Scaling up Safely: Making Smarter Decisions about Rate Dependency

Over the lifetime of a facility, it is almost a certainty that the throughput of a process will be increased, often repeatedly.  Rate dependency is frequently used as a way to identify pressure relief system sizing that would be affected by the scaling up of process throughput.   This paper will define rate dependency as it relates to pressure relief systems and describe the various ways in which rate-dependent classifications may be affected by the mechanical and thermodynamic constraints of the process and equipment.  In addition, examples of when the "rate dependent" designation may no longer apply due to common assumptions and methodological choices will be provided.