Pemadaman dengan air berbahaya untuk:
1. Kebakaran pelarut organik (heksan, eter, pereleum eter dan sebagainya), karena justru akan membesarkan atau memperluas kobaran api. Kecuali pelarut organik tersebut lebih berat dari air atau larut dalam air.
2. Kebakaran akibat listrik, karena akan menimbulkan hubungan pendek. Kecuali apabila listrik dipadamkan lebih dahulu.
3. Kebakaran logam-logam alkali seperti Na dan K karena akan memperbesar reaksi kebakaran.
On Jumat, 07 Mei 2010
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On Rabu, 05 Mei 2010
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1. Bahan Kimia Beracun (Toxic)
Adalah bahan kimia yang dapat menyebabkan bahaya terhadap kesehatan manusia atau menyebabkan kematian apabila terserap ke dalam tubuh karena tertelan, lewat pernafasan atau kontak lewat kulit.
Pada umumnya zat toksik masuk lewat pernafasan atau kulit dan kemudian beredar keseluruh tubuh atau menuju organ-organ tubuh tertentu. Zat-zat tersebut dapat langsung mengganggu organ-organ tubuh tertentu seperti hati, paru-paru, dan lain-lain. Tetapi dapat juga zat-zat tersebut berakumulasi dalam tulang, darah, hati, atau cairan limpa dan menghasilkan efek kesehatan pada jangka panjanng. Pengeluaran zat-zat beracun dari dalam tubuh dapat melewati urine, saluran pencernaan, sel efitel dan keringat.
Beracun: HCN, HF, HCl, H2S, dan AgNO3
2. Bahan Kimia Korosif (Corrosive)
Adalah bahan kimia yang karena reaksi kimia dapat mengakibatkan kerusakan apabila kontak dengan jaringan tubuh atau bahan lain. Zat korosif dapat bereaksi dengan jaringan seperti kulit, mata, dan saluran pernafasan. Kerusakan dapat berupa luka, peradangan, iritasi (gatal-gatal) dan sinsitisasi (jaringan menjadi amat peka terhadap bahan kimia).
Korosif: HBr, HCOOH, CH3COONa, (NH4)2SO4, dan CH3COOH
3. Bahan Kimia Mudah Terbakar (Flammable)
Adalah bahan kimia yang mudah bereaksi dengan oksigen dan dapat menimbulkan kebakaran. Reaksi kebakaran yang amat cepat dapat juga menimbulkan ledakan.
Mudah Terbakar: alkohol, aseton, fosfor, eter, dan hidrida logam
4. Bahan Kimia Peledak (Explosive)
Adalah suatu zat padat atau cair atau campuran keduanya yang karena suatu reaksi kimia dapat menghasilkan gas dalam jumlah dan tekanan yang besar serta suhu yang tinggi, sehingga menimbulkan kerusakan disekelilingnya. Zat eksplosif amat peka terhadap panas dan pengaruh mekanis (gesekan atau tumbukan), ada yang dibuat sengaja untuk tujuan peledakan atau bahan peledak seperti trinitrotoluene (TNT), nitrogliserin dan ammonium nitrat (NH4NO3).
5. Bahan Kimia Oksidator (Oxidation)
Adalah suatu bahan kimia yang mungkin tidak mudah terbakar, tetapi dapat menghasilkan oksigen yang dapat menyebabkan kebakaran bahan-bahan lainnya.
Oksidator: KMnO4, K2Cr2O7, H2SO4 pekat, KClO4dan HNO3
6.Bahan ‘irritant’
adalah tidak korosif tetapi dapat menyebabkan inflamasi jika kontak dengan kulit atau selaput lendir. Frase-R untuk bahan irritant : R36, R37, R38 dan R41. Contoh bahan dengan sifat tersebut misalnya isopropilamina, kalsium klorida dan asam dan basa encer
Iritan/Harmful: K2CrO4, NH4OH, NH3, CaCl2, dan CaO
On Senin, 03 Mei 2010
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- Bahan Kimia Oksidator
Penanganan Bahan Tumpahan
Tumpahan zat padat atau cairan ditutup atau dicampur dengan reduktor seperti garam hipo, bisulfit dan ferosulfat yang ditambah sedikit 3M asam Sulfat. Pindahkan dalam suatu wadah dan dinetralkan sebelum dibuang lewat bak air.
Pembuangan / Pemusnahan Bahan
Tambah sejumlah larutan pereduksi (hipo,bisulfit, atau ferosulfat yang ditambah H2SO4). Biarkan reaksi selesai dan netralkan dengan NaOH atau HCl. Buang dengan banyak air
- Bahan Kimia Reduktor
Penanganan Bahan Tumpahan
Tutup atau campur dengan NaHCO3. Biarkan reaksi selesai dan pindahkan ke dalam suatu adah. Tambahkan kalsium hipoklorit, Ca(OCl)2 perlahan-lahan. Tambah air dan biarkan reaksi selesai. Encerkan dan netralkan sebelum dibuang ke dalam air.
Pembuangan / Pemusnahan Bahan
Gas (seperti SO2): alirkan ke dalam larutan NaOH atau larutan Kalsium hipoklorit.
Padat : Campur dengan NaOH (1:1), tambah air sampai membentuk slurr. Tambahkan kalsium hipoklorit dan air serta biarkan selama 2 jam. Netralkan sebelum dibuang ke dalam pembuangan air.
- Bahan mudah terbakar
Penanganan Bahan Tumpahan
Hilangkan semua sumber api. Serap bahan ke dalam kertas tisue/bekas. Uapkan sampai kering di dalam almari asam. Setelah uap hilang semua, kertas dibakar.
Pembuangan / Pemusnahan Bahan
(1) Siram ke atas tanah yang terbuka. Biarkan proses penguapan dan bakar dari jarak jauh, dengan amat hati-hati, atau
(2) Larutkan dalam pelarut yang lebih mudah terbakar, Bakar dalam insenator.
On Sabtu, 01 Mei 2010
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Prinsip utama dalam penanggulangan kebakaran, adalah bahwa api sebelum membesar harus segera dapat dipadamkan. Semakin besar api semakin sukar dapat dikuasai karena suhu yang telah tinggi akan mempercepat proses kebakaran. Selagi api masih kecil harus segera dipadamkan dengan kain atau karung basah atau selimut api (fire blanket).
- Air: berfungsi sebagai pendingin dan menylimuti bahan dari O2 oleh adanya uap air yang terbentuk. Air amat baik untuk api kelas A yaitu kebakaran kertas, kayu, karet dan sebagainya
- Pemadam kebakaran jenis busa berfungsi mengisolasi bahan dan oksigen. Busa cukup efektif untuk api kelas A dan B, tetapi juga berbahaya untuk api kelas C dan D.
- Bubuk kering (dry powder): Dalam pemadaman api, bahan tersebut berfungsi sebagai :
(a) Melindungi bahan dari O2
(b) Melindungi bahan dari radiasi panas
(c) Menyerap radikal pembentuk reaksi rantai
Jenis pemadaman ini amat baik unutk api kelas A, B dan D tetapi tidak efektif untuk tempat yang berangin atau di luar.
- Gas CO2 bertekanan tinggi, dengan efektif dapat dipakai untuk pemadaman segala jenis kebakaran (api A,B,C dan D). Hal ini karena terjadi gas tersebut yang lebih berat dari udara dapat menutupi atau mengisolasi bahan yang terbakar dari O2.
- Halon: Jenis pemadam kebakaran ini berfungsi sebagai :
(a) Pembentuk selimut inert yang mengisolasi
bahan dari O2
(b) Penyreap yang efektif terhadap radikal-radikal
penyerap reaksi-reaksi berantai.
Sebagaimana gas CO2, halon dapat dipakai pemadaman api jenis A,B,C,dan D.
On Rabu, 07 April 2010
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Anonymous Contributions
- A student knocked over a 100 ml bottle of butyric acid in the fumehood. Most of the acid was cleaned up by the teacher but the plastic containment was not cleaned up. The teacher left the fumehood on all night to vent the remaining vapor. When the teacher entered the school the next day he was confronted by the head of maintenance who questioned him about a mysterious smell in the home economics room. To the teachers astonishment the room smelt strongly of butyric acid. As it happened the superintendent, principal and assistant principal were all out of town at conferences. The guidance councilor was in charge. When he arrived he called the poison control center and was told that the vapor was flammable and that the fumes could put students at risk. In the interim the chemistry teacher and the head of maintenance had entered the attic space and found the problem. The summer before a pitched roof had been placed over the original flat roof. In the process the fumehood had not been connected to the outside of the new roof but extended about halfway into the new space below the roof. It appeared that the vented butyric acid vapors had been swept into the area above the home economics area and vented into the room. The guidance councilor decided the risk was too great for pregnant girls and proceeded to call all the girls he thought might be pregnant to the office and dismissed them.
- A custodian was rendered unconscious when he entered a storage area in a middle school. The teacher had spilled a solution of 37% formaldehyde in the room and failed to tell anyone. Fortunately the custodian was rescued by a friend. After a brief stay at a local hospital he was released.
- A high school chemistry teacher spilled a one quarter pound bottle of bromine in a wooden box. He was overcome by the vapor and had to be hospitalized. He returned to work six months later and suffered a 20% loss of lung capacity from the incident.
- Students in a high school chemistry class were studying the difference between mixtures and compounds. In the first part of the lab sulfur was mixed with iron and the sulfur was removed by dissolving the sulfur in carbon disulfide. In the second part of the lab iron and sulfur were mixed in the correct proportions to make iron sulfide. The sample was heated to bring about the desired reaction. Unfortunately some of the students were much faster than others and the two parts of the experiment were occurring at the same time. One student placed her solution of sulfur and carbon disulfide in the chemical crock and put the cover back on. Shortly thereafter a second student placed a hot test tube in the crock. The resulting explosion sent broken glass flying in all directions. Fortunately all the students were wearing goggles and no one was hurt.
- A student knocked over a 100 ml bottle of butyric acid in the fumehood. Most of the acid was cleaned up by the teacher but the plastic containment was not cleaned up. The teacher left the fumehood on all night to vent the remaining vapor. When the teacher entered the school the next day he was confronted by the head of maintenance who questioned him about a mysterious smell in the home economics room. To the teachers astonishment the room smelt strongly of butyric acid. As it happened the superintendent, principal and assistant principal were all out of town at conferences. The guidance councilor was in charge. When he arrived he called the poison control center and was told that the vapor was flammable and that the fumes could put students at risk. In the interim the chemistry teacher and the head of maintenance had entered the attic space and found the problem. The summer before a pitched roof had been placed over the original flat roof. In the process the fumehood had not been connected to the outside of the new roof but extended about halfway into the new space below the roof. It appeared that the vented butyric acid vapors had been swept into the area above the home economics area and vented into the room. The guidance councilor decided the risk was too great for pregnant girls and proceeded to call all the girls he thought might be pregnant to the office and dismissed them.
- A custodian was rendered unconscious when he entered a storage area in a middle school. The teacher had spilled a solution of 37% formaldehyde in the room and failed to tell anyone. Fortunately the custodian was rescued by a friend. After a brief stay at a local hospital he was released.
- A high school chemistry teacher spilled a one quarter pound bottle of bromine in a wooden box. He was overcome by the vapor and had to be hospitalized. He returned to work six months later and suffered a 20% loss of lung capacity from the incident.
- Students in a high school chemistry class were studying the difference between mixtures and compounds. In the first part of the lab sulfur was mixed with iron and the sulfur was removed by dissolving the sulfur in carbon disulfide. In the second part of the lab iron and sulfur were mixed in the correct proportions to make iron sulfide. The sample was heated to bring about the desired reaction. Unfortunately some of the students were much faster than others and the two parts of the experiment were occurring at the same time. One student placed her solution of sulfur and carbon disulfide in the chemical crock and put the cover back on. Shortly thereafter a second student placed a hot test tube in the crock. The resulting explosion sent broken glass flying in all directions. Fortunately all the students were wearing goggles and no one was hurt.
On Selasa, 06 April 2010
1 komentar
An Aroostook County, Maine, teacher elects to dispose of one quarter pound of potassium metal by attaching the container to a long wooden stick and dumping it into a metal waste basket full of water in the school parking lot. The resulting explosion sends shrapnel flying and does minor damage to cars in the parking lot. Miraculously no one was injured. (Personal communication, July, 1988)
A Connecticut High School teacher substituted mercuric oxide for silver oxide in an experiment. Twenty-two students working in pairs heated 1.75 grams over a Bunsen burner for 15 minutes. After massing the heated material the teacher realized that the mercury was being vaporized and the students were evacuated. Three days after the incident, testing of the students revealed 8 of them had elevated mercury in their urine. Three months later one student still had elevated mercury levels. (Morbidity and Mortality Weekly Report, CDC, March 18, 1988)
A students gains access to a storage room and deliberately breaks a mercury barometer. The cost of the cleanup and disposal exceeds $5000. (Personal communication, May, 1998)
A student at a health career fair squeezes the bulb on a mercurial sphygmomanometer until mercury spurts out the top of the apparatus. The cost of the cleanup and disposal exceeded $1500. (Personal communication, February, 1999)
A 14-year old boy put potassium dichromate in a bottle of soda two students were sharing in a physical science lab. The two students became seriously ill and were rushed to a hospital. Reported by Dr. Waren Kingsley in Chemical Health and Safety, March/April 1999, volume 6, number 2, p.48.
The following incidents are abstracted from Dr. Jay Young’s column Anecdotal Accidents which appears in each issue of Chemical Health and Safety published by the American Chemical Society and the ACS Division of Chemical Health and Safety, 1155 16th St., N.W., Washington, D.C. 20056.
1. A student received minor facial injuries when she added concentrated sulfuric acid to a wet test tube provided by her lab partner. The contents boiled out of the tube a struck her in the face. Her lab partner had not dried the tube as instructed. January/February 2000 volume 2, number 1, p. 4
2. One person was killed and another injured when a bottle of hydrofluoric acid was compacted in a garbage truck as the attendant stood by the side of the truck. March/ April 1997, volume 4, number 2, p. 7.
3. Students in a high school science lab were allowed to fill empty alcohol burners using a funnel and a container of alcohol located on a side bench. When the funnel was misplaced, students began filling the burners directly from the container. Alcohol was spilled on the lab bench. When a student approached the bench with a still glowing burner a fire ensued in which the alcohol container was knocked over and a student was drenched in alcohol. The student was eventually knocked to the floor and the flames extinguished. Unfortunately it was too late and the student died of her burns. /October 1995, volume 2, number 5, p.5.
4. The first recorded case of a fatality from ingestion of sulfuric acid occurred when a teenager drank what he thought was milk. Someone had placed sulfuric acid in a cardboard milk carton which is lined with a chemically resistant coating. The boy died two weeks after ingesting several milliliters. September/October 1998, volume 5, number 5, p.4.
5. A carpenter who attempted to unplug a drain was found dead. A bottle of 95% sulfuric acid and an alkaline solution of sodium hypochlorite (bleach) was found at the site of the accident. From the evidence presented it was estimated the man had inhaled chlorine gas at a concentration of 25,000 ppm for 5-10 seconds. The immediately dangerous to life and health concentration (IDLH) is 30 ppm. July/August 1998, volume 5, number 4, p.4.
6. A four year old received chemical burns over 40% of his body when he slipped and fell into a spill of sulfuric acid. The custodian was using a 95% sulfuric acid drain cleaner to clean a toilet bowl. When he left to get something to clean up the cleaner he had spilt on the floor, the boy entered the rest room and slipped on the spill. The boy was washed off and rushed to the hospital but lost the use of one leg and arm. July/August 1995, volume 2, number 4, p.5.
7. Two students were severely burned when they attempted to pour methanol in a "juice cannon" which had recently been fired. The residual methanol was still burning and flashed back causing the gallon container of methanol to explode. March/April 1999, volume 6, number 2, p.5.
A Connecticut High School teacher substituted mercuric oxide for silver oxide in an experiment. Twenty-two students working in pairs heated 1.75 grams over a Bunsen burner for 15 minutes. After massing the heated material the teacher realized that the mercury was being vaporized and the students were evacuated. Three days after the incident, testing of the students revealed 8 of them had elevated mercury in their urine. Three months later one student still had elevated mercury levels. (Morbidity and Mortality Weekly Report, CDC, March 18, 1988)
A students gains access to a storage room and deliberately breaks a mercury barometer. The cost of the cleanup and disposal exceeds $5000. (Personal communication, May, 1998)
A student at a health career fair squeezes the bulb on a mercurial sphygmomanometer until mercury spurts out the top of the apparatus. The cost of the cleanup and disposal exceeded $1500. (Personal communication, February, 1999)
A 14-year old boy put potassium dichromate in a bottle of soda two students were sharing in a physical science lab. The two students became seriously ill and were rushed to a hospital. Reported by Dr. Waren Kingsley in Chemical Health and Safety, March/April 1999, volume 6, number 2, p.48.
The following incidents are abstracted from Dr. Jay Young’s column Anecdotal Accidents which appears in each issue of Chemical Health and Safety published by the American Chemical Society and the ACS Division of Chemical Health and Safety, 1155 16th St., N.W., Washington, D.C. 20056.
1. A student received minor facial injuries when she added concentrated sulfuric acid to a wet test tube provided by her lab partner. The contents boiled out of the tube a struck her in the face. Her lab partner had not dried the tube as instructed. January/February 2000 volume 2, number 1, p. 4
2. One person was killed and another injured when a bottle of hydrofluoric acid was compacted in a garbage truck as the attendant stood by the side of the truck. March/ April 1997, volume 4, number 2, p. 7.
3. Students in a high school science lab were allowed to fill empty alcohol burners using a funnel and a container of alcohol located on a side bench. When the funnel was misplaced, students began filling the burners directly from the container. Alcohol was spilled on the lab bench. When a student approached the bench with a still glowing burner a fire ensued in which the alcohol container was knocked over and a student was drenched in alcohol. The student was eventually knocked to the floor and the flames extinguished. Unfortunately it was too late and the student died of her burns. /October 1995, volume 2, number 5, p.5.
4. The first recorded case of a fatality from ingestion of sulfuric acid occurred when a teenager drank what he thought was milk. Someone had placed sulfuric acid in a cardboard milk carton which is lined with a chemically resistant coating. The boy died two weeks after ingesting several milliliters. September/October 1998, volume 5, number 5, p.4.
5. A carpenter who attempted to unplug a drain was found dead. A bottle of 95% sulfuric acid and an alkaline solution of sodium hypochlorite (bleach) was found at the site of the accident. From the evidence presented it was estimated the man had inhaled chlorine gas at a concentration of 25,000 ppm for 5-10 seconds. The immediately dangerous to life and health concentration (IDLH) is 30 ppm. July/August 1998, volume 5, number 4, p.4.
6. A four year old received chemical burns over 40% of his body when he slipped and fell into a spill of sulfuric acid. The custodian was using a 95% sulfuric acid drain cleaner to clean a toilet bowl. When he left to get something to clean up the cleaner he had spilt on the floor, the boy entered the rest room and slipped on the spill. The boy was washed off and rushed to the hospital but lost the use of one leg and arm. July/August 1995, volume 2, number 4, p.5.
7. Two students were severely burned when they attempted to pour methanol in a "juice cannon" which had recently been fired. The residual methanol was still burning and flashed back causing the gallon container of methanol to explode. March/April 1999, volume 6, number 2, p.5.
On Senin, 05 April 2010
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komentar
I noted this item over at C&E News today, a report on a terrible chemical accident at T2 Laboratories in Florida back in 2007. I missed even hearing about this incident at the time, but it appears to have been one of the more violent explosions investigated by the federal Chemical Safety and Hazard Board (CSB). Debris ended up over a mile from the site, and killed four employees, including one of the co-owners, who was fifty feet away from the reactor at the time. (The other co-owner made it through the blast behind a shipping container and suffered a heart attack immediately afterwards, but survived)
Well, the same sort of thing that can go wrong with a lot of reactions, large and small: a thermal runaway. That's always a possibility when a reaction gives off waste heat while it's running (that's called an exothermic reaction, and some are, some aren't - it depends on the energy balance of the bonds being broken versus the bonds being made, among other things). Heating chemical reactions almost invariably speeds them up, naturally, so the heat given off by such a reaction can make it go faster, which makes it give off even more heat, which makes it. . .well,, now you know why it's called a runaway reaction.
On the small scales where I've spent my career, the usual consequence of this is that whatever's fitted on the top of the flask blows off, and the contents geyser out all over the fume hood. One generally doesn't tightly seal the top of a reaction flask, not unless one knows exactly what one is doing, so there's usually a stopper or rubber seal that gives way. I've walked back into my lab, looked at the floor in front of my hood, and wondered "Who on earth left a glass condenser on my floor?", until I walked over to have a look and realized where it came from (and, um, who left it there).
But on a large scale, well, things are always different. For one thing, it's just plain larger. There's more energy involved. And heat transfer is a major concern on scale, because while it's easy to cool off a 25-milliliter flask, where none of the contents are more than a centimeter from the outside wall, cooling off a 2500-gallon reactor is something else again. Needless to say, you're not going to be able to pick it up quickly and stick it into 25,000 gallons of ice water, and even that wouldn't do nearly as much good as you might think. The center of that reactor is a long way from the walls, and cooling those walls down can only do so much - stirring is a major concern on these scales, too.
What's worth emphasizing is that this explosion occurred on the one hundred seventy-fifth time that T2 had run this reaction. No doubt they thought they had everything well under control - have any of you ever run the same reaction a hundred and seventy-five times in a row? But what they didn't know was crucial: the operators had only undergraduate degrees (Update: here's another post on that issue), and the CSB report concludes that the didn't realize that they were walking on the edge of disaster the whole time. As it turns out, the MCMT chemistry was mildly exothermic. But if the reaction got above the normal production temperature (177C), a very exothermic side reaction kicked in. Have I mentioned that the chemistry involved was a stirred molten-sodium reaction? Yep, methylcyclopentadiene dimer, cracking to monomer, metallating with the sodium and releasing hydrogen gas. This was run in diglyme, and if the temperature went up above 199C, the sodium would start reacting energetically with the solvent. Update: corrected these temperature values
Experienced chemists and engineers will recognize that setup for what it is: a black-bordered invitation to disaster. Apparently the T2 chemists had experienced a few close calls in the past, without fully realizing the extent of the problem. On the morning of the explosion, the water cooling line experienced some sort of blockage, and there was (fatally) no backup cooling system in place. Ten minutes later, everything went up. In retrospect, the only thing to do when the cooling went out would have been to run for it and cover as much ground as possible in the ten minutes left, but that's not a decision that anyone usually makes.
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