Impress Sensors & Systems - PRODUCT NEWS

Temperature, pressure and level switches now come with SIL2 approval

A UK-based company is now offering a range of temperature limiters/controllers, pressure transmitters, screw-in transmitters, submersible probes and level control switches, all with SIL2 (Safety Integrity Level 2) approval for hazardous environments.

The new range, supplied by Impress Sensors & Systems, a specialist manufacturer and distributor of sensors, instrumentation and complete system packages, based in Aldermaston, Berkshire – is targeted at safety and hazardous area applications, including process manufacturers, chemicals, oil and gas, nuclear and Atomic Weapons establishments. The devices are also suitable for medical device applications.

The process industry demands the highest degree of safety and reliability these days. The current Safety Integrity Level (SIL) international safety standard provides suppliers and users with a common framework on which to design products and systems for safety related applications. The standard also provides a more scientific, numerical approach to specifying and designing safety systems, enabling the nature of the risk to be quantified.

SIL means risk reduction to a tolerable level. The required safety level of a process plant is classified in accordance with the international IEC 61 511 standard and depends on the risk constituted by a plant. The IEC 61 508 standard describes the requirements of electrical, electronic and programmable electronic devices used in such plants. Both standards subdivide plants and devices into 4 safety levels, from SIL1 for low risks, to SIL4 for very high risks. The allocation to these safety levels is based on the use of a risk graph and depends on:

Extent of possible damage
Frequency of persons present in hazardous areas
Possibility of damage prevention
Probability of an unwanted event occurring

The standards also describe the type of risk assessment and procedures for integrating certain safety functions into sensors and plants. Generally, the significant hazards for equipment and any associated control system have to be identified by the specifiers or developers via a hazard analysis. The analysis identifies whether functional safety is necessary to ensure adequate protection against each significant hazard.

Examples within safety related systems for mechanical engineering include auxiliary disconnected systems; fire detector and gas warning systems; monitoring of turbines; safety interlock and auxiliary disconnected systems for machines; devices for medical applications; and remote monitoring based on network, handling and programming of procedural constructions.

For more information on Impress Sensors’ range of SIL2-certified pressure, temperature and level control switches, contact the sales department at Impress Sensors & Systems Ltd on 0118 981 7980 or visit the website at

For more information, please contact...

Sam Drury
IMPress Sensors & Systems Ltd.
Unit 6B, Mercury House,
Calleva Park, Aldermaston Berkshire RG7 8PN
Tel: +44(0) 1189 817980
Fax: +44(0) 1189 817990

November 2007

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