This page provides an overview of the centrifugal compressor source type reporting requirements for Subpart W. 

Please see Reporting Form Instructions on downloading the blank reporting form and uploading the completed reporting form.
You may also refer to Optional Calculation Spreadsheet Instructions to download the Subpart W calculation spreadsheet.

The centrifugal compressor source type is applicable to Onshore petroleum and natural gas production [98.230(a)(2)], Onshore natural gas processing [98.230(a)(3)], Onshore natural gas transmission compression [98.230(a)(4)], Underground natural gas storage [98.230(a)(5)], Liquefied natural gas (LNG) storage [98.230(a)(6)], LNG import and export equipment [98.230(a)(7)], and Onshore petroleum and natural gas gathering and boosting [98.230(a)(9)].

Tables O.1, O.2.i, and O.2.ii must be completed by all facilities with centrifugal compressors subject to reporting under 98.232 (except Onshore petroleum and natural gas production facilities and Onshore petroleum and natural gas gathering and boosting facilities).

Tables O.3.i and O.3.ii must be completed by facilities using “as found” measurement sample data, i.e., 98.233(o)(2 or 4) and (o)(6) (except Onshore petroleum and natural gas production facilities and Onshore petroleum and natural gas gathering and boosting facilities).

Table O.4 must be completed by facilities using “continuous” measurement data, i.e., 98.233(o)(3 or 5) (except Onshore petroleum and natural gas production facilities and Onshore petroleum and natural gas gathering and boosting facilities).

Table O.5 must be completed by Onshore petroleum and natural gas production facilities and Onshore petroleum and natural gas gathering and boosting facilities.

Table O.6 is required for the identification of missing data procedures used for centrifugal compressor emission calculations.

Indicate if the facility has the source type via the radio buttons.

If the source type is present you must report required elements. 

                    

If the facility has the source type, then indicate whether missing data procedures were used.

                     

Reporting Requirements

Table O.1 Compressor-Specific Activity Data must be completed for each centrifugal compressor (except for those in the Onshore petroleum and natural gas production and Onshore petroleum and natural gas gathering and boosting segments). Required data elements include:

• Compressor ID or Unique Name (98.236(o)(1)(i))
• Total time in operating-mode (98.236(o)(1)(ii))
• Total time in not-operating-depressurized-mode (98.236(o)(1)(iii))
• Was the compressor measured in operating-mode? (98.236(o)(1)(iv))
• Was the compressor measured in not-operating-depressurized-mode? (98.236(o)(1)(v))
• Did the compressor have blind flanges installed? (98.236(o)(1)(x))
  • If so, provide the dates for blind flange installation (98.236(o)(1)(x))
• Seal type (wet or dry) (98.236(o)(1)(xi))
  • If seals were wet, report the number of wet seals (98.236(o)(1)(xii))
• Power output of compressor driver (98.236(o)(1)(xiii))
• Did the compressor have scheduled depressurized shutdown during reporting year? (98.236(o)(1)(xiv))

Table O.1 Compressor-Specific Activity Data

Enlarged View of Table O.1 Compressor-Specific Activity Data

Enlarged View of Table O.1 Compressor-Specific Activity Data (continued)

Table O.2.i Compressor Source-Specific Data must be completed for each compressor source at each centrifugal compressor (except for those in the Onshore petroleum and natural gas production and Onshore petroleum and natural gas gathering and boosting segments). Required data elements include:

• Compressor ID or Unique Name (98.236(o)(2)(i)(A)) (this data element is autofilled by the Smart Form from Table O.1)
• Centrifugal compressor source (98.236(o)(2)(i)(B)) (this data element is autofilled by the Smart Form to identify a blowdown valve and an isolation valve, for each centrifugal compressor, and to identify a wet seal for centrifugal compressors with wet seals)
• Unique Name or ID for leak or vent (98.236(o)(2)(i)(C))
• Unit Name or ID for leak or vent if the release point changed or controls were added during the reporting year (98.236(o)(2)(i)(C)) (leave this data element blank if no changes were made to release point or controls)

Table O.2.i Compressor Source-Specific Data

 

Table O.2.ii Compressor Leak or Vent Data must be completed for each individual leak or vent and each manifolded vent for centrifugal compressors (except for those in the Onshore petroleum and natural gas production and Onshore petroleum and natural gas gathering and boosting segments). Required data elements include:

• Unique Name or ID for leak or vent (98.236(o)(2)(i)(C)) (this data element is autofilled by the Smart Form from Table O.2.i)

• Was the leak or vent for a single compressor source or a manifolded group? (98.236(o)(2)(ii)(A), 98.236(o)(1)(vi))

• Where were leak or vent emissions released? (98.236(o)(2)(ii)(A), 98.236(o)(1)(vii) through (ix))
  • If the emissions were released to the atmosphere, complete the following data elements:
    • Was an "as found" measurement conducted on the leak or vent? (98.236(o)(2)(ii)(B))
    • Were continuous measurements conducted on the leak or vent? (98.236(o)(2)(ii)(C))
    • CO₂ emissions vented to atmosphere (mt CO₂) (98.236(o)(2)(ii)(D)(1))
    • CH₄ emissions vented to atmosphere (mt CH₄) (98.236(o)(2)(ii)(D)(2))
  • If the emissions were released to control devices (i.e., flare, combustion (fuel or thermal oxidizer), vapor recovery), complete the following data element:
    • Percentage of time the device was operational when compressor source emissions were routed to device (98.236(o)(2)(ii)(E))

Table O.2.ii Compressor Leak or Vent Data

Enlarged View of Table O.2.ii Compressor Leak or Vent Data

Enlarged View of Table O.2.ii Compressor Leak or Vent Data (continued)

Table O.3.i Leak or Vent “As Found” Measurement Sample Data must be completed for each centrifugal compressor leak or vent  with “as found” measurement sample data determined using 98.233(o)(2) or (4) (except for those in the Onshore petroleum and natural gas production and Onshore petroleum and natural gas gathering and boosting segments). Required data elements are described below.

If multiple measurements events for a specific leak/vent occurred, report these events on separate rows of Table O.3.i.

• Unique Name or ID for leak or vent (98.236(o)(3)(i)(A)) (you populate this data element using a pulldown list generated by the Smart Form from Table O.2.ii leaks or vents with "as found" measurements)
• Measurement date (98.236(o)(3)(i)(B))
• Measurement method (98.236(o)(3)(i)(C))
  • If you detected no emissions when using a screening method according to 98.233(o)(2)(i)(D) or (o)(4)(ii)(E), report the screening method that you used. If emissions were detected when using a screening method, report only the method subsequently used to measure the volumetric emission [98.236(o)(3)(i)(C)].
• Measured flow rate (standard cubic feet/hour) (98.236(o)(3)(i)(D))
• Is the measurement location prior to or after commingling with non-compressor emission sources? (98.236(o)(3)(i)(F))
• Mode for each compressor during leak or vent measurement (98.236(o)(3)(i)(E)). List the compressor ID or IDs associated with the appropriate mode (operating or not-operating) for the measured leak or vent. For a manifolded leak or vent with two or more connected compressors in the same mode at the time of the measurement, use semicolons to separate the compressor IDs.

Table O.3.i Leak or Vent “As Found” Measurement Sample Data

 

Table O.3.ii Reporter Emission Factors for “As Found” Measurement Sample Data must be completed for each centrifugal compressor mode-source combination where a reporter emission factor was used to calculate emissions. The reporter emission factor is calculated using Equation W-23 with “as found” measurement sample data from individual (non-manifolded) leaks or vents from compressors in the applicable mode in the current year and the preceding two years, as specified in 98.233(o)(6)(iii) and (iv) (except for those in the Onshore petroleum and natural gas production and Onshore petroleum and natural gas gathering and boosting segments). Required data elements include:

• Compressor Mode (98.236(o)(3)(ii)(A)) - this data element is autofilled by the Smart Form
• Compressor Source (98.236(o)(3)(ii)(A)) - this data element is autofilled by the Smart Form
• Compressor mode-source combination reporter emission factor (98.236(o)(3)(ii)(B))
• Total number of compressors measured in the compressor mode-source combination in current reporting year and preceding two reporting years (98.236(o)(3)(ii)(C))
• Is the reporter emission factor facility-specific or based on all of the reporter's applicable facilities? (98.236(o)(3)(ii)(D)) 

Table O.3.ii Reporter Emission Factors for “As Found” Measurement Sample Data

Table O.4 Leak or Vent Continuous Measurement must be completed for each centrifugal compressor leak or vent with “continuous” measurement data determined using 98.233(o)(3) or (5) (except for those in the Onshore petroleum and natural gas production and Onshore petroleum and natural gas gathering and boosting segments). Required data elements include:

• Unique Name or ID for leak or vent (98.236(o)(4)(i)) (this data element is autofilled by the Smart Form from Table O.2.ii leaks or vents with "continuous" measurements)
• Measured volume of flow during the reporting year (million standard cubic feet) (98.236(o)(4)(ii))
• Did the measured volume of flow during the reporting year include compressor blowdowns? (98.236(o)(4)(iii))
• Is the measurement location prior to or after commingling with non-compressor emission sources? (98.236(o)(4)(iv))

Table O.4 Leak or Vent Continuous Measurement

 

Table O.5 Onshore Petroleum and Natural Gas Production and Onshore Petroleum and Natural Gas Gathering and Boosting Centrifugal Compressors must be completed for facilities in the Onshore petroleum and natural gas production and Onshore petroleum and natural gas gathering and boosting segments. Required data elements include:

• Number of centrifugal compressors with wet seal oil degassing vents (98.236(o)(5)(i))

• Total annual centrifugal compressor CO₂ emissions (mt CO₂) (98.236(o)(5)(ii))

• Total annual centrifugal compressor CH₄ emissions (mt CH₄) (98.236(o)(5)(iii))

Table O.5 Onshore Petroleum and Natural Gas Production and Onshore Petroleum and Natural Gas Gathering and Boosting Centrifugal Compressors

Table O.6 Missing data procedures used for Centrifugal Compressor emission calculations is required if your facility relied on missing data procedures to develop data elements used in calculating emissions for centrifugal compressors. Complete only the applicable sections (note that the ID columns are tailored to the different Tables):

• Compressor ID, Leak or vent ID, Compressor mode, Compressor source (as appropriate for the target Table and Parameter)
• Parameters 
• Measurement Frequency

• Number of quarters missing data procedures were used [98.236(bb)(1)] (required only if the measurement frequency was quarterly)

• Total number of hours in the year missing data procedure was used [98.3(c)(8)], [98.236(bb)(2)] (required unless the measurement frequency was quarterly, annually, biannually, or N/A)

• Procedures used for missing data [98.235(h)]

Table O.6 Missing data procedures used for Centrifugal Compressor emission calculations

Total Emissions

The total emissions roll-up at the top of the sheet reflects the sum of each gas emission reported for the source type. These summations are calculated automatically by the Smart Form and tabulated on the Introduction tab.