Safety first for seed treatment plant

A Siemens Automation and Drives product story

Edited by the Engineeringtalk editorial team Aug 20, 2003

By using products from the Siemens Safety Integrated range, Wynnstay Arable has been able to combine every aspect of process control and data management at its seed treating plant.

Agri-supply company Wynnstay Arable has a large seed treating plant that relies on safe controlled distribution of chemicals around the production site.

By using products from the Siemens Safety Integrated range, and working with systems integrator DB Brooks the company has been able to combine every aspect of process control and data management.

This is one of the most recent safety applications from Siemens Automation and Drives (A and D), which involved working closely with Bayer Cropscience, Wynnstay Arable and electrical engineers DB Brooks, to provide the highest level of safety for the system using the Safety Integrated concept.

Bayer Cropscience, which provides chemicals for seed treatment, recently supplied Wynnstay Arable with a Twin Vanguard seed-treating machine, which was installed at its site in Shrewsbury.

For companies such as Wynnstay Arable that specialise in treating seeds for the agricultural industry, there is a high reliance on the safe distribution of chemical substances around sites.

DB Brooks based in Heanor, worked with Siemens Safety Integrated products to create a tailored solution to fit the sites requirements.

The company adapted the basic Siemens ASi concept and built a specific controller - the Bayer Cropscience pump transfer system.

In order for the Twin Vanguard to function it is reliant on the pumping of chemicals from large intermediate bulk containers (IBCs) on the ground level of the factory to the base of the machine on an upper floor.

Processing 24 tonnes of seed per hour, at 15s batch process intervals requires accurate distribution of 36 litres of fluid during the period.

In an industrial environment where chemicals are being pumped from one floor in the factory to another, the highest levels of control are required.

Without such a safety system, the risk of site damage due to a malfunction in the pumping equipment could be dramatic.

Communicating information and allowing for control of fluid flow, required an information transfer system to connect all the containers and instruct them when to pump fluid from the individual IBCs and distribute around the site.

Each container that holds seed-treating chemicals has been connected by a singular Siemens AS-Interface (ASi) cable with modular capabilities - rather than multiple cabling.

This two-core yellow cable connected to display panels enables illustration of how full the container is, and allows information to feed back through the transfer system to an S7 200 programmable controller (PLC).

The PLC transmits signals to pump controllers that would either top up or decant fluid.

Jim Donald at Bayer Cropscience commented: "Distributing chemicals around a manufacturing site can be a difficult business.

This is why we take safety very seriously, demanding the highest of standards.

We identified that great benefits could be sought from using the Siemens ASi transfer system.

Apart from it being a simple, effective, and highly reliable solution, the chance of making a mistake in installation was negligible due to the use of a single cable.

The money savings were also a big motivation for using this kind of network - not only has it reduce the wiring and installation costs, but it also reduces the risk of fault".

Disruption at the Wynnstay site during installation was minimal.

Due to the system's simplicity, design engineer DB Brooks was able to test the system by setting it up in its works at Heanor prior to the site installation.

Lack of complexity in the network also meant that the downtime on site was reduced dramatically, in comparison with conventional methods.