Heating safety precautions

Shipment and Storage. Sulfur dichloride, if kept dry, is noncorrosive at ambient temperatures, thus carbon steel and Hon can be used Hi the constmction of tanks, piping, and dmms. However, when water or humidity is present, materials resistant to hydrochloric acid must be used, eg, glass-lined pipe. Teflon, titanium, HasteUoy C, or possibly a chemically resistant, glass-reiaforced polyester. Threaded pipe joHits should be assembled with Teflon tape. Hoses should be constmcted with a Teflon inner lining with the outer tube constmcted of Neoprene or braided 316 stainless steel protected by an adequate thickness of Teflon. Sulfur dichloride should be stored away from heat and away from dHect rays of the sum. Toluene and sulfur dichloride react exothermically when catalyzed by Hon or ferric chloride. Safety precautions should be foUowed when such a mixture is present (165). 

During pyrolysis to silver (via silver dicyanamide), initial heating must be slow to avoid explosion [1], High intensity illumination will also cause explosive decomposition of a confined sample [2], Safety precautions for preparation and subsequent use of the explosive salt are detailed [3],... 

As a result of the experimental studies, the simulations, and the calculations, the following safety precautions were taken. The only foreseeable process upset resulting in a temperature excursion in the nitrators is a deviation in the feed ratios. Control features and interlocks were installed to reduce this possibility. The sulfuric acid flow control station was designed in such a way that flow of this process heat sink is not halted upon complete failure of the flow controller. Low sulfuric acid flow results in automatic shutdown of the nitric acid and benzene feeds. 

Warning Formulas in this book relate to mixtures, some or all of which may be highly volatile and could react violently if ignited by heat, spark, or friction. High-energy mixtures should be prepared or handled by anyone untrained in proper safety precautions work in connection with pyrotechnics and explosives... 

It must be reiterated that, whereas aromatic azo compounds are relatively stable thermally and can be subjected to typical reactions of aromatic compounds [67, 68a, 88], the aliphatic azo compounds may be substantially less stable thermally. Aliphatic azo compounds, such as oc,a -azobis(isobutyro-nitrile), do decompose on heating and are used as free radical sources. Hence adequate safety precautions must be taken in handling them. This, by the way, does not mean that aliphatic azo compounds have not been subjected to distillation and to vapor phase chromatography. Many have been distilled and, as will be pointed out in a subsequent section, their preparation by isomerization of hydrazone depends on a distillation technique. 

Nitroethanol prepared by the formaldehyde-nitromethane method should not be distilled without use of diphenyl ether as a heat-dispersing agent. The residue, consisting of di- and tricondensation products of formaldehyde with nitromethane, when hot and concentrated, and particularly when the vacuum is broken and air is let in on the hot distillation residue, is very likely to undergo a flash detonation, or at least a fume-off which may proceed with explosive violence. Use of diphenyl ether is a wise safety precaution in the distillation of 2-nitroethanol made by other methods as well. 

The tubes are extruded from the hot material, under high pressure (200-700 kg/cm2) using hydraulic presses, with the cylinders heated with hot water to a temperature of 90°C. Since the pressing operation is rather dangerous and sometimes leads to explosion, the cylinders are usually fairly small and hold at most 10-25 kg of paste. As a safety precaution the press should be separated by a wall from the conveyor... 

As a safety precaution against EXPLOSION (in case the purification has been insufficiently thorough) at least a quarter of the total volume of ether should remain in the distilling flask when the distillation is discontinued. To minimize peroxide formation, ethers should be stored in dark bottles and, if they are liquids, they should be left in contact with type 4A Linde molecular sieves, in a cold place, over sodium amalgam. The rate of formation of peroxides depends on storage conditions and is accelerated by heat, light, air and moisture. The formation of peroxides is inhibited in the presence of diphenylamine, di-tert-butylphenol, or other antioxidant as stabilizer. 

Should the platinum become poisoned, that is, rendered inactive by contamination with impurities which have escaped the initial purification process, it can generally be revivified by heating in a current of a reducing gas such as hydrogen. Safety precautions for the operators are desirable during the process.5... 

Figure 3.14. The lower ends of fractionators, (a) Kettle reboiler. The heat source may be on TC of either of the two locations shown or on flow control, or on difference of pressure between key locations in the tower. Because of the built-in weir, no LC is needed. Less head room is needed than with the thermosiphon reboiler, (b) Thermosiphon reboiler. Compared with the kettle, the heat transfer coefficient is greater, the shorter residence time may prevent overheating of thermally sensitive materials, surface fouling will be less, and the smaller holdup of hot liquid is a safety precaution, (c) Forced circulation reboiler. High rate of heat transfer and a short residence time which is desirable with thermally sensitive materials are achieved, (d) Rate of supply of heat transfer medium is controlled by the difference in pressure between two key locations in the tower, (e) With the control valve in the condensate line, the rate of heat transfer is controlled by the amount of unflooded heat transfer surface present at any time, (f) Withdrawal on TC ensures that the product has the correct boiling point and presumably the correct composition. The LC on the steam supply ensures that the specified heat input is being maintained, (g) Cascade control The set point of the FC on the steam supply is adjusted by the TC to ensure constant temperature in the column, (h) Steam flow rate is controlled to ensure specified composition of the PF effluent. The composition may be measured directly or indirectly by measurement of some physical property such as vapor pressure, (i) The three-way valve in the hot oil heating supply prevents buildup of excessive pressure in case the flow to the reboiier is throttled substantially, (j) The three-way valve of case (i) is replaced by a two-way valve and a differential pressure controller. This method is more expensive but avoids use of the possibly troublesome three-way valve.

Most of the complexes were conveniently prepared by the reaction in ethanol of the appropriate ligand with hydrated nickel perchlorate which had sometimes been dehydrated previously by stirring it with an excess of 2,2-dimethoxypropane or triethyl orthoformate. It must be remembered that transition metal perchlorate complexes with amines are potentially hazardous and can explode even under mild conditions. Safety precautions must be used in preparations Ni(C104)2(H20)2 has been prepared by carefully heating the hexahydrate under vacuum at about 100 °C.1584... 

Extreme safety precautions must be exercized in handling bombs(especially GP LC bombs) and protecting them from shock or heat. Containers should not be tumbled, dragged, thrown, dropped on each other or rolled on the floor. Bombs equipped with shipping bands may be rolled if care is exercized... 

Caution. Proper safety precautions are advised during all operations in the heating of both cerium and hydrogen. In the event of a leak, the sudden inflow of air reacting with hot cerium and hydrogen could lead to an explosion. Consequently, safety shields should be installed in the vicinity of the furnace and glass portions of the system. 

Gaseous diazomethane may explode on ground glass surfaces and when heated to about 100°C. Safety precautions for the use of diazomethane have been published.2-7 Alkali Metals. Explodes on contact.2... 

Sulfuric acid (oil of vitriol, H2S04) is a colorless, oily liquid, dense, highly reactive, and miscible with water in all proportions. Heat is evolved when concentrated sulfuric acid is mixed with water and, as a safety precaution, the acid should be poured into the water rather than water poured into the acid. Anhydrous, 100% sulfuric acid, is a colorless, odorless, heavy, oily liquid (boiling point 338°C with decomposition to 98.3% sulfuric acid and sulfur trioxide). Oleum is excess sulfur trioxide dissolved in sulfuric acid. For example, 20% oleum is a 20% sulfur trioxide-80% sulfuric acid mix. Sulfuric acid will dissolve most metals and the concentrated acid oxidizes, dehydrates, or sulfonates most organic compounds, sometimes causing charring. 

Heat-stable solutions, rubber bungs and liners, bottles with plastic caps, ultrafiltration apparatus etc. are all sterilised by steam treatment at elevated pressure. Although the time required to sterilise is usually only about 15 min at 15 lb pressure the cycle time for modem autoclaves is several hours. This is because of the safety precautions built into these machines to prevent the doors being opened until the temperature of liquid within bottles has fallen to 80°C. 

Table XI, page 144, gives indications of temperatures of processing for a number of materials. With cellulose nitrate plastics in particular there was a risk of explosion if over-heating took place, so besides all normal safety precautions for press-work the operating temperature of presses was subject to strict control.

General safety precautions are important when dealing with hot materials. Because heat increases the activity level of chemicals, the chemicals become more dangerous when heated (nitric acid is dangerous, hot nitric acid is very dangerous). When you add the fact that heated chemicals can splatter or be ejected from a container, the dangers are compounded. In addition, the heat source and heated containers can also be dangerous. 

SAFETY PRECAUTIONS - Very stable, but should be made up as needed. AN should be kept dry to ensure proper detonation. This explosive is a definite fire hazard. Flame and heat should be avoided. Not shock sensitive as explosives go, but can be detonated by a very sharp blow (30cm drop of a 2 Kg. weight will detonate). Copper and brass should be avoided in manufacture and all munitions loading and finished products. 

With the tap closed, heat the sealed tube at the required temperature taking adequate safety precautions (see above). After the required time, allow the reaction mixture to cool to room temperature before opening the tap carefully. 

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