Cal. Code Regs. tit. 17 § 93101.5
This Airborne Toxic Control Measure (ATCM) shall apply to each thermal spraying operation at a stationary source that uses materials containing chromium, chromium compounds, nickel, or nickel compounds. This ATCM does not apply to portable thermal spraying operations.
For the purposes of this section, the following definitions shall apply:
All existing thermal spraying operations must control hexavalent chromium and nickel emissions as follows:
Table 1: Point Sources -- Control Efficiency Requirements for Existing Thermal Spraying Operations
| Tier | Annual Hexavalent Chromium Emissions from Thermal Spraying1 | Annual Nickel Emissions from Thermal Spraying1 | Minimum Control Efficiency Requirements2 |
| 1 | >= 0.004 lbs/yr and [LESS THAN EQUAL TO] 0.04 lbs/yr | >= 2.1 lbs/yr and [LESS THAN EQUAL TO] 20.8 lbs./yr | 90% by weight (e.g., a water curtain) |
| 2 | > 0.04 lbs/yr and [LESS THAN EQUAL TO] 0.4 lbs/yr | > 20.8 lbs/yr and [LESS THAN EQUAL TO] 208 lbs/yr | 99.999% @ 0.5 microns (e.g., a high-efficiency dry filter) |
| 3 | > 0.4 lbs/yr | > 208 lbs/yr | 99.97% @ 0.3 microns (e.g., a HEPA filter) |
| 1. Emissions are controlled emissions from all thermal spraying operations at a stationary source, if the thermal spraying operation is already equipped with a control device. | |||
| a. For non-permitted sources, annual emissions must be determined in accordance with the emission calculation methods specified in Appendix 1 or based on the results of an emissions source test that has been reviewed and approved by the permitting agency. | |||
| b. For permitted sources, annual emissions must be calculated based on the potential to emit or in accordance with the allowable limits set forth in the permit conditions. Emissions must be determined in accordance with the emission calculation methods specified in Appendix 1 or based on the results of an emissions source test that has been reviewed and approved by the permitting agency. | |||
| 2. Control efficiency requirements must be certified by the manufacturer/supplier of the control device and/or filter media. Thermal spraying operations are not required to conduct an emissions source test to verify the control efficiency at the listed particle sizes. | |||
Table 2: Volume Sources -- Control Efficiency Requirements for Existing Thermal Spraying Operations
| Tier | Annual Hexavalent Chromium Emissions from Thermal Spraying1 | Annual Nickel Emissions from Thermal Spraying1 | Minimum Control Efficiency Requirements2 |
| 1 | >= 0.001 lbs/yr and [LESS THAN EQUAL TO] 0.01 lbs/yr | >= 0.3 lbs/yr and [LESS THAN EQUAL TO] 3.1 lbs./yr | 99% by weight (e.g., a dry filter) |
| 2 | > 0.01 lbs/yr and [LESS THAN EQUAL TO] 0.1 lbs/yr | > 3.1 lbs/yr and [LESS THAN EQUAL TO] 31 lbs/yr | 99.999% @ 0.5 microns (e.g., a high-efficiency dry filter) |
| 3 | > 0.1 lbs/yr | > 31 lbs/yr | 99.97% @ 0.3 microns (e.g., a HEPA filter) |
| 1. Emissions are controlled emissions from all thermal spraying operations at a stationary source, if the thermal spraying operation is already equipped with a control device. | |||
| a. For non-permitted sources, annual emissions must be determined in accordance with the emission calculation methods specified in Appendix 1 or based on the results of an emissions source test that has been reviewed and approved by the permitting agency. | |||
| b. For permitted sources, annual emissions must be calculated based on the potential to emit or in accordance with the allowable limits set forth in the permit conditions. Emissions must be determined in accordance with the emission calculation methods specified in Appendix 1 or based on the results of an emissions source test that has been reviewed and approved by the permitting agency. | |||
| 2. Control efficiency requirements must be certified by the manufacturer/supplier of the control device and/or filter media. Thermal spraying operations are not required to conduct an emissions source test to verify the control efficiency at the listed particle sizes. | |||
All existing thermal spraying operations that are subject to subsection (c)(1)(A) must use air pollution control systems that meet the following criteria by January 1, 2006. All modified or new thermal spraying operations that are subject to subsection (c)(2)(A)2. or (c)(3)(A)1., respectively, must use air pollution control systems that meet the following criteria upon initial startup.
The inward face velocity must be confirmed by a velocity measuring device approved by the permitting agency (e.g., a pitot tube or anemometer.) Measurement of inward face velocity must be performed in accordance with the methods set forth in Appendix 2 or an alternative method approved by the permitting agency. This subsection does not require the use of an independent tester to measure inward face velocity.
For existing thermal spraying operations, the exhaust gas stream from the air pollution control system required by subsection (c)(1)(B) must be ducted to a particulate matter control device meeting the applicable control efficiency requirements of subsection (c)(1)(A) by January 1, 2006.
For modified or new thermal spraying operations, the exhaust gas stream from the air pollution control collection system required by subsection (c)(1)(B) must be ducted to a particulate matter control device meeting the applicable control efficiency requirements of subsection (c)(2)(A)2. or (c)(3)(A)1., respectively, upon initial startup.
All unpermitted existing thermal spraying operations must submit a permit application to the permitting agency no later than October 1, 2005. This permitting requirement applies only to existing thermal spraying operations that use materials containing chromium, chromium compounds, nickel, or nickel compounds.
All new thermal spraying operations must submit a permit application to the permitting agency prior to initial startup, in accordance with permitting agency requirements. This permitting requirement only applies to new thermal spraying operations that use materials containing chromium, chromium compounds, nickel, or nickel compounds.
As specified in subsection (e)(5), this negative pressure verification must have been performed at least once during the12-month period immediately before operations begin, and at least once after the enclosure is changed in any way that may impact air flow.
Existing thermal spraying operations that are subject to Tier 2 or Tier 3 control efficiency requirements specified in subsection(c)(1)(A), modified thermal spraying operations that are subject to the requirements of subsection (c)(2)(A)2., and new thermal spraying operations that are subject to the requirements of subsection (c)(3)(A)1., must use control devices with a control efficiency verified by the manufacturer. This verification must be provided to the permitting agency upon request. The control device manufacturer must verify the control efficiency using one of the following test methods, which are incorporated by reference herein:
Owners or operators of thermal spraying operations may choose to quantify hexavalent chromium and/or nickel emissions using data from a source test rather than using the calculation methods specified in Appendix 1. In addition, a permitting agency may require that a source test be performed to quantify hexavalent chromium and/or nickel emissions from thermal spraying operations. The use of source test data must comply with the requirements specified in this subsection (d)(3).
A source test conducted prior to January 1, 2006, may be used to quantify emissions or demonstrate compliance with the standards in subsection (c)(1)(A), if the permitting agency approves the use of that test. The test must be conducted by an independent tester, in accordance with a test protocol that was reviewed and approved by the permitting agency.
If the owner or operator of a thermal spraying operation conducts a source test to quantify emissions of hexavalent chromium and/or nickel, the testing must be conducted in accordance with the following listed test methods, which are incorporated by reference herein, or in accordance with alternative test methods approved by the permitting agency.
ARB Test Method 425, "Determination of Total Chromium and Hexavalent Chromium Emissions from Stationary Sources", last amended July 28, 1997, section 94135, title 17, California Code of Regulations (CCR).
EPA Test Method 306, "Determination of Chromium Emissions From Decorative and Hard Chromium Electroplating and Chromium Anodizing Operations -- Isokinetic Method", 40 CFR 63, Appendix A, as promulgated on January 25, 1995.
South Coast Air Quality Management District (SCAQMD) Test Method 205.1, "Determination of Hexavalent and Total Chromium from Plating", August 1991.
ARB Test Method 433, "Determination of Total Nickel Emissions from Stationary Sources", last amended September 12, 1989, section 94145, title 17, California Code of Regulations (CCR).
ARB Test Method 436, "Determination of Multiple Metals Emissions from Stationary Sources" (for nickel only), adopted July 28, 1997, section 94161, title 17, California Code of Regulations (CCR).
All thermal spraying operations with air pollution control systems must comply with the applicable monitoring requirements listed in Table 3 of this subsection (e)(1). In addition, any other operating parameters designated by the permitting agency must be monitored while conducting thermal spraying to ensure compliance with the requirements set forth in subsection (c).
Table 3 -- Summary of Monitoring Requirements for Thermal Spraying Operations Using Add-on Air Pollution Control Devices
| Control Equipment | Monitoring Requirements | |
| (A) | Dry particulate filter system (e.g., dry filter cartridge, HEPA filter) | 1. Ensure that the pressure differential gauge continuously monitors pressure drop across the control device while conducting thermal spraying. |
| 2. Record pressure drop once per week while conducting thermal spraying. | ||
| (B) | Conventional Water Curtain | 1. Ensure that the flow meter continuously monitors the water flow rate while conducting thermal spraying. |
| 2. Monitor the water curtain continuity by visual observation to ensure that there are no gaps while conducting thermal spraying. | ||
| 3. Record water flow rate and water curtain continuity once per week while conducting thermal spraying. | ||
| (C) | Pumpless Water Curtain | 1. Monitor parameters that indicate booth performance, per manufacturer's recommendations, while conducting thermal spraying. |
| 2. Visually inspect the water curtain for continuity to ensure that there are no gaps while conducting thermal spraying. | ||
| 3. Record recommended parameters and water curtain continuity once per week while conducting thermal spraying. |
All dry particulate control devices (e.g., dry filter cartridges or HEPA filters) must have gauges that continuously monitor the pressure drop across each control device when thermal spraying is occurring. The gauge must have a high and low setting for the pressure drop and must trigger an alarm system when the high or low set points are exceeded. The gauge must be designed to accurately measure pressure drops within the expected range and have an accuracy of at least + 5% of full scale. The gauge must be located so that it can be easily visible and in clear sight of the operation or maintenance personnel. The pressure drop must be maintained per manufacturer's specifications. If the pressure drop is outside of the acceptable limits, the owner or operator must shut down the thermal spraying operation immediately and take corrective action. The thermal spraying operation must not be resumed until the pressure drop is within the specified limit(s).
For thermal spraying operations that are conducted in water curtain booths, the owner or operator must monitor booth operating parameters during thermal spraying to ensure compliance with the requirements specified in subsection (c). Water curtain booths must provide a continuous sheet of water down the rear wall of the booth. For all water curtain booths, the owner or operator must visually monitor the water curtain during thermal spraying to ensure that the sheet is continuous without any gaps or dry spots. The owner or operator of a conventional water curtain booth must continuously monitor the water flow rate with a flow meter during thermal spraying to ensure the water flow meets or exceeds the minimum flow rate recommended by the manufacturer. The owner or operator of a pumpless water curtain booth must monitor the parameters recommended by the booth manufacturer to ensure that these parameters meet or exceed the manufacturer's recommendations. If the water curtain fails the continuity and/or flow requirements, the owner or operator must shut down the thermal spraying operation immediately to take corrective action. The thermal spraying operation must not be resumed until the monitored parameters meet or exceed the manufacturer's recommendations.
All thermal spraying operations with air pollution control systems must comply with the applicable inspection and maintenance requirements listed in Table 4.
Table 4 -- Summary of Inspection and Maintenance Requirements for Thermal Spraying Operations Using Add-on Air Pollution Control Devices
| Control Equipment | Inspection & Maintenance Requirements | Frequency | |
| (A) | Dry particulate filter system | 1. Conduct a visual inspection to ensure there are no leaks in accordance with Appendix 3. | At least once every 90 days. |
| (e.g., dry filter cartridge, HEPA filter) | 2. Visually inspect ductwork from work area to the control device to ensure there are no leaks in accordance with Appendix 3. | At least once every 90 days. | |
| 3. Replace filter. | Per manufacturer's specifications or permitting agency's requirement. | ||
| (B) | Water Curtain | 1. Visually inspect ductwork from booth to the exhaust stack to ensure there are no leaks in accordance with Appendix 3. | At least once every 90 days. |
| (C) | All | 1. Measure inward face velocity at each opening in accordance with Appendix 2. This requirement does not apply to existing thermal spraying operations that are remotely located and comply with the standards in section (c)(1)(E). | At least once per calendar year and whenever the air pollution control system is changed in any way that may impact air flow. |
Thermal spraying operations that are operating pursuant to subsection (c)(1)(B)5. (i.e., operating with the enclosure door open), must demonstrate negative pressure at least once every 12 months and whenever the enclosure is changed in any way that may impact air flow.
The owner or operator must maintain records of monitoring data required by subsection (e), including the date and time the data are collected. Recordkeeping logs must include the applicable acceptable limit(s) for: pressure drop (dry particulate control); water flow rate (conventional water curtain); or manufacturer's recommended parameter limits (pumpless water curtain).
The owner or operator must maintain inspection records that clearly document all inspections and maintenance activities to enable the permitting agency to determine whether the requirements of subsection (e)(4) have been met. The records may take the form of a checklist and must identify:
For thermal spraying materials that contain chromium, chromium compounds, nickel, or nickel compounds, the owner or operator must record the name and quantity of material used during each month of the annual reporting period, and the total usage to date for that calendar year.
The owner or operator must maintain test reports documenting the conditions and results of all source tests.
The owner or operator must maintain records of the occurrence, duration, cause (if known), and action taken for each equipment malfunction and/or failure. This recordkeeping requirement applies only to equipment malfunctions or failures that cause or may cause uncontrolled emissions to be released.
All records required by this subsection (f) must be readily accessible for inspection and review at the thermal spraying operation for at least five years. If so requested by the permitting agency, the owner or operator must provide copies of the records to the permitting agency.
All existing thermal spraying operations must submit an emission inventory for hexavalent chromium and nickel to the permitting agency no later than October 1, 2005. This inventory must quantify the emissions from thermal spraying operations conducted during the 12-month period between July 1, 2004 and July 1, 2005. The emission inventory must be prepared in accordance with Appendix 1 or must be based on an emissions source test approved by the permitting agency.
Existing thermal spraying operations that qualify for the standards specified in subsection (c)(1)(E) or the exemption specified in subsection (c)(1)(F) must submit an annual report to the permitting agency by March 1st of each calendar year that quantifies emissions of hexavalent chromium and nickel from thermal spraying operations during the previous calendar year.
Existing thermal spraying operations that intend to begin using materials containing chromium, chromium compounds, nickel, or nickel compounds on or after January 1, 2005, must notify the permitting agency at least 45 days prior to using any of these materials. If the use of these materials begins before the operative date of this section, this notification may be delayed until the operative date of this section.
The owner or operator of a thermal spraying operation must report breakdowns, equipment malfunctions, and failures as required by the permitting agency. This reporting requirement only applies to equipment malfunctions or failures that cause or may cause uncontrolled emissions to be released.
The owner or operator of a thermal spraying operation must notify the permitting agency of his or her intention to conduct a source test to measure emissions of hexavalent chromium and/or nickel. The owner or operator must provide this notification to the permitting agency at least 60 days before the source test is scheduled. The notification must include a pre-test protocol and any other documentation required by the permitting agency.
The owner or operator of a thermal spraying operation must provide the source test results to the permitting agency no later than 60 days following completion of the testing.
A permitting agency may change the timeline for submittal of periodic reports, allow consolidation of multiple reports into a single report, establish a common schedule for submittal of reports, or accept reports prepared to comply with other State or local requirements. Prior to allowing any of these changes, the permitting agency must determine that the change will provide the same information and will not reduce the overall frequency of reporting.
Each part of this section is deemed severable, and in the event that any part of this section is held to be invalid, the remainder of this section shall continue in full force and effect.
Appendix 1 -- Emission Calculation Method
Emissions of hexavalent chromium (Cr+6) and nickel (Ni) from thermal spraying operations must be calculated in accordance with the procedures specified in this Appendix 1.
Step 1: Identify all thermal spraying materials that contain chromium (Cr) or nickel (Ni) at a concentration of at least 0.1% by weight (or less than 0.1%, if listed on the Material Safety Data Sheet.) Include materials that contain chromium or nickel in the form of a metallic compound or alloy. Examples of compounds and alloys include, but are not limited to, stainless steel; chromium carbide (Cr3C2); nichrome alloys (NiCr); and chromium oxide (Cr2O3).
Step 2: Determine the total percentage of chromium and/or nickel contained in each thermal spraying material. These data can be obtained from the material safety data sheet (MSDS) or by contacting the manufacturer. If the MSDS contains a range of percentages, use the upper value of the range. If the material contains a compound (e.g., Cr3C2), include only the portion that is chromium or nickel.
Step 3: For each thermal spraying operation, compile the annual usage for each thermal spraying material that contains chromium or nickel. For thermal spraying operations that have air permits, the annual usage is the maximum allowable under the permit.
Step 4: For each thermal spraying operation, calculate the annual usage quantities for chromium and nickel using the following equations:
Eqn. 1: [Annual Usage, lbs Cr/yr] = [Material Usage, lbs material used/yr]*[weight % Cr in Material]
Eqn. 2: [Annual Usage, lbs Ni/yr] = [Material Usage, lbs material used/yr]*[weight % Ni in Material]
Step 5. Identify the applicable emission factor(s) for each thermal spraying operation, based on the applicable control efficiency level. If a material is used for multiple thermal spraying operations and material usage records document the quantity of material used for each operation, use the applicable emission factors for each operation. If material usage records do not document the quantity of material used for each operation, use the highest emission factor.
Table 1-1 specifies the applicable emission factors for thermal spraying operations using materials that contain chromium, chromium compounds, or chromium alloys.
Table 1-2 specifies the applicable emission factors for thermal spraying operations using materials that contain nickel, nickel compounds, or nickel alloys.
Table 1-1: Thermal Spraying Emission Factors for Hexavalent Chromium
Emission Factors (lbs Cr+6/lb Cr sprayed)*
| Operation | 0% Control Efficiency (Uncontrolled) | 90% Control Efficiency (e.g. Water Curtain) | 99% Control Efficiency (e.g. Dry Filter) | 99.97% Control Efficiency (e.g., HEPA Filter) |
| Single-Wire Flame Spray | 4.68E-03 | 4.68E-04 | 4.68E-05 | 1.40E-06 |
| Twin-Wire Electric Arc Spray | 6.96E-03 | 6.96E-04 | 6.96E-05 | 2.09E-06 |
| Flame Spray | 6.20E-03 | 1.17E-03 | 6.20E-05 | 1.86E-06 |
| HVOF | 6.20E-03 | 1.17E-03 | 6.20E-05 | 1.86E-06 |
| Plasma Spray | 1.18E-02 | 6.73E-03 | 2.61E-03 | 2.86E-06 |
| Other Thermal Spraying | 7.17E-03 | 2.05E-03 | 5.70E-04 | 2.01E-06 |
| * Some emission factors are based directly on stack test results while others are calculated values, derived from stack test results and control efficiencies. | ||||
Table 1-2: Thermal Spraying Emission Factors for Nickel
Emission Factors (lbs Ni/lb Ni sprayed)*
| Operation | 0% Control Efficiency (Uncontrolled) | 90% Control Efficiency (e.g. Water Curtain) | 99% Control Efficiency (e.g. Dry Filter) | 99.97% Control Efficiency (e.g., HEPA Filter) |
| Twin-Wire Electric Arc Spray | 6.0E-03 | 6.0E-04 | 6.0E-05 | 1.8E-06 |
| Flame Spray | 1.10E-01 | 4.64E-02 | 1.10E-03 | 3.30E-05 |
| HVOF | 1.10E-01 | 4.64E-02 | 1.10E-03 | 3.30E-05 |
| Plasma Spray | 1.5E-01 | 3.67E-02 | 1.5E-03 | 1.72E-05 |
| Other Thermal Spraying | 9.4E-02 | 3.25E-02 | 9.4E-04 | 2.13E-05 |
| * Some emission factors are based directly on stack test results while others are calculated values, derived from stack test results and control efficiencies. | ||||
Step 6 -- Annual Emissions. For each thermal spraying operation, calculate the annual emissions by multiplying the applicable emission factors by the annual usage rates, using the following equations:
Eqn. 3: [Annual Emissions, lbs Cr+6/yr] = [Emission Factor, lbs Cr+6/lb Cr sprayed]*[Annual Usage, lbs Cr sprayed/yr]]
Eqn. 4: [Annual Emissions, lbs Ni/yr] = [Emission Factor, lbs Ni/lb Ni sprayed]*[Annual Usage, lbs Ni sprayed/yr]
Step 7 -- Maximum Hourly Nickel Emissions: For each thermal spraying operation that uses nickel, calculate the maximum hourly emissions by multiplying the applicable emission factors by the maximum hourly usage rates, using the following equations:
Eqn. 5:
[Max. Hourly Emissions, lbs Ni/hr] = [Emission Factor, lbs Ni/lb Ni sprayed]*[Max. Hourly Usage, lbs Ni sprayed/hr]
Eqn. 6:
[Max. Hourly Usage, lbs Ni sprayed/hr] = [Max. Gun Spray Rate, lbs material sprayed/hr]*[Max. wt.% Ni in material]
where
"Maximum Gun Spray Rate" is the highest material throughput rate that a thermal spraying gun can achieve, based on manufacturer specifications or actual user experience, whichever is greater. If multiple guns have the potential to be operated at the same time (e.g., in two separate booths), the maximum gun spray rate must include the total throughput from all guns.
"Maximum Weight % Nickel in Material" is the highest weight percentage of nickel for all of the thermal spraying materials that are used in thermal spraying operations at a facility.
Point Source Example:
Thermal Spraying Inc. operates two thermal spraying booths. One booth is used for plasma spraying and the other booth is used for flame spraying and twin-wire electric arc spraying. Listed below is information on the facility's operations:
| Booth | Control Device | Operation | Materials Used | Quantity Used | % Total Chromium | % Nickel |
| Booth #1 | HEPA Filter | Plasma Spray | Powder ABC | 25 lbs/yr | 25% | 0% |
| Powder XYZ | 50 lbs/yr | 20% | 75% | |||
| Booth #2 | Dry Filter | Flame Spray | Powder 123 | 10 lbs/yr | 0% | 95% |
| (99% effic.) | Powder XYZ | 75 lbs/yr | 20% | 75% | ||
| Twin-Wire | Wire #1 | 80 lbs/yr | 20% | 5% |
An example calculation is provided below for Thermal Spraying Inc.:
Step 1: Identify all thermal spraying materials that contain at least 0.1% by weight of chromium (Cr), chromium compounds, nickel (Ni), or nickel compounds.
The following four products contain chromium or nickel: Powder 123; Powder ABC; Powder XYZ; Wire #1.
Step 2: Determine the total percentage of chromium and/or nickel.
| Materials Used | % Total Chromium | % Nickel |
| Powder 123 | 0% | 95% |
| Powder ABC | 25% | 0% |
| Powder XYZ | 20% | 75% |
| Wire #1 | 20% | 5% |
If a thermal spraying material contains a compound, include only the portion that is chromium or nickel. For example, if the material contains 95% chromium oxide (Cr2O3), the weight percent of chromium would be calculated as follows:
[Chromium Weight %]=[Weight % Cr2O3]* ([Molecular Weight of Chromium (Cr2)])/([Molecular Weight of Chromium Oxide (Cr2O3)])
Molecular Weight of Chromium (Cr2) = (52 g/g-mol)*(2) = 104 g/g-mol
Molecular Weight of Chromium Oxide (Cr2O3) = (52 g/g-mol)*(2)+(16)*(3) = 152 g/g-mol
[Chromium Weight %]=[95 % Cr2O3]* ([104 g/g-mol])/([152 g/g-mol]) = 65%
Step 3: Compile the annual material usage.
| Operation | Materials Used | Quantity Used |
| Plasma Spray | Powder ABC | 25 lbs/yr |
| Powder XYZ | 50 lbs/yr | |
| Flame Spray | Powder 123 | 10 lbs/yr |
| Powder XYZ | 75 lbs/yr | |
| Twin-Wire | Wire #1 | 80 lbs/yr |
Step 4: Calculate the annual usage quantities for chromium and nickel.
| Materials Used | Quantity Used | % Total Chromium | % Nickel | Qty. of Total Chromium Used | Qty. of Nickel Used |
| Powder ABC | 25 lbs/yr | 25% | 0% | [25 lbs/yr]x[25% Cr] = 6.25 lbs Cr/yr | [25 lbs/yr]x[0% Ni] = 0 lbs Ni/yr |
| Powder XYZ | 50 lbs/yr | 20% | 75% | [50 lbs/yr]x[20% Cr] = 10.0 lbs Cr/yr | [50 lbs/yr]x[75% Ni] = 37.5 lbs Ni/yr |
| Powder 123 | 10 lbs/yr | 0% | 95% | [10 lbs/yr]x[0% Cr] = 0 lbs Cr/yr | [10 lbs/yr]x[95% Ni] = 9.5 lbs Ni/yr |
| Powder XYZ | 75 lbs/yr | 20% | 75% | [75 lbs/yr]x[20% Cr] = 15.0 lbs Cr/yr | [75 lbs/yr]x[75% Ni] = 56.25 lbs Ni/yr |
| Wire #1 | 80 lbs/yr | 20% | 5% | [80 lbs/yr]x[20% Cr] = 16.0 lbs Cr/yr | [80 lbs/yr]x[5% Ni] = 4.0 lbs Ni/yr |
Step 5: Identify the applicable emission factors.
| Control Device | Operation | Emission Factor -- Hexavalent Chromium (lb Cr+6/lb Cr sprayed) | Emission Factor -- Nickel (lb Ni/lb Ni sprayed) |
| HEPA Filter | Plasma Spray | 2.86E-06 | 1.72E-05 |
| Dry Filter | Flame Spray | 6.20E-05 | 1.10E-03 |
| (99% effic.) | Twin-Wire | 6.96E-05 | 6.0E-05 |
Step 6: Calculate annual emissions ([Annual Emissions] = [Emission Factor]*[Annual Usage].) For hexavalent chromium, the annual emissions are --
| Booth | Control Device | Operation | Materials Used | Qty. of Total Chromium Used (lbs Cr sprayed/yr) | Emission Factor (lb Cr+6/lb Cr sprayed) | Annual Emissions (lb Cr+6/yr) |
| #1 | HEPA Filter | Plasma Spray | Powder ABC | 6.25 | 2.86E-06 | [6.25]x[2.86E-06] = 1.79E-05 |
| Powder XYZ | 10.0 | 2.86E-06 | [10.0]x[2.86E-06] = 2.86E-05 | |||
| #2 | Dry Filter | Flame Spray | Powder 123 | 0 | 6.20E-05 | [0]x[6.20E-05] = 0 |
| (99% effic.) | Powder XYZ | 15.0 | 6.20E-05 | [15.0]x[6.20E-05] = 9.30E-04 | ||
| Twin-Wire | Wire #1 | 16.0 | 6.96E-05 | [16.0]x[6.96E-05] = 1.11E-03 | ||
| Total = | 0.002 |
Based on this emission level, Thermal Spraying Inc. is below the Tier 1 threshold for hexavalent chromium. Therefore, no new control efficiency requirements would be imposed by this ATCM because of hexavalent chromium emissions. However, Thermal Spraying Inc. will still need to comply with the permitting, monitoring, and recordkeeping requirements of the ATCM. In addition, if the workload increased and emissions exceeded Tier 1 thresholds, it would be necessary to upgrade the dry filter system or limit the usage of all chromium materials to the booth that has the HEPA filter.
For nickel, the annual emissions are --
| Booth | Control Device | Operation | Materials Used | Qty. of Nickel Used (lbs Ni sprayed/yr) | Emission Factor (lb Ni/lb Ni sprayed) | Annual Emissions (lb Ni/yr) |
| #1 | HEPA Filter | Plasma Spray | Powder ABC | 0 | 1.72E-05 | [0]x[1.72E-05] = 0 |
| Powder XYZ | 37.5 | 1.72E-05 | [37.5]x[1.72E-05] = 6.45E-04 | |||
| #2 | Dry Filter | Flame Spray | Powder 123 | 9.5 | 1.10E-03 | [9.5]x[1.10E-03] = |
| (99% effic.) | 1.05E-02 | |||||
| Powder XYZ | 56.25 | 1.10E-03 | [56.25]x[1.10E-03] = 6.19E-02 | |||
| Twin-Wire | Wire #1 | 4.0 | 6.0E-05 | [4.0]x[6.0E-05] = 2.40E-04 | ||
| Total = | 0.073 |
Based on this emission level, Thermal Spraying Inc. is below the Tier 1 threshold for nickel. Therefore, no new control efficiency requirements would be imposed by this ATCM because of nickel emissions. However, Thermal Spraying Inc. will still need to comply with the permitting, monitoring, and recordkeeping requirements of the ATCM. In addition, if the workload increased and emissions exceeded Tier 1 thresholds, it would be necessary to upgrade the dry filter system or limit the usage of all nickel materials to the booth that has the HEPA filter.
Step 7: Calculate the maximum hourly emissions for nickel. Powder 123 is the material that has the highest weight percentage of nickel (95%).
The maximum spray rate for the flame spraying gun is 10 lbs/hr.
The emission factor for flame spraying is 1.10E-03 lb Ni/lb Ni sprayed.
[Maximum Hourly Usage] = [Maximum Gun Spray Rate]*[Maximum Wt.% Nickel]
[Maximum Hourly Usage] = [10 lbs/hr]*[95% Ni] = 9.5 lbs Ni sprayed/hr
[Maximum Hourly Emissions] = [Emission Factor]*[Maximum Hourly Usage]
Maximum Hourly Emissions = [1.10E-03 lb Ni/lb Ni sprayed]*[9.5 lbs Ni sprayed/hr] = 0.01 lb Ni/hr
The maximum hourly emissions for nickel are 0.01 lbs Ni/hr, which is well below the compliance limit of 0.1 lb Ni/hr for point sources. Therefore, this thermal spraying operation complies with the maximum hourly limit for nickel.
Volume Source Example:
Machine Shop Inc. conducts flame spraying with powder on small parts. The parts are turned on a lathe while spraying is being performed. Since the lathe is not located in a booth, the shop uses a portable local exhaust fan to remove fumes from the worker's breathing area. This type of operation would be considered a volume source with 0% control efficiency. Listed below is information on the facility's operations:
| Booth | Control Device | Operation | Materials Used | Quantity Used | % Total Chromium | % Nickel |
| None | None | Flame Spray | Powder 123 | 20 lbs/yr | 0% | 95% |
| (uncontrolled) | Powder XYZ | 5 lbs/yr | 20% | 75% |
An example calculation is provided below for Machine Shop Inc.:
Step 1: Identify all thermal spraying materials that contain at least 0.1% by weight of chromium (Cr), chromium compounds, nickel (Ni), or nickel compounds.
The following two products contain chromium or nickel: Powder 123 and Powder XYZ.
Step 2: Determine the total percentage of chromium and/or nickel.
| Materials Used | % Total Chromium | % Nickel |
| Powder 123 | 0% | 95% |
| Powder XYZ | 20% | 75% |
Step 3: Compile the annual material usage.
| Operation | Materials Used | Quantity Used |
| Flame Spray | Powder 123 | 20 lbs/yr |
| Powder XYZ | 5 lbs/yr |
Step 4: Calculate the annual usage quantities for chromium and nickel.
| Materials Used | Quantity Used | % Total Chromium | % Nickel | Qty. of Total Chromium Used | Qty. of Nickel Used |
| Powder 123 | 20 lbs/yr | 0% | 95% | [20 lbs/yr]x[0% Cr] = 0 lbs Cr/yr | [20 lbs/yr]x[95% Ni] = 19.0 lbs Ni/yr |
| Powder XYZ | 5 lbs/yr | 20% | 75% | [5 lbs/yr]x[20% Cr] = 1.0 lbs Cr/yr | [5 lbs/yr]x[75% Ni] = 3.75 lbs Ni/yr |
Step 5: Identify the applicable emission factors.
| Control Device | Operation | Emission Factor - Hexavalent Chromium (lb Cr+6/lb Cr sprayed) | Emission Factor - Nickel (lb Ni/lb Ni sprayed) |
| Uncontrolled | Flame Spray | 6.20E-03 | 1.10E-01 |
Step 6: Calculate annual emissions ([Annual Emissions] = [Emission Factor]*[Annual Usage].)
For hexavalent chromium, the annual emissions are -
| Booth | Control Device | Operation | Materials Used | Qty. of Total Chromium Used (lbs Cr sprayed/yr) | Emission Factor (lb Cr+6/lb Cr sprayed) | Annual Emissions (lb Cr+6/yr) |
| None | None | Flame Spray | Powder 123 | 0 | 6.20E-03 | [0]x[6.20E-03] |
| F | = 0 | |||||
| Powder XYZ | 1.0 | 6.20E-03 | [1.0]x[6.20E-03] | |||
| = 6.20E-03 | ||||||
| Total = | 0.006 |
Based on this emission level, Machine Shop Inc. is classified as Tier 1 for hexavalent chromium. Therefore, the thermal spraying operation would need to install a new booth with a control device that met the Tier 1 minimum efficiency requirement of 99%. In addition, Machine Shop Inc. would need to comply with the permitting, monitoring, and recordkeeping requirements of the ATCM. Machine Shop Inc. could avoid having to install a new booth and control device, if they eliminated the use of chromium-containing materials.
For nickel, the annual emissions are -
| Booth | Control Device | Operation | Materials Used | Qty. of Nickels Used (lbs Ni sprayed/yr) | Emission Factor (lb Ni/lb Ni sprayed) | Annual Emissions (lb Ni/yr) |
| None | None | Flame Spray | Powder 123 | 19.0 | 1.10E-01 | [19.0]x[1.10E-01] = 2.09 |
| Powder XYZ | 3.75 | 1.10E-01 | [3.75]x[1.10E-01] = 4.13E-01 | |||
| Total = | 2.50 |
Based on this emission level, Machine Shop Inc. is below the Tier 1 threshold for nickel. Therefore, no new control efficiency requirements would be imposed by this ATCM because of nickel emissions. However, this ATCM requires thermal spraying operations to comply with the most stringent control efficiency. Since the control efficiency requirement based on hexavalent chromium is the most stringent, they must comply with the 99% control efficiency.
Step 7: Calculate the maximum hourly emissions for nickel.
Powder 123 is the material that has the highest weight percentage of nickel (95%).
The maximum spray rate for the flame spraying gun is 10 lbs/hr.
The emission factor for flame spraying is 1.10E-01 lb Ni/lb Ni sprayed.
[Maximum Hourly Usage] = [Maximum Gun Spray Rate]*[Maximum Wt.% Nickel]
[Maximum Hourly Usage] = [10 lbs/hr]*[95 % Ni] = 9.5 lbs Ni sprayed/hr
[Maximum Hourly Emissions] = [Emission Factor]*[Maximum Hourly Usage]
Maximum Hourly Emissions = [1.10E-01 lb Ni/lb Ni sprayed]*[9.5 lbs Ni sprayed/hr] = 1.1 lb Ni/hr
The maximum hourly emissions for nickel are 1.1 lbs Ni/hr, which exceeds the compliance limit of 0.01 lb Ni/hr for volume sources. Therefore, this thermal spraying operation does not comply with the maximum hourly limit for nickel and it would be necessary to reduce emissions (e.g., install a control device, limit usage, etc.)
Appendix 2 -- Method for Measuring Inward Face Velocity
Inward face velocity must be measured at least once every calendar year and whenever the air pollution control system is changed in any way that may impact air flow to ensure that the ventilation system is working properly. Measurements must be conducted in accordance with the procedures specified in this Appendix 2 or an alternative method approved by the permitting agency.
1. Hood Measurement:
Divide the face of the hood, the slot area, or the normal plane, at the capture velocity measurement point into equal area rectangles (see Figure 1). The side of each rectangular area should be no longer than 12 inches. Measure the air velocity (fpm) at the center of each rectangle using a calibrated anemometer or other measuring device approved by the permitting agency. The velocity measuring device must have an accuracy of at least +10% of full scale. The measuring device must be in good condition, of proper velocity range, and operated according to the manufacturer's instructions. The measuring device must be calibrated in accordance with the manufacturer's recommendations. Do not block or disturb the airflow while taking the readings.
Measure the volumetric airflow rate through the hood by measuring the velocity at the center of each equal-sized rectangular area (i.e., by performing pitot traverses.) If no suitable location exists for performing complete pitot traverses, measure the slot velocity and use this data to estimate the volumetric airflow rate through a hood.
2. Walk-in Booth Measurement:
For a cross-draft walk-in booth (i.e., air enters through filters in the front of the booth and leaves through filters in the back of the booth):
Divide the length of the booth into at least three cross-sectional areas to obtain the velocity profile in the booth. One cross-sectional area must be located near the exhaust plenum, one close to the supply plenum, and the other in the middle of the booth. Figure 2 illustrates the location of cross-sectional areas. Record the distance between each cross-sectional area and the exhaust or supply plenums. The distance between each cross-sectional area must not exceed ten feet.
Lay out imaginary grid lines through each cross sectional area. Use the intersections of the grid lines as locations to measure velocities inside the booth. The intersection points must be no more than six feet apart. Record the location of each point on the grid. Measure the air velocity (fpm) at each intersection point on the grid using a calibrated anemometer or other measuring device approved by the permitting agency. The velocity measuring device must have an accuracy of at least +10% of full scale. The measuring device must be in good condition, of proper velocity range, and operated according to the manufacturer's instructions. The measuring device must be calibrated in accordance with the manufacturer's recommendations.
For a down-draft walk-in booth (i.e., air enters through filters in the ceiling of the booth and leaves through filters that cover trenches under a metal grate floor):
Divide the height of the booth into at least three cross-sectional areas to obtain the velocity profile in the booth. One cross-sectional area must be located near the exhaust plenum, one close to the supply plenum, and the other in the middle of the booth. Record the distance between each cross-sectional area and the exhaust or supply plenums. The distance between each cross-sectional area must not exceed ten feet.
Lay out imaginary grid lines through each cross sectional area. Use the intersections of the grid lines as locations to measure velocities inside the booth. The intersection points must be no more than six feet apart. Record the location of each point on the grid. Measure the air velocity (fpm) at each intersection point on the grid using a calibrated anemometer or other measuring device approved by the permitting agency. The velocity measuring device must have an accuracy of at least +10% of full scale. The measuring device must be in good condition, of proper velocity range, and operated according to the manufacturer's instructions. The measuring device must be calibrated in accordance with the manufacturer's recommendations.
3. Average Value of Readings
Calculate the average value for all velocity readings, if all individual readings are within + 20% of the average value. Do not include turbulent readings when calculating the average (turbulent airflow may be indicated by negative or zero velocity readings.) Record and make available for inspection by the permitting agency the entire velocity profile to show the airflow distribution. Examples:
| Hood A - Velocity Readings (fpm) | ||
| 100 | 90 | 110 |
| 85 | 115 | 100 |
| 105 | 95 | 100 |
| Average Velocity = 900 fpm / 9 = 100 fpm | ||
| Hood B - Velocity Readings (fpm) | ||
| 200 | 200 | 0 |
| 200 | 50 | 0 |
| 100 | -5 * | -45 * |
| Average velocity = 750 fpm / 7 = 107 fpm ** | ||
* Negative values indicate airflow in reverse direction and are not included in the average.
** This is not a valid average, because individual readings are not within +20% of the average. The booth airflow needs to be adjusted and balanced before the velocity is measured again.
Appendix 3 -- Method for Measuring Inward Face Velocity
Visual inspections must be conducted at least once every 90 days to ensure that no leaks are present in the control device or ventilation system. At a minimum, the inspection must include the items listed in the following checklist that are applicable. In addition to the items on this checklist, thermal spraying operations must inspect items in accordance with manufacturers' recommendations.
| Y Acceptable | |||||
| X Unacceptable | |||||
| Dates of Inspection: | |||||
| Item to be Inspected | Look For - | ||||
| 1. Hoods | Dents, holes, corrosion | ||||
| 2. Ductwork | Dents, holes, corrosion | ||||
| Blockages, plugging | |||||
| 3. Dampers | Deterioration of seals/gaskets | ||||
| Settings | |||||
| 4. Access doors | Deterioration of seals/gaskets | ||||
| Gaps when door is closed | |||||
| 5. Fan housing | Deterioration of seals/gaskets | ||||
| Gaps in connection to ductwork | |||||
| 6. Dry filter media | Holes, gaps, abrasions | ||||
| Does filter need to be changed? | |||||
| Dust on clean side of filter? | |||||
| 7. Dry filter mounting frame | Deterioration of seals/gaskets | ||||
| 8. Other items inspected (provide descriptions): | |||||
| 9. Corrective actions (provide descriptions & dates): | |||||
| 10. Initials of person doing inspection: | |||||
Cal. Code Regs. Tit. 17, § 93101.5
Note: Authority cited: Sections 39600, 39601, 39650, 39658, 39659, 39666 and 41511, Health and Safety Code. Reference: Sections 39650, 39658, 39659, 39666 and 41511, Health and Safety Code.