MEMORANDUM

SUBJECT: Determination of Sampling Time for Affected and Nonaffected Sources at Large Hard Chromium Electroplating Facilities

From: William F. Hunt, Jr.
Director, Emissions, Monitoring, and Analysis Division (MD-14)

To: Kingsley Adeduro, Air and Toxics
Region IX (AIR-6)

Per your request, we have reviewed the information contained within the facsimile dated April 22, 1998 forwarded from Mr. Frank Bonillas of the Pima County Department of Environmental Quality, Tucson, Arizona. As we understand, the requested guidance is for affected and nonaffected emission sources located at a large hard chromium electroplating facilities.

The facsimile listed four subjects for either guidance or interpretation that are not addressed in the 40 CFR Part 63, Subpart N - National Emission Standards for Chromium Emissions From Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks regulation:

(1) Problem: The facility has five chromium tanks that are part of an electroplating process for which emissions are ducted to a common emission control device. Tanks T-1, T-4 and T-5 are classified as affected sources while tanks T-2 and T-3 are classified as nonaffected sources. The problem occurs because both the T-1 and T-2 tank emissions are exhausted via a common hood system and a single 14" dia. duct to the control device.

The T-4 and T-5 tanks have individual capture hoods that are connected to the control device via their respective 14" ducts.

§ 63.344 (e)(3)(I) refers to separate or one hood/duct per each affected or non affected tank (source) not the T-1 & T-2 combined hood/duct configuration.

Response

Each of the three capture hoods and three connecting 14" dia. inlet ducts are subject to the regulation according to their particular type of tank operation (affected / nonaffected) and/or their emission limitation. If either the inlet duct volumetric flow (dscm/m) or tank emissions (mg/dscm) can be altered from that of a single tank operation by separating or combining tanks (affected and nonaffected), the dilution effect on the controlled emissions must be determined and incorporated.

a. The two hoods and ducts capturing the affected emissions from T-4 and T-5 tanks respectively, are considered to be performing the same type of operation and are subject to the same emission limitation.

b. The single hood and duct system capturing the T-1 affected emissions and the T-2 nonaffected chrome etch emissions is capturing emissions from two different types of operations and therefore, is subject to an interpretation of the diluted emission limitation. However, neither the volumetric flow (dscm/m) nor the regulated tank emissions (mg/dscm) are changed from that of a single tank operation by placement of the two tanks under the one common hood. Therefore, calculating the total sampling time would be the same as for the T-1 affected source.

c. The T-3 chrome rinse tank (nonaffected source) does not have a hood and exhaust duct and therefore, is not included in this analysis.

(2) Problem: § 63.344 (e)(3)(ii) Sampling time determination is confusing when applied to the system in question. Need guidance for determining "total affected and non affected inlet duct area" and "total affected inlet duct area" for sampling time equation.

Response

Since neither the volumetric flow (dscm/m) nor the regulated tank emissions (mg/dscm) are changed by the placement of the T-1 and T-2 tanks under the one common hood, calculating the total sampling time would be the same as for the T-1 affected source.

a. Calculating the 14" dia. duct cross-sectional area:

14" dia. = 1.167 ft p d²

4 = 0.7854 X (1.167)² = 1.069 ft²

b. Inlet duct areas for affected and non affected sources:

affected tank areas nonaffected duct areas

T-1 1.07 ft² T-2 "0" (see Problem 1-b. above)

T-4 1.07 ft²

T-5 1.07 ft²

Total 3.21 ft² "0" ft²

c. Determine total sample time per run:

inlet duct area (affected/nonaffected) 3.21 ft²

inlet duct area (affected tanks) 3.21 ft² = 1 X 2 hours = 2 hours

(3) Problem: What if tanks T-1 and T-2 had their own separate hood and duct? Would this change the total sampling time?

Response

Yes the total sampling time would be 2.66 hours instead of 2 hours. A capture hood and 14" inlet duct has been added to the system. This addition will increase the volumetric flow (dscm/m) to the control device and in turn dilute the sample emissions ; (see following example).

a. Inlet duct areas for affected and non affected sources:

affected tank areas nonaffected duct areas

T-1 1.07 ft² T-2 1.07 ft²

T-4 1.07 ft²

T-5 1.07 ft²

Total 3.21 ft² 1.07 ft²

 

b. Determine total sample time per run:

inlet duct area (affected/nonaffected) 4.28 ft²

inlet duct area (affected tanks) 3.21 ft² = 1.33 X 2 hours = 2.66 hours

(4) Problem: 63.344 (e)(3)(iv) refers to an equation to determine the ventilation rate from the affected sources; please provide guidance for performing this calculation and for values for IDA_i and IA_total.

Response

The same interpretation applies that is listed in the Problem 2 response. As there is no change in either the volumetric flow nor the tank emissions, the total ventilation rate would remain the same as for T-1.

a. Inlet duct areas for affected and non affected sources:

affected tank areas nonaffected duct areas

T-1 1.07 ft² T-2 "0" (see Problem 1-b. above)

T-4 1.07 ft²

T-5 1.07 ft²

Total 3.21 ft² "0" ft²

b. (iv) Determine total ventilation rate from tanks (affected sources) by equation:

VR_tot X IDA_i = VR_inlet

S IA_total

VR_total = avg. total vent. rate in dscm/min for 3 M-306 tests conducted at the control device outlet.

IDA_i = total affected inlet ducts area = 3.21 ft²

IA_total = sum of all inlet ducts areas (affected & non affected) = 3.21 ft^2.

VR_inlet = total vent. rate for affected inlet ducts.

 

If you have any questions regarding this memo or require additional assistance, please contact Mr. Gene Riley at (919) 541-5239

 

cc:

David Fierra, Director, OEP, RO I

Conrad Simon, Director, AWMD, RO II

Thomas Maslany, Director, ARTD, RO III

Winston Smith, Director, APTMD, RO IV

David Lee, Director, ARD, RO V

Allyn Davis, Acting Regional Administrator, RO VI

William Spratlin, Director, Air, RCRA & TSCA, RO VII

Kerrigan Clough, Asst. Reg. Administrator, RO VIII

David Howekamp, Director, ATD, RO IX

Anita Frankel, Director, Office of Air, RO X

Elaine Stanley, Director, Office of Compliance (2221A)

Robert Van Heuvelen, Director, Office of Regulatory Enforcement (2241A)

Lalit Banker, EPA, OAQPS/ESD

Phil Mulrine, EPA, OAQPS/ESD

Robin Segall, EPA OAQPS/EMAD

Scott Throwe, EPA, OECA

Frank Bonillas, AZDEQ, Pima County