BAHAN PEMADAM POWDER ( DRY CHEMICAL )

Perkembangan dari teknik pemadaman kebakaran menghasilkan penemuan baru bahan-bahan pemadam api selain yang biasa digunakan, yakni air dan pasir.  Sekarang sudah banyak digunakan bahan pemadam api berupa serbuk kimia kering ( Powder Dry Chemical ), yang memiliki manfaat dan keunggulan tertentu dibandingkan dengan bahan pemadam lainnya'

Powder Dry Chemical efektif digunakan untuk pemadaman kebakaran klas B dan C.  Penggunaannya untuk klas C ( kebakaran peralatan listrik ) sangat tepat, karena bahan kimia ini juga dapat berfungsi sebagai penyekat arus listrik ( isolator ),  dan tidak merusak peralatan.

Selain digunakan untuk pemadaman klas B dan C,  bahan pemadam serbuk kimia kering juga bisa digunakan untuk klas A dan D ( kebakaran bahan logam ).  Dan mengingat penggunaannya yang bermacam-macam,  bahan pemadam ini sering dipromosikan sebagai bahan pemadam yang berfungsi ganda ( Multi Purpose Extinguisher ).

Seperti bahan pemadam CO2, serbuk kimia adalah bahan pemadam yang berfungsi untuk mengikat oksigen ( Cara Isolasi ).  Disamping itu serbuk kimia juga dapat mengikat gas-gas beracun yang mungkin ditimbulkan dalam suatu kebakaran,  sehingga hal-hal membahayakan dari dugaan timbulnya gas-gas beracun dapat ditiadakan.

Serbuk kimia kering disiapkan dalam tabung-tabung pemadaman kebakaran seperti yang digunakan untuk bahan pemadam CO2.  Bahan kimia yang digunakan biasanya ada dua macam,  pertama adalah Sodium Bicarbonate atau Natrium Bicarbonate,  dan ke dua gas CO2 atau Nitrogen yang fungsinya untuk menghembuskan bahan berupa serbuk keluar tabung.

Monoammonium phosphate, ABC_Dry_Chemical, tri-class or multi-purpose dry chemical is a dry chemical extinguishing agent used on class A, B, and C fires. It uses a specially fluidized and siliconized monoammonium phosphate powder. ABC dry chemical is usually a mix of monoammonium phosphate and ammonium sulfate, the former being the active one. The mix between the two agents is usually 40–60%, 60-40%, or 90-10% depending on local standards worldwide. The USGS uses a similar mixture, called Phos Chek G75F.

Dry Chemical

This is a powder based agent that extinguishes by separating the four parts of the fire tetrahedron. It prevents the chemical reactions involving heat, fuel, and oxygen and halts the production of fire sustaining "free-radicals", thus extinguishing the fire.

• Monoammonium phosphate, also known as "tri-class", "multipurpose" or "ABC" dry chemical, used on class A, B, and C fires. It receives its class A rating from the agent's ability to melt and flow at 177 °C (350 °F) to smother the fire. More corrosive than other dry chemical agents. Pale yellow in color.
• Sodium bicarbonate, "regular" or "ordinary" used on class B and C fires, was the first of the dry chemical agents developed. In the heat of a fire, it releases a cloud of carbon dioxide that smothers the fire. That is, the gas drives oxygen away from the fire, thus stopping the chemical reaction. This agent is not generally effective on class A fires because the agent is expended and the cloud of gas dissipates quickly, and if the fuel is still sufficiently hot, the fire starts up again. While liquid and gas fires do not usually store much heat in their fuel source, solid fires do. Sodium bicarbonate was very common in commercial kitchens before the advent of wet chemical agents, but now is falling out of favor, as it is much less effective than wet chemical agents for class K fires, less effective than Purple-K for class B fires, and is ineffective on class A fires. White or blue in color.
• Potassium bicarbonate (aka Purple-K), used on class B and C fires. About two times as effective on class B fires as sodium bicarbonate, it is the preferred dry chemical agent of the oil and gas industry. The only dry chemical agent certified for use in ARFF by the NFPA. Colored violet to distinguish it.
• Potassium bicarbonate & Urea Complex (aka Monnex/Powerex), used on class B and C fires. More effective than all other powders due to its ability to decrepitate (where the powder breaks up into smaller particles) in the flame zone creating a larger surface area for free radical inhibition. Grey in color.
• Potassium chloride, or Super-K, dry chemical was developed in an effort to create a high efficiency, protein-foam compatible dry chemical. Developed in the 60s, prior to Purple-K, it was never as popular as other agents since, being a salt, it was quite corrosive. For B and C fires, white in color.
• Foam-Compatible, which is a sodium bicarbonate (BC) based dry chemical, was developed for use with protein foams for fighting class B fires. Most dry chemicals contain metal stearates to waterproof them, but these will tend to destroy the foam blanket created by protein (animal) based foams. Foam compatible type uses silicone as a waterproofing agent, which does not harm foam. Effectiveness is identical to regular dry chemical, and it is light green in color (some ANSUL brand formulations are blue). This agent is generally no longer used since most modern dry chemicals are considered compatible with synthetic foams such as AFFF.
• MET-L-KYL / PYROKYL is a specialty variation of sodium bicarbonate for fighting pyrophoric liquid fires (ignite on contact with air). In addition to sodium bicarbonate, it also contains silica gel particles. The sodium bicarbonate interrupts the chain reaction of the fuel and the silica soaks up any unburned fuel, preventing contact with air. It is effective on other class B fuels as well. Blue/Red in color.    (  wikipedia.org )

Dibandingkan dengan CO2, serbuk kimia memiliki beberapa keunggulan,  diantaranya :

-  Dry chemical tidak berbahaya bagi manusia maupun binatang.

-  Memiliki kemampuan lebih besar dalam mengikat oksigen,  sehingga pemadaman lebih cepat.

-  Memiliki kemampuan untuk mengikat gas-gas beracun yang timbul sebagai akibat kebakaran.

-  Dry chemical berfungsi sebagai isolator,  sehingga paling baik digunakan dalam pemadaman kebakaran peralatan listrik.

-  Mudah dibersihkan dan tidak menyebabkan kerusakan peralatan.

-  Penyimpanan di dalam tabung lebih tahan lama.

-  Masih bisa digunakan pemadaman di tempat terbuka asalkan angin tidak terlalu kuat bertiupnya.