Dwyer Instruments UF35 User manual

DWYER INSTRUMENTS, INC. Phone: [phone] www.dwyer-inst.com
P.O. Box 373 • Michigan City, IN 46361-0373, U.S.A. Fax: [phone] e-mail: [e-mail]
The Portable Series UF Sonicflow Flowmeters are non-inva-
sive “transit time” ultrasonic flowmeters designed to help ser-
vice/maintenance and commissioning engineers to take quick,
accurate flow readings. Flow rates from 1.6 to 26 ft/sec (0.5 to 8
m/sec) of almost any clear or cloudy liquid can be measured with
±2% accuracy. Easy to install flow transducers mount directly to
a variety of pipe materials such as stainless steel, cast iron, duc-
tile iron, PVC, copper, and concrete with diameters of 2˝ to 15.75˝.
FAST TRACK SETUP PROCEDURE
Switch on and press ENTER.
Select Quick Start- Press ENTER.
Dimension Units?- Scroll to select units required, press ENTER.
Pipe OD- Enter data, press ENTER.
Pipe Wall Thickness- Enter data, press ENTER.
Pipe Lining Thickness- Enter data, press ENTER. Enter Zero if
there is no lining on the application.
Select Wall Material- Select using scroll keys, press ENTER.
Select Lining Material- This will only be displayed if a lining thick-
ness has been entered. Select using scroll keys, press ENTER.
Select Fluid Type- Select using scroll keys, press ENTER.
This instrument selects the mode of operation using the data
entered and will display the following:
Attach Sensor set
in XXXX mode
Approx. max. flow:
XXX m/s
Press ENTER to continue
Or SCROLL to change mode
Fluid Temp? Press Enter to input the application temperature in
the units required °C or °F then press ENTER.
Now retract the sensor blocks back into the guide rail by turning
the locking nuts clockwise.
Apply grease to both sensor blocks as shown in (Figure 1),
attach to the pipe using the appropriate mounting hardware in
either Reflex or Diagonal Mode. Ensure the Guide rail itself is
free of grease.
Figure 1
Inverted view
of grease
applied to sen-
sor block.
Model UF35
Specifications and Operating Instructions
Bulletin F-UF35
SPECIFICATIONS
Range: 1.6 to 26 ft/sec (0.5 to 8 m/s).
Pipe Range: 2˝ to 15.75˝ (50 to 400 mm) nominal bore.
Accuracy: ±2% of reading.
Repeatability: ±0.5% or ± 0.1 LPM (whichever is greater).
Display: 7-digit flow rate in GPM, LPM, LPS, m3/s, ft/sec and
m/s; 7-digit totalization in gallons, liters, or m3.
Display Resolution: 0.1% of reading.
Response Time: < 2 seconds.
Operating Temperature: 32 to 113°F (0 to 45°C).
Storage Temperature: -4 to 131°F (-20 to 125°C).
Transducer Operating Temperature: -4 to 257°F (-20 to
125°C).
Power: Four AA rechargeable batteries.
Guide Rail Length: 15.6˝ x 1.3˝ x 1.7˝ (395 x 33 x 42 mm).
Cable Length: 6.5 feet (2 m).
Housing: ABS, IP55 rating.
Weight: 17.5 oz (500 g) including transducers.
Connect the red and blue sensor cables to the electronics and
the guide rail assembly. The RED cable must be positioned
upstream to give a positive flow reading.
Figure 2- Sensor
Assembly
For Reflex Mode attach the guide rail (Figure 3) to the pipe as
shown below. Turn the locking nut on the fixed transducer anti-
clockwise, screwing it down on to the pipe surface. No not over-
tighten, causing the guide rail to lift off the pipe.
Set the separation distance (Figure 3) by sliding the floating trans-
ducer along the scale until the front edge of the block is at the
recommended distance displayed by the electronics. Now turn
the locking nuts on both the floating and the fixed transducers
anti-clockwise, until they make finger tight contact with the pipe
surface. To mount the transducers in DIagonal Mode, refer to
(Figure 4).
Now press ENTER to read flow. Pressing the appropriate key on
the keypad can change flow units. An additional key press will
change the time scale of the reading- hr/min/sec.
Figure 3: Reflex Mode Operation
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Figure 4: Diagonal Mode Operation
For Diagonal beam mounting, follow the sensor mounting instruc-
tions in this manual.
PARTS AND ACCESSORIES
Connectors
There are four sockets on the electronic housing. Two for the
transducer cable assemblies (Blue down/Red up), one for the
pulse output, one for the PSU/charger unit, and one for the
optional 4-20mA output. Please specify 4-20mA output in your
order so that it can be configured prior to dispatch.
Pulse Cable Connections
Pulse output- Centre (White) positive, Screen (Silver) negative.
Charger (Use only the charger supplied).
The charger is supplied with universal plug-in adapters. When
the instrument is charging, but switched off, the display reads
‘CHARGING’. It also displays a battery and plug symbol. CHRG
is displayed next to the word ‘Batt’ when in flow mode and the
battery charger is connected. When the battery charger is dis-
connected, the display will show a % battery level in the flow
mode.
Figure 5: Battery mains charger.
Battery Circuit
A battery management circuit controls the battery recharge. The
circuit helps to prevent the batteries from being damaged
through overcharging. The circuit automatically cuts off the high-
level charge current after 4hrs, after which it will provide only a
trickle charge. In operating mode a fully charged battery can
maintain functionality for up to 8hrs depending on the demand.
A large percentage of the demand is taken by the ‘Backlighting’.
and whilst it is continuously enabled the operating life will drop to
4hrs from a fully charged battery.
When in flow measurement mode the battery charge level is con-
tinually displayed as a percentage of full charge. When this indi-
cation reads approximately 40%, a warding message will appear
on the screen. This indicates that there are only 30 minutes of
use left in the battery. The battery can be charged when the
instrument is switched to the ON or OFF state.
See full instructions on charging and discharging the batteries
further in this manual.
Keypad
Programming is via a key tactile membrane keypad.
When measuring flow it is possible, by selecting keys 4, 7, 8, and
9, to change from one unit to another without the need to re-pro-
gram. Additional key presses will adjust the time scale of the
measurements.
Example:
• Press 4 for m/s, press 4 again for f/s
• Press 7 for l/s, press 7 again for l/m
• Press 8 for g/min, press 8 again for USG/min
• Press 9 for m3/min, press 9 again for m3/sec
There are some facilities that require the cursor to be moved from
left to right. This can be done using keys 5 (left) and 6 (right).
The pulse output can only be activated in the flow mode.
Transducers
The UF35 is supplied with one (matched) pair of transducers and
a single guide-rail to measure flow. The instrument selects the
mode of operation (Reflex or Diagonal) dependent on the pipe
size and flow velocity. The instrument can be used over a range
from 50 mm to 400 mm. In Reflex Mode the transducers are
positioned in the guide rail to assist correct alignment along the
pipe axis, (Figure 3). in Diagonal mode (Figure 4) the transducers
are removed from the rail and attached to the pipe using the gull-
wings and chains. The pipe is then measured and marked up
and the transducer blocks are clipped to the pipe wall using a
suitable amount of grease applied to the face of each transducer.
Separation Distance
The instrument calculates the separation distance when all para-
meters have been entered via the keypad. Also the instrument
calculates the maximum flow velocity allowed with the standard
sensors and indicates whether Reflex or Diagonal mode should
be used.
Utlrasonic Couplant
Ultrasonic couplant/grease must be used on the transducer face
to interface with the pipe wall.
Fluid Types
UF35 is capable of measuring clean liquids or oils that have less
than 2% by volume of particulate content and air bubbles.
During the set up procedure the user is prompted to select from
a list of liquids, which include water and oils.
Applications include- river water, seawater, potable water, demin
water, treated water, effluent, water/glycol mixes, hydraulic oil,
diesel oil and most chemicals.
PROGRAMMING MAIN MENU
Main Menu
Press SCROLL up or down to move the cursor to the required
option and press ENTER to select.
Main Menu- Quick Start
Selecting quick start offers the user the easiest and quickest
option to achieve a flow measurement. If the instrument has
already been used, it stores the last application data entered.
This allows the user to read flow on the same application without
spending time entering new data. Go to ‘Read Flow’ on the
main menu.
If QUICK START is selected, proceed with the following routine.
Use the scroll keys to select, then press ENTER.
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The instrument now asks for the Pipe outside diameter? After
entering the outside diameter in millimeters press ENTER.
Pipe wall thickness now appears on the display. Enter the pipe
wall thickness in millimeters, then press ENTER.
Pipe lining thickness now appears on the display. If the pipe you
are measuring has a lining, enter the Pipe lining thickness. If
nothing is entered, the instrument automatically assumes there is
no lining. Press ENTER to move on after entering the data.
The instrument now displays Select pipe wall material. Using the
scroll keys it is possible to scroll up or down the options avail-
able. Select the required material and press ENTER.
The following will only be displayed at this stage if a lining thick-
ness has been entered. Use the scroll keys to select the required
material, then press ENTER. If Other is selected, enter the sound
speed of the lining in meters/sec.
Select fluid type now appears on the display.
Use the scroll keys to select the fluid type and press ENTER.
If the liquid is not listed select Other and enter a liquid sound
speed in meters/second. The sound speed information can be
found in the back of the manual under Liquid Sound Speeds.
Attach Sensors
The instrument will now provide the user with details of the mode
of operation. It will also give the approximate maximum velocity
that can be achieved with the sensors provided. Use the keypad
to check the other maximum volumetric flow.
Connect the RED and BLUE sensor cables, between the guide
rail and the electronics.
Select Enter and the display will now show: Fluid Temp? (°C)
Enter the application temperature and press Enter.
The display will now show the sensor separation distance.
Adjust the moveable sensor to the required distance. Press
ENTER to read flow.
READ FLOW now appears on the display.
When reading volumetric flow, the instrument will display a posi-
tive and negative total. Selecting OPTIONS from the keypad can
reset these totals (See page 14).
The instrument will continually display the battery and signal lev-
els. Signal levels should be above 40%. If there is an error with
the site data entered or the application, the instrument will display
an Error or warning message, which will appear above the flow
reading. If there is more than one message it will scroll between
them all.
To stop reading flow, press ENTER ONCE. The display will read
the following:
This will stop all
outputs
Press ENTER to EXIT
SCROLL to return
to READ FLOW
Pressing ENTER a second time will stop outputs and return the
instrument to MAIN MENU or press the scroll key to return the
instrument to READ FLOW.
Main Menu- View/Edit Site Data
The VIEW/EDIT SITE DATA mode can be accessed from the
main menu. It allows the user to enter application details for up to
20 different sites. This facility is useful if a number of sites are
being monitored on a regular basis. Application data can be pro-
grammed into each site before getting to the site.
When scrolling up/down the menu press ENTER to select at
each prompt.
Note:
•Site Zero is always the QUICK START data and cannot be
changed.
•Changing the data in any site is automatically saved when leav-
ing this menu. Data will have to be re-entered to override the old
data.
List Sites
Selecting LIST SITES allows the user to view the names of up to
20 sites, numbers 1-5 appear first.
Pressing ENTER will display sites from 6-10. Pressing again will
display sites 11-15, and again to display 15-20.
Site Number
Site number allows the user to enter the number of the site data
wished to be displayed. If the site has not been used, then no
data will be stored. New application data can now be entered.
Site Name
Site name allows the user to edit or enter a site name. Use the
scroll keys to move the cursor to the letter/figure required and
press ENTER to select. Press zero to return the instrument to
VIEW/EDIT SITE DATA. The new site name will appear on the
display.
Dimension Units
Dimension units allow the user to switch between millimeters and
inches. The electronics converts all the application data in a par-
ticular site.
Pipe wall/lining thickness and Pipe wall/lining material can now
be changed as required. Lining material is ignored if a lining
thickness has not been entered. A selection of pipe wall/lining
materials will be displayed when these options are selected.
Fluid Type
Fluid type allows the user to scroll through a selection of fluid
types. Select OTHER in the menu if a liquid is not mentioned.
Select fluid type. When Other (m/s) is selected, the user must
enter the liquid sound speed in m/s.
Read Flow
Selecting Read flow informs the user of the mode of operation
and the approximate maximum flow rate. Pressing the appropri-
ate key can change the units required.
Pressing ENTER asks the user to enter a temperature in °C.
Now press scroll (up). The instrument will display the separation
distance before displaying flow.
Main Menu- Select Sensor mode
When the application information is programmed into the instru-
ment it selects and defaults to the most suitable mode of opera-
tion i.e. REFLEX or DIAGONAL.
Sensor Mode
Selecting Sensor Mode allows the user to choose the appropriate
method for clamping the sensors to the pipe. The default would
have been displayed on the previous screen and Sensor Mode
can be selected to give the user a choice between Reflex and
Diagonal.
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This option is available for two main reasons. First, lets assume
that the instrument has selected “mount sensors in DIAGONAL
MODE”. Your application may not allow you to achieve this
mode. Providing the velocity is low enough, it is possible to force
the sensors into REFLEX mode. Changing the sensor mode
from Diagonal to Reflex would allow the user to measure the flow.
The display may also read “sensor mode invalid for this pipe
size”.
Read Flow
Moving the cursor to Read flow and pressing ENTER informs the
user of the mode of operation and the maximum flow capable.
Should the actual flow be higher than the one specified on the
instrument, another mode of operation can be selected.
Selecting EXIT will take you back to MAIN MENU.
Main Menu- Set Up Instrument
Pulse Output Key
This can only be operated in flow mode.
Use the scroll key to move the cursor up or down the display. To
change the flow units, press the key required. This will also
change the flow units when returning to the flow mode.
Changing the flow units will also re-scale the liters per pulse.
Outputs allow the user to select from the following:
Selecting Off switches the pulse off and returns to the PULSE
OUTPUT display.
Selecting the Forward total counts the pulses of the forward flow
only.
Selecting Net total counts the pulses of the sum of the forward
total less the reverse total.
Max Pulse Rate
This option allows the user to select between fast/slow pulses or
large/small pulse width. Select 1 per second for slow pulses and
100 for a fast pulse. The pulse width for 1 per second is 100 ms
and 5 ms for 100 per second.
XXXX per pulse
This will change when the flow units are changed above. When
the correct flow units are selected this allows the user to scale
the pulses to his own requirements or it can be left in the default
setting.
Display Backlight
Use the scroll key to select Application Options and press
ENTER. This allows the user to enable or disable the backlight.
Enable means the backlight will stay on for 15 seconds with
every key press. It will stay on permanently with the mains
plugged in. Use the scroll key to select and press ENTER. The
backlight will draw power from the batteries and reduce the oper-
ating life of the battery cell.
Application Options
Use the scroll key to select Application Options and press
ENTER. Please enter the following password:
39502600
It is a facility that could enhance signal levels on difficult applica-
tions, primarily very small or large pipes. use enhanced mode
when signals are below 800. Below 800 the system may gener-
ate noise and therefore the accuracy of the measurement cannot
be guaranteed.
Sensor Parameters
This facility is passwords protected. It stores sensor information
used by Dwyer and is not available for the user.
Factory Settings
The facility is used by Dwyer in the process of instrument calibra-
tion. Pressing ENTER takes the user back to SETUP INSTRU-
MENT MENU.
EXIT
Means EXIT and will take you back to the Main Menu.
Main Menu- Read Flow
When choosing the Read flow option from the MAIN MENU, the
instrument reverts directly back to the data that was last entered.
The instrument will have to be reprogrammed if it is to be used
on a new application.
KEYPAD OPTIONS
The output options can only be adjusted/operated in flow mode.
Delete Key
If anything is entered in error, press the DELETE key and re-enter
the information required.
Options Key
This can only be used in flow mode. Scroll down the options
then press ENTER to select.
Cut Off
The instrument has an automatic CUTOFF that is calculated to
0.05 m/s. The maximum flow is calculated when the instrument
is programmed and is displayed when sensor set and mode of
operation are displayed. Dwyer cannot guarantee measuring
flows below this range because of instabilities in the measuring
system, but it is possible for the user to cancel any cut-off alto-
gether.
Reducing the cutoff to Zero allows the user to see or record any
flow that they may not want. For example, it may be that the
user may not want to measure flows below 50 LPM in a 50 mm
pipe that is equivalent to 0.42 m/sec, in which case 0.42 m/sec
would be entered into the instrument and nothing would be
recorded below that level. The maximum cutoff is 1 m/sec.
Set Zero Flow
On some applications and in some conditions it may be that
although there is no flow, the instrument may show a small offset
due to system noise. The offset can be cancelled out and will
increase the accuracy of the instrument. Selecting this option
and pressing ENTER on the display will show the following:
Stop the flow
COMPLETELY and
press ENTER or
SCROLL to cancel
Pressing ENTER before the flow has stopped will result
in an error message asking if you are sure that the flow has
stopped. This occurs when the flow is still above 0.25 m/sec.
When this facility has already been selected, press ENTER to
cancel the previous instruction, then it is possible to reset the
Zero balance. The option is not available when error messages
E1 and E2 (found further in this manual) are being displayed.
Total
This option allows the user to disable the positive and negative
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totalizers. When either of these options are selected, the totalizer
will start or stop functioning. It does not zero the total, this is a
separate function described below.
Reset + Total/- Total
The UF35 has a forward and reverse totalizer that can be reset
when this facility is selected. Use the scroll keys to select and
press ENTER to reset. The total is stored when the unit is
switched off or battery goes flat, therefore it may need to be reset
before each use.
Damping (sec)
This facility is used when the flow readings are unstable due to
the turbulence caused by obstructions, bends, etc. Damping or
averaging can be used to make the readings more stable. It can
be set to up-date the display, anything between 3 and 100 sec-
onds.
Calibration Factor
If for any reason the instrument goes out of calibration and the
readings may be higher or lower than normal, this facility enables
the user to correct the reading. If, for example, the reading is 4%
higher than normal, then entering 0.96 will reduce the reading by
4%. If the reading is 4% lower than normal, then entering 1.04
could increase the reading by 4%.
When the instrument is supplied it will always default to 1.00, and
when this is changed it will stay in the memory to whatever it has
been changed to, until such time as it needs to be changed
again.
Correction Factor
This is a facility that can be used when errors occur due to lack
of straight pipe or the sensors have been placed too close to a
bend (this could give an incorrect reading to what is expected).
The user can set this as a % in the same way as the calibration
factor, but it will not be stored in the memory.
DIAGNOSTICS
Calculated µs
This is a valve the instrument predicts will be the time in µsecs
that it should take for the transmitted signal to go across a par-
ticular pipe size. This value is ascertained from the data entered
by the user, i.e. Pipe size, material, sensor set, etc.
Up µs, Dn µs
This is the actual transit time measured by the instrument and will
be slightly (5-10 µs depending on the pipe size and signal condi-
tion) less than the calculated value above.
Measurement µs
A point in the signal is transmitted where the flow is taken from.
It is used to see if the signal is being taken from the burst at the
correct time to get the strongest signal. It is normally used on
smaller pipes when the instrument is being used in double or
triple bounce as signals can sometimes interfere with each other.
This value is normally a few µs below the Up µs, Dn µs value.
Phase up/dn µs
Only valid if Calculated µs and Up µs, Dn µs are correct. If the
reading is zero, then there is no signal, which could mean the
pipe is empty or the liquid is contaminated with particles or air.
Phase offset
This value will be between 0 and 15. The exact value is not
important and will vary between applications. It should, however,
be stable when the flow condition is good and velocity is within
the range of the transducers being used. As the flow rate
increases toward and beyond the maximum, this figure will con-
tinuously change. In flow mode the instrument will read unstable
or high flow.
Flow (m/s)
This displays flow velocity in m/sec to 3 decimal places.
Signal
This is the average value of Signal up/dn and is a value between
800 and 2400 which displays the signal’s strength as a percent-
age (800=0%, 2400=86%).
Signal up/dn
This value is internal to the electronics and must be greater than
800. There is an option in the SETUP INSTRUMENT menu to
allow this value to be taken down to 400 in extreme circum-
stances and is useful on some applications when the signal levels
are poor.
Sensor separation
This is a reminder for the user to check for correct sensor sepa-
ration and sensor mode.
STATUS/ERROR/WARNING MESSAGES
There are three types of messages that will appear: Status, Error,
and Warning. These messages appear under the time and date
on the display when in flow mode.
Status Messages
S1: initializing
Appears when first entering flow mode to show that the instru-
ment is starting up.
Error Messages
E1: UNSTABLE OR HIGH FLOW
This error message occurs when either the sensors have been
positioned too near an obstruction or bend, causing turbulence,
or the instrument is being used outside its normal flow range.
When the instrument is programmed, the user is informed of the
maximum flow rate that is possible to measure, and if this is
exceeded the high flow message occurs.
It may be possible to get around these problems by moving the
sensors to a straighter length of pipe, or, in the case of high
flows, another set of transducers may be used.
E2: NO FLOW SIGNAL
This message appears when the two transducers cannot send or
receive signals, which could happen for various reasons. First,
check that all cables are connected and transducers are on the
pipe correctly with grease on the face.
The no flow signal will show if the pipe is empty or partially filled.
when the liquid is aerated, when the particulate content of that
liquid is too high, or if the grease has not been applied to the
transducers and the condition of the pipe being measured is
poor.
Warning Messages
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W1: CHECK SITE DATA
This message occurs when the application information has been
entered incorrectly and the wrong sensors have been attached to
the wrong pipe size, causing the system timing to be in error.
The site data needs to be checked and the instrument repro-
grammed.
W2: SIGNAL TIMING POOR
Unstable signal timing or differing up/down stream times indicate
that the liquid is aerated or pipe surface is of poor quality.
W3: FLOW SIGNALS POOR
This warning appears when there is a signal lower than 25%.
This could be due to the application, a poor quality pipe, etc.
W4: mA OUT OVER-RANGE
The mA output is over-range when the flow is higher than the
maximum mA range. Once the 4-20 mA has been set up and
the flow goes above the range set, this message will appear. It is
possible to re-scale the 4-20 mA to be able to cope with the
higher flow.
W5: BATTERY LOW
The battery low warning occurs when battery indication is on
40%. The instrument has approximately 30 minutes usage
before it needs recharging.
W6: mA LOAD TOO HIGH
The 4-20 mA Output is designed to work with a load up to
750Ω. When the load is too high or not connected, the above
warning message will be displayed.
Other Messages
The messages below appear mainly when data has been entered
incorrectly or the UF35 is trying to be used on an application that
it is not capable of working on.
Pipe OD out of range
The outside diameter of the pipe has been entered and is out of
range of the instrument.
Wall thickness out of range
The wall thickness that has been entered is out of range of the
instrument.
Lining thickness out of range
The pipe lining thickness has been incorrectly entered.
Site range is 0 - 20
There are only 20 storage sites available with 0 being the QUICK
START site.
•CANNOT READ FLOW BECAUSE...
...Pipe dimensions are invalid
•CANNOT READ FLOW BECAUSE...
...Materials are invalid
•CANNOT READ FLOW BECAUSE...
...Pipe is too large for sensor set
•CANNOT READ FLOW BECAUSE...
...Pipe is too small for sensor set
•CANNOT READ FLOW BECAUSE...
...Sensor mode is invalid for this pipe size
Temperature range is -20°C to +125°C
The temperature range of the transducers is -20 to 125°C.
Enter a lining thickness first
This message appears when in VIEW/EDIT SITE DATA the user
has tried to enter a pipe lining material before entering a thick-
ness.
APPLICATION INFORMATION
The UF35 is a Transit Time ultrasonic flow meter. It has been
designed to work with Clamp On transducers, thus enabling
flowing liquid within a closed pipe to be measured accurately
without the need for any mechanical parts to be inserted either
through the pipe wall or protrude into the flow system.
The meter is controlled by a micro-processor containing a wide
range of data, which enables the instrument to measure flow in
any pipe diameter from 50mm bore up to 400mm, made from
any pipe material, over a wide range of operating temperatures.
The system operates as follows:
Figure 6: Reflex Mode
Figure 7: Diagonal Mode
When ultrasound is transmitted from Transducer ‘A’ to
Transducer ‘B’ (REFLEX MODE- Figure 6) or Transducer ‘A’ to
Transducer ‘B’ (DIAGONAL MODE- Figure 7), the speed at which
sound travels through the liquid is accelerated slightly by the
velocity of the liquid. If sound is transmitted in the opposite
direction from ‘B’ to ‘A’, it is decelerated against the flow of the
liquid. The differences in time taken to travel the same distance
in opposite directions are directly proportional to the flow velocity
of the liquid.
Having measured the flow velocity and knowing the pipe cross-
sectional area, the volumetric flow can be easily calculated. The
Microprocessor will determine the correct alignment of each
transducer.
To measure flow, it is first necessary to obtain detailed informa-
tion about each application, which is then programmed into the
processor via the Key Pad. This information must be accurate
otherwise flow measurement errors will occur.
Further, having calculated the precise position at which the trans-
ducers must be clamped onto the pipe wall, it is equally impor-
tant to align and separate the transducers accurately with
FLOW
'A'
'B'
FLOW
'A' 'B'
UF35 bulletin 6/13/03 10:50 AM Page 6

respect to one another, as failing to do so will again cause errors
in measurement.
Finally, to ensure accurate flow measurement, it is imperative that
the liquid is flowing uniformly within the pipe and that the flow
profile has not been distorted by any upstream or downstream
obstructions.
To obtain the best results from the UF35, it is absolutely neces-
sary that the following rules for positioning the transducers are
followed, and that the condition of the liquid and the pipe wall are
suitable to allow transmission of the sound along its predeter-
mined path.
TRANSDUCER POSITIONING
As the transducers for the UF35 are clamped to the outside sur-
face of the pipe, the meter has no way of determining exactly
what is happening to the liquid. The assumption therefore has to
be made that the liquid is flowing uniformly along the pipe either
under fully turbulent conditions or under laminar flow conditions.
Further, it is assumed that the flow velocity profile is uniform for
360° around the pipe axis.
Figure 8
A uniform profile as compared to a distorted profile.
The difference between (A) and (B) is that the Mean Velocity of
the flow across the pipe is different and because the UF35
expects a uniform flow as in (A), the distorted flow as in (B) will
give measurement errors which cannot be predicted or be com-
pensated.
Flow profile distortions result from upstream disturbances such
as bends, tees, valves, pumps, and other similar obstructions.
To ensure a uniform profile, the transducers must be mounted far
enough away from any cause of distortion such that it no longer
has an effect.
Figure 9
Sensor Mounting
The minimum length of upstream straight pipe is 20 diameters
and 10 diameters downstream that ensure accurate results will
be achieved.
Flow measurements can be made on shorter lengths of straight
pipe down to 10 diameters upstream and 5 diameters down-
stream, but when the transducers are sighted this close to any
obstruction, errors can be considerable.
It is not possible to predict the amount of error, as this depends
entirely upon the type of obstruction and the configuration of the
pipe work and flow profile.
The message therefore is clear: Do not expect to obtain accurate
results if the transducers are positioned closer than allowed to
any obstruction that distorts the uniformity of the flow profile.
MOUNTING THE TRANSDUCERS
It will be impossible to achieve the accuracy of measurement
specified for the UF35 if the transducers are not clamped to the
pipe correctly and if the data- I.D. O.D., Pipe Material-are not
accurate.
Apart from the correct positioning and alignment of the transduc-
ers, of equal importance is the condition of the pipe surface in
the area under each of the transducers.
An uneven surface that prevents the transducers from sitting flat
on the surface of the pipe can cause Signal Level and Zero Offset
problems. The following procedure is offered as a guide to good
practice with respect to positioning and mounting the transduc-
ers.
1) Select the site following the rules laid down under Transducer
Positioning.
2) Inspect the surface of the pipe to ensure it is free from rust or
is not uneven for any reason. Transducers can be mounted
directly on painted surfaces as long as the surface is smooth and
that the underlying metal surface is free from rust bubbles. On
bitumen or rubber coated pipes the coating must be removed in
the area under the transducer as it is preferable that the trans-
ducers are mounted directly on to the base metal.
3) Transducers can be mounted on both Vertical and Horizontal
Pipe Runs.
Figure 10
Sensor Mounting Position
4) Apply interface grease to the face of the transducers. The
amount of grease used is extremely important, particularly on
pipes of less than 89mm bore.
On stainless steel pipes, the amount of couplant applied should
FLOW
>20
FLOW
<20D
FLOW
10 20
FLOW
520
CORRECT INCORRECT
TOP
BOTTOM
TOP
BOTTOM
CORRECT INCORRECT
"A"
"B"
UF35 bulletin 6/13/03 10:50 AM Page 7

never exceed the amount indicated in the example earlier in this
manual. For large plastic and steel pipes, the amount of grease
applied is less critical, however, do not use more than absolutely
necessary.
5) Strap the guide rail assembly to the pipe so that it is perfectly
parallel to the pipe axis.
6) When screwing the transducers on to the pipe surface, use
only enough force to ensure that the transducer is flat against the
pipe surface, then lock in position.
7) Clamping the transducers in exactly the correct position is
extremely important. The separation distance is calculated by
the UF35 electronics and the transducers must be positioned
and clamped at exactly the distance specified.
8) Always use the sensor grease provided.
LIQUID CONDITIONS
Transit time ultrasonic meters perform best on liquids that are
totally free from entrained air and solids. With sufficient air in the
system, the ultrasound beam can be attenuated totally, and
therefore prevent the instrument from working.
Often it is possible to tell whether there is air in the system or not.
If a flow signal cannot be obtained, a simple test determines
whether the flow is aerated. This test involves stopping the flow
for a period of 10 - 15 minutes. During this time, the air bubbles
will rise to the top of the pipe, and the flow signal should return.
If the flow signal does return, switch on the flow, and if sufficient,
entrained air is locked in the system it will very quickly disperse
and kill the signal.
To correct the UF35 for operation in the laminar flow region, cal-
culate the Reynolds number and adjust the correction factor.
PROPAGATION VELOCITY or SOUND SPEED
To make flow measurement using the UF35 on any liquid, it is
necessary to know the propagation velocity in meters/second.
There is a short list of fluids that appear on the display when pro-
gramming, showing water and various other liquids. However, if
the liquid you wish to measure is not on this list, please revert to
the table at the back of this manual or contact Dwyer for advice.
REYNOLDS NUMBER
The UF35 has been calibrated to operate on turbulent flows with
a Reynolds Number of approximately 100,000. The calibration of
the unit will not be valid if the Reynolds No. is below 4000.
If the UF35 is to be used on laminar flow applications it will be
necessary to calculate the Reynolds No. for each application. To
calculate the Reynolds No. it is necessary to know the Kinematic
viscosity in Centistokes; the flow velocity and pipe inside diame-
ter. Please follow the table below:
MAXIMUM FLOW
The maximum flow is dependent on the velocity and pipe size.
APPLICATION TEMPERATURE
On any application whose operating temperature is either above
or below ambient temperature, ensure that the transducers reach
and are maintained at the application temperature before under-
taking a measurement.
When applying the transducers to low temperature applications,
do not allow the pipe surface to ice up between the transducer
and pipe wall. The ice will force the block away from the pipe
wall and consequently the signal will be lost.
DIAGONAL MODE SETUP
Figure 11: Diagonal Mode Parts Supplied
The UF35 kit contains two stainless steel gull wings, two springs,
and two lengths of chain.
Take the transducers from the reflex guide-rail.
Attach the gull-wing to each transducer using the washer & wing
nut provided.
Apply grease to the bottom of the transducer. Wrap the chain
around the pipe as shown. Expand the spring and carefully slide
the chain into the slot on the gull-wing. Plug the red connector
into the socket on the upstream sensor. The sensor with the red
cable must be positioned upstream. The stem of the sensor
must point towards the downstream sensor.
Figure 12: Attaching the Sensor to the Pipe
Program the electronics with the application data to obtain the
calculated separation distance.
Measure the circumference of the pipe and mark a position at the
halfway point (πd/2 where d=outside diameter of the pipe). Apply
grease to the second sensor and plug the blue connector into
the top of the sensor.
Re= dv (7730) or Re = d1v1(1000)
U1 U1
Where
d= inside pipe diameter in inches
d1= inside pipe diameter in millimeters
v= velocity in feet/second
v1= velocity in meters/second
U1= Kinematic viscosity in centistokes
UF35 bulletin 6/13/03 10:50 AM Page 8

Figure 13: Marking the Separation Distance
Using a marker pen or a strip of ticket paper, mark around the
pipe from the front edge of the first sensor “A” till you reach the
halfway point of the pipe. From “B”, measure the separation dis-
tance calculated by the electronics. Mount the second transduc-
er as per the first with the stem facing the other transducer.
Press ENTER to view the flow. The signal strength should be
greater than 50%. Should there be difficulty getting a signal,
remove the sensor from the gull-wing, reapply the grease and try
to find a signal by moving it by hand.
Figure 14: Positioning of the Sensor Cables
Position the RED sensor cable upstream and the BLUE sensor
cable downstream. The electronics will display a positive flow
reading with cables in this orientation. If the unit displays a nega-
tive reading, the cables have been connected to the wrong sen-
sors.
MAINTENANCE
Following installation, the UF35 requires no routine maintenance.
Aside from methods described in this manual, units are not field
serviceable and should be returned to the factory if repair is nec-
essary.
UF35 Flow Range
0
13
25
50
75
100
150
200
0.02 0.03 0.04 0.07 0.09 0.10 0.13 1.8 2.5 3.5 4.5 7.3 9.4 mps
0.07 0.10 0.13 0.22 0.29 0.32 0.42 5.9 8.2 11.40 14.76 23.94
FLOW RANGE- REFLEX MODE
FLOW RANGE- DIAGONAL MODE
30.90 fps
DWYER INSTRUMENTS, INC. Phone: [phone] www.dwyer-inst.com
P.O. Box 373 • Michigan City, IN 46361-0373, U.S.A. Fax: [phone] e-mail: [e-mail]
©Copyright 2003 Dwyer Instruments, Inc.
UF35 bulletin 6/13/03 10:50 AM Page 9