Compound hood

Compound hood An extraction hood that has two or more points of appreciable entry loss. 

Cross-linked polyethylene-based compounds that contain dame-retardant components and compounds based on PVC cross-linked by radiation have also received high temperature rating. They find use not only in appHance wires but also in manufacturing under-the-hood automotive wires. 

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 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. 

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. 

The filtered dough is then returned to a mixer and the alcohol content reduced to 25% by kneading under vacuum. Further reduction in the alcohol content is brought about by rolling the compound on a hooded two-roll mill. The milled product is then consolidated on a two-bowl calender and sheeted off in hides about j in thick. At this stage the solvent content is between 12 and 16%. 

Caution The following reactions should he conducted in a uell-ventilated hood, since in each step evil-smelling sulfur compounds are either used as starting materials or generated during the reaction. 

Caution Selenium compounds are exceedingly toxic (Note 1). Hydrogen peroxide attacks the skin and may decompose violently (Note 2). The reaction should be carried out behind a safety screen and in an efficient fume hood, and the operator should wear safety glasses and rubber gloves. 

Caution Thallium compounds are highly toxic.3 However, they may he safely handled if prudent laboratory procedures are practiced. Rubber gloves and laboratory coats should be worn and reactions should be carried out in an efficient hood. In addition, thallium wastes should be collected and disposed of separately (Note 1). 

Caution Most selenium compounds are toxic care should be exercised to avoid contact with skin. All operations in this procedure should be conducted in a well-ventilated hood. 

In a case where a fiune hood was to be placed on a portion of counter faced with plastic laminate, the planner found an economical solution. Since the plastic laminate was not suitable for use with a fume hood, he ordered a sheet of monolithic material Va inch thick and had it cut to the exact dimensions of the hood. The cost was just a fraction of that of a full thickness top. The sheet was put in place and the edges were treated with a silicone compound. This treatment stood up against highly corrosive materials as weU as heat for many years. 

Last but not least HMDS 2 is, in the laboratory and in pilot plants, quite stable when stored in a normal closed vessel whereas trimethylchlorosilane (TCS) 14 should be stored in a hood, because it reacts with humidity to hexamethyldisilox-ane 7 and HCl. Because HMDS 2 is a very non-polar compound, the silylation of very polar compounds, e.g. purines or pteridines, with HMDS 2 wiU often proceed only on addition of a polar solvent such as pyridine which is, however, readily removed after silylation, with excess HMDS 2, on codistillation with abs. xylene. Interestingly, it was recently reported that addition of catalytic amounts of iodine dramatically accelerates the silylation of alcohols, in particular tertiary alcohols, with HMDS 2 in CH2CI2 at room temperature [63]. 

Bangor Naval Submarine Base, on the Hood Canal in the State of Washington, provides fine recreational facilities for service people stationed there, as well as for civilian employees. A proposal to divert runoff from munitions-contaminated areas towards the recreational fishing pond, Cattail Lake, led to a decision to identify hazard levels for the compounds of interest. In addition to trout, there was concern over contamination of bivalves, such as oysters, cockles, and clams, at the pond s outlet to Hood Canal. Bioconcentration factors (BCFs), assumed applicable for both fish and bivalves, were developed for three compounds (Table III). BCFs, together with Uj. values and worst-case levels of fish or bivalve consumption (0.4 kg/day) provided PPLVs for the pond water, according to the equation... 

The reaction should preferably be carried out in a hood, as hydrazoic acid may be liberated in small amounts. This compound, which is volatile, is highly toxic, and its inhalation may cause temporary headache and giddiness. 

Water-soluble selenium compounds are poured down the sink in the hood and flushed with much water. Rubber stoppers and gloves can be freed from toxic compounds by soaking them for a few minutes in bromine or chlorine water and then in dilute sodium hydroxide solution. 

Most selenium compounds are toxic, and many have a vile odor. It is frequently advisable to work with them on alternate days. All manipulations should be done in a good hood. Rubber gloves should be worn, and it is well to keep the window of the hood down so that the glass is between the apparatus and the face of the operator. 

Caution. The arsenic compounds used here are extremely toxic and must be handled only in an efficient hood. Dimethyl-arsine is particularly dangerous because of its volatility (b.p. 36°/760 mm.) and its spontaneous flammability. 

Cautionl Many organotin compounds are toxic.2 Their preparation and use should he carried out in a well-ventilated hood. 

With stirring, add to each ml of the protein solution, 20 pi of 0.15 M tetranitromethane in 95 percent ethanol (Sigma). Make the addition in small aliquots if more than several milliliters of solution are to be derivatized. Note All operations with tetranitromethane should be done in a fume hood with extreme care, as this compound is sensitive to heat, friction, and shock or impact. 

Add 10 pi of 5 M sodium cyanoborohydride in 1N NaOH (Aldrich) per ml of the macromolecule solution volume prepared in (1). Caution Highly toxic compound. Use a fume hood and be careful to avoid skin contact with this reagent. 

Butanediol diglycidyl ether is a viscous liquid having a density of 1.45 at 20°C. It is a hygroscopic, corrosive compound with a displeasing odor that should be handled with care in a fume hood. Aqueous solutions of the bis-epoxide usually possess a characteristic oily film on their surfaces, indicating the limited solubility of the reagent. 

---