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S-Series (SPX, SPT)
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Low Flow Meter Instructions
General Information
These versatile impeller flowmeters in 3/8" to 1"
nominal pipe size employ jewel bearings for very low
minimum flows. The 6-24 VDC pulse output of these
meters is compatible with many different types of
control, including a full range of SeaMetrics rate displays
and controls. The SeaMetrics FT420 provides flow rate
and total flow, with 4-20 mA ouput. For metering pump
pacing or interfacing with lowspeed counters, the PD10
divider is recommended. The AO55 is a blind 4-20mA
transmitter.
S-Series meters are available in 3/8" to 1" nominal sizes.
The SPX body material is polypropylene, with transparent acrylic covers for visual flow indication.
Polypropylene covers are available as an option.
The SPT is available standard with TFE housing, TFE
cover, PVDF rotor, ceramic shaft, choice of o-ring
material (EPDM or Viton), and optional silicon carbide
shaft.
Specifications
Connections
3/8", 1/2", 3/4", 1"
Female NPT standard,
SAE thread optional
Materials
Body SPX: Polypropylene,
SPT: TFE
Cover SPX: Acrylic, Polypro optional
SPT: TFE
Rotor PVDF
Shaft SPX: Nickel tungsten carbide,
zirconia ceramic optional
SPT : zirconia ceramic, silicon
carbide optional
Bearings Ruby
Max. T emperature 160° F (70°C)
Max. Pressure 150 PSI (10 bar)
Accuracy ±1% FS
Flow Rates
Size GPM LPM
3/8" 0.07 - 5 0.27 - 18.9
1/2" 0.1 - 10 0.38 - 37.9
3/4" 0.2 - 20 0.75 - 75
1" 0.5 - 40 1.90 - 150
Features
Removable thread-in
18 ft. standard cable
Standard acrylic top
provides sight flow
indication
3/8"-1" NPT ports
machined into body
sensor 12 VDC pulse
for superior wear
Kynar rotor
Jewel bearings
and flow range
LT-10624A
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Installation
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Repair
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. Vertical, horizontal, or inverted (lens down)
installations are all acceptable.
Warning: This meter has lowfriction bearings. 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 certainly damage
the rotor, shaft, and/or bearings.
Electrical Connections. There are three conductors to
the sensor, two for positive and negative power and one
for the signal. See the diagram below for color coding.
(BLACK) Power (-)
Rotor Replacement. There is only one moving part to
this meter. The bearings are made of ruby , which rarely
wears out, and will not need replacement unless they
have been physically damaged by severe shock. The
shaft is integrally molded into the rotor, and shaft and
rotor are replaced as one part. To replace the rotor,
remove all pressure from the meter. Then remove the
four screws which hold the lens (or cover) in place. Lift
the lens, then remove the rotor. When putting in the
new rotor, be sure that the end of the shaft is started
into the bearing before the lens is put into place.
When putting on the lens, be sure that the shaft is
also started into the upper bearing before lowering the lens into place. If any resistance is met
when the lens is replaced, the shaft is not started
into one of the bearings. Check that the lens oring is also in place, then replace the four screws
and tighten.
Sensor Replacement. The sensor ordinarily does not
need replacement unless it is electrically damaged. If
replacement is necessary, unthread the sensor by
hand. Thread the replacement sensor in and tighten
by hand.
SPX sensor connection
Nominal K-factor
(WHITE) Signal
(RED) Power (+) 6-24 VDC
Field Replacement of Sensor
K-factor on
model/serial
label on back
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Connecting to non-SeaMetrics Control Devices
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It is often desirable to connect an S-Series flow sensor to a PLC or industrial computer board, and the
sensors are well suited for this. T ypically it can be connected directly , or with a single resistor added. The SSeries pickup sensors are GMR devices which need
5-24 Volts DC and 2 mA current, and they are current
sinking (NPN).
These sensors can connect directly to a PLC or computer board if:
1. The sensor power on the PLC is 5 - 24 VDC (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.
See Figure 1 for connections.
Input Designed for Current
Sinking (NPN) Devices
If the PLC input only accepts current sourcing devices,
a pull-up resistor must be added. Connection of this
resistor is shown in Figure 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 flow sensor with
some form of 4-20 mA tranmitter . Two options are the
AO55 blind transmitter and FT420 indicating transmitter. Follow the connection diagrams for these products to connect to the analog input.
Input Designed for Current
Sourcing (PNP) Devices
NPN
Device
Red
White
Black
Figure 1
+
DC Voltage
Signal
Ground
2.2k Ohm Pull-up
Resistor
NPN
Device
Red
White
Black
Figure 2
+
DC Voltage
Signal
Ground
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SPX, SPT Parts Listing
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1 Bearing Assembly 16772 (2 each)
2* Rotor with Shaft 11127 (Kynar/ceramic/2 magnet)
11129 (Kynar/carbide/2 magnet)
11133 (Kynar/silicon/2 magnet)
11132 (Kynar/ceramic/6 magnet)
11130 (Kynar/carbide/6 magnet)
26456 (Kynar/silicon/6 magnet)
3 Body
4 SPX Lens 16018 (Polypro)
16022 (acrylic)
SPT Lens 26174 (TFE)
5* O-Ring: EPDM 25081
VITON 16455
6 SPX Screw 07687 (4 each)
SPT Screw 07685 (4 each)
SPT Hexnuts 07705 (4 each)
7 Flow Direction Tag 19036
8* Sensor 26310
*recommended spare parts
20419 80th Ave. So., Kent, WA 98032 USA
Phone: 253-872-0284 Fax: 253-872-0285
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www.seametrics.com 1-800-975-8153
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