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Product category: Product Transportation
News Release from: Signatrol | Subject: Dataloggers SL400, 150, electronic signatures
Edited by the Processingtalk Editorial Team on 25 February 2003

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

Wherever instrumentation is used to monitor or control a process, operation or environment, its effectiveness is dependent on a number of factors One of the most important of these is ensuring that any measurements are taken at the optimum place to provide representative data

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.

Therefore data loggers play an important role in monitoring and recording data in a wide and diverse 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 significantly across a broad spectrum of industries.

These versatile, compact and self-contained products can be used to measure and record parameters including temperature, pressure, humidity, voltage and current.

Portable loggers typically comprise 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 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 set up and to extract data.

This is usually carried out in conjunction with a PC or lap-top computer using dedicated software.

There are three main methods used, namely 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 in the food chemical and environmental industries.

For certain applications data loggers can also transmit data via telemetry link.

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, consideration should be given to a number of criteria including: Measurement range; Number of measuring channels; Environment and sealing requirements; Set-up and down loading of data; Security; Size; Logging period; reading frequency; storage memory; Logger placement and retrieval.

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.

This system, which allows the user to measure, display and record real time temperature and humidity data, is already finding application in cold stores, supermarkets, warehouses, laboratories, computer buildings, museums, stately homes and art galleries.

In addition to measuring temperature and humidity, the SL400 can also be configured to measure light level and UV content, vital parameters in buildings such as art galleries, museums and stately homes.

The wireless technology means that the SL400 system offers significant savings in terms of wiring and installation costs, whilst providing the ultimate in flexibility.

Systems can be installed quickly and without any disruption to existing structures or buildings.

One consequence of this is that the SL400 can be used cost effectively for short-term installations.

A typical system consists of a receiving base station, permanently connected to a PC, and up to 256 remote monitoring stations.

Each station transmits data to the base unit and can have up to four sensor inputs, giving a total capability of 1024 channels per installation.

The frequency of data transmission can be set from 15 seconds up to 90 minutes.

The SL400 uses the latest pan-European, licence free 434 MHz radio transmission frequency in line with the new style directive 99/5/EC which becomes mandatory in December 2002.

Each remote transmitter has a built-in long life battery providing up to five years life at a sampling rate of 20 minutes and can be mounted up to 300 m away from the base station, extending to 1000 m with a direct line of sight.

An optimal liquid crystal display is also available to provide local indication of temperature and humidity.

Although one of the main uses for the SL400 is for monitoring temperature and humidity, the unit can be set up to measure almost any physical parameter as long as a suitable transducer is available which provides a milliamp or low level DC signal.

As a result SL400 transmitters can be positioned in strategic locations in industrial plants to measure not only temperature but also pressure, level, flow or load, transmitting back the data to the central location, using additional repeater stations if required.

The Windows based software can be configured to provide the operator with measured values in a variety of standard formats -from simple bar graphs to multi line traces, and graphics can be added which show the location of the remote transmitters.

Live data alarms can be set and using the North Communications Compass system, the data can be input into a compatible BMS or Programmable Controller.

An optional network adaptor allows the SL400 to be connected remotely on an existing Ethernet network providing access from anywhere on the local area network.

The base station uses the PC hard disk to store readings.

However, if the computer is turned off, the base station will store readings in its own internal memory for up to a week and then down load them automatically when the PC is turned on again.

The versatility of loggers can be increased by the use of ingenious packaging and design.

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 350C.

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, thus providing meaningful and accurate temperature data.

The data can also be used to optimise cooking times thus maximising throughput and minimising energy usage.

The barrier units are equally suited to use in chillers, spiral freezers and blast freezers.

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.

However, the effectiveness of any controls can only be as good as the equipment, procedures and, above all, diligence of the personnel involved at each and every stage.

Unfortunately, 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 to ensure complete product audit trails.

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.

Units like the SL150 temperature logger is specifically designed to travel directly with goods and provides a detailed date and time temperature profile, which can be used to highlight any problems so that corrective action can be taken.

The data logger is housed in a fully weld sealed crevice free, robust food grade plastic tag, which is only 10mm thick.

The SL150 uses a patented induction technique for set up and data down load which means that there are no plugs, sockets or entries of any kind to cause problems.

Powered by an internal battery, the unit can be selected to log at intervals from 1 minute up to 255 minutes and has a measurement range from -30C to +70C.

Food transportation is becoming more complex and presents a major challenge when it comes to controlling temperature requirements for different products.

We now expect our supermarkets to provide a diverse range of fresh food products all year round.

In order to do this, they must purchase food from around the world and ensuring that this reaches the shelves in prime condition is of paramount importance.

However, achieving this can be a logistical nightmare and any problems are expensive not only for the supplier but also in terms of supermarket reputations.

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.

The overall quality and freshness relies on strict temperature control throughout the journey.

Any excursions from their optimum storage temperature may go undetected, the only signs being a deterioration once on the supermarket shelf.

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.

The Signatrol SL150 data logger provided the perfect answer.

This logger is a small, self-contained unit which is fully sealed in a food grade plastic case.

The unique induction technique for accessing data means there are no external plugs or crevices and units can be placed directly with food without problems of contamination.

Units were used to monitor the temperature of the produce right from the start of the washing process at the farm through to the final destination at the supermarket.

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.

Other diverse cases have also been solved using portable loggers.

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 SL150 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 accounts 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 he could concentrate on his work!.

Another example where portable data loggers highlighted problems was in the transportation of star fruit from Malaysia.

Star fruit should be carried at 6C to ensure that it does not ripen too quickly.

A major company involved in the importation of star fruit decided to use the SL150 loggers to ensure product arrived in tip-top condition.

This decision paid dividends when problems arose with a complete shipment.

The consignment in question was due to arrive directly into Felixstowe as normal.

However, it was diverted to Rotterdam and then put onto a smaller vessel.

Three days later, the shipment arrived in Felixstowe and was transferred to road transport for the last leg of its journey.

When the consignment was received, the temperature was checked and, initially, the customer was satisfied that the produce had arrived within the specified temperature.

However, when the fruit went on sale it was discovered that there were problems and a significant loss of product resulted.

Interrogating the temperature logger, which had accompanied the consignment, highlighted where the problem had arisen.

The temperature of the consignment had risen to 9C while waiting to be loaded to the smaller vessel.

Between Rotterdam and Felixstowe the ships refrigeration system had brought the temperature down to 7.5C and the road vehicles system had subsequently brought the temperature down to the requisite 6C.

This information was subsequently used to make a successful insurance claim.

The standard SL150 data logger has a number of special security features, which facilitate its use in transport applications.

These include a convenient "through hole" which allows the unit to be security-sealed to the consignment.

Now, in order to meet requirements from US companies, a special high security software version has been developed which ensures it has full compliance with the US Food and Drugs Agency FDA 21 CFR Part 11 legislation ensuring the validity of stored electronic data.

This federal regulation also sets out the criteria under which the agency considers electronic signatures and hand written signatures executed to electronic records, to be trustworthy, reliable and generally equivalent to paper records and hand written signatures executed on paper.

Although this regulation has no official status in Europe any companies that export critical products to the US need to comply.

Brian Turner, MD of Signatrol, believes that similar regulatory control is not far away in Europe, and the SL150-HS provides all the necessary controls over systems and procedures to fully satisfy those requirements: not just of FDA, but also HACCP and EFSIS including the provisions for Electronic Signatures.

There are several key elements of the FDA standard as follows; the ability to discern invalid or altered records; the ability to generate accurate and complete copies of records; protection of records to enable their accurate and ready retrieval throughout the records retention period; limiting system access to authorised individuals; use of secure, computer generated, time stamped audit trails to independently record the date and time of operator entries and actions that create, modify, or delete electronic records; use of authority checks to ensure that only authorised individuals can use the system.

Signed electronic records shall contain information associated with the signing that clearly indicates all of the following: the printed name of the user; the date and time when the signature was executed; and the meaning (such as review, approval, responsibility, or authorship) associated with the signature.

Electronic signatures and handwritten signatures executed to electronic records shall be linked to their respective electronic records to ensure that the signatures cannot be excised, copied, or otherwise transferred to falsify an electronic record by ordinary means.

Signatures should: employ at least two distinct components such as an identification code and password; be used only by their genuine owners; be administered and executed to ensure that attempted use of an individual's electronic signature by anyone other than its genuine owner requires collaboration of two more individuals.

All the data in the SL150-HS logger is stored in an encrypted form to ensure that the data cannot be altered or in any way manipulated and yet they can be archived or exported to other sites (including FDA) for analysis.

System access is tightly controlled by a Systems Administrator who registers via the Signatrol website or by telephone and is responsible for entering a number of authorised 'Users' onto the system who are identified by a unique user code and password.

For added security, the system also prompts the user to change his password at six monthly intervals.

A contiguous audit trail of SL150 tag activity and stored data is maintained on the primary PC, from which all tags are issued.

Separate viewer software, available free from the website, enables any number of users to examine the data or provide secondary (un-signed) copies.

The construction of the system is such that, even though the transportation and distribution may be outside the direct control of the company, it can still be maintained as a 'closed system' within the FDA definition.

Alternatively, it can be run as an 'open system' by configuring the system to run with manual, rather than electronic, signatures.

Internal monitors, contained within the tag, provide the user with automatic notification that re-calibration (12 monthly intervals), is required or that the batteries are over their recommended four years life, when the loggers can be returned and traded in for replacement units.

In addition, the SL150 can be individually protected by a nine character ID code, which is stored within the tag for life and is required to issue a tag or to change any of the option settings.

There is little doubt that electronic records offer significant advantages, not only eliminating mountains of paper work, but also speeding up data processing and information exchange.

However, in any systems or process, Critical Control Points must be clearly identified and monitored so that effective corrective and pre-emptive action can be taken.

This is onerous enough within the confines of any organisation but becomes ten times more complex once products or goods are transported externally.

As Brian Turner concludes" Setting up any electronics record system is only the start and companies must ensure a consistent process to maintain an effective level of security and control.

Although products like our SL150 may appear to have only a tiny part to play in any process, they provide a vital continuity link in an important area".

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