Level detection switches reduce hazardous spills

It is critical that plant managers and engineers choose the right level detection switches as they can prevent the accidental discharge of toxic products into the environment. A well-selected, correctly installed level switch will save companies the expense associated with treating and disposing of spilt material. Moreover, it will safeguard companies against punitive fines in the event of an unavoidable accident.

Hazardous spillage often conjures up images of caustic ammonia liquid and fumes spewing out uncontrolled from huge tanks. This is definitely dangerous, but often the dangers associated with spillage exist in the most innocuous and unlikely places — like chicken processing plants and dairies, for example.

Food and beverage plants periodically undergo cleaning in place (CIP) and sterilisation in place (SIP) and this requires strong cleaning chemicals that need to be closely monitored and carefully managed. Accidental discharge of these chemicals into the surrounding environment can cause serious damage. In a dairy, even the accidental spillage of cream is cause for concern, as it will need to be carefully disposed of after being suitably treated. In pharmaceutical and chemical plants, spills can cause loss of life and serious damage to property and assets. In practically any situation where there is significant spillage, plant managers have to bear the cost of treating the spillage and absorb the financial loss of the processed product that has been spilt.

Unfortunately, such occurrences are all too common in Australia, but the good news is that they are easily preventable.

“In many cases, a simple $500 level detection switch is all that is needed to protect a company’s assets from the problems associated with spillage,” says John Immelman, managing director of Endress+Hauser Australia. Each process application is unique and temperature, pressure, corrosion, abrasion and atmospheric conditions must be taken into account in selecting the appropriate level switch.

Also to be factored in are process connections, housing types, power supply type, outputs (relay or transistor) and chemical compatibility. Safety ratings are becoming increasingly critical and a host of new standards, such as IEC 61508, must be considered in selecting a level switch. Endress+Hauser offer a free ‘Selection and Engineering Guide for Level Measurement’, which assists the user in making more informed decisions. This 58-page full-colour guide offers vital information on different measuring principles for level limit detection and their application and installation in liquids as well as in bulk solids.

Managers of plants, both large and small, must first assess the risks associated with the equipment being controlled and then determine the necessary risk reduction needed. “It is imperative to determine the SIL rating of a plant prior to ordering the process instrumentation,” stresses Immelman. Safety Integrity Level or SIL ratings 1, 2, 3 and 4 offer probability of a dangerous failure over time and can be used to measure the range of risk reduction afforded by a piece of equipment. The higher the SIL level, the more reliable the device.

SIL ratings are important — as was demonstrated not very long ago at an ethanol plant in NSW. In the absence of a level detection mechanism, ethanol spilled over and the fumes ignited. The ensuing blast rocked areas up to 25 km away and sparked such a huge fire that cars parked 60 m away had their taillights melted. The blaze caused immense loss of property and led to hefty fines for the plant owners. The possibility of this happening would have been dramatically reduced if the plant was appropriately SIL rated and had installed correctly rated detection switches.

Endress+Hauser has also developed radiometric detection switching gamma instrumentation for use where conventional methods for level detection switching in chemical, petrochemical, oil and gas, mining, paper and pulp and energy applications are inappropriate. Radiometric measurement is completely non-invasive to the process. The externally mounted switching unit ensures the highest degree of reliability and safety, making radiometric measurement the ideal solution for applications where the pressure, temperature or aggressiveness of the process prevents the introduction of measuring devices. Gammapilot M is Endress+Hauser’s radiometric level detection switch that complies with IEC 61 508 SIL 2 rating.

Whether unloading an oil tanker or manufacturing cream cheese, spills can be hazardous to people, property, the environment and to a company’s bottom line. Fortunately, this is often an easy problem to fix and basically requires an understanding of SIL ratings and the installation of relatively low-cost level switches.

Endress+Hauser Australia Pty Ltd
www.au.endress.com