The phrase "acts as primary" is correct and usable in written English.
It can be used in contexts where you want to describe something that serves as the main or most important element in a particular situation or function.
Example: "In this experiment, the catalyst acts as primary in facilitating the reaction."
Alternatives: "serves as the main" or "functions as the primary".
For starters, it acts as primary insurance — meaning, it provides coverage ahead of your personal insurance.
Ms. Brooks's revised ordinance couples the farms together with a storefront dispensary that acts as "primary caregiver".
The primary system, enclosed in the primary vessel, is filled with Lead Bismuth Eutectic (LBE) which acts as primary coolant.
The first route acts as primary shortest path between the sender node and its corresponding destination, which is setup by flooding control messages.
Prostacyclin acts as primary vasodilator as well as an inhibitor of leukocyte adhesion and platelet aggregation.
Tim21 induces presequence-release from Tom22 and Tim50 acts as primary receptor in the IMS [ 64, 65].
He is also among the 27percentt of American men who, according to a study conducted at the University of Minnesota School of Public Health, act as primary food handlers for their families.
They include the elimination of capitation agreements for primary care physicians with small practices, relaxing its mandatory "all products" requirement and allowing specialists to act as primary care physicians for very sick patients.
These materials are not bright enough to act as primary lights, but they nonetheless begin to blur the distinction between room lights and the surrounding floors, walls and ceilings.
At the Rose Bowl, where college football clings to tradition with white-knuckle fervor, fullbacks can still be in vogue, tight ends act as primary pass catchers and the punter can be valued as a skill position player.
Acting as primary and secondary structures, sandwich components made of laminated composite face sheets are widely applied in aerospace structures.
