The Arlington County Board of Zoning Appeals this week approved several exceptions to the county housing code that would allow a Chicago-based development firm to purchase the 437-unit Shirlington House apartment complex and convert it to condominiums.

Immediately after the vote Monday night, angry tenants vowed to appeal the ruling to the Arlington county Circuit Court.

Under the proposal by the development firm, CBI Fairmac, Shirlington House would be converted to dondominiums over a two-year period. The high-rise complex, off Shirley Highway near the Arlington-Alexandria line, now includes a mix of efficiencies, one-bedroom and two-bedroom apartments with rents ranging from $310 to $470 a month, according to the Shirlington House rental office. The complex currently is owned by Shirlington House Partnership, which includes John safer Properties.

Before the conversion plan can be completed, CBI Fairmac must submit plans to the county Survey Department and the Virginia Real estate Commission.

Nearly 100 tenants appeared at this week's meeting to protest the planned conversion, led by attorney Ira Lechner, who is representing the Shirlington House Tenants Association.

"The condominium crisis has effectively removed moderate-income housing from this community," Lechner told the five-member Board of Zoning Appeals, which voted 4-1 to grant the exemptions sought by CBI Fairmac.

Fairmac is the development corporation credited by many couty observers with starting the condominium stampede in Arlington almost 10 years ago.Its first project was the massive Fairlington Villages complex near Shirlington House.

Since that first county condominium conversion, 13 percent of the county's current housing supply has been transformed to condominium-type units, according to a report prepared in March by the county Housing Advisory Committee. Less than 10 years ago, there were no condominiums in Arlington, the report said. Lechner distributed copies of the report to the zoning commission members Monday night.

Between 1972 and 1978, the survey stated, 10 Arlington complexes were converted to condominiums. In 1979 alone, six additional complexes were added to the list of condo conversions, and last year, 11 buildings were converted.

At Monday's meeting, Shirlington House tenants took turns outlining their case against conversion of their apartments.The board heard the stories of:

* Mrs. Irvil Burdene, who has lived in Shirlington House 18 years and said she may not be able to afford to purchase her apartments.

* Polly Faulkner's elderly neighbor, who already has been displaced by condominium conversions at two other apartment complexes.

* Wallace Welsh, a young professional who estimated 75 percent of the tenants would be unwilling or financially unable to purchase units.

Most of the concern was for the elderly. Said Lechner, "The elderly have become the boat people of the Washington metropolitan area -- some of these people have been 'condoed' twice, and now they're facing a third time."

Current tenants would be given a substantial discount on purchase of their apartments, according to Patrick Mayberry, vice president of Fairmac. He said prices would range from the low $30,000s for an efficiency to the high $60,000s for two-bedroom units. No major remodeling would be completed on those units, he said.

The cost would jump substantially for outsiders, but would include major remodeling to the units, Mayberry said. Tenants would have the option of purchasing those apartments also.

In seeking approval of its plans, CBI Fairmac had requested variances from two housing code requirements: One restricts condominiums to buildings no taller than six stories, the other requires a substantially lower density than at Shirlington House.

Thomas J. Colluci, an attorney representing the developer, noted that the building met county building codes when it was built 20 years ago, and that his client's plan would require no major changes at the complex.

"Strict application of the (current housing) code would present an undue hardship," Colucci said. "It would prohibit use as a condominium when it would be allowed to operate in identical conditions as a rental apartment."

In addition to the Fairlington Village and Shirlington House condominium conversions, Fairmac has been involved in the development of Rosslyn Heights in Rosslyn and Fairlington Town in Alexandria. The firm unsuccessfully attempted to buy and convert the sprawling McLean Gardens complex in Northwest Washington several years ago.