Adiabatic calorimetry testing provides data for emergency relief system (ERS) design, safe scale-up of chemical processes, safer process design, and safe transport and storage. Safe design requires knowledge of chemical reaction rates, character and energy release - all of which can be obtained from a low thermal-inertia adiabatic calorimeter such as the VSP2 (Vent Sizing Package 2) or ARSST (Advanced Reactive System Screening Tool). Accelerating Rate Calorimeter (ARC) testing typically has higher thermal inertia and the measured reaction rates are limited and not directly scalable for vent sizing, however the ARC does provide good data for kinetic modeling and thermal stability analysis. A well-equipped process safety lab has all three of these instruments.
The VSP2 and the ARSST measure temperature and pressure under process upset conditions. Adiabatic temperature rise and evolved gas pressure are measured, but of particular importance are the rates of temperature and pressure rise which yield in turn the volumetric rates of vapor and gas generation which must be accommodated by a pressure relief system. (The VSP2 can also be configured to simulate two-phase venting which can occur due to liquid entrainment, and which must be considered when doing vent sizing.) A variety of process upset scenarios can be directly simulated to quantify hazards identified by a PHA or HAZOP study.
