Support
Email support is always available at support@tdcollaborative.com,
by phone at 781-933-6116, or by fax at 781-218-2682.
FAQs
- How fast does the
viscometer respond to changes in viscosity or temperature?
- What is the long
term stability of your measurements?
- How do I Connect
to a Computer?
- What's necessary
for Viscosity Control?
- Why Choose TD Collaborative?
- Do you offer demos?
- How Does it the Vibrating
Beam Viscometer Work?
- How it works: 300-Series
Viscosity Measurement [VSH323]
- What does the rigid
post do?
- What are the advantages
of vibrating cantilever beam measurement?
- How is temperature
measured?
- How is the Model
323 sensor different?
- What is the difference
between the various sensors?
- What is the measurement
accuracy?
- What about pressure
sensitivity?
- How do you clean
the sensor?
- Why is the body so
long?
- How does Temperature
Stabilized Viscosity differ from Temperature Corrected
Viscosity?
- How do I install
the sensor into a Process Line?
- How is the sensor
installed into a tank?
- What about electronics
for the sensors?
- Are there OEM configurations
available?
- How does the software
interface work?
- What is the response
time for viscosity and temperature?
- Can I set the shear
rate?
How fast does the viscometer
respond to changes in viscosity or temperature?
The viscosity measurement response
time is effectively two seconds. Measurements are
made 5 times per second; however, the analog outputs
are refreshed every two seconds. If data is being
read on the serial port, the fastest "Logging" [output]
refresh time is 10 seconds. Of course, to achieve
fast measurement response it is important to have
robust flow.
Temperature measurement has a thermal characteristic
time of about 30 seconds, so a step change in temperature
will be accurately sensed within two minutes. For
additional details see technical
note TN4355, "Thermal Response Time".
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What is the long
term stability of your measurements?
Measurements have been made over
a one month period to test stability with no observable
tendency for drift. For additional details see Technical
Note TN4200, "Measurement Stability".
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How do I Connect
to a Computer?
Our systems ship with a complementary
software which will run on any windows based computer.
The interconnect between our electronics and your
computer is through the serial port. To load the interface
software on your computer run the file VTMonitorx.xx.exe
which is provided with your system, or download a
spare copy from the web [link support/download], or
ask for help from support@tdcollaborative.com.
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What's necessary for Viscosity
Control?
All our circuit cards have either
0-4Vdc or 4-20ma analog outputs for monitoring or
control. The output is viscosity and temperature in
engineering units. To control, the analog outputs
need to be input into a third party controller which
outputs either a switch closure or an analog level
for control of a proportional switch. There are literally
hundreds of excellent controllers to choose among,
easily procured for several hundred dollars. An excellent
source for this equipment is Omega Engineering in
Stanford CN. Their web address is www.omega.com.
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Why Choose TD Collaborative?
Reliability. Our patented design
is simple and reliable. There are no motors, no gear
pumps, no rotating seals, no moving shuttles, and
no small orifices to jam or plug. Just one coil, two
wires, and a vibrating cantilever beam. This elegantly
simple design means more reliability and lower costs,
which we pass on to you. Refer to Technology/Principle
of Operation [PDF] to see how we do it.
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Do you offer demos?
We are confident of our equipment
and glad to provide a 60 day free demo, provided your
application fits our performance profile and you are
a new user. To apply for a demo system call TD Collaborative
at 781.933.6116, or email us at
sales@tdcollaborative.com.
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of faqs
How Does it the Vibrating
Beam Viscometer Work?
Our sensor measures both viscosity and temperature
directly in a process line. The viscosity sensing
head has a cantilever beam coupled magnetically to
a nearby coil. The coil excites the beam, then detects
its vibrations magnetically. The decay rate of the
oscillations depend upon the absolute viscosity of
the fluid. The 300-series viscometers such as the
new VSH323 eliminate the magnet on the beam, substituting
a piezoelectric element for vibration detection. Beam
excitation is also more robust and centered at the
beam's resonant frequency.
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How it works: 300-Series Viscosity
Measurement [VSH323]
The new 300 series sensing head
eliminates the permanent magnet on the cantilever
beam, and adds a piezo-electric element to the beam
tip to measure beam vibrations. We retain the patented
"hammer and anvil" technique for sensitivity and add
an excitation pulse train which is tuned to the vibration
frequency for better dynamic range and sensitivity.
A precision Pt RTD is positioned in either the center
or support post for precise, fast response temperature
measurement.
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What does the rigid post do?
In order to keep the sensing head small and still make
accurate measurements down to even 2 centipoise, a patented
"hammer and anvil" technique is used in which a rigid
post is positioned close (approximately 1mm) to the
vibrating beam tip. The fluid in the gap is sheared
during beam oscillation. Because it's viscous, it damps
the beam oscillation, enabling measurement of fluid
viscosities with oscillation frequencies of about 700
Hz. There is a visualization of this measurement technique
at http://www.tdcollaborative.com/_files/HotToAnim.html.
Measurement can be made from 2 to 1,000 centipoise in
four overlapping range, 2-40cp, 5-100cp, 20-400cp, and
50-1000cp. Temperature can be measured from 0 degC (32F)
to 180 deg C (356F).
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What are the advantages of
vibrating cantilever beam measurement?
Simplicity and reliability. There are no motors, no
gear pumps, no rotating seals, no moving shuttles, and
no small orifices to jam or plug, just a vibrating cantilever
beam.
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How is temperature measured?
Temperature measurement in the VS205 is based on measurement
of the resistance of the excitation/detection coil.
The Model 225, 223 and the new 323 sensors use a precision
1000 ohm platinum RTD buried inside one of the support
posts on the face of the device for faster and more
accurate temperature measurement.
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How is the Model 323 sensor
different?
The new VSH-323 uses the same patented "hammer and anvil"
measurement tip design, but the beam oscillation is
induced at the beam resonant frequency. The beam magnet
is replaced with a piezo-electric element, and decay
is measured ratio-metrically. The advantages of this
technique include greater dynamic range, elimination
of the magnet, and more accuracy.
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What is the difference between
the various sensors?
The VSH-223 viscometer [above] is intended for process
applications with a shorter 3-inch mounting stem and
a Pt RTD mounted inside the measurement cage support
post. The body and screen are 316 Stainless Steel.
The diameter is less than one inch. The mounting end
is ¼-inch NPT male thread. We offer adaptors
for direct insertion into various process lines. The
VSH-323 has the same outward appearance as the VSH-223
shown above, but has a different vibrating beam excitation
and detection technique which is ratio-metric. A piezo-electric
element substitutes for the permanent magnet.
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What is the measurement accuracy?
Viscosity measurement accuracy is +/- two percent of
full scale, however, typical accuracies are +/- one
percent of full scale. The sensor can be oriented in
any direction. Temperature measurement accuracy is ±0.2
degC for the VT205 and VS205 and ±0.1 degC for
the 20 series viscometers such as the VSH223 and VSH323.
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What about pressure sensitivity?
The measurement cantilever beam on the face of the device
inside a protective cage is freely flooded on both sides
so there are virtually no pressure effects. The face
of the device is thick enabling operation up to 1000
psi.
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How do you clean the sensor?
Immerse it into an appropriate solvent, then blow the
measurement cage dry and wipe the outside. 20-40 PSI
compressed shop air is quite effective, although gas
from a can of "circuit board" cleaner also can be used.
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Why is the body so long?
The long body of our sensors thermally isolates the
measurement head from the mount for more accurate temperature
measurements.
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How does Temperature Stabilized
Viscosity differ from Temperature Corrected Viscosity?
Our TSV systems control the measurement
temperature.. A small slip stream is heated to a set
temperature such as 40 or 50 degC [10 degC or more
above ambient] using a safe 24 volt resistive heater
with built in PID control. It enables continuous laboratory-like
measurements at a stable temperature even when the
process temperature is poorly controlled. The more
common and less accurate Temperature Corrected Viscosity
[which we also offer as a standard option] involves
a software correction of the measured viscosity based
on the difference between the actual temperature and
the desired reference temperature. This correction
is only as good as your estimate of the temperature-viscosity
gradient, so large errors are possible if the actual
temperature deviates substantially from the set point
temperature.
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How do I install the sensor into
a Process Line?
TD Collaborative viscometers can be inserted into a
process line using a simple adaptor plug [shown in gray].
The sensor adaptor is sized to whatever the bypass line
diameter is, say 1.5 inch pipe [minimum 1 inch]. The
standard configuration for the sensor is a ten foot
(3m) cable. Longer cable runs require an extension cable.
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How is the sensor installed
into a tank?
We offer an adaptor that has a protective cage for the
sensor and an extension shaft on the top for direct
immersion into the top of a tank. Alternatively, you
can use an adaptor like the process line adaptor to
insert into a wall flange on the side of a tank. The
mounting shaft can be any convenient length, and can
be as simple as ½" or ¾" stainless steel pipe.
We will also quote a custom shop-fabricated extension.
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What about electronics for
the sensors?
[approximately to scale]
Electronics excites the sensor and interprets the
response, so every sensor needs either an OEM circuit
card or an end user system with display, such as shown
above. If the circuit card is more than 3 meters from
the sensor, you will also need an extension cable.
In the case of the VSH323 you will always need an
XC3 extension cable. The system can operate in a stand
alone fashion and/or interconnected to any windows-based
computer. The electronics enclosure is a combination
bench top/wall mount configuration with 3½ digit
high intensity displays of viscosity and temperature
[model C100, C200 and C300]. Analog outputs are available
for remote monitoring and/or control in either a 0-4Vdc
or sourced 4-20ma format as well as a serial port
output with complementary monitoring software. TTL
[0-5Vdc] alarm levels are output with the C200 and
C300 systems and board-level OEM systems.
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Are there OEM configurations
available?
Yes. We offer Board Level OEM electronics with all the
functionality of the end user systems, including software,
but without the enclosure and displays. OEM board level
systems require 90-240Vac 50-60Hz mains power, or ±12Vdc
or ±15Vdc [100 series] or +9 to +36Vdc [200 and
300 series].
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How does the software interface
work?
We offer complementary software
for display of the data, field calibration, data download,
data log interval settings, etc. Software operates
on any windows-based computer. It includes a tabular
display of viscosity and temperature with a date and
time stamp and a built-in data graph option. Temperature-Corrected-Viscosity
and data logging are software-selectable options.
The computer display has easily set high and low alarm
levels on both viscosity and temperature with color
coded data entries based on proximity to alarm levels.
For further details see http://www.tdcollaborative.com/products.php4
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What is the response time
for viscosity and temperature?
Viscosity measurements are made
every 200 milliseconds. Every two seconds the data
is statistically processed and the analog outputs
refreshed. Data is further processed using a rolling
average of the 2 second data summaries computed at
the time of the log entry. The data log interval can
be set with one click at intervals from 10 seconds
to 10 minutes [see illustration below]. Viscosity
measurement response time typically depends more on
the fluid refresh rate than on our measurement frequency
unless a long logging interval has been selected.
Temperature characteristic response time is 25 seconds
or less. There is a graphical display recorded with
our standard graphing software at a ten second log
interval with a VS205 viscometer shown below illustrating
the measurements observed when a room temperature
[20degC] probe is plunged into 70 degC. water. 20
series viscometers such as the VSH-223 will have an
even faster response.
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Can I set the shear rate?
You cannot set the shear rate. It is approximately 5000
1/sec.
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