Agilent Technologies has agreed to pay $40,000 in fines to settle what state regulators say were safety lapses that contributed to the chemical explosion that seriously injured a worker at the company's Fountaingrove campus in April.

Agilent knew there were problems with the piece of high-tech machinery that exploded because similar incidents occurred two times in 2010 and the company failed to fix the problem, according to the state Division of Occupational Safety and Health.

Patrick Colbus, 46, suffered major burns when the machine he was working on exploded, shooting glass and several hazardous substances into his face and upper torso.

The Santa Rosa resident and 2005 graduate of Sonoma State University was cleaning a molecular beam epitaxy machine, which produces thin coatings on integrated circuits. Cal-OSHA referred to it as a "reactor."

Colbus was not wearing the required protective equipment and clothing at the time of the explosion, which released hazardous substances including phosphorous, arsenic and lead, according to Cal-OSHA.

More than 20 workers underwent decontamination after complaining of respiratory problems after the flash, which spewed smoke with a chemical odor.

"Agilent recognizes the serious of the accident that occurred in April, so Cal-OSHA's decision to issue citations with fines was not unexpected," Agilent spokesman Jeff Weber said.

Agilent's customers use its test and measurement equipment to manufacture an array of communications devices. Technology developed in Santa Rosa is used by companies that manufacture half of the world's cell phones.

No one was injured in the two previous explosions, which were much smaller than the incident in April, Weber said.

Following the prior incidents, the company formed a team to try to understand what was causing the flare-ups and "refine" maintenance procedures for the machines, Weber said. But those efforts fell short.

"There were still things we did not understand about the process," Weber said.

The company "failed to identify unsafe accumulations of Phosphorus inside the reactors as creating hazardous conditions for workers," Cal-OSHA found.

Molecular beam epitaxy, or MBE for short, is a process that allows various elements to be heated into gases, allowing atoms to be deposited onto circuitry. The process takes place in an extreme vacuum.

A liquid is supposed to create a barrier designed to prevent the volatile compounds from having contact with open air. In April there were "higher reactive deposits than we previously understood" in the machine, Weber said. So when it was opened for maintenance, not enough liquid was present to contain the volatile material, Weber said.

Cal-OSHA issued five separate citations from the incident. Three were related to the procedures that led to the explosion, while two stemmed from the failure to ensure Colbus wore eyewear or a respirator.

In the wake of the accident, the company hired Exponent, a "world class failure analysis consultant," Weber said. The firm has helped the company get to the bottom of the problem and put procedures in place the company is confident are safe, Weber said.

"The safety of employees has always been a top priority at Agilent and this commitment was really demonstrated in the response to the Santa Rosa accident," he said.

Colbus is still an employee of Agilent, but he has yet to return to work. He is going through the state disability process, Weber said.