The LEMO 0T series in action

Electronics isn't always glamourous, but there's vital work going on hidden away behind closed doors. Although the composting industry might appear to be an unlikely candidate for innovation, it is a perfect example of how systems need to be reliable in the harshest of conditions. Swiss connector manufacturer LEMO was able to apply the expertise gained over nearly 6 decades to provide a solution to a unique set of requirements. Let's take a look at the story.

Compost is a big business in the UK. The total amount of controlled organic waste treated annually in the UK is in excess of 10 million tonnes, and the majority of this is composted. Composting is the process of controlled biological decomposition of biodegradable materials under managed conditions that are predominantly aerobic. There are approximately 400 composting sites in the UK which employ around 1,300 people. These sites range from those managed by large waste companies, to operations run by dedicated composting companies, and local on-farm facilities. The majority of the waste is processed in open-air sites where it is formed into trapezoidal piles, known as windrows.

Soil & Land Consultants Ltd (SLC) was formed in 2004 as a company to provide consultancy services in the areas of soil science, organic waste recycling, and compost utilisation. The CompostManager system was developed by SLC over a period of six years to provide compost producers with a better degree of process control. The system is designed to allow the compost producers minimise the generation of odours and greenhouse gases and maximise product quality.

Fig 1:  The Compost Manager System from SLC

The CompostManager system itself consists of a portable analyser with a sampling probe, and a web-based software interface. Recorded data is transfered from the analyser to a PC using a USB link, and the data is then stored in an online database from where they can be viewed from anywhere in the world. The software analyses the data using algorithms developed by SLC to provide site operators with clear and concise instructions to help optimise their process.

The CompostManager system is currently in use on 40 sites situated across seven countries and, to date, has collected over 270,000 sets of data. The analyser measures four key parameters of the composting process: the proportion of oxygen and carbon dioxide are determined by extracting a gas stream, whilst temperature and moisture are simultaneously measured by the tip of the probe. The analyser itself is designed to be robust as it spends its life outside, in all weathers, and in an environment with high levels of dust, dirt, and moisture.

Fig 2:  The analyser of the Compost Manager System

The design of the analyser's rear panel includes two electrical connectors. The first is a 6-way LEMO 0K series socket connector which is used both for the USB signal and for charging the analyser - LEMO has designed and moulded a custom Y-shaped lead to acheive this. In day-to-day use, this connector is left unmated, and so to protect it from the environment, it is fitted with a self-closing spring cap. In the five years since the 0K series connector was chosen, it has proved itself to be a reliable and robust solution.

The second socket connects the sampling probe to be analyser. During everyday use, it is left in a mated condition, but is often disconnected on a daily basis to allow for easy storage of the sampling probe. In addition to conventional electrical signals, the probe uses a thermocouple to monitor temperature. The connection of thermocouples requires special handling, and thermocouple wires cannot be terminated with solder. Therefore, the connector used on the sampling probe needed to feature crimp contacts.

Fig 3:  The rear panel of the analyser

For the original design, the sampling probe was fitted with an industry-standard M8 circular connector. Selected for their small size and the ability to be wired or repaired in the field, the M8 connectors performed well for the initial 12 months following the product launch. However, SLC soon started to receive reports from customers regarding failed connectors. The demanding conditions in which the probe is required to work were starting to affect the functioning of the connector. Often, users would not correctly align the two halves when connecting the probe and the pins would become fatigued. The contacts would eventually snap off inside the sockets, which requires that both the probe and the analyser are returned to SLC for repair. Due to the size of the probes, they are shipped in 1.5m long flight cases, incurring alarmingly high shipping costs, especially for international clients.

With a rising number of connector failures, SLC took the decision to seek an alternative connector for the probe. By a happy coincidence, the LEMO 0T series of connectors had recently been released. Due to the excellent track record of the 0K series connector, and a sound working relationship with LEMO, the 0T was the first choice for a replacement. As we have seen in the past, the 0T series is a very slim, waterproof connector with a panel footprint almost identical to the M8 connector. As a result, it has been possible to retro-fit the connectors onto the entire fleet of instruments during their routine servicing. Since completing this task around a year, there has been a dramatic decrease in connector-related faults and the overall system reliability has been markedly improved. The 0T connectors have proved to be simple to install and very easy to use in the field, even whilst wearing gloves.

Fig 4. The 0T series from LEMO

SLC now have the confidence to begin to further expand the overseas market for the CompostManager product, incorporating the LEMO 0K and 0T Series. It is hoped that new European guidance on process monitoring and control for the biowaste industry due to be released later this year will provide a big incentive for larger operators to improve their processes and therefore minimise their environmental impact.

Dr Eric Crouch is the Development Scientist with SLC.

For more information about the CompostManager system, please click the logo below.

The 0T series of connectors are available now from RS Components. Click here to see the range.

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