Seametrics SES - Manual (Page 3)

INSTALLATION and CONNECTIONS
INSTALLATION
Piping Requirements.
Standard fittings are female NPT.
Straight pipe of at least five diameters upstream of
the meter is recommended. Vertical, horizontal, or
inverted (cover down) installations are all acceptable.
Warning: This meter has low-friction bear-
ings. DO NOT, AT ANY TIME, test operation
of the meter with compressed air! Doing so
will subject it to rotational speeds many times
those for which it was designed, and will cer-
tainly damage the rotor, shaft, and/or bearings.
CONNECTIONS
Connecting to Non-Seametrics Control Devices.
It is often desirable to connect an SES flow sensor to a PLC
or industrial computer board, and the sensors are well suited
for this. Typically it can be connected directly, or with a single
resistor added. The pickup sensors are current sinking (NPN)
GMR devices that require 5-24 Volts DC and 2 mA current. They
can connect directly to a PLC or computer board (see Fig. 1) if:
1. The sensor power supply on the PLC is 5 - 24 Vdc
(24 Vdc is typical).
2. The sensor power supply can provide at least 2 mA
(100mA is typical).
3. The sensor input on the PLC can accept a current
sinking device.
4. The PLC frequency response > flow meter output
frequency.
If the PLC input only accepts current sourcing devices, a pull-
up resistor must be added (see Fig. 2). Typically, on a 24 Vdc
input a 2.2 K Ohm resistor will be effective.
Since the three-wire pickup sensors are solid state, they do
not exhibit switch bounce and can be used at relatively high
frequencies.
If the PLC is equipped with a 4-20 mA analog input module,
it is necessary to order the SES flow sensor with some form
of 4-20 mA transmitter. Two options are the AO55 blind
transmitter and the FT420 indicating transmitter. Follow the
connection diagrams for these products to connect to the
analog input.
Red
White
Black
Signal
+DC Voltage
Ground
Figure 1
Input Designed for Current
Sinking (NPN) Devices
NPN Device NPN Device
Red
White
Black
Signal
+DC Voltage
Ground
Figure 2
Input Designed for Current
Sourcing (PNP) Devices
2.2K Ohm Pull-up
Resistor
NPN Device PNP Device
Page 3
K-FACTOR ON LABEL
K-Factor. The meter is factory calibrated. The K-factor is found
on the label on the meter body and must be input into the
control/display for accurate reading.