Fume hood

In professional laboratories fume hoods are big metal boxes resting on counter tops and are connected by ducts to blower motors on the roof of the facility. The blower motor is constantly sucking the air from the hoods to the outside so that chemists will not be exposed to the vapors of chemicals they are working with inside the hood. The same precautions are taken by non-dead underground chemists. 

A fume hood is constructed in the manner shown in figure 6. Strike drew the frame as being made of lumber but it can be made of rebar or, preferably, from PVC pipes and joints so that it can be assembled and disassembled with ease. The frame is enclosed with plastic drop cloths or any semiclear plastic sheeting. The front face of the hood is halfway covered with plastic while the bottom half is exposed to allow one to move objects in or out and to manipulate things. On top of the chamber is attached some clothes dryer duct or some such crap which is led to a leaf blower or blower motor. The exhaust from the blower is led away to the outside. 

What s left in the water now needs to be vacuum filtered and dried. This should be done carefully and under the fume hood. Up to this point the chemistry will have taken around 30 minutes, the drying might take a day or so. Often bromine liquid stays hanging around the crystals which makes them nasty, leave in the buchner funnel of your vacuum filter overnight to get rid of all that bromine. Unless all the bromine has gone, don t go near them without a fume cupboard or a mask. 

NOTE In the initial testing of any undesireable interaction between Sodium Azide, Acetic Acid and Sulfuric Acid, I mixed 5mL of each into a small cup underneath my "fume hood". Though I smelled nothing, within seconds my head felt like it was expanding, my heart started racing, and I felt more weak and confused than normal. I just barely escaped and recovered in 15 minutes, but, Needless to say, this procedure is a tad on the dangerous side. You have been warned. ... 

Vote 1. The distillation should therefore be conducted in a fume hood. 

Even small spills and leaks (<0.45 kg) require extreme caution. Unless the spill is contained in a fume hood, do not remain in or enter the area unless equipped with full protective equipment and clothing. Self-contained breathing apparatus should be used if the odor of acrolein or eye irritation is sensed. Small spills may be covered with absorbant, treated with aqueous alkalies, and flushed with water. 

Plutonium solutions that have a low activity (<3.7 x 10 Bq (1 mCi) or 10 mg of Pu) and that do not produce aerosols can be handled safely by a trained radiochemist in a laboratory fume hood with face velocity 125—150 linear feet per minute (38—45 m/min). Larger amounts of solutions, solutions that may produce aerosols, and plutonium compounds that are not air-sensitive are handled in glove boxes that ate maintained at a slight negative pressure, ca 0.1 kPa (0.001 atm, more precisely measured as 1.0—1.2 cm (0.35—0.50 in.) differential pressure on a water column) with respect to the surrounding laboratory pressure (176,179—181). This air is exhausted through high efficiency particulate (HEPA) filters. 

The radioactive isotopes available for use as precursors for radioactive tracer manufacturing include barium [ C]-carbonate [1882-53-7], tritium gas, p2p] phosphoric acid or pP]-phosphoric acid [15364-02-0], p S]-sulfuric acid [13770-01 -9], and sodium [ I]-iodide [24359-64-6]. It is from these chemical forms that the corresponding radioactive tracer chemicals are synthesized. [ C]-Carbon dioxide, [ C]-benzene, and [ C]-methyl iodide require vacuum-line handling in weU-ventilated fume hoods. Tritium gas, pH]-methyl iodide, sodium borotritide, and [ I]-iodine, which are the most difficult forms of these isotopes to contain, must be handled in specialized closed systems. Sodium p S]-sulfate and sodium [ I]-iodide must be handled similarly in closed systems to avoid the Uberation of volatile p S]-sulfur oxides and [ I]-iodine. Adequate shielding must be provided when handling P P]-phosphoric acid to minimize exposure to external radiation. 

The MSDS (46) for thiophosgene describes it as highly toxic, corrosive lachrymator and moisture sensitive compound. It may be fatal if inhaled, swallowed, or absorbed through the skin. When using this material one should wear the appropriate NIOSH/OSHA-approved respirator, chemical-resistant gloves, safety goggles, and other protective clothing. It should be used only in a chemical fume hood. 

Laboratory work with hydrogen cyanide should be carried out only in a well-ventilated fume hood. Special safety equipment such as air masks, face masks, plastic aprons, and mbber gloves should be used. A chemical proof suit should be available for emergency. Where hydrogen cyanide is handled inside a building, suitable ventilation must be provided. The people involved should be thoroughly trained in first aid. 

Unless specifically tested, all cyanocarbons should be considered as toxic as sodium cyanide or hydrogen cyanide (see Cyandes). They should be used only in a fume hood, and mbber gloves should be worn. 

The hydrolysis of 2- and 4/6-alkylthiopyrimidines to the corresponding pyrimi-dinones is best done in hot acidic media (within a fume hood). For example, N,N-dimethyl-2-methylthiopyrimidin-4-amine (365) in boiling 6M hydrochloric acid gives... 

O. 93. Dry with Na2S04, and distil as rapidly as possible under vacuum to avoid decomposition. Discard fractions boiling below 78-82 / 5mm. Store in the dark. USE AN EFFICIENT FUME HOOD as HCN (POISONOUS) is always present. [Org Synth Col.Vol. II 7 1940.]... 

Anthracene has also been crystd from EtOH, chromatographed through alumina in hot benzene (fume hood) and then vac sublimed in a pyrex tube that has been cleaned and baked at 100°. (For further details see Craig and Rajikan J Chem Soc, Faraday Trans 1 74 292 1978 and Williams and Zboinski J Chem Soc, Faraday Trans 1 74 611 1978.) It has been chromatographed on alumina, recrystd from n-hexane and sublimed under reduced pressure. [Saltiel J Am Chem Soc 108 2674 1986 Masnori et al. J Am Chem Soc 108 1126 1986.] Alternatively, it was recrystd from cyclohexane, chromatographed on alumina with n-hexane as eluent, and recrystd two more times [Saltiel et al. J Am Chem Soc 109 1209 1987]. 

Butyryi chloride (butanoyl chloride) [141-75-3] M 106.6, f -89°, b 101-102°/atm, 1.026, Hp 1.412. Check IR to see if there is a significant peak at 3000-3500 cm (br) for OH. If OH is present then reflux with less than one mol equiv of SOCI2 for Ih and distil directly. The fraction boiling between 85-100° is then refractionated at atm pressure. Keep all apparatus free from moisture and store the product in sealed glass ampoules under N2. LACHRYMATORY - handle in a good fume hood. [Org Synth Coll Vol I 147 794/.]... 

Fractionally distd at atmospheric pressure using a 40cm column. TOXIC vapour use a good fume hood. Store dry, v 2260 (NCO), 1818 (CO) and 1420 (NCO sym) cm l. [Chem Ber 106 1752 1975.]... 

Caution Because tellurium compounds have toxic effects similar to those of arsenic compounds care should be taken not to bring tellurium tetrachloride and its reaction products into contact with the skin. Avoid breathing fumes and dust of tellurium compounds. In addition, hydrogen chloride is evolved in Step A, and pyrophoric Raney nickel is used in Step B. Therefore all manipulations described in this procedure must be carried out in an efficient fume hood. 

Caution The reaction should be conducted in a well-ventilated fume hood. 

Caution The preparation op chloropyruvic acid should be carried out in a fume hood, as should the purification of 3-hydroxycincho-ninic acid and its decarboxylation. 

Saunders, G.T. (1993) Laboratory Fume Hoods A User s Manual, Wiley. 

Edema Edema is an abnormal accumulation of body fluid in tissues. An edema can be as trivial as a blister on your thumb, as life-threatening as a constriction of your airway. As in real estate, the three factors that determine the dangers associated with an edema are location, location, location. Exposure to toxic chemicals can cause a variety of edemas. Pulmonary edema (fluid in the lungs) is particularly dangerous, if not treated. Be sure to avoid inhalation of chemicals whenever possible and to use proper protective measures, as suggested on the MSDS (fume hoods, respirators, etc.). 

Lachrymator A lachrymator is an irritant that causes tearing (watering of the eyes). Examples include onions, tear gas, and pepper spray (capsaicin). Some typical lachrymating chemicals are thionyl chloride (SOClj) and acrolein (CHj=CH-CHO). Certain chemicals may say lachrymator on the label so treat these with respect. Use these only in a fume hood. Goggles or safety glasses are not adequate protection for lachrymators, because the fumes can still reach your eyes directly or through inhalation. 

Narcosis Narcosis is a state of deep stupor or unconsciousness, produced by a chemical substance, such as a drug or anesthesia. Inhalation of certain chemicals can lead to narcosis. For example, diethyl ether and chloroform, two common organic solvents, were among the first examples of anesthesia known. Many other chemicals that you would not suspect can also cause narcosis. For example, even though nitrogen gas comprises 80% of the air we breathe and is considered chemically inert (unreactive) it can cause narcosis under certain conditions. Always work with adequate inhalation and avoid inhaling chemical fumes, mists, dusts etc. whenever possible. Use fume hoods and respirators as necessary. 

Astec Microflow Manufacturers of fume cupboards, fume hoods and fume cabinets. Leaders in filtration and containment technology. http //www.astec-microflow. co. uk... 

This latter equation can also be used for systems without a local exhaust hood by setting the capture efficiency to zero. It could also be used to show the result of recirculation from, e.g., a laboratory fume hood with immediate recirculation. In such a hood all contaminants are generated within the hood and usually also all generated contaminants are captured, so the capture efficiency is 1. The equation demonstrates that if the... 

Fixed systems are those where movement of the hood or other changes to the system, except perhaps opening and closing of lids and doors, is not possible. One example is the hood with a sliding door surrounding a drilling or a milling machine another is the laboratory fume hood and another is the canopy hood above or the enclosure around a paper machine. 

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