What is the safest way to separate a process and the attached pressure measurement technology? The HSG 253 standard must be applied to this question, and it answers unequivocally: by means of an instrumentation valve with double block & bleed (DBB). This …
Failure
SIL-certified: Functional safety with mechanical switches
| July Yang | Know-howMechanical pressure and temperature switches perform sensitive tasks in safety-relevant applications, e.g. monitoring limit values. Their functional safety must be guaranteed accordingly. This is always the case if the instruments fulfil the requirements of the …
MTTF and MTTFD – What is the difference?
| Arndt W. Jahns | Know-howThe MTTF value is a term from the field of risk analysis & risk evaluation. The exact meaning is m ean t ime t o f ailure or simply the mean life of a component. The MTTF has gained particular relevance due to EN ISO 13849-1. In accordance with this standard, …
New ScrutonWell ® design for thermowells
| Kai Grabenauer | TemperatureIn order to avoid any damage to the thermowell during operation due to mechanical loads, a thermowell calculation per ASME PTC 19.3 TW-2016 is recommended for critical process conditions. In case of a calculation with negative results, the only constructive solution so …
SIL? PL? What is the probability of failure of a safety function?
| Stefan Heusel | Know-howCustomers often ask us: “Can my product be part of a safety function? Which standards or directives apply in this case?” The most important safety directives and standards available today are SIL (Safety Integrity Level) and PL (Performance Level). These …