K-Patents Technical Assistance and FAQ

K-Patents Technical Assistance

If you need local technical assistance from K-Patents authorized representative, please choose the right region in the map to find the appropriate representative for your country.

If you need technical assistance from the K-Patents factory, please refer to the contacts below.


All Countries Except the United States:

 Harri Salo, Technical Manager [harri.salo(at)kpatents.com]
Markku Keurulainen, Service Technician [markku.keurulainen(at)kpatents.com]

United States:

 Mike Dedmond, Service Manager [mike.dedmond(at)kpatents-usa.com]


Please attach the following information to your technical assistance request:
  • Instrument model code
  • Sensor and Indicating transmitter Serial Number
  • Photo of optical image and slope
  • Photo of installation
  • Measured medium, flow rate

 How long will it take to get an answer?
Turn around time of requests is normally one calendar day except in weekends and holidays.


Frequently Asked Questions:

General Questions
Technical Support Questions
General Questions

What does a process refractometer do?
A process refractometer is an instrument for in-line (production line or vessel) measurement of concentration based on the refractive index of a liquid.

What is a "refractive index"?
 The refractive index or RI is a physical property of a liquid, which is proportional to the concentration. The RI can be described as the bending power of light at the surface of a liquid.
Read more: Refractive Index as a Concentration Measurement Principle pdf

Why use the refractometer principle for concentration measurement?
This principle makes it possible to design an instrument with
  • no influence by bubbles in the medium (something that gets all other types of measurement to show too low concentration)
  • no vibrating or moving parts, no thin-walled pipes that burst
  • no radioactivity, i.e. no special permits, no paperwork, no hassle with used radioactive sources.
 But why just a K-Patents process refractometer?
K-Patents design makes full use of the advantages of the measurement principle:
  • Completely digital design: No signal drift, no need for regular recalibration, no influence by bubbles or suspended solids.
  • Robust design: Probe tip machined out of one piece of solid steel, light source a light emitting diode (LED)
  • Wide variety of uses: there are refractometer models for food industry, heavyduty industry, corrosive industry and even for ultra-pure fine non-metallic processes.
Whether you want to measure orange juice, black liquor in a pulp process or the process of diluting HCl, K-Patents has a refractometer to suit your needs.

What is my economical gain if I start to use a K-Patents Process Refractometer in my process?
If you get a continuous measurement (or control) of the concentration in your process, how would you estimate your economical gain?

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What exactly can a K-Patents refractometer measure?

Is it correct that a K-Patents Process Refractometer can measure any materials that can be measured by an Abbe refractometer?
Yes, this is correct. Although the K-Patents instrument is digital, the principle of measurement is the same.

Can the accuracy of measurement of a process refractometer be predicted?
For dissolved solids we can as a rule promise ±0.1 % by weight. For other solutions the accuracy depends on the Refractive Index.

Can a process refractometer measure wood pulp fibers in water ("consistency")?
No, it cannot, because that is a suspension and not a solution and thus there's no liquid concentration to measure.

Can a process refractometer measure kaolin ("china clay") in water?
No, because kaolin clay is chemically inert and doesn't dissolve in water, thus there's no concentration, just particles in water.

Can a process refractometer measure Titanium Dioxide (TiO2) in water? No. Distinct from dyestuffs which operate on a molecular level, pigments (TiO2 among them) tend to be particulate and insoluble and thus there's no liquid concentration for the refractometer to measure.

No lower temperature is mentioned in the specs, can we measure at 0ºC?
We may even measure at sub-zero temperature, but the Indicating Transmitter has to be placed in a warmer environment because of the Liquid Crystal Display (LCD) operating range 0-50ºC. In low temperatures there may also be problems with condensation in and ice outside of the probe.

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Calibration of a K-Patents Refractometer

Can the refractometer output be calibrated in density units (specific gravity)?
Yes, it can.

Can the refractometer output be calibrated in Baumé? Balling? Brix? ºBx? ºPlato? ºOeschle? Gram per liter?
Any unit is fine as long as it is a (liquid) concentration unit.

Why is the K-Patents Process Refractometer factory calibration made in room temperature with R.I. standard liquids? Wouldn't actual process solutions at actual process temperature be better?
The advantage with the standard liquid calibration is that it is easily reproduced anywhere later on.

...but then you may have to make a field calibration after start-up?
Yes, but when we make a field calibration we are sure that we have the actual process conditions, and also that we calibrate according to the customer's normal concentration determination method, e.g. use laboratory method as a reference.

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Questions and Answers on Refractometer Parts

Temperature Sensor

Wouldn't a separate temperature probe be faster than the built-in temperature sensor, and thus give better temperature compensation?
The sample is a thin film on the surface of the prism. The temperature of this film is more like the prism temperature than like the process medium temperature. Thus a temperature sensor near the prism gives more accurate results than a separate temperature probe in the process line would.

Prism

Why do you use Spinel for prism material?
Because the K-Patents Process Refractometer is an in-line instrument, the prism has to be harder than anything that moves in the process pipe. Spinel has a cubic crystal structure and thus very good optical properties, the R.I. is the same in all directions (isotropic).

How about the heat shock of prism? For example when the prism is cleaned with steam?
Because Spinel is an isotropic crystal, it is very resistant to heat shocks. Steam will not cause problems.

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Durability of the process refractometer materials

What is the minimum temperature of sensor and electronics?
The components are specified to -40ºC except the Liquid Crystal Display (LCD) in the indicating transmitter that is limited to operating temperature 0ºC and storage temperature -20ºC.

Can you guarantee that your material stands our process conditions?
We can only guarantee that the material is as specified in the order, the customer has to take the responsibility for material selection. However, the more exact information you can give us on your process conditions, the more likely it is for you to get a refractometer suited for your conditions.

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Technical Support Questions

Installing and using a process refractometer

 It is very important to try to arrange a good velocity of the process liquid at the prism. We recommend at least 1.5 m/s (5 ft/s) to keep the prism clean.

The velocity in my process is 1.5 m/s but the flow is not continuous, i.e. it stops at some intervals. Does this cause problems with the refractometer?
Yes, but the problems can be avoided by mounting the refractometer in a recirculation loop with continuous flow.

What if the flow is only 0.6 m/s?
Do you think you could use a smaller diameter process line to achieve higher velocity?

What about the pressure drop?
For a venturi type restriction the remaining pressure drop is small. This kind of restrictions are often used for magnetic flow meters.

Anything else I could do instead of using a smaller process line?
It is probably possible to install an automatic prism wash for your refractometer to clean the prism when the velocity isn't high enough.

When is a regular automatic prism wash recommended?
If the process velocity is low or if the process medium is so sticky that you get coating problems despite the good velocity.

What can we do, when the output signal doesn't agree with our laboratory values?
Fill in a Calibration Data Report (see the last page of your Process Refractometer Manual), e.g. 6 to 10 points would be OK. Then send your report to K-Patents or your local representative and they will calculate your new Calibration Constants for you.

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Troubleshooting

Identifying a Problem in PR-23 or PR-03 Process Refractometer

If the following criteria are met, the problem is not likely to be electronic:
  • Indicating transmitter displays information and keyboard is OK
  • Optical image can be seen
  • Current output is between 4 ..20 mA most problems are process or configuration related, not physical failures
To further troubleshoot a problem in PR-23 or PR-03 refractometer hardware, display, power supply, prism wash, diagnostic LEDs or diagnostic messages, please refer to Troubleshooting Section at the appropriate Manual.

Identifying a Problem in PR-01-S Process Refractometer
To troubleshoot PR-01-S refractometer, please refer to Trouleshooting and correcting PR-01-S Sensor problems pdf or the Maintenance Section at the appropriate Manual.

Identifying a Problem in DD-01 Divert Control System
To troubleshoot DD-01 divert control system, please refer to the Maintenance Section at the appropriate Manual.

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Warranty Policy and Claims

K-Patents warrants that all products made by K-Patents shall be free of defects in material and workmanship. K-Patents agrees either to replace or repair free of charge, any such product or part thereof which shall be returned to the nearest authorized K-Patents repair facility within two (2) years from the date of delivery.

Before returning a defective product for service or replacement, please contact K-Patents or your nearest K-Patents representative.

For the health and safety of personnel handling your return, clean the instrument, especially the parts that have been in contact with the process liquid, before packing it. Ship the cleaned instrument to the address given to you.

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Availability of spare parts

Can I still get spare parts for my old refractometer?
The warranted availability of K-Patents spare parts for all refractometer lines is ten (10) years from the moment that the manufacturing of the refractometer line has been discontinued.

Availability of Spare Parts for Different Refractometer Lines
The following Process Refractometer lines have been or are currently in the KPatents manufacturing schedule:
Refractometer line:
PR-01
PR-01-E
PR-01-B
PR-01-S
PR-03
PR-23

 		Years in manufacture:
1983 - 1987
1986 - 1990
1989 - 1995
1992 -
2000 -
2004 -
K-Patents has a small stock of spare parts for the Refractometer PR-01-E line, and it is advised to check their availability in advance.

K-Patents support and provision of spare parts for the Refractometer PR-01-B line was discontinued at the end of 2005. But, K-Patents may supply some spare parts for the PR-01-B on a limited basis. It is advised to check their availability in advance.

The spare part availability for all other refractometer lines is currently at least ten (10) years.

Upgrade Policy:

K-Patents recommends that refractometers of PR-01, PR-01-E and PR-01-B lines would be upgraded to PR-23 refractometers.

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