A majority of Montgomery County Council members agreed yesterday to a measure that would significantly change the structure of the county's firefighting system, bringing greater central control to the county's 18 independent volunteer and paid fire departments.

The legislation would create a seven-member fire commission, including two public members, to "provide the policy and regulatory framework" for the fire departments and to develop countywide fire service. It would also bring the firefighters under centralized personnel regulations.

The council gave its support to the measure yesterday by a 4-to-3 straw vote at a work session. That vote is not binding and could change. One more vote added to the majority would be necessary to pass the bill as "emergency" legislation. Such enactment would make the law effective immediately and protect it from being suspended if its opponents mount a successful petition drive. A petition drive by volunteer firefighters blocked a fire reorganization plan 11 years ago.

Attempts to centralize firefighting have been highly controversial in the county, with many of the approximately 600 volunteer firefighters opposing legislation that would diminish their independence and authority. Each department is an autonomous unit buying its own equipment and with its own chain of command.

The goal of the bill under consideration is to make the firefighting system more efficient and reduce costs by assuring adequate financial accountability.

"It tries to assure effective firefighting capability, especially in the case of multialarm fires," said council member Scott Fosler (D). "Questions had been raised about the adequacy of integrated command at fires where there is more than one department."

Under the present system, one well-manned fire department could continue handling minor fires in its area or choose to do nothing while a short-staffed neighboring fire department trbied to cope with a major fire.

The bill was called a compromise between County Executive Charles W. Gilchrist, who had initially proposed centralizing the fire department and making firemen county employes, and the council, some of whose members wanted to retain some of the features of the decentralized departments.

Individual stations would retain the right to hire and fire under the bill. But paid firemen would be subject to county personnel regulations, and volunteers would be subject to personnel regulations and minimum standards established by the fire commission.

The fire stations, which now buy equipment and pay bills independently, would have to operate through a central purchasing system. New equipment would belong to the county, although the stations would retain the land, buildings and equipment they now own.