Unlike batch chemistry, reagents have a short tenure at the energized zone in flow format. More importantly, reagents must exit the reactor through the outlet of the reactor tube at a steady flow-rate. Limiting the tenure of the reagents (and the product) within the boundary of the reactor tube brings a myriad of benefits, from limiting degradation of the product into by-product(s) to enhancing overall process safety. However, conducting a flow reaction under pressure and extracting the product out of the pressurized reactor without depressurizing the reactor tube is challenging. One common technique to accomplish both (flowing under pressure and liberating product) continuously uses constricted flow-path (e.g., a BPR) downstream of the energized zone. The back-pressure from the constricted path forces the reagents to stay energized within the confinement of the reactor. The BPR holds the liquid reagent in its liquid state even when the reactor temperature exceeds its boiling point. However, a BPR device comes with its own demerits. A stream that carries solids or a viscous matter struggles to move through the restricted flow-path of the BPR and often experiences over-pressurization due to clogging. Downstream cross-contamination between experiments is also a major drawback of BPR-based pressurized reactors.