OUR F.A.Q.
Why would I need a process viscometer?
There are many reasons to get an automated process viscometer. Some are:
- to have real-time feedback regarding product evolution or stability,
- to avoid bad production, scraps, rejects and waste,
- to minimize raw materials consumption,
- to optimize process control,
- to control product quality,
- to verify the quality of purchased goods,
- to reduce the number of laboratory measurements.
What should I look for in a process viscometer?
Mainly 2 things:
- robustness to avoid unnecessary maintenance and downtime
- repeatability to get timely and reliable information
Other parameters:
What technology is used in sofraser viscometer?
In 1981, Sofraser patented the first viscometer maintained in vibration at its resonance frequency. More than 40 years later, we still use this technology because it has been proven to be the most reliable and precise for process viscosity measurement.
What is resonance frequency?
It is the natural vibration frequency of a mechanical system (like a diapason). The resonance frequency allows a system to oscillate with the greatest amplitude of a vibration. In our system, the amplitude of the vibrating rod is about 0.1 mm.
Using this principle makes our instruments unaffected by external vibrations and explains the outstanding reliability.
If the instrument uses vibration for measurement, won't process vibrations disturb the reading?
No. The viscometer vibrating at resonance frequency is not affected by external vibrations and disturbances.
How is sofraser's sensor calibrated?
The vibrating technology provides a relative measure. The calibration is realized by correlation to certified mineral oils. By measuring the vibration amplitude in these viscosity standards, the mathematical model parameters are programmed in the electronics.
How often do I have to re-calibrate the sensor?
In normal working conditions, the parameters will not change once they are entered in the electronics. As a matter of fact due to the specific mechanical design, the thermal treatment, and precise assembly, our viscometers have no drifts in time. Most of the time the re-calibration is unnecessary.
Is the installation of the sensor difficult?
The mounting flange delivered with the sensor must be welded to the process by a certified professional. An electrician should connect the power supply to the electronics and wire the outputs.
The sensor comes with clear mounting instructions that describe how to mount and start the sensor. If necessary, a Sofraser team member or one of its distributors can come on site to help with the starting up.
Do I need special skill to start-up the viscometer?
Once the sensor is installed on an empty pipe (no fluid present), the first and most important thing is offsetting the electronics (zero in the air). This is a simple procedure that involves pushing a few buttons; detailed instructions are in the User Manual. Any time the sensor is removed and re-installed, the offset must be performed.
How often do we have to clean the probe?
When cleaning the process, leave the viscometer in place. The motion of the vibrating rod combined with the cleansing solution washes the sensor.
What kind of maintenance is required?
No regular maintenance is required on the sensors as our viscometers have no wearing parts and have proven to be very robust.
The MIVI is delivered with a 7-year warranty.
The MIVI is delivered with a 7-year warranty.
What if I need to check calibration?
You can check calibration by measuring a lab referenced Newtonian fluid (silicon or certified mineral oils) for which viscosity at room temperature is known. Re-calibration of the instrument, using certified mineral oils, can be done at our factory in France or at our Houston office.
Can I measure non-newtonian (pseudoplastic, thixotropic, etc.) fluids?
The MIVI sensor is extremely repeatable, even in non-Newtonian fluids.
The process generates a shear rate, thus altering a non-Newtonian product. In this particular situation, no principle in the world is able to provide an absolute measurement. Regarding non-Newtonian products, it is always necessary to make a correlation with reference values (lab measurements). In this situation, the best sensor for non-Newtonian fluids will be the sensor that provides the most repeatable measurement.
The repeatable MIVI viscometer operates at a high shear rate which allows, in many pseudoplastic fluids, viscosity measurement in the “Newtonian Range”. In essence, this is the flatter part of the shear rate vs. the viscosity curve. It is within this range that pseudoplastic fluids exhibit a Newtonian behavior.
What are the sensor's limitations in process?
Since our viscometers are designed to adapt to every process, pipe size or viscosity range; it works in difficult conditions: high temperature, pressure changes, corrosive elements, clogging fluids, etc. Refer to each sensor technical leaflet.
What materials and coatings are available?
Our standard sensor is manufactured with 316L SS. Wetted parts in Hastelloy® or other special alloys (e.g. 316Ti) are available upon request. To prevent abrasion or corrosion, a wide range of coatings is available: PTFE, PFA, Enamel, ADLC, etc.
What mountings are available?
We have 5 standard mountings:
– on reactor
– on pipe angle
– on measuring chamber
– on immersion tube
– straightline mounting
If I cannot use standard mountings, what are my options?
If the above-mentioned mountings are not sufficient, Sofraser can make custom mountings according to your specifications.
Why do I need the electronics?
The sensor is matched to its own electronic unit and cannot work without it.
Can 1 PLC supervise several sensors?
Yes. Up to 4 sensors can connect to the same PLC using and intermediate digital transmitter.
Do the electonics have temperature compensation?
Thanks to an internal temperature measurement, all sensors have temperature drift correction. Some electronics allow viscosity calculation at reference temperature (temperature compensated viscosity, TCV). To do this, option Pt100 (a temperature probe) is recommended, as it measures the product’s temperature in process.
What type of outputs/relays do the electronics have?
Depending on the electronics, there are:
– 4-20 mA outputs
– RS485 / RS232 outputs (using MODBUS / CANBUS)
– Relays for low / high alarms and diagnostics
Please refer to the technical leaflets
What is the maximum distance between the sensor and the electronics?
The sensors are delivered with 3 meter of cable (this is standard). Depending on the electronic device, up to 1,000 meters (3,300 feet) can be between the sensor and electronics.
How are repairs and service handled?
Sofraser has a worldwide distributor network and can service most of the countries in the world. Contact the company from which the sensor was purchased or contact Sofraser directly. Most repairs are made at the factory in France.
What if I want to change an electronics unit but keep the sensor?
If the sensor was manufactured after 1993, this option is possible. Since our sensors are very robust, it is not uncommon for customers to upgrade the electronics without changing the sensor.However, the sensor must go back to the factory where it will be matched with its new electronics unit before being returned.
Where can I find my serial number?
Our serial numbers have the following format : “1234”.The most common place to find the serial is on marking plate on the sensor itself. The serial number can also be found on the sensor literature as well as on the inside of the electronics. In the case of newer electronics, the serial number is entered in the program and can be displayed by accessing the proper menu (see the User Manual for more information).
What FM classifications does your sensor carry?
Our MIVI sensor :
FM approval for class Ι, Division 1, Group A, B, C, D hazardous locations T4A
What ATEX or IECEx classifications does the viscometer carry?
Our MIVI sensor:
In Zone 1: II 2GD
Ex db IIC T6..T1 Gb
Ex tb IIIC IP6X T75..T180 Db
In Zone 0: II 1 G
Ex ia IIC T6…T1 Ga
