CONNECTIONS
Connecting to Control Devices.
It is often desirable to
connect an FPR 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 con-
nect 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
(100 mA 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 FPR flow sensor with some form
of 4-20 mA transmitter. One option is the Omega DPF75-
A, which provides rate and total readings as well as 4-20
mA output.
Red
White
Black
Red
White
Black
Signal
+DC Voltage
Ground
Signal
+DC Voltage
Ground
Figure 1
Figure 2
Input Designed for Current
Sinking (NPN) Devices
Input Designed for Current
Sourcing (PNP) Devices
2.2K Ohm Pull-up
Resistor
NPN
Device
NPN
Device
INSTALLATION and CONNECTIONS
Red
White
Black
Red
White
Black
Signal
+DC Voltage
Ground
Signal
+DC Voltage
Ground
Figure 1
Figure 2
Input Designed for Current
Sinking (NPN) Devices
Input Designed for Current
Sourcing (PNP) Devices
2.2K Ohm Pull-up
Resistor
NPN
Device
NPN
Device
Figure 2
Input Designed for Current
Sourcing (PNP) Devices
NPN Device
PNP Device
Figure 1
Input Designed for Current
Sinking (NPN) Devices
NPN Device
NPN Device
Piping Requirements.
Standard fittings are female NPT. If
the piping connected to the meter is metallic, care should
be taken not to overtighten. Straight pipe of at least five
diameters upstream of the meter is recommended. Verti-
cal, horizontal, or inverted (lens down) installations are all
acceptable.
Installation
K-factor on label
Warning:
This meter has low-friction
bearings. Do not at any time test op-
eration of the meter with compressed
air. Doing so will subject it to rotational
speeds many times those for which it
was designed, and will certainly damage
the rotor, shaft, and/or bearings.
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. If the K-fac-
tor becomes unreadable, nominal K-factors from chart on
previous page may be used.
