---
kind: "range"
citation: "40 C.F.R. §§ 63.985–63.995"
title: "40"
from: "63.985"
to: "63.995"
count: 11
url: "https://uscodex.org/cfr/40/63.985..63.995"
---

# §63.985. Nonflare control devices used to control emissions from storage vessels and low throughput transfer racks.

- (a) **Nonflare control device equipment and operating requirements.** The owner or operator shall operate and maintain the nonflare control device so that the monitored parameters defined as required in [paragraph (c)](#c) of this section remain within the ranges specified in the Notification of Compliance Status whenever emissions of regulated material are routed to the control device except during periods of start-up, shutdown, and malfunction as specified in the referencing subpart.
- (b) **Nonflare control device design evaluation or performance test requirements.** When using a control device other than a flare, the owner or operator shall comply with the requirements in paragraphs [(b)(1)(i)](#b-1-i) or [(ii)](#b-1-ii) of this section, except as provided in paragraphs [(b)(2)](#b-2) and [(3)](#b-3) of this section.
  - (1) **Design evaluation or performance test results.** The owner or operator shall prepare and submit with the Notification of Compliance Status, as specified in [§ 63.999(b)(2)](/cfr/40/63.999.md?p=b-2), either a design evaluation that includes the information specified in [paragraph (b)(1)(i)](#b-1-i) of this section, or the results of the performance test as described in [paragraph (b)(1)(ii)](#b-1-ii) of this section.
    - (i) **Design evaluation.** The design evaluation shall include documentation demonstrating that the control device being used achieves the required control efficiency during the reasonably expected maximum storage vessel filling or transfer loading rate. This documentation is to include a description of the gas stream that enters the control device, including flow and regulated material content, and the information specified in [paragraphs (b)(1)(i)(A) through (E)](#b-1-i-A..b-1-i-E) of this section, as applicable. For storage vessels, the description of the gas stream that enters the control device shall be provided for varying liquid level conditions. This documentation shall be submitted with the Notification of Compliance Status as specified in [§ 63.999(b)(2)](/cfr/40/63.999.md?p=b-2).
      - (A) The efficiency determination is to include consideration of all vapors, gases, and liquids, other than fuels, received by the control device.
      - (B) If an enclosed combustion device with a minimum residence time of 0.5 seconds and a minimum temperature of 760 °C is used to meet an emission reduction requirement specified in a referencing subpart for storage vessels and transfer racks, documentation that those conditions exist is sufficient to meet the requirements of [paragraph (b)(1)(i)](#b-1-i) of this section.
      - (C) Except as provided in [paragraph (b)(1)(i)(B)](#b-1-i-B) of this section for enclosed combustion devices, the design evaluation shall include the estimated autoignition temperature of the stream being combusted, the flow rate of the stream, the combustion temperature, and the residence time at the combustion temperature.
      - (D) For carbon adsorbers, the design evaluation shall include the estimated affinity of the regulated material vapors for carbon, the amount of carbon in each bed, the number of beds, the humidity, the temperature, the flow rate of the inlet stream and, if applicable, the desorption schedule, the regeneration stream pressure or temperature, and the flow rate of the regeneration stream. For vacuum desorption, pressure drop shall be included.
      - (E) For condensers, the design evaluation shall include the final temperature of the stream vapors, the type of condenser, and the design flow rate of the emission stream.
    - (ii) **Performance test.** A performance test, whether conducted to meet the requirements of this section, or to demonstrate compliance for a process vent or high throughput transfer rack as required by [§ 63.988(b)](/cfr/40/63.988.md?p=b), [§ 63.990(b)](/cfr/40/63.990.md?p=b), or [§ 63.995(b)](/cfr/40/63.995.md?p=b), is acceptable to demonstrate compliance with emission reduction requirements for storage vessels and transfer racks. The owner or operator is not required to prepare a design evaluation for the control device as described in [paragraph (b)(1)(i)](#b-1-i) of this section if a performance test will be performed that meets the criteria specified in paragraphs [(b)(1)(ii)(A)](#b-1-ii-A) and [(B)](#b-1-ii-B) of this section.
      - (A) The performance test will demonstrate that the control device achieves greater than or equal to the required control device performance level specified in a referencing subpart for storage vessels or transfer racks; and
      - (B) The performance test meets the applicable performance test requirements and the results are submitted as part of the Notification of Compliance Status as specified in [§ 63.999(b)(2)](/cfr/40/63.999.md?p=b-2).
  - (2) **Exceptions.** A design evaluation or performance test is not required if the owner or operator uses a combustion device meeting the criteria in paragraph [(b)(2)(i)](#b-2-i), [(ii)](#b-2-ii), [(iii)](#b-2-iii), or [(iv)](#b-2-iv) of this section.
    - (i) A boiler or process heater with a design heat input capacity of 44 megawatts (150 million British thermal units per hour) or greater.
    - (ii) A boiler or process heater burning hazardous waste for which the owner or operator meets the requirements specified in paragraph [(b)(2)(ii)(A)](#b-2-ii-A) or [(B)](#b-2-ii-B) of this section.
      - (A) The boiler or process heater has been issued a final permit under [40 CFR part 270](/cfr/40/part270.md) and complies with the requirements of [40 CFR part 266](/cfr/40/part266.md), [subpart H](/cfr/40/subpartH.md), or
      - (B) The boiler or process heater has certified compliance with the interim status requirements of [40 CFR part 266](/cfr/40/part266.md), subpart H.
    - (iii) A hazardous waste incinerator for which the owner or operator meets the requirements specified in paragraph [(b)(2)(iii)(A)](#b-2-iii-A) or [(B)](#b-2-iii-B) of this section.
      - (A) The incinerator has been issued a final permit under [40 CFR part 270](/cfr/40/part270.md) and complies with the requirements of [40 CFR part 264](/cfr/40/part264.md), [subpart O](/cfr/40/subpartO.md); or
      - (B) The incinerator has certified compliance with the interim status requirements of [40 CFR part 265](/cfr/40/part265.md), [subpart O](/cfr/40/subpartO.md); or
    - (iv) **A boiler or process heater into which the vent stream is introduced with the primary fuel.**
  - (3) **Prior design evaluations or performance tests.** If a design evaluation or performance test is required in the referencing subpart or was previously conducted and submitted for a storage vessel or low throughput transfer rack, then a performance test or design evaluation is not required.
- (c) **Nonflare control device monitoring requirements.**
  - (1) The owner or operator shall submit with the Notification of Compliance Status, a monitoring plan containing the information specified in § [63.999(b)(2)(i)](/cfr/40/63.999.md?p=b-2-i) and [(ii)](/cfr/40/63.999.md?p=b-2-ii) to identify the parameters that will be monitored to assure proper operation of the control device.
  - (2) The owner or operator shall monitor the parameters specified in the Notification of Compliance Status or in the operating permit application or amendment. Records shall be generated as specified in [§ 63.998(d)(2)(i)](/cfr/40/63.998.md?p=d-2-i).

# §63.986. Nonflare control devices used for equipment leaks only.

- (a) **Equipment and operating requirements.**
  - (1) Owners or operators using a nonflare control device to meet the applicable requirements of a referencing subpart for equipment leaks shall meet the requirements of this section.
  - (2) Control devices used to comply with the provisions of this subpart shall be operated at all times when emissions are vented to them.
- (b) **Performance test requirements.** A performance test is not required for any nonflare control device used only to control emissions from equipment leaks.
- (c) **Monitoring requirements.** Owners or operators of control devices that are used to comply only with the provisions of a referencing subpart for control of equipment leak emissions shall monitor these control devices to ensure that they are operated and maintained in conformance with their design. The owner or operator shall maintain the records as specified in [§ 63.998(d)(4)](/cfr/40/63.998.md?p=d-4).

# §63.987. Flare requirements.

- (a) **Flare equipment and operating requirements.** Flares subject to this subpart shall meet the performance requirements in [40 CFR 63.11(b)](/cfr/40/63.11.md?p=b) (General Provisions).
- (b) **Flare compliance assessment.**
  - (1) The owner or operator shall conduct an initial flare compliance assessment of any flare used to comply with the provisions of this subpart. Flare compliance assessment records shall be kept as specified in [§ 63.998(a)(1)](/cfr/40/63.998.md?p=a-1) and a flare compliance assessment report shall be submitted as specified in [§ 63.999(a)(2)](/cfr/40/63.999.md?p=a-2). An owner or operator is not required to conduct a performance test to determine percent emission reduction or outlet regulated material or total organic compound concentration when a flare is used.
  - (2) [Reserved]
  - (3) Flare compliance assessments shall meet the requirements specified in [paragraphs (b)(3)(i) through (iv)](#b-3-i..b-3-iv) of this section.
    - (i) Method 22 of appendix A of [part 60](/cfr/40/part60.md) shall be used to determine the compliance of flares with the visible emission provisions of this subpart. The observation period is 2 hours, except for transfer racks as provided in (b)(3)(i)(A) or (B) of this section.
      - (A) For transfer racks, if the loading cycle is less than 2 hours, then the observation period for that run shall be for the entire loading cycle.
      - (B) For transfer racks, if additional loading cycles are initiated within the 2-hour period, then visible emissions observations shall be conducted for the additional cycles.
    - (ii) The net heating value of the gas being combusted in a flare shall be calculated using Equation 1:
    - (iii) The actual exit velocity of a flare shall be determined by dividing the volumetric flow rate (in unit of standard temperature and pressure), as determined by Method 2, 2A, 2C, 2D, 2F, or 2G of [40 CFR part 60](/cfr/40/part60.md), appendix A, as appropriate, by the unobstructed (free) cross sectional area of the flare tip.
    - (iv) Flare flame or pilot monitors, as applicable, shall be operated during any flare compliance assessment.
- (c) **Flare monitoring requirements.** Where a flare is used, the following monitoring equipment is required: a device (including but not limited to a thermocouple, ultra-violet beam sensor, or infrared sensor) capable of continuously detecting that at least one pilot flame or the flare flame is present. Flare flame monitoring and compliance records shall be kept as specified in [§ 63.998(a)(1)](/cfr/40/63.998.md?p=a-1) and reported as specified in [§ 63.999(a)](/cfr/40/63.999.md?p=a).

# §63.988. Incinerators, boilers, and process heaters.

- (a) **Equipment and operating requirements.**
  - (1) Owners or operators using incinerators, boilers, or process heaters to meet a weight-percent emission reduction or parts per million by volume outlet concentration requirement specified in a referencing subpart shall meet the requirements of this section.
  - (2) Incinerators, boilers, or process heaters used to comply with the provisions of a referencing subpart and this subpart shall be operated at all times when emissions are vented to them.
  - (3) For boilers and process heaters, the vent stream shall be introduced into the flame zone of the boiler or process heater.
- (b) **Performance test requirements.**
  - (1) Except as specified in [§ 63.997(b)](/cfr/40/63.997.md?p=b), and [paragraph (b)(2)](#b-2) of this section, the owner or operator shall conduct an initial performance test of any incinerator, boiler, or process heater used to comply with the provisions of a referencing subpart and this subpart according to the procedures in [§ 63.997](/cfr/40/63.997.md). Performance test records shall be kept as specified in [§ 63.998(a)(2)](/cfr/40/63.998.md?p=a-2) and a performance test report shall be submitted as specified in [§ 63.999(a)(2)](/cfr/40/63.999.md?p=a-2). As provided in [§ 63.985(b)(1)](/cfr/40/63.985.md?p=b-1), a design evaluation may be used as an alternative to the performance test for storage vessels and low throughput transfer rack controls. As provided in [§ 63.986(b)](/cfr/40/63.986.md?p=b), no performance test is required for equipment leaks.
  - (2) An owner or operator is not required to conduct a performance test when any of the control devices specified in [paragraphs (b)(2)(i) through (iv)](#b-2-i..b-2-iv) of this section are used.
    - (i) A hazardous waste incinerator for which the owner or operator has been issued a final permit under [40 CFR part 270](/cfr/40/part270.md) and complies with the requirements of [40 CFR part 264](/cfr/40/part264.md), [subpart O](/cfr/40/subpartO.md), or has certified compliance with the interim status requirements of [40 CFR part 265](/cfr/40/part265.md), [subpart O](/cfr/40/subpartO.md);
    - (ii) A boiler or process heater with a design heat input capacity of 44 megawatts (150 million British thermal units per hour) or greater;
    - (iii) A boiler or process heater into which the vent stream is introduced with the primary fuel or is used as the primary fuel; or
    - (iv) A boiler or process heater burning hazardous waste for which the owner or operator meets the requirements specified in paragraph [(b)(2)(iv)(A)](#b-2-iv-A) or [(B)](#b-2-iv-B) of this section.
      - (A) The boiler or process heater has been issued a final permit under [40 CFR part 270](/cfr/40/part270.md) and complies with the requirements of [40 CFR part 266](/cfr/40/part266.md), [subpart H](/cfr/40/subpartH.md); or
      - (B) The boiler or process heater has certified compliance with the interim status requirements of [40 CFR part 266](/cfr/40/part266.md), subpart H.
- (c) **Incinerator, boiler, and process heater monitoring requirements.** Where an incinerator, boiler, or process heater is used, a temperature monitoring device capable of providing a continuous record that meets the provisions specified in paragraph [(c)(1)](#c-1), [(2)](#c-2), or [(3)](#c-3) of this section is required. Any boiler or process heater in which all vent streams are introduced with primary fuel or are used as the primary fuel is exempt from monitoring. Monitoring results shall be recorded as specified in § [63.998(b)](/cfr/40/63.998.md?p=b) and [(c)](/cfr/40/63.998.md?p=c), as applicable. General requirements for monitoring and continuous parameter monitoring systems are contained in the referencing subpart and [§ 3.996](/cfr/40/3.996.md).
  - (1) Where an incinerator other than a catalytic incinerator is used, a temperature monitoring device shall be installed in the fire box or in the ductwork immediately downstream of the fire box in a position before any substantial heat exchange occurs.
  - (2) Where a catalytic incinerator is used, temperature monitoring devices shall be installed in the gas stream immediately before and after the catalyst bed.
  - (3) Where a boiler or process heater of less than 44 megawatts (150 million British thermal units per hour) design heat input capacity is used and the regulated vent stream is not introduced as or with the primary fuel, a temperature monitoring device shall be installed in the fire box.

# §63.989. Reserved



# §63.990. Absorbers, condensers, and carbon adsorbers used as control devices.

- (a) **Equipment and operating requirements.**
  - (1) Owners or operators using absorbers, condensers, or carbon adsorbers to meet a weight-percent emission reduction or parts per million by volume outlet concentration requirement specified in a referencing subpart shall meet the requirements of this section.
  - (2) Absorbers, condensers, and carbon adsorbers used to comply with the provisions of a referencing subpart and this subpart shall be operated at all times when emissions are vented to them.
- (b) **Performance test requirements.** Except as specified in [§ 63.997(b)](/cfr/40/63.997.md?p=b), the owner or operator shall conduct an initial performance test of any absorber, condenser, or carbon adsorber used as a control device to comply with the provisions of the referencing subpart and this subpart according to the procedures in [§ 63.997](/cfr/40/63.997.md). Performance test records shall be kept as specified in [§ 63.998(a)(2)](/cfr/40/63.998.md?p=a-2) and a performance test report shall be submitted as specified in [§ 63.999(a)(2)](/cfr/40/63.999.md?p=a-2). As provided in [§ 63.985(b)(1)](/cfr/40/63.985.md?p=b-1), a design evaluation may be used as an alternative to the performance test for storage vessels and low throughput transfer rack controls. As provided in [§ 63.986(b)](/cfr/40/63.986.md?p=b), no performance test is required to demonstrate compliance for equipment leaks.
- (c) **Monitoring requirements.** Where an absorber, condenser, or carbon adsorber is used as a control device, either an organic monitoring device capable of providing a continuous record, or the monitoring devices specified in [paragraphs (c)(1) through (3)](#c-1..c-3), as applicable, shall be used. Monitoring results shall be recorded as specified in § [63.998(b)](/cfr/40/63.998.md?p=b) and [(c)](/cfr/40/63.998.md?p=c), as applicable. General requirements for monitoring and continuous parameter monitoring systems are contained in a referencing subpart and [§ 63.996](/cfr/40/63.996.md).
  - (1) Where an absorber is used, a scrubbing liquid temperature monitoring device and a specific gravity monitoring device, each capable of providing a continuous record, shall be used. If the difference between the specific gravity of the saturated scrubbing fluid and specific gravity of the fresh scrubbing fluid is less than 0.02 specific gravity units, an organic monitoring device capable of providing a continuous record shall be used.
  - (2) Where a condenser is used, a condenser exit (product side) temperature monitoring device capable of providing a continuous record shall be used.
  - (3) Where a carbon adsorber is used, an integrating regeneration stream flow monitoring device having an accuracy of ±10 percent or better, capable of recording the total regeneration stream mass or volumetric flow for each regeneration cycle; and a carbon bed temperature monitoring device, capable of recording the carbon bed temperature after each regeneration and within 15 minutes of completing any cooling cycle, shall be used.

# §63.991. Reserved



# §63.992. Implementation and enforcement.

- (a) This subpart can be implemented and enforced by the U.S. Environmental Protection Agency (EPA), or a delegated authority such as the applicable State, local, or tribal agency. If the EPA Administrator has delegated authority to a State, local, or tribal agency, then that agency has the authority to implement and enforce this subpart. Contact the applicable EPA Regional Office to find out if this subpart is delegated to a State, local, or tribal agency.
- (b) In delegating implementation and enforcement authority of this subpart to a State, local, or tribal agency under section [40 CFR part 63](/cfr/40/part63.md), [subpart E](/cfr/40/subpartE.md), the authorities contained in [paragraphs (b)(1) through (5)](#b-1..b-5) of this section are retained by the EPA Administrator and are not transferred to the State, local, or tribal agency.
  - (1) Approval of alternatives to the nonopacity emissions standards in §§ [63.983(a)](/cfr/40/63.983.md?p=a) and [(d)](/cfr/40/63.983.md?p=d), [63.984](/cfr/40/63.984.md), [63.985(a)](/cfr/40/63.985.md?p=a), [63.986(a)](/cfr/40/63.986.md?p=a), [63.987(a)](/cfr/40/63.987.md?p=a), [63.988(a)](/cfr/40/63.988.md?p=a), [63.990(a)](/cfr/40/63.990.md?p=a), [63.993(a)](/cfr/40/63.993.md?p=a), [63.994(a)](/cfr/40/63.994.md?p=a), and [63.995(a)](/cfr/40/63.995.md?p=a) under [§ 63.6(g)](/cfr/40/63.6.md?p=g). Where these standards reference another subpart, the cited provisions will be delegated according to the delegation provisions of the referenced subpart.
  - (2) [Reserved]
  - (3) Approval of major changes to test methods under § [63.7(e)(2)(ii)](/cfr/40/63.7.md?p=e-2-ii) and [(f)](/cfr/40/63.7.md?p=e-2-f) and as defined in [§ 63.90](/cfr/40/63.90.md).
  - (4) Approval of major changes to monitoring under [§ 63.8(f)](/cfr/40/63.8.md?p=f) and as defined in [§ 63.90](/cfr/40/63.90.md).
  - (5) Approval of major changes to recordkeeping and reporting under [§ 63.10(f)](/cfr/40/63.10.md?p=f) and as defined in [§ 63.90](/cfr/40/63.90.md).

# §63.993. Absorbers, condensers, carbon adsorbers and other recovery devices used as final recovery devices.

- (a) **Final recovery device equipment and operating requirements.**
  - (1) Owners or operators using a final recovery device to maintain a TRE above a level specified in a referencing subpart shall meet the requirements of this section.
  - (2) Recovery devices used to comply with the provisions of a referencing subpart and this subpart shall be operated at all times when emissions are vented to them.
- (b) **Recovery device performance test requirements.** There are no performance test requirements for recovery devices. TRE index value determination information shall be recorded as specified in [§ 63.998(a)(3)](/cfr/40/63.998.md?p=a-3).
- (c) **Recovery device monitoring requirements.**
  - (1) Where an absorber is the final recovery device in the recovery system and the TRE index value is between the level specified in a referencing subpart and 4.0, either an organic monitoring device capable of providing a continuous record or a scrubbing liquid temperature monitoring device and a specific gravity monitoring device, each capable of providing a continuous record, shall be used. If the difference between the specific gravity of the saturated scrubbing fluid and specific gravity of the fresh scrubbing fluid is less than 0.02 specific gravity units, an organic monitoring device capable of providing a continuous record shall be used. Monitoring results shall be recorded as specified in § [63.998(b)](/cfr/40/63.998.md?p=b) and [(c)](/cfr/40/63.998.md?p=c), as applicable. General requirements for monitoring and continuous parameter monitoring systems are contained in [§ 63.996](/cfr/40/63.996.md).
  - (2) Where a condenser is the final recovery device in the recovery system and the TRE index value is between the level specified in a referencing subpart and 4.0, an organic monitoring device capable of providing a continuous record or a condenser exit (product side) temperature monitoring device capable of providing a continuous record shall be used. Monitoring results shall be recorded as specified in § [63.998(b)](/cfr/40/63.998.md?p=b) and [(c)](/cfr/40/63.998.md?p=c), as applicable. General requirements for monitoring and continuous parameter monitoring systems are contained in a referencing subpart and [§ 63.996](/cfr/40/63.996.md).
  - (3) Where a carbon adsorber is the final recovery device in the recovery system and the TRE index value is between the level specified in a referencing subpart and 4.0, an organic monitoring device capable of providing a continuous record or an integrating regeneration stream flow monitoring device having an accuracy of ±10 percent or better, capable of recording the total regeneration stream mass or volumetric flow for each regeneration cycle; and a carbon-bed temperature monitoring device, capable of recording the carbon-bed temperature after each regeneration and within 15 minutes of completing any cooling cycle shall be used. Monitoring results shall be recorded as specified in § [63.998(b)](/cfr/40/63.998.md?p=b) and [(c)](/cfr/40/63.998.md?p=c), as applicable. General requirements for monitoring and continuous parameter monitoring systems are contained in a referencing subpart and [§ 63.996](/cfr/40/63.996.md).
  - (4) If an owner or operator uses a recovery device other than those listed in this subpart, the owner or operator shall submit a description of planned monitoring, reporting and recordkeeping procedures as specified in a referencing subpart. The Administrator will approve, deny, or modify based on the reasonableness of the proposed monitoring, reporting and recordkeeping requirements as part of the review of the submission or permit application or by other appropriate means.

# §63.994. Halogen scrubbers and other halogen reduction devices.

- (a) **Halogen scrubber and other halogen reduction device equipment and operating requirements.**
  - (1) An owner or operator of a halogen scrubber or other halogen reduction device subject to this subpart shall reduce the overall emissions of hydrogen halides and halogens by the control device performance level specified in a referencing subpart.
  - (2) Halogen scrubbers and other halogen reduction devices used to comply with the provisions of a referencing subpart and this subpart shall be operated at all times when emissions are vented to them.
- (b) **Halogen scrubber and other halogen reduction device performance test requirements.**
  - (1) An owner or operator of a combustion device followed by a halogen scrubber or other halogen reduction device to control halogenated vent streams in accordance with a referencing subpart and this subpart shall conduct an initial performance test to determine compliance with the control efficiency or emission limits for hydrogen halides and halogens according to the procedures in [§ 63.997](/cfr/40/63.997.md). Performance test records shall be kept as specified in [§ 63.998(a)(2)](/cfr/40/63.998.md?p=a-2) and a performance test report shall be submitted as specified in [§ 63.999(a)(2)](/cfr/40/63.999.md?p=a-2).
  - (2) An owner or operator of a halogen scrubber or other halogen reduction technique used to reduce the vent stream halogen atom mass emission rate prior to a combustion device to comply with a performance level specified in a referencing subpart shall determine the halogen atom mass emission rate prior to the combustion device according to the procedures specified in the referencing subpart. Records of the halogen concentration in the vent stream shall be generated as specified in [§ 63.998(a)(4)](/cfr/40/63.998.md?p=a-4).
- (c) **Halogen scrubber and other halogen reduction device monitoring requirements.**
  - (1) Where a halogen scrubber is used, the monitoring equipment specified in paragraphs [(c)(1)(i)](#c-1-i) and [(ii)](#c-1-ii) of this section is required for the scrubber. Monitoring results shall be recorded as specified in § [63.998(b)](/cfr/40/63.998.md?p=b) and [(c)](/cfr/40/63.998.md?p=c), as applicable. General requirements for monitoring and continuous parameter monitoring systems are contained in a referencing subpart and [§ 63.996](/cfr/40/63.996.md).
    - (i) A pH monitoring device capable of providing a continuous record shall be installed to monitor the pH of the scrubber effluent.
    - (ii) A flow meter capable of providing a continuous record shall be located at the scrubber influent for liquid flow. Gas stream flow shall be determined using one of the procedures specified in [paragraphs (c)(1)(ii)(A) through (D)](#c-1-ii-A..c-1-ii-D) of this section.
      - (A) The owner or operator may determine gas stream flow using the design blower capacity, with appropriate adjustments for pressure drop.
      - (B) The owner or operator may measure the gas stream flow at the scrubber inlet.
      - (C) If the scrubber is subject to regulations in 40 CFR parts [264](/cfr/40/part264.md) through [266](/cfr/40/part266.md) that have required a determination of the liquid to gas (L/G) ratio prior to the applicable compliance date for the process unit of which it is part as specified in a referencing subpart, the owner or operator may determine gas stream flow by the method that had been utilized to comply with those regulations. A determination that was conducted prior to that compliance date may be utilized to comply with this subpart if it is still representative.
      - (D) The owner or operator may prepare and implement a gas stream flow determination plan that documents an appropriate method that will be used to determine the gas stream flow. The plan shall require determination of gas stream flow by a method that will at least provide a value for either a representative or the highest gas stream flow anticipated in the scrubber during representative operating conditions other than start-ups, shutdowns, or malfunctions. The plan shall include a description of the methodology to be followed and an explanation of how the selected methodology will reliably determine the gas stream flow, and a description of the records that will be maintained to document the determination of gas stream flow. The owner or operator shall maintain the plan as specified in a referencing subpart.
  - (2) Where a halogen reduction device other than a scrubber is used, the owner or operator shall follow the procedures specified in a referencing subpart in order to establish monitoring parameters.

# §63.995. Other control devices.

- (a) **Other control device equipment and operating requirements.**
  - (1) Owners or operators using a control device other than one listed in [§§ 63.985 through 63.990](/cfr/40/63.985..63.990.md) to meet a weight-percent emission reduction or parts per million by volume outlet concentration requirement specified in a referencing subpart shall meet the requirements of this section.
  - (2) Other control devices used to comply with the provisions of a referencing subpart and this subpart shall be operated at all times when emissions are vented to them.
- (b) **Other control device performance test requirements.** An owner or operator using a control device other than those specified in [§§ 63.987 through 63.990](/cfr/40/63.987..63.990.md) to comply with a performance level specified in a referencing subpart, shall perform an initial performance test according to the procedures in [§ 63.997](/cfr/40/63.997.md). Performance test records shall be kept as specified in [§ 63.998(a)(2)](/cfr/40/63.998.md?p=a-2) and a performance test report shall be submitted as specified in [§ 63.999(a)(2)](/cfr/40/63.999.md?p=a-2).
- (c) **Other control device monitoring requirements.** If an owner or operator uses a control device other than those listed in this subpart, the owner or operator shall submit a description of planned monitoring, recordkeeping and reporting procedures as specified in a referencing subpart. The Administrator will approve, deny, or modify based on the reasonableness of the proposed monitoring, reporting and recordkeeping requirements as part of the review of the submission or permit application or by other appropriate means.