Find engineers and scoped services that produce a equipment sizing calculation. Contracts pay against deliverables, so being specific about what you need handed over is the single most useful thing you can put in a brief.
A equipment sizing calculation is a thing that either exists and meets its acceptance criteria or does not. That is why contracts here are structured around deliverables rather than effort — it makes the milestone objectively assessable rather than a negotiation.
When you name this deliverable in a brief, also state what “done” looks like: the format, the level of detail, the standard it is checked against, and who needs to be able to read it. A deliverable without acceptance criteria is a dispute waiting for a reason.
Process Optimization Engineering specialist — bioprocess scale-up & relief system design
Chemical Engineering specialist — water treatment process & hazop facilitation