A CEMS percent monitor availability (PMA) is a key component in determining how well a CEMS program is performing. If the PMA is below 95%, you may face consequences like additional reporting requirements for Part 60 facilities and more punitive data substitution values for Part 75 facilities.
Below, we detail 6 strategies you can implement to help you increase the CEMS PMA and reduce potential reporting and data replacement consequences.
1. Utilize Regulatory Valid Hour Provisions to Minimize CEMS Downtime
Both Part 60 and 75 have specific requirements defining what constitutes a valid hour of emissions monitoring data. During an hour where maintenance or quality assurance activities occur, you’ll need two data points separated by a minimum of fifteen minutes to constitute a valid emissions monitoring hour. This stipulation provides an opportunity to perform maintenance or quality assurance activities without losing a monitoring hour as invalid or downtime.
2. Schedule Daily Calibration Drift Checks
To increase the opportunity to retain a valid hour of emissions data, daily calibration drift checks should be scheduled at the very beginning of the hour. For example, if a daily calibration drift check begins at 6:02 A.M., takes twelve minutes to be completed, and subsequently fails, there may be time to go to the CEMS and perform a manual calibration adjustment followed by another calibration drift check. If this can be completed with a minimum of sixteen minutes left in the hour, the hour is considered valid and no downtime is incurred.
3. Stagger Calibration Drift Checks for Facilities With More Than One CEMS
If a facility has more than one CEMS, the daily calibration drift checks should be staggered. For example: a facility with three CEMS could schedule calibration drift check times to occur at 6:02 A.M., 7:02 A.M. and 8:02 A.M. By staggering the calibration drift check times by one hour, a window has been created to respond to a failed calibration drift check at one or more of the CEMS. Of course, this strategy is only effective if there is a prompt response to a failed calibration drift check.
4. Schedule Blowbacks
Many facilities utilize blowbacks in their CEMS to keep the sample path of extractive CEMS clear. Blowbacks should be scheduled at an hour after at least one minute of data has been captured. This is because Part 60 and 75 require at least one data point in partial operating hours for that hour to be considered valid. If a unit shuts down and no data has been captured in that hour due to a blowback occurring, that hour is considered invalid resulting in downtime. This recommendation is especially helpful for facilities that frequently start up and shut down.
5. Perform Preventative Maintenance and Quality Assurance Checks
When performing scheduled preventative maintenance tasks and quality assurance checks — such as cylinder gas audits (CGA) or linearity tests — facilities can minimize CEMS downtime by beginning these tasks at specific minutes of the hour. A window of just under an hour and a half can be created by beginning the activity at the sixteenth minute of the hour and completing the activity by the forty-fourth minute of the next hour. Both hours have two data points separated by a minimum of fifteen minutes and are therefore considered valid emissions monitoring hours. The window that has been generated by beginning the task at the sixteenth minute should be large enough to complete most common preventative maintenance tasks and quality assurance tests (depending on response time and the number of analyzers).
6. Develop A Robust Preventative Maintenance Program
The biggest key to minimizing CEMS downtime is an effective and efficient CEMS preventative maintenance program. Preventative maintenance activities should be scheduled on a weekly, monthly, quarterly, semi-annual, and annual basis. The program should be flexible and adjusted when opportunity for improvement is found. That improvement can mean performing tasks more frequently or less frequently depending on the results of daily calibration drift checks, quality assurance checks, and most importantly input from technicians who are performing the work. The goal of the preventative maintenance program should be to limit equipment malfunctions and to maximize CEMS data accuracy, reliability, and availability.
Utilizing the capabilities of CEMLink6 to monitor analyzer diagnostics is incredibly useful for identifying possible performance issues in the analyzers before they result in analyzer downtime. Additionally, maintaining the necessary spare parts to perform preventative maintenance and replace malfunctioning components on-site is a must for any successful preventative maintenance program. Repairs can’t be made if the required parts are not available to the CEMS technicians.
