Seametrics FT420 User manual

SET
PUB -19750-0999
Page 1 of 4
SpecificationsGeneral Information
FT420 Flow Computer
Instructions
The FT420 is a loop-powered microcontroller-based
transmitter/indicator. Itdisplaysrateandtotal,andpro-
vides a 4-20 mA analog signal proportional to flow. A
programmable pulse output is also standard for meter-
ing pump control or data logging.
The rugged cast-aluminum housing is gasketed for
maximum environmental protection, and the electron-
ics are potted into a solid block of urethane. A mem-
brane keypad allows settings to be changed without
removing the cover. The universal mount version
comes with brackets for wall mounting, and also with
an adaptor for field installation on 80-series flow sen-
sors. The FT420 can also be factory or field installed
on a TX100/200 series sensor or WT meter.
Power 4 mA DC (4-20 mA loop),
12-32 VDC
DisplayRate 6-digit autorange, 1/2"
charater height
Total 8-digit, 5/16" character
height
Pulse Output • 0.1 second open collector
pulse (scaled)
• sensor pulse (unscaled)
Input Pulse frequency + 5 VDC
K factor Range 0.050 - 2000
Pulse Output Range 0.1 - 200,000 units/pulse
Temperature 0 C - 70 C
Environmental NEMA 4X
Features
Sturdy gasketed cover
with electronics
potted in
Removeable foot brackets
for wall mounting
Large rate numerals
Easy set-up
prompts Triple bosses for
watertight input/output
connections
10.5
2341678.9
SET K RESET
Two wire
4-20 mA output standard

0
1
2
3
4
5
6
RUN
BATT
CPU
POWER
CPU
7
OUTPUT 24VDCOUTPUT RELAY
AB INPUT 4-20mA AB
Installation
To mount the FT420 on a wall, hold the unit in the
desired position, mark the holes in the mounting feet,
drill, and mount with screws.
This unit can also be mounted directly on a flow
sensor for local reading. If the unit was ordered as
an FT420, factory mounted to the top of a 100 or 200
Series flow sensor, no further installation is required.
To mount the unit on a flow sensor, remove the
housing cover. Place the lower half of the housing in
the groove on the top of the flow sensor. An adaptor
is included in the packaging of the FT420 which
threads into the top of any 80-Series flow sensor. Pull
the sensor wires through the hole in the center of this
adaptor, then thread the adaptor into place. Tighten
the adaptor using a screwdriver. (See diagram).
Connect the wires, then replace the housing cover,
orienting it any direction as desired for viewing
convenience.
Connection
To connect to the FT420 to a flow sensor, follow the
diagram marked “Connections”. This diagram also
shows the connections for an external device, such
as a chemical metering pump.
If the 4-20 mA current signal is not required, connect
the power terminals to any 12-30 VDC current
source.
Programming
At a minimum, every FT420 must be programmed
with the “K-factor”. This is simply the number of
pulses per gallon which the meter or flow sensor
produces. (If you wish the FT420 to read in another
unit, enter the number of pulses per that unit. For
example, if the desired units are liters, the K-factor is
the number of pulses per liter that the flow sensor
produces.)
To find the K-factor on any SeaMetrics flow sensor
fitting or in-line meter, look on the model-serial label.
The line reading K = xxxx is the desired number. For
adjustable sensors (101,201,115,215) look in the
instruction manual under your pipe size.
Set K. Begin by pressing the key SET once. The
prompt SET K should appear on the display. The digit
to the far right will be blinking. Use the up arrow key
to reach your desired digit. Then press the left arrow
key to move to the next digit. Repeat the process
until the entire number is entered. (Note that the
decimal is fixed at three places. If you only have two
decimal places for your K-factor, enter a zero for the
third digit.)
Set P. If the pulse output is to be used, set the
desired pulse rate. This is the number of gallons (or
other units, if you are using them) between pulses.
The second time the SET key is pressed, SET P will
appear. Follow the same process as above to enter
the desired number.
Set 20 mA. Set the flow rate, in units per minute, at
which 20 mA is desired. The processor will automati-
cally scale the 4-20 mA loop accordingly, with 4 mA
at zero flow.
Set Decimal Point. The fourth time the SET key is
pressed, a D prompt appears. Pressing the up arrow
key switches back and forth between no decimal
place and one decimal place.
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!
Caution: If output is being used
tocontrolan external device, such
as a metering pump, do not con-
nect the device until programming
is completed. If malfunction or in-
correct programming of the output could cause
personal injury or property damage, separate
safeguards must be installed to prevent such in-
jury or damage.
Typical 4-20 mA Application
Loop power supply
(if not provided
on PLC)

Standard Connections
Sensor Mount: Step 1 Sensor Mount: Step 2
Sensor Wires
Sensor Wires
Remove
Mounting Feet
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TX81
Flow Sensor
Pulse Responsive
Metering Pump
To Other
Control
12-30 VDC
Loop Power,
4-20 mA Output
Power
4-20 mA Sensor
Pulse
Output Sensor
Output
Red
White
Black

SET
FT420
Sensor-Mount
Dimensions
Operation
To return to normal operation after entering settings,
press SET for a fifth time. The rate and total indicator
numbers should appear in the display. If the unit is
connected to an operating flow sensor, the larger-
sized digits indicate flow rate and the smaller-sized
digits indicate total.
Unless the unit has been ordered with the non-reset
option, a RESET prompt is constantly visible in the
lower right corner, above the up arrow key. Press this
key at any time to reset the totalizer to zero.
FT420
with Wall Mount Brackets
2.06
3.89
3.89
4.31 2.67
2.57
10.5
2341678.9
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power
supply
Chemical
FT420
on TX81
Control Pulses
Flow
Proportional
Chemical
Typical Chemical Metering Pump
Applications