In this blog, Kevin Green of Vaisala and Dave Lobach of Rocky Mountain Instrumentation answer several questions received during their webinar “Unlocking Efficiency: Refractive Index Insights for Chemical Industry Concentration Applications”.  If you haven’t yet seen it, you are free to watch the recording. 

Question: Do refractometers need a prism wash system?

Answer: A common question that arises in various challenging chemical applications is the necessity of prism wash systems. These systems are often required when there is a buildup or deposits in the piping or vessels that necessitate regular maintenance. Identifying the need for a prism wash system is crucial for maintaining the efficiency and longevity of the equipment. Determining the need for a refractometer prism wash system in chemical applications involves assessing whether there is a buildup or deposits.

When deciding to replace pH or conductivity measurements with refractive index, the need for a prism wash system can often be discerned from the process conditions and the maintenance requirements of the existing probes.

For more information, we have a blog on this topic: "How refractometer prism washing in challenging applications can create a competitive advantage".

Question: Does the critical angle change with concentration or is it determined by prism? 

Answer:  The critical angle will vary depending on the concentration of the solution. Additionally, the number of facets and the angles at which the facets are cut in the prism determine the refractive index range. This relationship is essential for accurate measurements and optimal performance of refractometers. Learn more about the mechanical specifications of the prism in this data sheet. 

Question: How many refractometers can be connected to an Indigo transmitter? 

Answer: When it comes to integrating refractive index (RI) sensors with transmitters, two Vaisala Polaris sensors can be connected to a single Vaisala Indigo520 transmitter. Each Indigo unit has Modbus TCP/IP digital communication or four analog outputs that can be utilized for both RI and temperature measurements. This flexibility allows for comprehensive monitoring and control within various industrial processes.

Question: Can we monitor the amount of undissolved solids by monitoring the dark side of the reflection? (I.E., the number of spots or brightness) 

Answer: While refractometers measure the total dissolved solids concentration, undissolved solids are typically measured with a density instrument. This measurement can then be used to determine the amount of insoluble product present in the process.

Question: Can refractive index measurement be used in Hydrocarbon and mineral powder slurry mixture? 

Answer: Refractometry is a valuable tool in analyzing hydrocarbon and mineral powder slurry mixtures. It can assess the viscosity of hydrocarbons while ignoring the solids in the process. By providing detailed information about the chemical slurry mixture, refractometers can offer precise and reliable measurements, which are essential for optimizing production and ensuring quality control.

We have a related application note: "Natural gas liquids NGL: Liquid hydrocarbons identification"

Learn more about liquid concentration measurement for process control and optimization in chemical applications.

Vaisala’s Polaris™ process refractometer range for liquid concentration measurement covers a wide variety of industries and applications. But what if your process needs something a bit special? Perhaps a custom connection size or coupling, or a flow cell size that our standard offering doesn’t have. Vaisala’s Engineer to Order service is here to help.

Vaisala’s pioneering Polaris optical inline process refractometers optimize manufacturing processes, enhance productivity, and save resources, energy, and time in various industries and hundreds of applications. The Polaris family includes products for, among other applications, liquid concentration measurement in food and beverage production, chemical manufacturing, and pulp and paper production – all highly specialized processes with their own unique requirements.

Tailor products for your specific needs with Engineer to Order

"Although the standard Polaris offering covers a wide variety of liquid measurement needs, customers might have special requirements that mean they need something that our off-the-shelf products don’t offer," says Niko Jaakkola, Project Engineer, Engineer to Order, Vaisala. "For example, they might need connections or couplings with different sizes to fit their process pipelines or require a specific type of material because of hygiene reasons or the process media that’s involved."

Other potential modifications that can be done through the Engineer to Order service include adding an EX certified housing for use in explosive environments – a common requirement in the petrochemical and chemical industries – or customer flow cell sizing to allow refractometers to be installed on the free ends of piping.

Engineer to Order is a one stop shop for customers who need to tailor Vaisala process refractometer products for their specific needs. "Some industrial processes, like pulp and paper production or petrochemical manufacturing, involve very harsh environments with extreme temperatures and corrosive chemicals," says Kati Ikonen, Manager, Engineer to Order, Vaisala. "In pulp and paper, for example, there could be a need to mount the refractometer using a spool size that we don’t have in our offering, or perhaps the customer has extremely specific requirements for the surface roughness of the housing. With Engineer to Order we can address their needs and provide a tailored solution."

Expert consultancy to identify the optimal solution 

For customers who want to take advantage of the Engineer to Order service, it is critical to gather as much information as possible about their process requirements, including pressures, connections, materials used, and the process media. The next step is to contact their local Vaisala sales representative.

"We liaise with the sales teams to review the customer’s requirements and develop a solution to meet them. The more information they can provide up front, the faster and easier it is for us to tailor their process refractometer solution. We can provide everything they need – cost information, what’s involved in the customization, and an idea of the lead time," says Jaakkola. "We’re always ready to act as an expert consultant to help the customer fine-tune their specifications and determine the most effective and economical outcome."

Process refractometer products that are tailored through the Engineer to Order service are covered by the same warranty as all other Vaisala products. All the customization work is performed at our production facility in Vantaa, Finland.