6. Using Flow Sensors Or Flow Meters With Different Gases .............. 13
1. General ...................................................................................... 15
2. Cleaning And Flushing ................................................................ 16
3. Returning Units For Repair Or Recalibration .................................. 16
F-20-TFP-G, pg. 2 of 27
A.Introduction
1.Unpacking
All sensors are suitably packaged to prevent damage during shipping. If
external damage is noted upon receipt of the package, please contact
shipping company
to the device once it has left the manufacturing premises.
Open the package from the top, taking care not to cut too deeply into the
package. Remove all the documentation and contents. Take care to remove
all the items and check them against the packing slip. The products should
also be checked for any concealed shipping damage. If any shortages or
damage is noted, please contact the shipping company and/or Dwyer
Instruments to resolve the problem.
immediately. Dwyer Instruments is not liable for damage
Typical Contents of Box
CAUTION: Take care not to
drop
your sensor or subject it to
sudden impact. Read the installation section of this manual before
providing power or tubing connections to the unit. Any damage
caused by improper installation or careless handling will not be
repaired under warranty (see limited warranty on page 27 for
more details).
F-20-TFP-G, pg. 3 of 27
2.Product Overview and Principle of Operation
TFP Series Flow Meters and Flow Sensors for gases are capable of
measuring volumetric flows as low as 20-100 ml/min or as high as 100500 l/min. Highly repeatable results are achieved using a patented Pelton
Turbine Wheel flow sensor design. This proven design minimizes zero drift
while maintaining fast response and linear outputs with virtually no
maintenance.
Patented technology measures flow using a miniature turbine wheel similar
in size to a U.S. dime (16 mm diameter, 0.75 mm thick). The micro-turbine
wheel is supported on a very small sapphire shaft that is held in position by
two sapphire bearings.
As flow passes through the flow sensor, a precision machined nozzle directs
the gas onto the very small teeth of the micro-turbine wheel. This causes the
wheel to spin at a speed proportional to the volumetric flow rate.
The micro-turbine wheel has alternating white and black sections evenly
spaced on one side of the wheel. An infrared light beam is directed onto the
wheel. As the wheel rotates the infrared beam is reflected off each white
section. The reflected beam is detected by a phototransistor that converts the
reflections into electrical pulses. As the wheel spins faster the pulse rate
increases. Processing circuitry provides analog and/or pulse output that are
linearly proportional to the volumetric flow rate
When the wheel stops (under zero flow conditions), no pulses are
generated. Consequently, zero drift is not possible and zero adjustments are
never required.
Every unit is supplied with a calibration certificate detailing the results
obtained during calibration. Units are calibrated using AIR as the reference
media. Flowing gases with different physical characteristics may affect the
calibration.
F-20-TFP-G, pg. 4 of 27
B.Installation
CAUTION: Do not exceed the pressure, temperature or power
operating ranges detailed in the Specifications section of this
manual. Dwyer Instruments shall not be liable for any damage or
injury caused by incorrect operation of their products.
1.General Considerations
It is recommended that a safety shut-off valve be installed upstream of
(before) the sensor.
All wetted parts should be checked for compatibility with the gas to be used.
If there are any incompatibilities e.g. highly corrosive gas, then the unit may
be damaged or fail prematurely. Such damage will not be repaired under
warranty.
Units should be installed in a clean, dry environment with an ambient
temperature that is as stable as possible. Avoid areas with strong magnetic
fields, strong air flows or excessive vibration.
If the gas to be used may contain particles larger than 25 microns then a
filter (25 microns or less) should be installed upstream of (before) the unit.
2.Mounting The Flow Sensor Or Flow Meter.
CAUTION: On high flow units (2.0-10.0 L/min and above) DO
NOT disassemble the shunt / mounting plate assembly or the unit
will not operate correctly and the warranty will be void.
The TFP Series of Flow Sensors and Flow Meters have no particular
installation requirements so may be mounted in any convenient position. For
optimum results the unit should be mounted with the mounting feet horizontal
on top of a flat horizontal surface. This is the same position that the unit is
calibrated in at the factory. Please contact Dwyer Customer Service if
calibration for mounting in another orientation is desired.
It is recommended that units be fixed to a suitable substrate with #4 screws
using the two mounting holes provided.
F-20-TFP-G, pg. 5 of 27
Mounting The Sensor
(Mounting hardware not included with sensor)
3.Tubing Connections
CAUTION: DO NOT FLOW ANY LIQUID THROUGH A GAS
FLOW SENSOR OR FLOW METER. THIS WILL SERIOUSLY
AFFECT THE PERFORMANCE AND VOID THE WARRANTY.
CAUTION: DO NOT FLOW A HIGH PRESSURE GAS
THROUGH THE SENSOR. A burst of high pressure gas may
cause the unit to be damaged. Always flow gas at a pressure and
flow rate within the specifications of the unit.
All tubing must be clean, dry and without crimps, burrs or scratches.
Only use the factory installed fittings on the unit. If the fittings are removed
the calibration of the unit may be effected and leaking may occur. If
different fittings are required please contact the Dwyer Instruments Service
Department for assistance.
When connecting the sensor to the tubing a wrench should be used to stop
the fitting rotating in the sensor body. Take care not to over tighten the
fittings or leaking may occur.
F-20-TFP-G, pg. 6 of 27
Connecting and tightening the Fittings
CAUTION: DO NOT over tighten the fittings into the sensor
body. Excessive force may damage the sensor body. This type of
damage will NOT be repaired under warranty.
The flow direction for the unit is clearly marked on the label. Do not reverse
the flow direction or the unit will not function.
Close Up of Label Showing Flow Directions
(All models similar)
The tubing ID should be as large as possible to avoid restrictions and
turbulence. For the best results, a straight length of tubing before the unit is
recommended. This should be 20 times the tubing I.D. or greater.
F-20-TFP-G, pg. 7 of 27
4.Electrical Connections
CAUTION: Incorrect wiring may cause severe damage to the
unit. Applying an AC voltage (115VAC or 230VAC) directly to
the unit will cause damage. Read the following instructions
carefully before making any connections.
a)Overview
The TFP-GV Series provides a 0-5VDC output proportional to the volumetric
flow rate. This output may be connected to a display, data acquisition
system or voltmeter.
The TFP-GI Series features an integral display that provides a local flow
reading. These units also have a 0-5VDC analog output available. If
required, this may be connected to another display, data acquisition system
or voltmeter.
A stable D.C. power supply is required to operate the unit. The voltage and
current requirements depend on the configuration of the unit. Full details
may be found in the Specification section of this manual.
Connecting wires should be as short as possible to avoid voltage drops.
Twisted 2 pair conductor cable of a suitable gauge should be used if the
length of the power wires is to be longer than 1 meter (3.2 feet).
Units are supplied with an integral 4 pin connector. Connections to the unit
are made using a mating cable assembly or power adapter package as
detailed in the following sections. A connector pin and wire color cross
reference may also be found in Appendix F (Page 18) of this manual.
b)Connecting a Cable Assembly
The connector on the cable assembly should be pushed into the mating
socket on the sensor taking care to ensure that it is the correct way up.
Connecting the Cable Assembly
(All models similar)
F-20-TFP-G, pg. 8 of 27
c)Electrical Connections – Voltage Output Units
The cable assembly should be connected to the sensor as detailed in section
4(b) above. Do not apply power to the sensor until all the connections have
been made and checked. Electrical connections should be made as follows:
Wiring Schematic For Voltage Output Units.
The RED wire should be connected to the Positive of the power source.
The BLACK wire should be connected to the Negative ( Ground ) of the
power source.
The WHITE wire provides the signal output and should be connected to the
positive terminal of the display, data acquisition system or voltmeter with an
impedance greater than 2500Ω (Ohms).
The GREEN wire is not used.
CAUTION: Avoid high voltage static discharges to any of the
connections. Do not short the input/output signal wires or allow
them to contact the power wires at any time. DAMAGE WILL
RESULT!
F-20-TFP-G, pg. 9 of 27
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