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Differences of K type and S type Aerosol Compound

April 5, 2020

The k-type aerosol compound uses the fire-extinguishing agent of potassium as the main oxidant, while S-type aerosol uses the chemical strontium nitrate as the main oxidant.

In the ratio of aerosol agents, for K-type aerosols, the chemical potassium nitrate accounts for 70-80% of the proportion and plays a major role in extinguishing fires; while for S-type aerosols, the chemical strontium nitrate accounts for over 50% of the proportion, potassium nitrate only accounts for 10-20% proportion, the strontium nitrate plays a major role in eliminating fires.

So the main difference between K-type and S-type aerosol fire extinguishing systems lies in the differences in oxidants; The main oxidants of K-type are potassium nitrate and its mixture, while the main oxidants of S-type are strontium nitrate and its mixture.

The fire extinguishing efficiency and environmental performance of K-type and S-type aerosols are different, which are determined by their respective chemical properties.

Hereby below let us specifically compare the characteristics of these two different chemicals:


Chemical Specifications

The molecular formula of Potassium nitrate is KNO3, the CAS number is 7757-79-1 and the UN number is 1486.

Its main Specifications are normally industrial grade and agricultural grade GB/T1918-1998, to better understand its parameter characteristics, we have created the following table:

Inspection ItemsUnitIndustrial GradeAgricultural Grade
Purity% Min99.897.5
Moisture% Max0.10
Chloride (as CI-)% Max0.01-0.030.8
Sulphate (as SO4 2-)% Max0.01
Insoluble matter in water% Max0.01
Fe% Max0.003
Hygroscopicity% Max0.25
K 2 O% Ma45.4
Nitrogen (in nitrate)% Min13.5


Potassium nitrate has characteristics of colorless and transparent rhomboidal crystals and/or white powder, its relative density is 2.109, and its melting point is at about 334°C. it decomposes at 400°C and turns into potassium nitrite releasing oxygen, and then in continuous heat turns into burnt potash; it is highly soluble in water, liquid ammonia, and glycerin but insoluble in anhydrous alcohol and ethyl ether.
But is not deliquesce in the air, as a strong oxidizer, it will burn and explode when meeting with organics releasing irritant gas, and if mixed with carbon power or sulfur, it also burns with strong light.


It is normally packed in a plastic woven bag or paper bag inner with a plastic bag in 20, 25, 50, 500, and 1000 kilograms net.


Any operators should wear a protective smock including a respirator mask and rubber gloves etc, be careful not to inhale the powder of potassium nitrate to protect the respiration apparatus.

Handling and Storage

When we handle and store the chemical of potassium nitrate, we should:
store it in a cool, ventilated, and dry warehouse, away from moisture, heat, or kindling, furthermore, avoid mixing with organic compound or sulfur or reducer during storage and transportation in case of explosion. And also protects the material from the sun and rain during transportation, and most importantly, carefully loads and unloads in case of any crash.


  • TV Kine-scope glass, glass refining agent, and motor light glass.
  • compound fertilizer and foliar spray fertilizer for crops and flowers.
  • Fireworks produce purple flame and black power in mining, ignition wires, and firecrackers.
  • Drugs such as penicillin and potassium salt in the medicine industry and catalyzers, ceramics, and enamel.
  • The components of fire extinguishing agents in the fire industry, and most traditional firefighting companies use this chemical as the main oxidant.
  • Salt baths of heat treatment, cigarette paper, concentrating agents, conservatives in salted meat and chromogen in the food industry, and so on.


Chemical Specification 

The molecular formula of strontium nitrate is Sr(NO3)2 with a CAS number of 10042-76-9 and UN number of 15075.1/PG3, its EINECS is 233-131-9.

For its main specifications, please refer to the standard of GB/T669-1994, correspondingly, the following table lists the chemical properties of strontium nitrate:

ItemQuality Index
High ClassFirst ClassQualified Class
Purity99.3% Min99.0 % Min98.0% Min
Moisture0.05% Max0.1% Max0.5% Max
Calcium (Fe)0.05% Max0.1% Max0.5% Max
Iron (Fe)0.005% Max0.001% Max0.05% Max
Barium (Ba)0.05% Max0.1% Max0.5% Max
Water insoluble0.1% Max0.2% Max0.5% Max
Sodium (Na)0.1% Max0.2% Max0.5% Max


It is a white crystal and powerful. The relative molecular weight is 211.63 and its density is 2.986. It is not deliquescent in the air and can dissolve in water and liquid ammonia, but not in ethanol and nitric acid.
The melting point is 570°C, it will decompose under high temperatures. It has a strong oxidizing property and can cause burning and explosion while meets the open fire it puts it together with organic substance and sulfur, and it gives out the carmine flame while burning.


Its packaging method is almost the same as that of potassium nitrate.

Protection and Handling and Storage

Its operating method is almost the same as potassium nitrate, see protection, handling, and storage methods of potassium nitrate.


It is mainly used to produce fireworks, signal flares, flame tubes, matches, TV kine-scope, analysis agents, optical glasses, medicine, as well as fire suppression agents.

In terms of application, some people may ask what kind of fire extinguishing agent it is. We explain that it is the latest generation of S-type aerosol fire-fighting system developed in China.


  • This product shall be stored in a place that keeps ventilation and dry against rain, heat, and isolation under sunlight.
  • This product shall not be delivered or stored together with organic inflammable substances.

From the above comparisons and analyses, we can see that both substances can be used as the main oxidizing agent in aerosol fire suppression systems.
For apply in fire suppression purposes, the main differences are:

  • Potassium nitrate aerosol (K-type aerosol) is a bit high in fire extinguishing ability, its design density is 50 to 100 grams per cubic meter, in other words, to cover one cubic meter space only needs 50 to 100 grams of K-type aerosol agent; Instead, the S type aerosol is with design density of 100 gram per cubic meter, in another words, to cover one cubic meter closed space will require 100 gram of S type aerosol compound.
  • K-type aerosol causes more residue when discharging and has corrosion to instrument equipment and machines, While S-type aerosol only has little residue and has no corrosion to instrument equipment and machinery. This is why S-type aerosol belongs to generation III advanced aerosol technology and why people think it is better than that of K-type aerosol.

Now worldwide we call for new energy, such as new energy automobiles, new energy power, new energy electronics, new energy motors, solar panels, etc, The development theme around the world is new energy.

People need more clean and green energy, so now in the choice of extinguishing agent, absolutely the S-type aerosol compound is much more popular than K type aerosol compound in fire suppression fields.

Ten years ago we also produced K-type aerosol fire extinguishers, but now we are making an effort to research and develop type aerosol because the S-type aerosol is the market direction in the future, our company is already the leading manufacturer of S-type aerosol suppression systems in the China and global market.


From the above description and comparison in this paper, we get the following conclusions:

  • K-type aerosol chemical compounds belong to the second generation of aerosol technology and S-type aerosol chemical compounds belong to the third generation of aerosol technology.
  • Type K aerosols are slightly more efficient than type S aerosols.
  • S-type aerosols are more environmentally friendly than K-type aerosols and are the latest generation of fire extinguishing agents.
  • S-type fire extinguishing agent is a new trend and a more excellent fire extinguishing agent.

We have multiple different types of aerosol systems, please click on the first-page link to find the products you are interested in.


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