Obtaining Data When & Where It Is Needed- Signatrol UK

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 and time to provide representative real time 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, thus 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, acceleration, inclination, 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 so the sealing integrity is assured. This is vitally important in harsh environments in the food chemical and environmental 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 data logging 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
Setup and down loading of data
Security
Size
Logging period, reading frequency and storage memory
Logger placement and retrieval

Temperature Data logging

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 data logging 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 versatility of loggers can be increased by the use of ingenious packaging and design. For instance, 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 350ºC. 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.

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.

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.

A Bright Future

The increasing use of computer Ethernet networks within buildings and warehouses offers an ideal method for accessing data from logging equipment. Adaptors allow data loggers to be connected to existing Ethernet networks and each adaptor is given a unique address (IP address). Software is then installed on the host computer that communicates with the network and creates a pseudo COM port, making it look as though a new COM port has been fitted. Communication is then available as if the data logger were sitting on the desk next to the operator.

Modern communication technology is also rapidly increasing the use of data loggers, allowing the remote extraction of data, especially from unmanned and geographically remote sites. This can be achieved either using conventional modem-to-modem communication or via GSM if a PSTN telephone line is not available at the remote site. For these applications, the data logger is connected to a GSM modem, fitted with a data enabled SIM card from a service provider that offers good reception in the area to be monitored. The data logger, fitted with a suitable adaptor, can then be accessed via a conventional modem and configured and backed up as if it were next to the operator. The remote data logger can also be configured to dial out in the event of an alarm condition occurring. Solar panels can also available if power is unavailable at the remote site.