Proven-in-use

Because normal radioisotopic decay lowers the thermal output by about 2.5%/yr in these units, they are purposefully overdesigned for beginning of life conditions. Several of these generators have successfully operated for as long as 28 years. This is approximately equal to the half-life of the strontium-90 isotope used in the heat sources. The original SNAP-7 series immobilized the strontium-90 as the titanate, but the more recent ones have used it in the form of the fluoride, which is also very stable. A number of tiny nuclear-powered cardiac pacemaker batteries were developed, which have electrical power outputs of 33—600 p.W and have been proven in use (17). 

Calorimetry is a measuring technique that allows, based on temperature measurements, conclusions to be drawn about the amount of heat produced over time by chemical or physical phenomena. Reaction calorimeters with reaction volumes of 0.1 to 2 litres that can mimic a process under conditions that resemble full-scale conditions have been proven in use. 

Normally the sensors and valves that are on these approved or recommended lists for the BPCS could also be considered as proven-in-use for SISs subject to the assessment required by 61511-1. This list of instruments should include the version of the device and be supported by documented monitoring of field returns at the user and at the manufacturer. In addition the manufacturer should have a modification process which evaluates the impact of reported failures and modifications. 

Application language translators that are proven in use and/or have been certified to accepted industry standards are preferred. 

Proven-in-use PE logic solvers should demonstrate sufficient diagnostics in the PE logic solver design. The diagnostics can be software or hardware based and should cover the entire logic solver, including input modules, main processor, output modules, and communications. 

The Rosemount 3051S SIS (Figure 9-8) received its lEC 61508 assessment rating in 2004. As one of most popular transmitters in the process control market, the 3051S has accumulated substantial proven in use hours during... 

ABB TH02, TH102, TH202 exida Proven In Use exida... 

When would a designer choose "proven in use" justification in preference to full 61508 assessment ... 

Proven in use, reliable hardware and installation methods shall be implemented. The PCE safety device must be simple in construction. Fault effects (e.g. secondary or sequential faults in the PCE safety device) should, if possible, be limited by suitable barriers to fault propagation, e.g. high-impedance decoupling, short-circuit strength, galvanic isolation, etc. 

The systematic safety requirements can also be fulfilled by demonstrating that the system is proven in use. Such criteria are discussed by Beurden, 2004. 

Beurden, I. van Amkreutz, R. 2004. Proven-in-use criteria for safety instrumented systems. Hydrocarbon processing 81(11) 6U70... 

Record keeping (e.g., proven in use, prior use, unsafe failure identification, data collection)... 

NOTE - Prior use Is a process Industry sector term that Is used In lieu of the I EC 61508 term proven-in-use. The intent is that the user should have knowledge through prior use that the selected device can operate as required and can support the SIF SIL in the intended operating environment. 

NOTE -- ANSI/ISA-84.00.01 -2004-1 refers to proven in use (PIU) at times in lieu of consistently using the term "prior use. In each of these cases, "PIU" should be Interpreted as prior use unless the PIU term is used with a specific reference to lEC 61508. 

The following SIL certification is for a smart transmitter. The third-party certifying authority declares the transmitter as Type B (a smart transmitter with software—see Table Vl/4.2-2 for definitions). S1L2 with HFT 0 (single connection use) has an SFF of 75%. This example was chosen to show how lEC proven use can be used. Readers should note that this certification is given by a world renowned certifying authority to a manufacmrer who is also world renowned. It has PROVEN IN USE, which is allowed by lEC 61511. The certification declaration states ... 

As the pressure transmitter XXX is supposed to be a proven in use device an assessment of hardware with additional prior use demonstration for the device and its software was carried out. The prior use investigation was based on field return data collected and analyzed by. .. manufacturer. This data cannot cover process connection. Prior-use justification for the process connection still needs to be done by end user (to make a note by reader)... 

In some cases, even with 2oo3 sensor redundancy, without certification (keeping aside proven in use as per lEC 61511), a system wUl only achieve SILl. Hence if this architecture is chosen for higher SIL applications, then in reality it is below target SIL2 or 3. 

Proven-in-use When a documented assessment has shown that there is appropriate evidence, based on the previous use of the component, that the component is suitable for use in a safety instrumented system. —lEC 61511. 

SIL 4 systems should be both proven in use, as mentioned above, and have third-party... 

It should be noted that the minimum configuration table given in Section 3.3.2a of this chapter permits higher SIL claims, despite lower levels cf diagnosis, by virtue of either more redundancy or a higher proportion of fail safe type failures. The 2010 version allows a proven-in-use alternative (see Section 3.3.2b). 

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