E.Quarterly Neutral Density Filter Audits (NDFA) for COMS under Part 60

Regulatory references:
Appendix F to Part 60 – Procedure 3, Section 10.2 (What are the quarterly auditing requirements for my COMS?), and Performance Specification 1 (PS-1), of Appendix B.

Besides the audit itself, the operator of a COMS needs to: [See Section 10.2 (1), (3), and (4)]
a) Check the optical alignment of the COMS in accordance with the manufacturer’s recommendation. There is a place to check a box and record the date on the Opacity Test record that this check has been performed. [Section 10.4 (3) (i).] And
b) For units with automatic zero compensation, you must determine the zero compensation for the COMS. The compensation applied to the effluent by the monitor system must be recorded. The compensation check is failed if the zero compensation exceeds 4 percent opacity. There is a place to check a box and record the date on the Opacity Test record that this check has been performed. [Section 10.4 (3) (ii).]

Pre-Audit Activities:
This audit involves checking the response to the optical systems within your opacity system to calibrated filters/lenses/attenuators inserted into a test jig or holder. The neutral density filters require special handing so that you do not wipe off the coating material on the lens, making them useless. These filters or lenses must be returned to the factory at the frequency specified in PS-1, section 10.2 (2), for the purpose of having them checked and recertified.
The quarterly audit, conducted for the purposes of validating the opacity data recorded by the COMS must be performed using audit lenses which have been certified. The certificate of certification also must be kept and retained on site for a period of no less than five (5) years.

1. Review your in-house RATA procedure making sure you understand it and can answer questions directed at you by anyone.

2. The quarterly audit is conducted using lenses of three different reference values, typically a low, mid- and high readings. Make sure the certification is still valid for these lenses. If not, send them to the factory immediately to get them certified. The factory usually can turn them around in 3-5 days. It’s a good idea to have two sets of lenses and rotate them. Or, one can be the backup to the first set in case something goes wrong.

3. This audit is very similar to a linearity check for gaseous monitors. Actually, the linearity check is based on this opacity audit. It uses reference materials of three different values and the response of the system to each calibration lens is measured three separate times, for a grand total of nine (9) readings.

4. Each lens is placed into the light path at least three separate times. The audit procedure is using minute averages so in order to obtain at least one full and steady minute average, you will need to keep track of when the lens is dropped into place and to leave it in place for three minutes. The audit data will use that steady minute average so leaving it in place for longer than just three minutes is not a bad idea.

5. Your in-house procedure probably has a place on it where the times (use data logger time) when the lenses are dropped into place and removed can be written down. 

6. Since this audit is done outside and up at the COMS, take at least two pens or pencils to write down times and information.

7. Try to schedule the audit when the weather conditions are favorable.

8. Pick a date in the future to schedule the opacity audit and schedule it for that date with the various parties involved (your boss, the operating staff, etc.).

9. Make sure all preventative maintenance activities have been completed successfully on the COMS system.

10. Performing this audit will cause downtime to be recorded, but there is no way around that. It usually takes about an hour to complete once you start.

Day of Audit Activities:

11. Review your in-house audit procedure making sure you understand it and can answer questions from those whom you will work or interface with.

12. Be sure you follow and utilize all appropriate safety precautions while you are up on the stack or out on the ductwork with the opacity system.

13. Be sure to review the testing schedule for that day with the control room operator and the supervisory operating staff. Give them an estimate for how long it will probably take to complete today’s testing. Make sure they understand that as you perform this audit, their opacity readings are going to be jumping around.

14. As you perform the audit, and drop the lenses into the test jig, let it sit in place for at least three (3) minutes so the data controller can calculate at least one steady minute average. Leaving it in place for longer than three minutes is fine, but anything longer than say five (5) minutes isn’t getting you anything extra.

15. Be sure to let the control room operator know when you are done.

Post Audit Activities:

16. I would recommend printing out the minute opacity averages from SV for the period of time that the audit was being performed. You’ll be able to more easily identify the steady minute averages you want to use to build your audit record.

17. Use the “Opacity Tests” report builder to generate or add a new “Calibration Error Test”. From the Main Menu of SV, select “Tools → QA and Certification → Opacity Tests”. Using the information you recorded while performing the audit, and the associated information from your in-house procedure, you should be able to fill in the information about the opacity and stack installation, as well as the times and system responses to the audit itself. Use the “Calculate” option to have SV calculate the results.

18. Remember, because the “Monitor Path Length” and the “Outlet Path Length” are probably not the same, SV will calculate an adjusted optical density.

19. At the end, make sure the “Test Result” fields say “Passed”, the record has been saved and the “Locked?” box is checked.

Download the pdf document here.

Jon Konings, Senior Regulatory and Reporting Engineer, ESC    Published: 9/13/2016 5:10:39 PM

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