Stack Emissions Monitoring

Stack Emissions monitoring is referred as Stack emission testing, stack emission monitoring, stack sampling, Source Emission Monitoring or Source Testing. It is a process to measure emission of industrial waste or pollutants emitted into atmosphere. The pollutants emitted from stack can be solid, gaseous, liquid organic or inorganic.
What is Stack?
Stack is nothing but chimney which is used to disperse the hot air at a great height, emissions & particulate matters that are emitted from the various types of stacks like boiler, flue gas etc. At these heights the polluted air disperse in a very large area so that concentrations at ground are within permissible limits and not harmful for humans, animals and vegetation.
There are several types of flue-gas stack based on fuel injections. Eg. DG set stack, flue gas stack, process stack, furnace stack, boiler stack, chimney etc.Stack Emission Monitoring
CPCB guidelines for Stack Height
Chimney, Boiler, DG set, DG exhaust pipe etc. Stack height calculation plays an important role in determination of dispersion of pollutants in upper level of air relevant to local building height.
Chimney / Boiler/ Stack Height Calculation Formula
H = h + 0.2 *  âˆšKVA
H = Total height of stack in metre
h = Height of the building in metres where the generator set is installed
KVA = Total generator capacity of the set in KVA
Based on the above formula stack height to be provided can be categorized as follow: This is inline with CPCB guidelines for stack height.

Sr no

For Generator Sets

Total Height of stack in metre


50 KVA

Ht. of the building + 1.5 metre


50-100 KVA

Ht. of the building + 2.0 metre


100-150 KVA

Ht. of the building + 2.5 metre


150-200 KVA

Ht. of the building + 3.0 metre


200-250 KVA

Ht. of the building + 3.5 metre


250-300 KVA

Ht. of the building + 3.5 metre




What are Requirements of Stack Emissions Monitoring & Testing?

One Stop Safety Services is a stack emission testing company having more than 30 years of experienced experts. They know how to carry out these tasks in efficient manner.
• To determine the quality and quantity of air pollutants emitted by the source
• To measure effectiveness of pollutants controller equipment before and after installation
• To measure effectiveness of pollutants controller equipment for given condition
• To compare results with emission standards to take required action
• To compare changes in emission with the changes in processes or raw materials

Stack Monitoring Kit or Equipment

• Stack Monitoring kit used to find gaseous pollutants in emission from stationary source such as Boiler Chimney, Process outlets, Scrubber outlets Etc by stack emission testing companies.
• It also can be used to determine physical parameters such as exit emission velocity from stack, temperature & flow of Air emission.
• Determination of total particulate matter using isokinetic Sampling Technique.
• Analysis of gaseous contaminants like SO2, SO3, NOx, Cl2, HCL, NH3 etc by using gas monitoring system.
Stack emission monitoring Equipment is divided into Four Parts

Velocity Measuring Kit

Consist of inclined manometer, Digital Temperature Indicator, ‘S’ type Pitot tube & thermocouple.

Particulate Sampling Train

Thimble Holder & set of nozzles, condenser, Rotameter, Dry Gas Meter, Time indicator & power source for synchronizing vacuum pump with sampling train.

Multigas Sampling Train

Consists four glass impingers housed in FRP casing with Rotameter for gaseous sampling.

Vacuum pump

Diaphragm type vacuum pump of suitable capacity.

Stack Emissions Monitoring & Testing Procedure

Measurements of these pollutants follow specific predefined stack emission testing procedures and protocols to ensure accurate and representative data of total amount of pollutants emitted into the atmosphere from a given source in given time is collected.
Learn more about Stack Emission monitoring MethodsStack Monitoring
It is the most Important that sample collected must truly represent the conditions of flue gas stack. Accurate measurement of Pressure, moisture, humidity, gases, velocity, temperature and Particulate matter is required during Industrial stack monitoring procedure.
It is also required to measure accurately rate of flow gases accurate of weight and volume of samples collected.
Also When wide range of particles are present in emission flow, there is possibility that only smaller particles can enter into sampler inlet and larger particles may not enter due to their inertia. So to avoid this situation Calculating isokinetic ratio i.e. Isokinetic stack Sampling method can be helpful to achieve accurate results in gas boiler emissions monitoring.

IsoKinetic Stack Sampling

Read More about how to select traverse Point or Iso-kinetic Stack Sampling in Stack Monitoring.

Stack Emission Measurement Parameters

Collected Sample then tested and analysed in laboratory for Parameters (Stack Emission Monitoring Parameters) NOx (Oxides of Nitrogen), CO2 (Carbon Dioxide), CO (carbon monoxide), SO2 (sulphur dioxide), VOC (Volatile Organic Compound) etc.

What is The Limit of PM Emission For Stack Monitoring?

As per CPCB or Indian standards for Industrial Stack Monitoring the flue gas emission from boiler stack, DG set emissions, furnace should not exceed the limit for Particulate matter beyond 150 mg/Nm3. However this limit can vary depending on industry type.
Read more about Fugitive Emission Monitoring and Testing

Stack Monitoring Parameters and Standards / Limits as per CPCB for Boiler & DG Sets Emission

Please refer below table of Stack Monitoring Parameters and Standards / Limits as per CPCB for Boiler & DG Sets Emission:

Sr no

Stack Monitoring Parameters for Boilers and DG Sets

Stack Monitoring Limits / Standards As per CPCB (in mg/Nm3)


Particulate Matter (PM)



Sulphur Dioxide (SO2)



Oxides of Nitrogen (NOx)



Total Fluoride (F)



Mercury (Hg)



Chlorine (Cl)



Hydrochloric Acid Vapor & Mist (HCl)



Sulphuric Acid Mist (H2SO4)



Carbon Monoxide (CO)



Lead (Pb)


Also you can use our online Stack monitoring calculators to calculate Velocity head and Velocity of gaseous flow in Stack.
Recently in Stack Emission Monitoring below mentioned two technologies introduced to measure online stack emissions:

Piezoelectric Monitor – Industrial Stack Monitoring Equipment

In this equipment particles are electrostatically deposited on to a piezoelectric sensor by stack emission testing companies.

Beta Attenuation Monitor – Industrial Stack Monitoring Equipment

In this equipment particulate sample is filtered using a continuous filter tape and the mass of particulates filtered out is determined by measuring its radiations.

Stack Emissions Monitoring & Testing Services by our Company

Perfect Pollucon Services offers Stack emission testing and Source Emission monitoring services to keep check on industrial waste stream that being released into the atmosphere.
Every industry or manufacturing company has to notify their stack emission levels to pollution control board. We carry out various tests to determine pollutants concentrations, emission rate or parameter in Gas Boiler emissions monitoring process. We also offer testing for benzene testing, toluene testing, heavy metal testing in air, VOC emission monitoring and VOC Testing and analysis.