Abstract: At approximately 3:00 p.m. on August 12, 2005, Employee #1, a cylinder cleaner, was working at the distribution center at Matheson Tri-Gas Incorporated, in Newark, California. An acid scrubber was used to purify contaminated spent gases before release into the atmosphere. Employee #1 was initially performing a titration to determine the molar concentration of hydrogen ions in the wash solution of sodium hydroxide in water. Employee #1 decided to check a flow sensor valve on a pipe of the supply line containing solution of sodium hydroxide in water. He attempted to shut off the supply line to the acid scrubber. Then, he turned a ball valve adjustment handle of the orange color to a position horizontal to the pipe containing solution of sodium hydroxide in water. Next, Employee #1 reached up to remove the sensor flow unit by unscrewing the unit from a threaded opening on the pipe. At the moment when the flow sensor unit was removed from the threaded opening, a caustic solution of sodium hydroxide in water flowed out of the sensor unit opening onto Employee #1's forehead. The caustic solution then flowed or seeped beneath Employee #1's safety glasses and flowed into both of his eyes. Employee #1 was partially blinded at that moment. He then attempted to recheck the valve to ensure full closure of the flow shut off valve. Upon doing this, the strong flow of the solution of sodium hydroxide in water stopped. Employee #1 stumbled to the titration table to retrieve a 2-way radio to request assistance. He walked to an orange colored eyewash and shower station, approximately 40 ft from the original exposure site, because he thought a coworker might be near this area to assist him. Employee #1 activated the eyewash unit and washed his eyes out for approximately 30 minutes. About 5-10 minutes later, a coworker activated the chemical safety shower above Employee #1's head, and after the following 15 minutes, the paramedics arrived. The employee was taken to Washington Hospital in Fremont in California. Employee #1 stated that he removed the flow sensor valve to verify the proper function of the flow monitor. He also stated that he acted independently, and was not directed to perform a flow sensor valve check by the employer.