### Date: November 6

, 2014

To: Jeff Telander, EPA/OAQPS/SPPD

From: Gabrielle Raymond and Kristin Sroka

, RTI International

Subject: Analysis of Potential Subcategories in the Clay Ceramics Source Category

I. I ntroduction

In accordance with section 112 of the Clean Air Act (CAA), the U.S. Environmental Protection Agency (EPA) established national emission standards for hazardous air pollutants (NESHAP) on May 16, 2003

, for the clay ceramics manufacturing industry, specifically the sanitaryware and ceramic tile industry sectors. Sanitaryware includes plumbing and bathroom fixtures such as toilets and sinks. Ceramic tile is used to cover floors and walls. The NESHAP regulated emission s of hydrogen fluoride (HF), hydrogen chloride (HCl), and particulate matter (PM)

— a surrogate for hazardous air pollutant ( HAP ) metals

— from new and reconstructed kilns located at clay ceramics facilities. On March 13, 2007, the D.C. Circuit Court vacated t he emission standards for clay ceramics manufacturing due to issues associated with the methodology used to determine the minimum regulatory “floors” for new and existing units. 1 

### Therefore, the EPA is proposing new standards for clay ceramics manufacturing , including standards for HF, HCl, mercury (Hg), non

- Hg HAP metals (specifically, the PM surrogate), and dioxins/furans

. The list of affected sources to be regulated has been expanded to include new and existing kilns, spray dryers (ceramic tile only), pr ess dryers (floor tile only), and spray glaze operations

. The facilities currently projected to be subject to the proposed NESHAP include three sanitaryware facilities. The ceramic tile facilities ( including floor and wall tile facilities) have taken the necessary steps to become synthetic area sources (i.e., have obtained a federally enforceable limit reducing emissions below major source thresholds 2 

### ) and would not be subject to the major source clay ceramics NESHAP. The objective of this memo is to descr ibe and document the determination of subcategories for clay ceramics sources

.

1 Sierra Club v. EPA , 479 F.3d 875 (D.C. Cir. 2007)

. 2 A major source of HAP is a facility that has the potential to emit 10 tons per year (tpy) or more of any single HAP or 25 tpy or more of any combination of HAP.

### 2 II. Subcategories Evaluated

Under CAA section 112(d)(1), the EPA has the discretion to “...distinguish among classes, types, and sizes of sources within a category or subcategory in establishing...” standards. As explained in the preamble to the proposed rule, there are three distinct sectors within the clay ceramics manufacturing industry

, with differences in raw materials, processes, and final products: (1) ceramic floor tile; (2) ceramic wall tile; and (3) sanitaryware. For most sources within these industry sectors, the differences between source sizes, types, or emissions were not significant enough to warrant subcategories. The exception was the various types of glazing operati ons used at sanitaryware facilities; therefore, we examined the potential for subcategories of sanitaryware glazing operations.

III. Sanitaryware Glazing Operations

T here are three different types of spray glaze applications used at sanitaryware facilities :

man ual, spray machine, and robot

. M ost m anually operated spray booths are designed with a single spray gun to be handled by a single operator , although some can have more than one spray gun. Manual booths are typical ly used for application of glaze to a small number of pieces or when multiple glaze color changes are necessary

. Spray machines have multiple fixed reciprocating spray guns with automated control . Ware is moved through these spray machines with a “chain

- on

- edge” conveyor system. Spray machines are typically used to apply a single glaze color to high volume s of ware. Finally, robot spray booths have a single robot fixed with a single spray gun for automatic application of glaze , resulting in the lowest glaze spray rate of the three types (Cassid y, 2013a).

In all cases, operators try to apply a specific amount of glaze to a piece so that it has proper glaze coverage when fired, regardless of the type of glazing operation used. The glaze transfer efficiency and the control device efficiency vary ba sed on the type of booth, but the goal is to minimize the amount of glaze sprayed and maximize recovery of any excess glaze that is sprayed, which minimizes emissions as well as the cost of production (Cassidy, 2013b)

.

Table 1 describes the differences in operation between the types of sanitaryware spray glaze application

.

### 3 Table 1. Characteristics of Various Types of Sanitaryware Glazing Operations a

Manual Spray Machine b Robot How spray gun controlled Manual (operated by human operator) Automatic, reciprocating from fixed location. Spray gun does not move at all, fixed. Automatic, mounted on robot arm with high level of mobility. Arm moves like a human arm.

Number of spray guns One spray gun per station per booth 10

- 20 fixed reciprocating spray guns per booth One spray gun per booth

How ware moved Manual set up Automatically moved on “chain

- on

- edge” conveyor system Manual set up

Ware volume Low. Dependent on ware shape; often used when multiple glaze color changes are necessary. High. Typically used when all products will be the same color. L ow. Dependent on ware shape.

N umber of pieces able to spray at a time 1 to 2 6 to 7 1

Glaze application rate Low High Low

a Information provided by Kohler Co. (Cassidy, 2013a: Cassidy, 2013b).

b Also referred to as “chain

- on

- edge” or “COE,” as that is the term used to describe the conveyor system for the ware.



### The emission profiles from any spray booth are a function of glaze spray transfer efficiency and control device efficiency. As noted abov e, these parameters will vary de pending

on the type of glazing operation, so we evaluated the available test data to determine if there were significant differences in emissions rates for these glazing operations. Table 2 shows the sanitaryware glazing ope rations test data available to the EPA, including emission factors, which were calculated from the emissions data and the rate a t which the glaze was sprayed. More details about the test data can be found in the memorandum Test Data Used in Clay Ceramics P roposed Rule (Raymond, 2014)

.

### 4 Table 2, Sanitaryware Glazing Operations Test Data

F acility ID APCD Type a New

- Source ID Glazing Operation Type Glaze Spray Rate (tph) PM (lb/ton of

glaze sprayed)

KOHL

- TX Baffles, Water Curtain SO3/SO4 Manual 0.128 3.33
KOHL

- SC No Baffles, Water Curtain LBM Manual 0.066 16.62

KOHL

- TX Baffles, Water Weir EO13 (EPN013

- Manual SB) Manual 0.079 22.84

KOHL

- TX Baffles, Water Weir EO14 (EPN014

- Bowl SM 1) Spray Machine ( COE ) 0.331 1.95

KOHL

- SC Baffles, Water Curtain BBM Spray Machine ( COE ) 0.232 6.53

KOHL

- SC Baffles, Water Curtain NTM Spray Machine ( COE ) 0.090 9.32

KOHL

- TX Baffles, Water Curtain SR1 (EPN 104

- 1P) Robot 0.073 1.32
KOHL

- TX Baffles, Water Curtain SR5 (EPN251

- Robot) Robot 0.100 3.26
KOHL

- SC Baffles, Water Curtain Robot 3 Robot 0.084 6.28
KOHL

- WI Baffles, Water Curtain P18

- Q24/S18 Robot 0.059 6.84 Average

– Manual 0.091 14.26 Average

– Spray Machine 0.22 5.93 Average

– Robot 0.079 4.42

a A baffle with a water curtain or water weir is a common air pollution control device (APCD) used on sanitaryware

spray glaze booths , particularly spray machine and robot booths . The baffles collect most of the solid particles in the excess glaze, which can be scraped off and reused. Keeping these solids from reaching the water curtain or water weir device prolongs the life of the water in the device and minimizes water use and wastewater generation.



### The differences in operating characteristics in Table 1 an d the differences between the glaze spray rates and emission rates in Table 2 for man ual, spray machine, and robot glaze spray applications are significant enough to support three subcategories of sanitaryware glazing operations.

I V. References

Cassidy, M. 2013a. “RE: Glaze spray booth PM emissions” E

- mail and attachment from Michael Cassidy , Kohler Co., to Jeff Telander, EPA. January 29, 2013.

Cassidy, M. 2013b. “RE: Chain on edge vs robot spray booths.” E

- mail from Michael Cassidy

, Kohler Co., to Sharon N izich, EPA. June 20 , 2013.

Raymond, G. 2014. Test Data Used in Clay Ceramics Proposed Rule

. Memorandum from Gabrielle Raymond, RTI International, to J eff Telander, EPA/OAQPS/SPPD

. November 6

, 2014.