KOBOLD Model DF Flow Sensor
User Instructions
Kobold Instruments Inc. • 1801 Parkway View Drive • Pittsburgh PA 15205
Phone 1-800-998-1020 • Fax (412) 788-4890 • www.kobold.com
DF-SEN_manual_12/13
Table of Contents
1.0 General . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 1
2.0 Specifications . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 2
3.0 Installation Instructions . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 5
4.0 Operation . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 6
5.0 Arrival of Damaged Equipment . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 7
6.0 Maintenance .. . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 7
7.0 Need Help with your DF Flow Sensor? . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 7
List of Diagrams
Diagram 2.4: Sensor Dimensions .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 4
Diagram 3.1: Wiring . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 5
List of Tables
Table 2.1: Material Combinations and Maximum Limits . . . . . . . . . . . . . . . . . . . 2
Table 2.2: Electrical Data . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 3
Table 2.3: Flow Ranges and Fitting Sizes. . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 3
DF-SEN
KOBOLD Model DF Flow Sensor
User Instructions
CAUTION: For safety reasons, please read the cautionary information located at
the end of the manual, before attempting installation.
1.0 General
The KOBOLD DF flow sensor is intended for use in applications where flow
measurement is desired and the flow rate data needs to be transmitted as a pulse rate
output. The DF sensor contains a flow transducer which transmits a 0-100 Hz (nominal)
signal. This output frequency is linearly proportional to the flow measured by the
instrument and is transmitted by a bipolar transistor operating in an open collector
configuration.
The DF uses a paddle wheel to determine flow. The principle of operation is quite
simple; the paddle wheel rotation speed is calibrated for the maximum flow rate. This
rotation-flow relationship is linear in theory. In practice, theory is nearly borne out,
leading to a very precise measuring device. Any non-linearity is within the stated
measurement error of the device.
The paddle wheel approach to flow measurement has the advantage that the instrument
may be installed in both vertical and horizontal orientations (the axle, however, must
remain in a horizontal plane). Further, this measurement technique is relatively
insensitive to dirt in the medium (large quantities of ferritic contaminants, however, must
be avoided).
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2.0 Specifications
Table 2.1: Material Composition & Operational Limits
Material
Combination
I II/IIB * III IV * VI * VII *
Fittings NPT NPT NPT
Housing
Window
Fittings
Locking Pins
O-Rings
Paddle Wheel
Axle
Axle Bearing
Orifice
Trogamid®
Trogamid®
NP-Brass SS/PP NP-Brass SS NP-Brass SS
Brass Brass Brass - - -
Buna-N FKM Buna-N FKM Buna-N FKM
POM PTFE POM PTFE POM PTFE
SS
PTFE PTFE PTFE PTFE PTFE PTFE
2
PTFE
Polysulfone/PP
Polysulfone/PP
SS/
Ceramic
PTFE
2
NPT or
FLANGE
NP-Brass SS NP-Brass SS
Polysulfone Polysulfone NP-Brass SS
SS SS SS SS
PTFE
2
PTFE
2
NPT
PTFE
FLANGE
2
PTFE
NPT or
2
HIGH PRESSURE
VERSION
1450 PSIG
or
580 PSIG
with flange
Maximum
Pressure
Maximum Media
Temperature
STANDARD VERSION
145 PSIG
145°F 180°F 180°F 180°F 180°F 180°F
145/85
PSIG
230 PSIG 230 PSIG 1450 PSIG
* Fittings not Rotatable Abbreviations: PP - Polypropylene
2
SS on Model DF-XX01 NP - Nickel Plated
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Table 2.2: Electrical Data
Power Supply: +5 to +24 VDC
Open Collector Output: +5 to +24 VDC
@ 10 mA max.
Operating Temperature Range: -10° F to 180° F
(+145°F for DF-01..)
Environmental Protection: NEMA 4
Table 2.3: Flow Ranges & Fitting Sizes
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DF-SEN 4
Diagram 2.4; Sensor Dimensions
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5DF-SEN
3.0 Installation Instructions
CAUTION: For safety reasons, please read the cautionary information located at
the end of the manual, before attempting installation.
To install, proceed as follows:
1. Make sure that the actual flow rate in your system lies within the flow range of
the instrument. The flow range can be read off the identification tag. Flow rates
in excess of 120% of the range maximum will, in continuous use, lead to
bearing and/or paddle wheel damage.
2. Ensure that the power supply voltage is in accordance with that specified on
the identification tag. Electrical connections are made with a 3-pin terminal
block as specified by the wiring diagram (Diagram 3.1).
3. If the sensor is to be used to provide a voltage pulse output, a sourcing output
pull-up resistor MUST be connected between the supply voltage terminal and
the open collector output terminal (pins 1 and 3). This resistor should be sized
such that the collector to emitter current is nominally limited to 5 mA or less
during the transistor “on” state. Under no circumstances should the collector
to emitter current be allowed to exceed 10 mA.
Diagram 3.1; Wiring
V supply
R pull-up = ______________ Ohms
0.005
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DF-SEN 6
If you have an OEM version (supplied without terminal box), a connector with three wires
will be visible. Depending on the color combination of wires your sensor has, attach
these as follows:
Blue - (-) Ground Blue - (+) VDC
Yellow - Open Collector or Yellow - Open Collector
Red - (+) VDC Green - (-) Ground
You are now ready to mechanically connect the unit.
1. The flow direction is indicated by an arrow on the housing. Install the
instrument with the arrows aligned with the flow direction in your pipes. To
achieve the operational design accuracy, output cons istency over the entire
measuring range and longest service life, orient the unit so that the axle
always remains in a horizontal plane.
2. Connect with appropriately sized fittings. Take care not to place stresses on
the housing - use a wrench to hold the instrument fittings static while you
tighten the fittings on your pipe. As with any flowmeter, this device must not be
used as a structural member of the piping system to avoid damage.
3. Should there be small amounts of ferrite contaminants in the medium, we
recommend the installation of our magnetic filter (type MFR or equivalent).
4. Medium should always be introduced to the system slowly to avoid pressure
surges which could damage the instrument.
4.0 Operation
The device is delivered with a calibration diagram describing its frequency versus flow
rate behavior. You must use this to calculate rate of flow in your system. Modification of
the sensor (by physically modifying or replacing sensor components) requires
recalibration of the unit.
4.1 - Turning the Unit On
The sensor is operational as soon as it is wired into a power supply.
4.2
- Flow Measurement
A frequency counting device must be used to read the sensor output and convert that
measurement to rate of flow (output frequency is directly proportional to flow rate). The
nature of this relationship is described by the sensor’s “k-factor” which is the number of
pulses the sensor generates per gallon of water flow through the sensor. The device’s
nominal k-factor can be easily calculated with the use of the provided output frequency
(in Hz) and knowing the maximum flow rate of the particular sensor.
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7DF-SEN
5.0 Arrival of Damaged Equipment
Your instrument was inspected prior to shipment and found to be defect-free. If damage
is visible on the unit, we advise that you carefully inspect the packing in which it was
delivered. If damage is visible, notify your local carrier at once, since the carrier is liable
for a replacement under these circumstances. If your claim is refused, please contact
Kobold Instruments for further advisement.
6.0 Maintenance
The KOBOLD DF sensor requires little maintenance provided the measured medium is
kept free of contaminants. In particular, ferritic pollutants can cause problems for this
device due to the incorporation of magnets into the paddle wheel. To avoid this, we
recommend the installation of a magnetic filter, such as KOBOLD's model MFR or
equivalent.
DO NOT tamper with the electronics as this voids your warranty.
7.0 Need help with your DF Flow Sensor?
Call one of our friendly engineers at 412-788-2830.
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9DF-SEN
Caution
PLEASE READ THE FOLLOWING GENERAL FLOW METER/ MONITOR
WARNINGS BEFORE ATTEMPTING INSTALLATION OF YOUR NEW
DEVICE. FAILURE TO HEED THE INFORMATION HEREIN MAY
RESULT IN EQUIPMENT FAILURE AND POSSIBLE SUBSEQUENT
PERSONAL INJURY.
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• Inspect instrument for damage upon arrival. Cracked, fractured, bent or otherwise
damaged instruments must not be put into use, since the device is weakened to an
unknown extent. (The operations and installation guide will explain how to make a
claim on damaged instruments.)
• Under NO circumstances must the maximum tolerances (temperature and pressure)
be exceeded.
• The maximum tolerances of the device have been determined using water, air and/or
oil. If using other media, especially corrosive ones, it is critically important that the
user determine chemical compatibility with our instruments. A list, detailing material
composition of our instruments, is available from KOBOLD Instruments Inc. upon
request. KOBOLD Instruments Inc. cannot accept responsibility for failure and
consequences resulting from use of media other than water, mineral oil, air, and
nitrogen.
• Install the device in a fully supported position within your flow system. This avoids
excessive stresses which may damage the instrument. In particular:
a. Ensure that the plumbing leading to and from the instrument is fully supported
and that the instrument does not perform the physical function of a joint.
b. When calculating stress on the device caused by plumbing, the weight of the
medium in the pipes must be considered as well.
c. Misaligned runs of rigid piping can cause large stresses when connected to
the instrument. Do not connect in such a fashion.
• During installation, avoid stresses on the instrument by following guidelines given
below:
a. When connecting fittings, hold the instrument fittings rigid with a correctly
sized wrench. Do not install by twisting the instrument into the pipe fittings.
b. Do NOT install by holding the device housing to provide counter-torque to the
pipe fitting.
c. Use an appropriate amount of PTFE tape on male threads of fitting. This
reduces the twisting stresses produced by tightening the fittings into each
other.
d. Do not use pliers or wrenches on the housing, as this may damage it.
e. Do not overtighten, as this may fracture the fittings.
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11 DF-SEN
• During operation, there are a number of situations to avoid:
a. The sudden cessation of fluid flow causes what is typically referred to as
"water hammer". Most people are familiar with this phenomenon from their
home experience - it is the cause behind the loud clank of water pipes which
occurs when faucets are turned off too suddenly. The cause behind this
"water hammer" is quite easy to visualize. Water is fairly massive. The
amount of water in long runs of pipe is quite subst antial. When the faucets are
turned off suddenly, especially from a full on condition, the water has
considerable momentum and does not want to stop flowing. The situation is
similar to stopping a car by running into a wall, rather than by applying brakes.
Both are sudden rather than gradual. The damage to the wall can be
substantial (not to mention the car).
The "water hammer" causes surges in fluid pressure which could cause the
measurement instrument's pressure limit to be exceeded, resulting in failure
and possible personal injury.
b. Fluid surges, as well as the water hammer, can be particularly damaging to
empty flowmeters since there is no back pressure in the device. The damage
is caused, once again, by momentary excess pressure. To avoid these
surges, fluid lines should remain full (if possible) and water flow should be
introduced to the device slowly.
c. If the instrument is isolated with inlet and outlet valves, the instrument must be
completely drained when said valves are both closed. Failure to do so could
result in damage to the device caused by thermal expansion of fluid.
d. Freezing of water in the instrument MUST be avoided si nc e t he r esu lt ant
expansion will damage the instrument and make it unsafe for use.
FM Rev. 12/13
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