Product category:
Telemetry, data acquisition + loggers
News Release from: Signatrol | Subject: Dataloggers
Edited by the Processingtalk Editorial
Team on 11 July 2005
Principles and uses of dataloggers
Dataloggers can be used to measure and record a wide range of parameters including temperature, pressure, humidity, voltage and current: David Green reviews the options
Dataloggers can be used to measure and record a wide range of parameters including temperature, pressure, humidity, voltage and current In some applications, fixed instrumentation may only provide limited information based on measurements taken at a particular point while for others it may not be practical to install permanent instruments
This article was originally published on Processingtalk on 25 Feb 2003 at 8.00am (UK)
Related stories
The advances with modern data loggers
The latest technology in dataloggers from Signatrol is providing invaluable information across all areas of industry, with total traceability in food and pharmaceuticals transport around the World
The Effectivenes of Modern Data Loggers
The latest in dataloggers from Signatrol is providing invaluable information across all areas of industry: wherever instrumentation is used to monitor or control a process, operation or environment
Therefore data loggers play an important role in monitoring and recording data in a wide range of industries.
In the past, data loggers have tended to be relatively bulky devices which often needed to be powered via the mains supply or large battery packs, restricting their use to permanent or semi-permanent installations.
Significant developments in low power electronics and battery technology have enabled manufacturers to design smaller and smaller portable data loggers and as a result, their use is increasing across a broad spectrum of industries.
Further reading
Undercover detectives for food transportation
The food industry is highly competitive: companies are under increasing pressure to improve productivity and profitability: so, to account for food quality problems, data loggers are now indispensible
ATEX pressure data loggers on natural gas network
Over 250 ATEX certified pressure data loggers supplied by Signatrol are playing a crucial role in ensuring effective natural gas distribution throughout Latvia
Assisting optimisation of sterilisation processes
The Signatrol Temp-IT universal data logging software now has F0 calculation functionality, specifically developed for the validation of anti-bacterial steam sterilisation and cooking processes
Portable loggers typically are comprised of signal conditioning electronics, one or more sensors (either internal or external), built-in memory unit, clock and internal battery.
Unit configurations include: single channel, multiple channel - single parameter or multiple channel - multiple parameter (for example temperature and humidity, or temperature, humidity and pressure).
One of the most important aspects of their design is the method used to communicate with the logger in order to carry out the set-up and extraction of data.
This is usually carried out in conjunction with a PC or laptop computer using dedicated software.
There are three main methods used: direct cable link, infra red and induction.
The latter two do not require any form of electrical connector of the sealing; integrity is assured.
This is vitally important in harsh environments such as the food and chemical industries.
In order to conserve battery life, loggers use special low power electronics and can be set up to measure and record at discrete pre-set periods.
Depending on the application, sample rates are usually set anywhere between several times a second up to several days and therefore the total logging period is a function of this period and the internal memory size.
Depending on the design and set-up, data may be stored until the memory is full (fill then stop) or stored on a continual basis with the older data being automatically replaced (first in - first out).
The key to successful datalogging is being able to place the logger right at the heart of where the parameter has to be measured.
When selecting a logger for a particular application, consider: measurement range, number of measuring channels, environment and sealing requirements, setup and downloading of data, security, size, logging period, reading frequency and storage memory, logger placement and retrieval.
Temperature Datalogging.
The logging of temperature represents one of the widest uses for data loggers with applications as diverse as monitoring blood product transportation for the British Armed Forces, the manufacture of compost from sewage sludge and recording temperature profiles in bread ovens and industrial washing machines.
The reasons for datalogging are equally diverse and include product or process verification, traceability and long term environmental research.
Temperature loggers are ideal for checking temperature profiles and find application in areas such as museums, art galleries, environmental chambers, vehicles, ovens and freezers.
Depending on the application, either a number of individual loggers can be used or single units with multiple sensors.
Individual units have the advantage of being compact, discrete and easy to place.
For certain applications loggers with combined humidity and temperature sensors provide important environmental information.
The flexibility of the data loggers can be radically extended by the use of thermal barrier boxes, which allow the loggers to operate at temperatures up to 350 degrees C.
The loggers are kept insulated and sealed inside the barrier's stainless steel box while external sensors measure the temperature.
This arrangement is ideal for oven temperature profiling to provide documentary evidence that products are reaching and maintaining the required cooking temperatures.
The barriers can travel through the oven with the food.
The data can also be used to optimise cooking times thus maximising throughput.
The barrier units are equally suited to use in chillers, spiral freezers and blast freezers.
Safety and Traceability.
With heightened awareness of issues relating to safety and quality of a wide range of perishable products and goods, increased legislation is leading to the implementation of new procedures and controls for storage and transportation.
As equipment and systems become more sophisticated, the opportunity for error or fraudulent misuse increases and therefore unambiguous and strict product traceability systems are vital.
Temperature control is one of the most critical factors in ensuring the quality of perishable goods such as food, drugs, medical products and pharmaceuticals, especially during transportation.
Routings can be complex with goods often being transhipped using several different methods and carriers.
Direct monitoring of the temperature of the product is infinitely more reliable (and hence more diligent) than the general monitoring of the environment inside vehicles and containers.
The important factor is that compact portable loggers can monitor the total journey even when this involves several stages of responsibility.
Consider the example of beans picked fresh in Zimbabwe.
These must be transported swiftly to the field picking station, washed, graded and then packed.
From here they are transported to the airport, airfreighted to the UK, transhipped on to the supermarket distribution centre and then on to the individual stores.
When a major supplier in Zimbabwe was faced with claims for premature food deterioration, they needed a simple yet effective way of finding the source of the problem.
Analysis of the data over a few weeks highlighted that sometimes the temperature of the produce was rising above acceptable levels.
The data gave clear information on when this had occurred and it was not difficult to identify that this coincided with the time when the produce should have been airborne on its way to London.
However checks with the airline at Harare airport showed that flights were regularly delayed.
Planes could sit on the runway in searing heat for up two hours and this caused the consignment to heat up.
The produce is now packed in insulated containers and this has solved the problem.
One of the strangest arose when a fish processing company were having problems with their cold stores.
Engineers carried out thorough checks on the equipment and could find nothing wrong.
However the problems continued and the company decided to place a number of datalogger tags inside the rooms.
Analysis of the data showed that on Sunday the temperature went above the company tolerances.
A special watch on the cold store revealed that on Sunday the company's account clerk would come into his office to catch up with his paperwork.
This happened to be located next to the cold store plant room and he turned off the refrigeration system so that the noise would not distract him from his work! Conclusion.
Portable data loggers present powerful tools for monitoring and validating parameters in a wide range of processes and environments.
Data can be used for simple checking of permanent instrumentation and controls through to more complex validation processes and even litigation and insurance claims.
Their applications will continue to grow as demands from users increase.
As well as their use in storing physical data these products are also being used in applications as diverse as monitoring operator efficiency on production lines by measuring pulses from proximity switches to providing data for management.
This review is provided by David Green of DCG Associates.
• Signatrol: contact details and other news
• Email this article to a colleague
• Register for the free Processingtalk email newsletter
• Processingtalk Home Page
Search the Pro-Talk network of sites
