Series, Five Ways a CEMS DAS Improves Monitoring and Reporting

This is the fourth in a series of five articles describing key ways a full-featured CEMS Data Acquisition System (DAS) can improve monitoring, reporting and the ability to withstand an audit or compliance evaluation.

Knowing an event happened after it occurred doesn’t help you to avoid it. You can use a continuous monitoring system DAS to recognize current performance history and use it to predict the likelihood of hazardous or legally challenging situations occurring. A predictive average can be used to warn when operating conditions are leading to an exceedance or other undesirable situations.

Monitoring with Averages

Let's go back to our one-hour average example used in an earlier post in this series. The average is built from four, fifteen minute, averages that are themselves built from one minute averages. As each one-minute period of data is collected and validated it can be averaged and then averaged with the other minutes in that period, without waiting for the full fifteen minutes to be collected. A projection based on the collected averages can predict a limit exceedance, or specific thresholds can be set for alarming.

Multi-level Alarming

Multiple alarms can be configured for a single parameter or signal. So, alarms can be set to warn when the values reach critical thresholds moving toward an upper limit for an exceedance on something like SO2 or a lower limit like FCCU exhaust gas temperature or oxygen. When the defined thresholds are reached, alarms about the event can be shared with other people and systems through various means like Modbus, displays, email, reports or closing a hardware contact.

Why should you care?

Predictive averages and alarming can be used to help you avoid hazardous or legally challenging situations like exceedances and deviations. In most cases predictions using raw values instead of quality assured averages won't give you the values for which you will be held legally accountable.

Periods averaged and alarmed can be short, like six-minute opacity averages or long periods like monthly or quarterly averages building the year. These tools can be employed in various ways to stay out of trouble, not only from an environmental or permit perspective, but also to maximize operating efficiency.


Predictive calculations based on building averages can let you know when you are trending toward problems before they happen. Not all DAS offer these capabilities. If you are planning to implement a DAS at your facility, this should be one of the questions that you ask the vendor.

Whether you just want to learn more about what a DAS can do for you, or would like to arrange for a complimentary data system review, we'd enjoy hearing from you. Contact us at 512-250-7902, sales@envirosys.com or use our online form.

...    Published: 2/28/2017 9:06:08 AM

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