DRAFT 

WORK PRACTICE STANDARDS 

FOR HF AND HCI EMISSIONS 

FROM WOOL FIBERGLASS MELTING FURNACES 

In 2010 and 2012, emissions testing at wool fiberglass facilities was conducted for all HAP 

believed to be emitted from wool fiberglass glass melting furnaces. The results of 

measurements for the acid gases HF and HCI were returned below the test method detection 

limits in 80% of the HCI measurements and over 85% of the HF measurements, including 

measurements at facilities that add small amounts of fluorides to the glass formulation. Where 

these Haps were measured at detectable levels in the furnace emissions, they were measured 

at very low levels. We therefore proposed (78 Fed. Reg. at 22370) to require work practice 

standards for the acid gases HF and HCI from furnaces at major sources, and are promulgating 

such standards for these pollutants in the final rule. 

Emissions of the acid gases HF and HCI can originate from the chloride and fluoride contained in 

the raw materials used for glass formulations. Refined raw batch materials such as sand and 

purchased cullet may contain trace amounts of chlorides, which in much higher concentrations 

are undesirable in a wool fiberglass furnace environment. Chlorides can readily form HCI, and 

significant levels of chlorides can damage furnaces. Fluorine can enter the purchased cullet 

stream as a component of glass from cathode-ray tubes (CRTs) or computer monitors that 

include cathode ray tubes. Fluoride emissions can occur when CRT glass enters the purchased 

cullet stream from the recycling center. 

Wool fiberglass facilities can monitor chloride content of the cullet or finished glass to verify 

and to maintain insignificant trace levels of chlorides. This is done by standard chemical 

analytic techniques. 

Wool fiberglass facilities monitor their purchased cullet to ensure that it does not contain 

excessive fluoride-bearing CRT glass. The facility typically requires the providers of purchased 

cullet to verify that the cullet does not contain glass from such sources. Facilities can also test 

the fluoride content of the finished glass. 

Wool fiberglass manufacturing facilities subject to NNN shall comply with one of the following 

alternative work practices for HCI: 

• An alternative work practice for HCI: Facilities subject to NNN are required to use a 

feedstock of raw materials having a 12 month rolling average of chloride content at or 

below 0.1 percent as measured using methods similar to ASTM 1152C/1152M, 

"Standard Test Method for Acid-Soluble Chloride in Mortar and Concrete," or companydeveloped methods using wavelength-dispersive x-ray fluorescence, or ion electrode 

analysis, ion chromatography, or using other standard laboratory methods. 
• An alternative work practice for HCI: Facilities subject to NNN will maintain glass 

formulation records that show that no ingredient containing intentionally added 

chloride will be added to the batch used to produce wool fiberglass insulation. 

Manufacturers will maintain records for 5 years and such records may be inspected by 

EPA. 

• An alternative work practice for HCI: Facilities subject to NNN will measure HCI 

emissions during emission testing once every 5 years to confirm that the level of HCI 

emissions is similar to the industry levels measured during the rulemaking process. 

• An alternative work practice for HCI: Facilities subject to NNN will generate a baseline 

set of data (i.e., 2 years of data- minimum of 8 samples, existing or new- raw materials 

or finished glass) and establish the mean and standard deviation. If the manufacturer 

maintains levels that are less than the mean plus two standard deviations, no further 

action is required. lfthe analytical results rise above two standard deviations above the 

baseline, the manufacturer must take action to assess and document the impact on HCI 

emissions. Action could include stack testing to verify HCI emissions are within <+25% 

{1.25 X) of the originaiiCR results, investigation of raw material chloride content, 

verification of analytical results, new raw material supplier, etc. Actions must be 

documented and maintained for a minimum of 5 years. 

Wool fiberglass manufacturing facilities subject to NNN shall comply with one of the following 

alternative work practices for HF: 

• An alternative work practice for HF: Facilities subject to NNN must maintain records 

from their own sampling program, or obtain annual certification from cullet providers 

verifying that the cullet does not contain excessive CRT glass. 

• An alternative work practice for HF: Facilities subject to NNN will measure HF emissions 

during emission testing once every 5 years to confirm that the level of HF emissions is 

not more than the industry levels measured during the rulemaking process. 

Facilities must maintain records of the selected work practices for a 5 year period for raw 

materials and/or records of glass formulations indicating the facility is maintaining low HF and 

HCI emissions, and make these records available for inspection by the permitting authority 

upon demand. Failure to maintain such records would constitute a deviation from the 

requirement.