The D.C. City Council voted yesterday to halt for 90 days nearly all further conversions of apartments into condominiums and cooperatives.

The moratorium, adopted under an emergency procedure, outraged spokesmen for the real estate industry but elated tenant groups. It extends an existing ban on the conversion of low-rent units to cover all other apartments in the city.

Despite a plea by the Washington Board of Realtors that he veto the bill, Mayor Marion Barry said he would sign it promptly and draft regulations to carry out its terms.

The council's vote was 12 to 1, with council member Betty Ann Kane (D At Large) the lone dissenter. Just two weeks ago, the council turned back a similar measure by one vote.

Willie J. Hardy (D-Ward 7), chairman of the council's housing committee and floor manager of the bill, said the moratotium was needed because the tide of conversions "threatens to squeeze out low and middle-income people . . . who now rent."

Mayor Barry, citing figures from the city's housing department, estimated that the moratorium would halt as many as 116 projects with at least 9.180 uniits for which conversion certificates have been issued but not yet acted upon by developers.

Another 26 conversion projects with 1,910 units can move ahead, he said. Most are concentrated near downtown or west of Rock Creek Park.

The measure permits the mayor to exempt any project in which there has been substantial progress or investment leading toward conversion and those in which tenants have agreed to buy and convert a project themselves.

Under the emergency provision used by the council, the measure will be in effect for 90 days without being subject to a congressional review and veto. It can be renewed.

During the 90 days, the council bill calls for the creation of an 11-member study commission to propose permanent laws that would restrict condominium conversions and preserve rental housing.

Existing law prohibits converting low-rent rental housing. The new emergency bill extends that prohibition to so-called "high-rent" housing.

As defined by the city's rent control law, high-rent projects are those in which rents range from at least $221 a month for an efficiency unit to $408 for a unit with three or more bedrooms.

Leaders of the Emergency Committee to Save Rental Housing, a coalition of tenant groups that pushed for the moratorium were elated. "There are great probabilities for success provided the mayor writes good regulations," said Kathryn Eager, chairman of the group.

Spokesmen for the real estate industry said they were outraged.

Raymond J. Howar, president of the Washington Board of Realtors, called the bill "a breach of faith and trust" with the real estate industry, and predicted it would stunt investment in @ashington development.

John T. O'Neill, executive vice president of the Apartment and Office Building Association, said the bill "ignored the issue of why owners are getting out of the rental business [and converting buildings to condominiums]." He said the problem is rent control, which, he said, makes rentals unprofitable.

A consumer-oriented real estate lawyer, Benny L. Kass, said the measure may have the undesirable effect of blocking or delaying some tenant-sponsored conversions the bill purports to protect.

Under the bill's terms, he said, the mayor cannot exempt tenant groups from the moratorium until the detailed regulations are prepared. He said one 166-unit conversion on Connecticut Avenue, ready for immediate settlement and financing, apparently will be stalled by the bill.

City housing director Robert L. Moore said the bill will be difficult to administer, and said he may have to ask for extra staff to expand his three-person condominium office.

Yesterday's debate was tranquil, in contrast to the noisy session on May 8 at which the council voted 6 to 5 against considering the earlier condominium proposal. Word was passed before a noon recess that supporters of the bill had more than enough votes to assure passage, and that made the debate anticlimactic.Just before the recess, the council was handed a new proposal by Mayor Barry calling for a 90-day moratorium on the issurance of new condominium conversion certificates. He said this would be followed by new rules under which certificates would expire in six months if not used by developers.

The council ignored the mayor's proposal, and moved on its own version. That bill was drafted in recent days chiefly by John L. Ray (D-AtLarge), John A. Wilson (D-Ward 2), David A. Clarke (D-Ward 1) and Polly Shackleton (D-Wad 3).

"Everybody wanted to solve this problem and get it off our backs," Shackleton said after the vote. She said tenants and landlords alike were near panic from indecision over the moratorium, and she was getting numerous calls as late as midnight. Kane, the only council member to oppose the measure, said she was not necessarily against stronger condominium regulations. She said she objected to the fact that neither public hearings nor detailed legal analysis had preceded passage of the bill.

Kane said the legislation is vague, and depends too much on the mayor's future interpretations.

Voting against it, she said, was "a hard thing to do, but I felt there had to be one voice there."

Yesterday's action by the D.C. Council followed a vote Monday by the Montgomery County Council rejecting a 90-day condominium conversion moratotium there.

Conversion in the District has been a growing legal and emotional issue as increasing numbers of buildings have been sold by longtime investors to firms specializing in condominium development.