ambiguity

Brendan, Welcome to A2K. As I know nothing of chemical engineering, I can't interpret your given sentence, but I can say this:

They are the designers and builders of the mechanical, thermal and fluid-flow related aspects, of all such systems.

It sounds to me as though "they" design and build "mechanical, thermal and fluid related aspects" of the system to which the reference is made.

Hope that comma after "aspects", clears up the meaning for you.

Letty, I don't agree with the use of the comma there. Related definitely pertains to fluid-flow. Mechanical and thermal are adjectives, whose definition already carries the notion of related to , while fluid-flow is a noun with no readily apparent adjectival form (hydrofluxation?). To preserve the parallelism of the list the writer has made fluid-flow part of an adjectival phrase.

Brendan, I'm not quite sure how the uncertain association of related makes the sentence ambiguous. If you ask me, aspects is a much fuzzier word in the sentence.

Well, as I said, Val, it helps to understand the syntax from the on set.

I think related refers to all three; the mechanical aspects, the thermal aspects, and the fluid-flow aspects.

But what's the difference between the mechanical aspects and the mechanical-related aspects? The fluid-flow aspects and the fluid-flow related aspects? I think you could take "related" out of the sentence completely.

Mechanical is an adjective that means "relating to mechanics". Mechanics-related would be fine (as mechanics is a noun), but not mechanical-related. Fluid flow is a noun and, when combined with related, forms an adjective (not, technically an adjectival phrase). In fact, if I were writing it, I would hyphenate the entire combination (fluid-flow-related).