water passing through the meter, the rapid
changes in conductivity may cause sudden spikes and drops
in the meter’s reading, resulting in inaccurate measurement.
The magmeter will restabilize, however, with a steady flow of
fluid of uniform conductivity.
Metal
Pipe
Metal
Pipe