CPCB Guidelines for Stack Monitoring
CPCB (Central Pollution Control Board) guidelines for stack monitoring testing includes frequency of testing, parameters, time of the year & depending of industry type number of stations.
Stack monitoring is a procedure for sampling of gas stream from an emission point. It measures emissions of industrial waste or pollutants entering the atmosphere.
Since the advent of industrial revolution, the air pollution levels have touched the sky! With the current scenario regarding to air pollution, it has become a necessary evil to curb the pollution at its source or find alternatives to reduce air pollution.
Using stack has definitely aided to reduce air pollution. A stack is a vertical pipe structure through which flue gases (combustion product gases) are exhausted out in the atmosphere, it can also be known as a chimney.
But, has the installation of stack really aided in control of air pollution or is it just a myth?
Such questions can only be answered with the help of analytical results, i.e; Stack monitoring. Stack monitoring will provide results which puts light on the pollutants beings released in the atmosphere and their levels.
To conduct Stack monitoring in India CPCB (Central Pollution Control Board) have put forth guidelines and permissible limits. Let’s have a look into CPCB Guidelines for Stack Monitoring.
CPCB Guidelines for Stack Monitoring;
The industrial units are required to monitor ambient Air Quality and stack emissions as the pollutants released in the atmosphere will have a detrimental effect on the human health and environment.
General Requirements from CPCB for Stack Monitoring;
- Stack monitoring will be conducted at the frequency mentioned by State Board for each industry and report shall be sent to the concerned State Board in a standardized format.
- Ambient air quality sampling shall be done on 24 hour basis every alternate day and reports for each month shall be sent to concerned State Board.
- The parameters for stack monitoring must include the air flow rate and the production during period of sampling. In additions to pollutants, it shall include metrological data of wind speed and directions and temperature.
- Depending upon the industry type the no of monitoring stations and monitoring frequency shall be stated by concerned industrial units in consultation with relevant State Pollution Control Board.
Stack monitoring equipment and testing procedure according to CPCB Guidelines
Stack sampling is conducted by diverting a part of the gas stream through a sampling train which includes the following basic components;
The sampling train consists of a nozzle placed in gas stream, a sampling probe through which the sample is drawn at different traverses, particulate and gas collection devices, a flow measuring device and a prime mover such as a vacuum pump.
Minimum requirement of a stack monitoring equipment
A stack monitoring equipment or kit should have following components:
- Pilot Tube: Modified S-type pilot tube shall be fabricated from SS 204 or equivalent
- Sampling Probe: Fabricated from SS 204 tube of suitable diameter.
- Nozzles: A set of nozzles fabricated from SS 305 or equivalent material with internal diameters suitable to cover full range of stack velocities
- Thimble Holder:- Filter paper holders
- Thermocouple:- Thermocouple sensor capable of measuring temperature from 0 to 600°C covered .
- Mounting Flange:- Flanges fabricated out of mild steel with proper hole for mounting thermocouple sensors, sampling tube and pilot tube.
- Panel Box Sides:- It should have suitable arrangements for housing stop-watch, manometer, rotameter, etc.
- Back Panel:- Cold box with 6 impingers
- Inclined-cum-Vertical Manometer: – Velocity range – 0 to 30 m/sec.
- Rotameter:- 0 to 100 ppm for particulate monitoring and 0 to 3 Ipm for gaseous monitoring.
- Stop-Watch:- 0 to 60 minutes, one second readout with hold facility.
- Impingers:- 4 impingers of 100 ml and 2 impingers of 300 ml capacity along with ice box.
- Vacuum Pump
- Dry Gas meter
- Pump Housing
CPCB Guidelines for Stack Height
The Central Pollution Control Board (CPCB) mandates stack height adherence with the following specifications:
- Minimum height: 30 meters (90 feet)
- Formula: H = 14(Q)^0.3, where H is the stack height in meters, and Q is the emission rate of SO2 in kg/hr
- Diesel generators: H = h + 0.2 * capacity of DG in KVA, where H represents the total stack height in meters
Additionally, CPCB requires gases to undergo either recycling or oxidation in an after-combustor before venting. Stack emission monitoring is crucial for scrutinizing pollutants released into the air through stack emissions.
General Testing Procedure:-
The General Stack testing procedure would be as follows;
- Selection of Sampling Site
- Determination of no of traverses
- Molecular weight determination
- Velocity determination
- Moisture determination
- Analysis and Results
On obtaining the results they will be compared with the permissible limits prescribed by CPCB. The guideline given by CPCB is like a Bible which helps us conduct stack monitoring efficiently. If in any scenario, the stack emission exceeds the permissible limit set by CPCB, stack monitoring will be an indication for adoption of new pollution control strategies. This will eventually help us curb air pollution.
As per CPCB, frequency for stack emissions monitoring depends upon various factors such as industry, parameter and plant capacity. For cement, fertilizer, thermal plants, and other major air polluting units, stack sampling ranges from once a week to once in eight weeks. Emissions from cells should be monitored for total particulates and fluorides every week. Emissions from other stacks should be monitored once every four weeks.
Stack monitoring involves measuring the total volume, velocity, flow rate, and moisture content of released gaseous pollutants. The gases to be measured are specified by government agencies such as the CPCB and EPA.
According to CPCB guidelines, the prescribed minimum stack height is 30 meters. Nevertheless, there’s a provision for relaxation to H=74(Q) po 27, where Qp represents the particulate emission in tonnes per hour.
Respected Sir/ma’am ,
I want to ask one question
what is the frequency of Environment monitoring for Orange zone industry ??? & where it mention ?
pl clarify the same..
Thanks & Regards
krunal Kunjar
Hi Krunal,
The frequency to conduct Environmental Monitoring is mentioned on your “Consent To Operate” document. Frequency and number of parameters to be tracked are very stringent for Red and Orange category.
Thank you for replying. Keep reading.
i have question regarding thermocouple Calibration.
After the Calibrating the thermocouple what will be their acceptable tolerence as per CPCB guidelines
I have the following questions
1) What are the parameters along with specifications to be monitored during Stack Monitoring of DG Set ?
2) How many hours or minutes a DG should run during Stack Monitoring ?
3) Should the DG attain full load during Stack Monitoring ?
Hi KK,
I have the following questions
1) What are the parameters along with specifications to be monitored during Stack Monitoring of DG Set ? — As per consented Parameters
2) How many hours or minutes a DG should run during Stack Monitoring ? — 2 hours
3) Should the DG attain full load during Stack Monitoring ? – Yes at full capacity
Thank you. 🙂
PLS ANSWER
DG STACK MONITORING REQUIRED BELOW 125KVA??
PLS SHARE GUIDLINE FOR INFORMATION
Dear Amol,
As per the Air Act, 1981; every source of the pollutant emission has to be monitored frequently. You can refer to https://cpcb.nic.in/displaypdf.php?id=Tm9pc2VfYW5kX0dlbnNldHMvRW1pc3Npb24tU3RhbmRhcmRzLWZvci1EaWVzZWwtRW5naW5lcy1tb3JlLXRoYW4tODAwLUtXLnBkZg== for more infor.
Thanks,
PPS Team