scope:

Description of Driving Event:

A particulate sampling filter was ruptured during use due to excessive differential pressure. The filter was in use in an oxygen system, and the Quality Assurance technician recording the sampling results noted that the failed filter element was not the type required for the procedure, as it was incompatible with the sampling being performed.

The failed filter was not the type required by the users. The users had received the filter housing "cleaned and ready for service" from another organization. The type of filter element installed was not considered an issue, because both organizations used only one type of filter and presumed that it was the same type.

The users thought that the filter was Teflon, which was normal for their use. The actual filter element was cellulose ester. In addition to being incapable of handling the differential pressure, cellulose ester filters are not recommended for use in oxygen service by the manufacturer. Manufacturing, Materials, and Process Technology Division (EM) has recommended a maximum service pressure of 20 psia for cellulose ester filter elements in oxygen service.