Safeguards for Hydrofluoric Acid Tested

The danger of an accidental release of hydrofluoric acid, which some environmentalists say could be as extreme as that of India’s Bhopal disaster, can be greatly reduced by the costly installation of a system of fog-nozzle showers and pumps, according to preliminary results from an industry-sponsored testing program here.

Ronald Koopman, a Lawrence Livermore Laboratory scientist who is directing the closely watched $3.5-million test program, said that showers drenching the highly toxic fumes with large volumes of water mist have been able to knock down up to 90% of the hydrogen fluoride vapor in some of the 70 tests run here since Aug. 10.

“We have very encouraging results,” said Klaus Schatz, a Mobil Oil Corp. employee who is chief scientist for the tests.

But the two stressed that the results of the program, being conducted at the Nevada Test Site, 65 miles northwest of Las Vegas, have yet to be analyzed carefully.

Hydrogen fluoride, an extremely corrosive chemical used as a catalyst by oil refineries and as raw material by refrigerant manufacturers, is considered immediately threatening to life after half an hour of exposure in concentrations as low as 20 parts per million.

The test results are of particular interest in Los Angeles, where four oil refineries and two manufacturing facilities--some adjacent to residential neighborhoods--use hydrofluoric acid.

In addition, the South Coast Air Quality Management District created a task force to consider the elimination of all industrial uses of the chemical after the release of 100 pounds of it during an explosion and fire at Mobil’s Torrance refinery in November.

The AQMD and the city of Torrance, which is investigating the use of hydrofluoric acid at the Mobil refinery, have sent observers to the tests.

The oil refining industry also is watching. About half the refineries in the country use hydrofluoric acid and they could be forced into an expensive conversion to less dangerous sulfuric acid if the test results fail to demonstrate that hydrofluoric acid releases can be handled safely.

In addition to Mobil, the Union Pacific Resource refinery in Wilmington and the Golden West and Powerine refineries in Santa Fe Springs use hydrofluoric acid. Allied Signal Corp. Inc. in El Segundo and Jones Co. in South Los Angeles also use the chemical.

Concern about hydrofluoric acid first was raised by a 1986 series of tests here, sponsored by Amoco, indicating that the release of 1,000 gallons during a two-minute period would create a dense cloud of gas that could be immediately dangerous to life as far as five miles or more downwind. If an accident released a similar plume in Los Angeles County, thousands of people living near refineries would be threatened.

“It was awesome,” said Koopman, who also was test director for the 1986 series.

But the 1986 test results provoked a technical debate over whether experiments in desert conditions were relevant to spills in areas with higher humidity, and the data did not come to public attention.

Then on Oct. 30, 1987, the largest known release of hydrofluoric acid occurred in Texas City, Tex. About 6,000 gallons of hydrofluoric acid were released over a period of hours after a crane at the Marathon Petroleum Co. refinery dropped a piece of equipment onto a pipeline containing hydrofluoric acid.

Firefighters attempted to saturate the cloud with water sprays, but the toxic cloud that was formed forced the evacuation of 4,000 and the hospitalization of several hundred people.

Test officials here said further analysis of the test results is needed before they can say how effective a system of sprays would have been in limiting the impact of the Texas City release.

After that accident, the private Environmental Policy Institute, citing the 1986 tests results, warned that hydrogen fluoride had the potential to create another disaster like the one in Bhopal. The escape of a deadly cloud of methyl isocyanate there caused more than 2,800 deaths in 1984.

Hydrofluoric acid manufacturers and users quickly formed the Industry HF Mitigation Program to study ways to diminish the effect of a hydrofluoric acid release. The program is supported by 20 firms, including Chevron, Mobil, Exxon, Shell, Unocal and Texaco.

Experiments here typically spill about 50 gallons in a wind tunnel where humidity is carefully controlled. The facility is the only one in the country that can be used for studying the large-scale release of toxic gas.

Researchers, the industry and fire officials have long believed that the appropriate way to fight a hydrofluoric acid release is to douse it with water. Once the data is analyzed and made public, the experiments will provide company engineers with the knowledge they need to design the most effective system of pumps, nozzles and water lines. Another challenge for the engineers will be designing systems that can withstand the force of an explosion or other violent catastrophe.

“The actual work will start next spring,” said Frank Buyan, a Mobil Oil official involved in the test program. “Companies have already put aside funds. They are anxious to get the results of the tests and start building hardware.”

In addition to water sprays, the industry mitigation program also is examining vapor barriers that would prolong gas dispersion and thereby prevent the formation of a dense gas cloud, as well as the installation of large pumps that could drain a breached reactor vessel within minutes to minimize the release of chemicals.

But while some are trying to figure out how to diminish the impact of a spill, other hydrofluoric acid users are considering a switch.

Some 61 oil refineries use hydrofluoric acid as the catalyst in a process--the alkylation reaction--to boost octane in unleaded gas. About 35% of those, including one in Los Angeles County, are considering a conversion to less dangerous sulfuric acid, according to Terry Robertson, executive chief officer of Stratco Inc. of Kansas City, Mo.

Robertson said in an interview that Stratco, which licenses both sulfuric and hydrofluoric acid alkylation technology, decided after the Texas City release to stop using hydrofluoric acid.

Either conversion or mitigation is bound to be expensive.

Buyan said that installing mitigation devices such as water sprays and pumps would cost “tens of millions” for a large refinery. On the other hand, converting to sulfuric acid would cost about $100 million, he said.

In Los Angeles, Carol Coy, the AQMD’s senior enforcement manager for air toxics control, said it was “premature” to say whether the test results mean that hydrofluoric acid is safe enough to use near populated areas.