Injector manifold pressure-order checks can be done in cold flow: chamber pressure cancels out

If an injector design relies on one propellant manifold staying above the other (for example, one face seal that seals in one direction only), you might think you need manifold pressure transducers on every hot fire to confirm it. You usually do not. Each manifold sits at chamber pressure plus its own injector drop, so the difference between them is just the difference of the two drops. At a given pair of flows and densities, that does not depend on chamber pressure. A cold-flow run at the same flows (same valve timing, same start and shutdown order) shows the same margin, including during priming transients. Do the check once in cold flow with borrowed transducers in the manifold ports, keep the ports plugged in the flight-like build, and rely on the facility feed transducers plus a once-calibrated line-loss (proportional to mdot^2/rho) for injector drop in hot fire. Caveats: propellant temperature changes density and so the drops, so cold-flow with the real cryogen (or correct for it). Feed-system oscillations still show on facility feed PTs and the chamber PT, just not at the exact manifold amplitude. Sensors on a long thin stainless standoff tube stay near room temperature, so they need no cryogenic rating.