LANSDALE, Pa.-Central Sprinkler Co. continued to make certain fire sprinklers with rubber O-rings-blamed for preventing some of its Omega-line sprinkler heads from functioning properly-even after the company announced it had switched to silicone O-rings.

Central announced in August that since June 1996, all its Omega sprinkler heads have been made with improved silicone O-rings instead of rubber. But the company recently issued a statement saying it discovered that 20,000 Flow Control sprinklers-a part of its Omega line-were made between June 6, 1996, and May 7, 1997, with the rubber O-rings.

Some of the rubber O-rings have swelled under pressure and failed to release water during fires. Central has said it thinks contaminants introduced as a result of pipe cutting and fitting cause the problem.

"Central Sprinkler intended to replace the (rubber) O-ring in June 1996 at the same time the Omega product line was modified to address the issue of hydrocarbon contamination, and management believed we had done so," the statement said.

Unfortunately, internal confusion interfered with implementation of the decision to modify the Flow Control sprinkler, the Oct. 20 statement continued.

Flow Control sprinklers are made to shut off automatically once a fire is extinguished. Other sprinklers do not automatically shut off. The Flow Control type are used in certain types of commercial buildings with contents particularly sensitive to water damage, such as museums.

Observers point out that Central's newest problem may not be a huge one, because only 20,000 Flow Control sprinklers were made with the older, rubber-style O-rings.

"Certainly those need to be tested and replaced if necessary, but 20,000 in sales is pretty minuscule," said Steve Muncy, president of the American Fire Sprinkler Assn., of which Central is a member. "Twenty thousand sold in the past year or so-they can trace those pretty easily. That is less of a problem than the Omegas that have been put in over a number of years and could have been put in by contractors that no longer exist. So it is hard to trace those."

About 8 million Omega sprinklers are in service nationwide. Some of those have the rubber O-rings.

Central's original problem with Omega heads received widespread media attention in August (BI, Aug. 18). Fire officials, property insurers and loss-prevention experts praise many of Central's products, but they had known for some time before that of potential shortcomings associated with Omega heads.

But media outlets discovered in August that some Omega heads installed in buildings had failed to operate during fires. By then, Central already had spent months alerting its customers and had set aside $4 million to fund a program to test samples of Omega heads customers think might be defective. Central along with Underwriters Laboratories made kits available for sending in the heads for inspection.

Meanwhile, a lawsuit filed Aug. 1 in Los Angeles Superior Court against Central continues to move forward, said Clifford H.

Pearson, a plaintiffs' attorney with Wasserman, Comden & Casselman in Tarzana, Calif. (BI, Aug. 25). Attorneys are set to start deposing witnesses.

The lawsuit was filed on behalf of Los Angeles-area building owners and seeks class-action status, though the class has not been certified. A spokeswoman for Central could not say if other lawsuits have been filed.