Is it water or orange juice?

11/12/2010


Dear Control Engineering: I am working in the process to automate a pasteurizer. I am looking for a sensor technology to detect the change from water to orange juice, and from orange juice to water in the output process. It has a color sensor, but it doesn't detect the change all that well. Do you know a better sensor? Thank you. –Erick

When looking at a question like this, we have to think about how water is different from orange juice, and then which of those differences is the easiest to detect or quantify. Apparently color, the most obvious choice, isn’t good enough, so what are some of the other possibilities? Orange juice is more acidic and has more sugar in it, so those might be more practical to detect. I asked Jim Gray, application manager at Rosemount Analytical Instruments for some suggestions. He says, “I think conductivity using a toroidal sensor would be the way to go. That would be the easiest from a maintenance standpoint. The conductivity of OJ should be greater than the conductivity of water, although I don’t have any number handy. The problem with pH would likely be the sensor drying out when the process is down. A Coriolis flowmeter would provide a continuous inferential measurement of concentration but is much more expensive. Conductivity should be sufficient for a status indication.”

A toroidal conductivity sensor.A toroidal conductivity sensor is a doughnut-shaped probe that inserts into the process liquid stream. The toroid itself has two coils. One is powered and creates a magnetic field. The second is a receiver. The current induced in the receiver is in proportion to the conductivity of the surrounding liquid. The probe can be encased in an appropriate grade of plastic to withstand the process liquid. Units are available that are designed for sanitary applications in food processing.

--Peter Welander, pwelander(at)cfemedia.com



No comments
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by...
Each year, a panel of Control Engineering editors and industry expert judges select the System Integrator of the Year Award winners.
Control Engineering Leaders Under 40 identifies and gives recognition to young engineers who...
Learn more about methods used to ensure that the integration between the safety system and the process control...
Adding industrial toughness and reliability to Ethernet eGuide
Technological advances like multiple-in-multiple-out (MIMO) transmitting and receiving
Virtualization advice: 4 ways splitting servers can help manufacturing; Efficient motion controls; Fill the brain drain; Learn from the HART Plant of the Year
Two sides to process safety: Combining human and technical factors in your program; Preparing HMI graphics for migrations; Mechatronics and safety; Engineers' Choice Awards
Detecting security breaches: Forensic invenstigations depend on knowing your networks inside and out; Wireless workers; Opening robotic control; Product exclusive: Robust encoders
The Ask Control Engineering blog covers all aspects of automation, including motors, drives, sensors, motion control, machine control, and embedded systems.
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
News and comments from Control Engineering process industries editor, Peter Welander.
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
This is a blog from the trenches – written by engineers who are implementing and upgrading control systems every day across every industry.
Anthony Baker is a fictitious aggregation of experts from Callisto Integration, providing manufacturing consulting and systems integration.
Integrator Guide

Integrator Guide

Search the online Automation Integrator Guide
 

Create New Listing

Visit the System Integrators page to view past winners of Control Engineering's System Integrator of the Year Award and learn how to enter the competition. You will also find more information on system integrators and Control System Integrators Association.

Case Study Database

Case Study Database

Get more exposure for your case study by uploading it to the Control Engineering case study database, where end-users can identify relevant solutions and explore what the experts are doing to effectively implement a variety of technology and productivity related projects.

These case studies provide examples of how knowledgeable solution providers have used technology, processes and people to create effective and successful implementations in real-world situations. Case studies can be completed by filling out a simple online form where you can outline the project title, abstract, and full story in 1500 words or less; upload photos, videos and a logo.

Click here to visit the Case Study Database and upload your case study.