Executive Summary:
This document outlines the revised calibration protocol from the Central Pollution Control Board (CPCB) effective July 2025 for Online Continuous Emission Monitoring Systems (OCEMS). It details the calibration requirements and performance testing for particulate matter (PM) and gaseous emissions, as well as temperature, pH, BOD, COD, TOC and TSS in effluents. The protocol specifies the frequency and methods for calibration checks and annual performance testing.
Key Points / Main Content:
Particulate Matter (PM) CEMS Calibration:
* Initial calibration is required at the time of installation by the instrument supplier.
* Quarterly calibration checks against isokinetic sampling methods (six samples under running load) are required in-house.
* Annual performance testing must be conducted by an EPA Recognized/NABL Accredited lab.
* Recalibration against isokinetic sampling is needed if comparison values deviate by more than 10% for two consecutive monitoring periods.
* Incidental calibration is required after major repairs, lamp changes, or alignment readjustments.
Gaseous Emissions Monitoring Calibration:
* Initial calibration is required at the time of installation by the instrument supplier.
* Fortnightly two-point zero and span calibration checks are required in-house.
* Three-monthly multipoint calibration at different concentration levels is required in-house.
* Annual performance testing must be conducted by an EPA Recognized/NABL Accredited lab.
* Certified portable gas analyzers with proper sampling systems may be used for calibration.
* Incidental calibration is required after major repairs, lamp changes, or alignment readjustments.
* Calibration includes the entire CEMS system.
Temperature and pH Calibration:
* Initial calibration is required at the time of installation by the instrument supplier.
* Fortnightly calibration checks against a calibrated thermometer are required in-house for temperature.
* Annual performance testing must be conducted by an EPA Recognized/NABL Accredited lab.
* Recalibration is needed if temperature values deviate by more than 1 degree Celsius for two consecutive monitoring periods.
* Recalibration is needed if pH values deviate by more than 0.2 from certified reference material for two consecutive monitoring periods.
* Incidental calibration is required after major repairs.
BOD, COD, TOC, and TSS Calibration:
* Initial calibration is required at the time of installation by the instrument supplier.
* Monthly calibration checks are required in-house.
* Annual performance testing must be conducted by an EPA Recognized/NABL Accredited lab.
* Recalibration is needed if comparison values deviate by more than 20% from lab results for two consecutive monitoring periods.
* Incidental calibration is required after major repairs.
Impact Analysis:
Instrument Suppliers:
* Impact: Must perform initial calibrations for all OCEMS parameters (PM, gaseous emissions, temperature, pH, BOD, COD, TOC, TSS) at the time of installation.
* Action Required: Ensure instruments are calibrated according to the specified methods before installation.
Facility Operators/Owners:
* Impact: Responsible for ongoing calibration checks and ensuring annual performance testing is conducted. Must adhere to recalibration requirements based on deviation thresholds.
* Action Required: Implement a schedule for in-house calibration checks (quarterly for PM, fortnightly for gaseous emissions and temperature/pH, monthly for BOD/COD/TOC/TSS), engage EPA Recognized/NABL Accredited labs for annual performance testing, and recalibrate when necessary.
EPA Recognized/NABL Accredited Labs:
* Impact: Required to conduct annual performance testing for OCEMS parameters.
* Action Required: Provide accredited testing services according to the updated protocol.
Central Pollution Control Board (CPCB):
* Impact: Responsible for enforcing the revised calibration protocol.
* Action Required: Monitor compliance with the new protocol.
Key Entities Referenced
Central Pollution Control Board: The governing body that issued the revised OCEMS Calibration Protocol.
OCEMS Calibration Protocol: The subject of the document, detailing calibration procedures for Online Continuous Emission Monitoring Systems.
Continuous Emission Monitoring System: A system for monitoring emissions, specifically for particulate matter (PM) and gaseous emissions.
Particulate Matter: Pollutant monitored by CEMS
EPA: Environmental Protection Agency. The document does not specify country. Needs clarity on which EPA.
NABL Accredited lab: Laboratories accredited by the National Accreditation Board for Testing and Calibration Laboratories.
BOD, COD, TOC, TSS: Parameters used to measure water quality. BOD: Biochemical Oxygen Demand. COD: Chemical Oxygen Demand. TOC: Total Organic Carbon. TSS: Total Suspended Solids
NDIR/NDUV/FTIR: Technologies used in certified portable gas analyzers
Central Pollution Control Board
Revised OCEMS Calibration Protocol
July 2025
Parameter Calibration/Calibration Description
Check/Performance Testing
Requirements
Initial: Initial calibration at the time of The Continuous Emission Monitoring
installation (by instrument supplier). System for Particulate Matter (PM CEMS)
Quarterly: Calibration Check (in- shall ideally be calibrated against isokinetic
sampling method at six samples under
house), quarterly.
running load.
Emission
Annual: Annual Performance Testing
Note: In case, deviation of the comparison
PM (by EPA Recognized/NABL
values (dust factor) for 02 (two) consecutive
Accredited lab).
monitoring is more than 10%, the system
Incidental: Calibration after any major
shall be recalibrated against isokinetic
repair in the system, change of lamp,
sampling method, if possible, at six samples
readjustment of the alignment.
under running load.
Initial: Initial calibration at the time of The instruments/analyzers for real time
installation (by instrument supplier). monitoring of gaseous emissions shall be
calibrated with respect to their proper
Fortnightly: Two Point (Zero and Span) functioning, drift, linearity, detection limit
Calibration Check (in-house), once in and other relevant parameters, using
every fortnight. standard methods and certified reference
materials.
Three Months: Multi-point (at
different concentration levels)
Apart from certified gas cylinder-based
Calibration (in-house), once every
Emission audit, certified portable gas analyzers
three months.
having NDIR/NDUV/FTIR, with proper
Gaseous
Annual: Annual Performance Testing sampling system, may also be used for
(by EPA Recognized/NABL calibration.
Accredited lab)
Incidental: Calibration after any major
repair in the system, change of lamp,
readjustment of the alignment.
Note: Calibration shall include the
whole CEMS System.
Page 1 of 2Parameter Calibration/Calibration Description
Check/Performance Testing
Requirements
Initial: Initial calibration at the time of Temperature: In case, deviation of the
installation (by instrument supplier). comparison values for 02 (two) consecutive
monitoring is more than +/- 1 Degree
Fortnightly: Calibration Check (in- Celsius. The system shall be recalibrated
from the calibrated thermometer.
house), once in every fortnight.
Effluent
pH: In case, deviation of the comparison
Temperature, pH Annual: Annual Performance Testing
values for 02 (two) consecutive monitoring
(by EPA Recognized/NABL
is more than +/- 0.2 from certified reference
Accredited lab).
material, the system shall be recalibrated.
Incidental: Calibration after any major
repair in the system.
Initial: Initial calibration at the time of BOD, COD, TOC, TSS: In case, deviation of
installation (by instrument supplier). the comparison values for 02 (two)
consecutive monitoring is more than +/-
Monthly: Calibration check (in-house), 20% from lab results, the system shall be
recalibrated.
once every month.
Effluent
Annual: Annual Performance
BOD, COD, TOC, TSS
Testing (by EPA Recognized/NABL
Accredited lab).
Incidental: Calibration after any major
repair in the system.
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