Flow General Inc. of McLean, once a fast-growing biomedics firm, is considering divesting at least one of its subsidiaries to help reduce a staggering $70 million load of debt.

The company, which 10 days ago replaced its top management, began looking seriously at divestiture after ruling out a merger or outright sale of total corporate assets as possible ways to end its financial woes.

"There will be no merger or sale of Flow General itself," said Douglas H. Poretz, Flow's director of communications. He said the company's new leaders dumped those options last week, largely because they believe the potential for improved future earnings at Flow General "is too great."

"The goal is not to weaken the company or its future profitability. The goal is to improve the company's balance sheet," Poretz said.

Flow General reported a net loss of $1.35 million (17 cents a share) for the quarter ending Dec. 31, 1982--the company's latest reporting period and its third consecutive quarter in the red. By comparison, Flow General had profits of $2.35 million (28 cents) in the same quarter of 1981.

Divestiture "of a piece or pieces of the existing business" is "one of the options that has to be considered" in the campaign to put Flow General "on a more firm financial footing," Poretz said. He declined to say what "pieces" are possible sales items.

But some analysts speculated that Flow General might drop one of its largest and most troublesome units, General Research Corp. The subsidiary's legal problems, including an admitted violation of federal conflict-of-interest laws, played a major role in the devaluation of Flow General stock, which soared to 45 3/8 on the New York Stock Exchange in 1981 before plummeting to single-digit lows last year.

"Wall Street has never been enamored by General Research," because scientific research firms usually are seen by investors as risky ventures, said Jules L. Marx, an analyst with New York-based Laidlaw Adams & Peck Inc. General Research's record over the past year has done little to change that view, Marx said.

General Research's strongest supporter at Flow General was Joseph E. Hall, the company's former president and chief executive officer, who resigned March 3 amid controversy over his leadership of the company. "There's probably a little bit more likelihood that with Hall out of there, the board might consider the divestiture of General Research," Marx said.

Michael Mead, an analyst with Richmond-based Scott & Stringfellow, Inc., said the new leadership "probably will go through Flow and clean house by June 30th." The housecleaning most likely would include divestiture, which could include the sale of General Research and other properties, Mead said.

"They're going to have to do something to restructure debt. I think they'll go through the business right away and reevaluate their holdings. Right now is the time for them to decide what write-downs, if any, must be done," Mead said.

Robert Middleton, an analyst with New York-based Fahnestock & Co., which has one of the longest associations with Flow General, agreed that the company will have to move quickly to restructure its debt. But he says he does not believe that divestiture will play a role in that effort.

"I really think they want to keep this as an independent, integrated company," Middleton said. "I don't see divestiture as probable. I believe they are going to try to find a more constructive way to handle the debt question," he said, without offering specifics.

Middleton said a "Wall Street misperception that Flow would merge with another company or spin off" units contributed to the relatively large rise in Flow's stock prices after the announcement of Hall's resignation March 3.

Flow General's stock rose from 17 1/2 per share March 3 to 18 5/8 two days later. The stock closed at 16 3/8 on the New York Stock Exchange Friday.

All of the analysts agreed that Hall's resignation and the retirement of Thomas C. Bazemore as chairman of the board were good for the company. Both men were replaced by Grant C. Ehrlich, a founding director of the company, who took over as board chairman and who also is serving as acting chief executive officer.

Besides legal battles, Hall's tenure had been marked by an aggressive acquisition of subsidiaries--seven altogether under Hall's stewardship, which began in 1976.

Middleton recommended that Ehrlich, who is 68, retain "all of the operating people on the board, because they are pretty strong people." Ehrlich should also move fast to find "a very strong chief executive officer" to control operations, Middleton said.

Ehrlich will hold the chairmanship permanently, the spokesman said.