Employees were pulling a chemical sample from a device (sample port). The sample wouldn't come out because there were two samples in the port. The employees then turned off and deenergized the machine to 0 pounds per square inch. They unscrewed the top of the machine to retrieve the stuck samples when a small amount of pressure caused liquid to squirt out and onto one of the employee's face shields as the lid was removed. The employee was hospitalized due to chemical exposure.