Application Story

Toxic Gas Alert!

Crowcon alarm minimises risk the easy way

Toxic gases are one of the many hazards facing people working in enclosed environments. A poisonous gas alarm system is one of the best ways to minimise this risk.

However, there are many types of toxic gas which can build up to dangerous levels at any time. A big challenge facing designers of these systems is controlling the sequence, frequency and period of sampling to monitor eight or more different gas concentration levels. Crowcon, one of the leading suppliers of gas monitoring and alarm systems has solved this problem using Moeller's easy controller. Working with Moeller's Key Dealer, WGA, Crowcon took a record-breaking two months from initial concept to the completed product leaving the factory floor.

Crowcon Detection Instruments Ltd, based in Abingdon, Oxfordshire, is a specialist manufacturer of toxic and flammable gas detection equipment. The company was formed in 1970 and is now part of Halma PLC with offices in the USA, the Netherlands, India and Singapore supported by a network of specialist agents worldwide. Crowcon now operates in over 100 countries. The company's modern manufacturing centre in Abingdon employs high volume automated production techniques including surface mount placement and automatic test equipment. This ensures that customers receive a consistently high quality of competitively priced products.

Andy Avenell, Senior Project Engineer at Crowcon said: "We have been using easy for a number of our products for quite a while and are familiar with its flexible and quick programming. We wanted to avoid a complex PLC solution that needed a dedicated PLC engineer to program the sampling sequence of our new Vortex gas alarm system."

Crowcon then approached WGA, and the two worked together to configure an Easy 620-DC-TC to control gas sampling. The Vortex is designed to ensure the safety of workers entering road tunnels and has eight sampling channels monitoring such levels as: hydrogen sulphide, carbon monoxide, oxygen, methane and petrol vapour. The Vortex is then linked to a central monitoring and control centre so tunnel managers are aware of any gas hazards instantly. Reliable and easily adaptable sampling is essential for this kind of operation. WGA assisted in the configuration of the easy. "This synergy of WGA's and Crowcon's expertise enabled us to realise the full potential of the easy", Avenell added.

Value added distributor, WGA, has considerable experience of industrial control systems and Moeller products in particular. With engineers from a production engineering background themselves, WGA understands precisely customer requirements and offers a complete support package from specification through to everyday use. WGA's Engineering Manager, Chris Paterson said: "We offer an 'holistic' approach to our clients. By being involved with formulating the exact requirements of the system at the outset we can ensure the smooth operation of the control system when it is up and running."

The importance of a non-PLC route for sampling control is further explained by Avenell: "With a PLC you need time and a high level of expertise for programming. This adds to the time-to-market for your product and you have the opportunity cost of not being able to commit highly skilled people and time to other projects. Another major problem is you require specialist equipment for any on-site modifications. The easy's conveniently placed display and buttons makes it ideal for this job. We export our equipment all over the world so this capability is a big advantage."

"WGA worked with us to integrate the easy into our Vortex gas alarms. They were with us every step of the way, their excellent service and Moeller's easy controller enabled us to meet a tight deadline and deliver a product ideally matched to the customers requirements," he added. Crowcon has also used the advantages of easy intelligent controllers in a number of other products. In their Ditech systems monitoring the voltage of the power supply is achieved through two Easy 412-DC-R controllers. Easy is also a key component of the company's Gasmonitor range of products.

The easy control relay adds a new dimension to user friendly programmable control, as precise sequences of switching and control operations can be simply implemented. For example, gas sampling sequence and period can be done automatically. The control relay's front panel, with liquid crystal display, cursor and function keys, provides the user with quick configuration and operation. Because all of the necessary timing and switching circuit connections are implemented 'internally' by simple keystrokes, easy cuts down on wiring thus saving both mounting time and wiring costs. Sampling configurations can be displayed on easy's LCD which can also be used to show the user which channel is being used for sampling.

This page last updated: 25 January 2002