Safety Integrity Level, SIL, is a measure of safety system performance expressed in terms of probability of failure on demand (PFD). In the oil and gas industry, particularly in the fire and gas detection systems where safety integrity is critical, SIL 2 is becoming a common standard across systems. To meet the growing demand in the oil & gas industry, E2S Warning Signals, the leading independent audible and visible warning device manufacturer, has recently added additional fault monitoring to give SIL 2 compatibility to its products.
Initially available for its BEx explosion proof 117 dB(A) horns and 5, 10 and 15 Joule strobes, its explosion proof GNEx GRP family will be the next one to be upgraded. In large petro-chemical installations, the safety-critical warning devices are installed over large distances, so central monitoring is a key requirement. While fire and gas detection systems continually monitor the integrity of the cabling, the warning devices themselves are not checked. The new SIL 2 technology in the E2S horns means that the functionality can be remotely checked and an alert sent to the control panel in case of any fault.
A smart combination of software and hardware removes the need for time-consuming inspection and test of each individual warning device by intelligently reading the sound output of the horn or the light emitted by the strobe to check it is working properly. State-of-the-art technology ensures that spurious signals are not picked up by the sensors to ensure a reliable monitoring at all times. To comply with SIL 2 requirements, this is only done during an automatic test of the system and any faults are reported back when the system returns to its normal monitoring state. Communication with the system control panel can be configured in two ways: either a contact is closed or a series resistor is brought into the monitoring circuit in the event of a fault. A dedicated SIL 2 information page can be found at http://www.e2s.com/information/sil2-certified-audible-and-visual-warning-signals.
The web site www.e2s.com has full product information, distributor contact details and a useful reference section, with technical bulletins and white papers on various aspects of warning signalling, freely available as a resource for specifiers, system designers and consultants.