SIS-TECH”s DIAMOND-SIS high-integrity protective system is a low-cost standalone logic solver certified for use in applications up to Safety Integrity Level (SIL) 3. The device is used to provide over-pressure protection for scenarios where the opening of the pressure-relief valve poses unacceptable process safety risks. API 521 and Code Case 2211 of ASME Section VIII, Division 1 and 2 allow the use of a High Integrity Protective System (HIPS), such as the DIAMOND-SIS HIPS, in lieu of a pressure-relief device as long as the instrumented system meets or exceeds the protection provided by the pressure-relief device.

To achieve this performance, the HIPS design and management must also follow IEC 61511 and the logic solver should be compliant with IEC 61508 SIL 3. The DIAMOND-SIS HIPS complies with these requirements. The device is an SIL 3 logic solver with 2oo3 voting, which provides the end-user with a fault tolerant logic solver that it is physically and functionally independent from the process control and unit safety instrumented system. With the device, each vessel or pipeline is independently protected against overpressure such that no single HIPS failure results in simultaneous overpressure of multiple vessels or pipelines. By using an independent logic solver for each HIPS, the potential for common cause failure impacting multiple process units is significantly reduced. The device is rated for –30 C to 75 C and suitable for installation in Class I Div II environments, allowing it to be installed in the field near the process equipment. This reduces the implementation costs typically associated with systems using cabinet-mounted safety PLCs.