workers-in-respirators

Tank farm workers wearing respirators equipped with filter cartridges.

Air-Purifying

Respirators

A respirator is a device worn by workers to protect against harmful dust, fumes, vapors or gases. Respirators come in a wide range of types and sizes used by the military, private industry and the public.

Respirators used at Hanford typically fall into two categories: air-purifying respirators (APRs) and air-supplying respirators. APRs use a filter cartridge to clean the air before it enters the respiratory tract. Supplied-air respirators provide clean breathing air from either a hose and air compressor or an air cylinder that the worker wears on their back. The self-contained breathing apparatus (SCBA) is one type of supplied-air respirator worn while working inside Hanford's tank farms.

However, one of the Tank Vapor Assessment Team (TVAT) recommendations suggests testing the filter cartridges used with APRs to assess the effectiveness of the equipment when used in the tank farms environment as a potential alternative to SCBA use.

Testing

Process

To evaluate the cartridges’ effectiveness in protecting workers, WRPS designed a process to test specific filter cartridges in actual tank farm conditions using methods approved by the Occupational Safety and Health Administration (OSHA). In the AP Tank Farm, cartridges were tested by connecting them to an exhaust stack and blowing vapors and gases directly from the tanks through the filters.

The data collected during testing were analyzed by Pacific Northwest National Laboratory (PNNL) scientists. A summary report and a Q&A document produced by WRPS, in conjunction with the workforce, is also available.

Typical respiratory cartridge filter

SCBA vs. APR use

Consistent with the August 2016 Memorandum of Agreement (MOA) between WRPS and HAMTC, the use of supplied air has been made mandatory for work inside the tank farms until two conditions have been met:

  1. Cartridge testing is completed and documented results have been satisfactorily demonstrated to provide worker protection from tank vapor emissions.
  2. A third-party qualified independent entity, selected by HAMTC, reviews the testing methodology/protocols and results of the cartridge testing data and concurs with the results.

With completion of the above conditions, conducted on a farm-by-farm basis, those respiratory cartridges that were proven effective in protecting against tank vapors and gases may be available to workers for use inside the farm.

Third-party review

HAMTC selected the Center for Construction Research and Training (CPWR) as its independent reviewer. CPWR based its evaluation on reports supplied by WRPS and PNNL. The reports were supplemented by interviews with staff from WRPS, PNNL, and leaders and representatives of HAMTC and Building Trades.

The following reports are now available:

APRs in AP Farm

After considering engineering controls, administrative controls, properly fitted respiratory protection, and a conservative cartridge change-out schedule, CPWR concurred with WRPS’ proposal to use APRs in AP Farm as an alternative to the use of SCBA or other available supplied-air systems. CPWR's support assumes implementation of certain conditions, including development of an updated industrial hygiene exposure assessment strategy and continued source, area, and personal sampling.

With the MOA conditions satisfied, WRPS and HAMTC have jointly decided that some tank farm workers can use APRs for limited work activities in AP Farm. Specifically, workers in the AP tank farm, working outside of a Vapor Control Zone on non-waste-disturbing and non-tank-intrusive activities, ill have the option of wearing APRs equipped with approved filter cartridges (Scott 7422-SC1 [Chemical - multipurpose] or Scott 7422-SD1 [Chemical - multipurpose/P100]) instead of SCBA or other available supplied-air systems. As always, workers will continue to have the option to use SCBA or other available supplied-air systems if they choose, so long as the equipment does not produce additional safety hazards.

Initially, the use of filter cartridges at AP Farm will be limited to tasks that may generally include performing operator rounds, routine radiological surveys, preventive maintenance, visual inspections, equipment calibrations, housekeeping, job setup and take down.

Path Forward

Evaluation of filter cartridge data gathered from other tank farms is underway. Consistent with the August 2016 Memorandum of Agreement between WRPS and HAMTC, decisions on filter cartridge use will be made on a tank farm-by-tank farm basis.

WRPS thanks all the workers who supported the design, mock up, and field executions thus far. Those efforts have resulted in a path forward to transitioning from SCBA to full-face APRs at AP Tank Farm. The process and methodology lays the groundwork and paves a path to evaluate other farms and activities for APR use.