Flash paper

Lhemical reactions are truly the heart of chemistry, and their applications abound. For instance, the magician in Figure 9.25 has just ignited a sheet of nitrocellulose, also known as flash paper. In a moment, it will appear to have vanished. You know from the law of mass conservation, however, that materials don t simply vanish. Rather, they are transformed into new materials. Sometimes we can t see the new materials, but that doesn t mean they don t exist. One of the reactions that occur as flash paper burns is... 

They are made of nitrocellulose, which is the same highly combustible material used to make gun cotton as well as flash paper (see page 318). 

Colored Flashes, Paper lor making. ..2125 Lights. Colored.2112. 4c. Red Lights.2116... 

A Flash paper is used by magicians for dramatic effect. It can be made by treating paper with nitric and sulfuric acids. This process converts the cellulose fibers into nitrocellulose, which burns cleanly and rapidly. 

In a series of papers by Leung and coworkers (AlChE J., 32, 1743-1746 [1986] 33, 524-527 [1987] 34, 688-691 [1988] J. Loss Prevention Proc. Ind., 2[2], 78-86 [April 1989] 3(1), 27-32 [Januaiy 1990] Trans. ASME J. Heat Transfer, 112, 524-528, 528-530 [1990] 113, 269-272 [1991]) approximate techni ques have been developed for homogeneous equilibrium calculations based on pseudo-equation of state methods for flashing mixtures. 

Segregate the materials from other ehemieals, partieularly redueing agents, paper, straw, eloth or materials of low flash point. 

H. T. Kohlbrand, Case History of a Deflagration Involving an Organic Solvent/Oxygen System Below its Flash Point, Paper presented at AlChE Loss Prevention Symposium, San Diego, Aug. 1990. 

In a later paper, Brasie (1976) gives more concrete recommendations for determining the quantity of fuel released. A leak potential can be based on the flashing potential of the full amount of liquid (gas) stored or in process. For a continuous release, a cloud size can be determined by estimating the leak rate. For a combined liquid-vapor flow through holes of very short nozzles, the leak rate (mass flow per leak orifice area) is approximately related to the operating overpressure according to ... 

Fauske, H. K., Turbulent and Laminar Flashing Flow Considerations, Paper Presented at the 4th International Symposium on Multi-phase Flow, Miami Beach, FL, December 15-17, 1986. 

In general, the flow rate F(t) consists of the following additive components the controlled flow rate Fd of the entering gas, the flow rate Fi which is due to parasitic leaks and/or diffusion, and the flow rate Fw resulting from possible adsorption-desorption processes on the system walls (in Section I, references are given to papers dealing with the elimination or control of the wall effects in the flash filament technique). In each of these flow rate components a particular ratio of the investigated adsorbate and of the inert gas exists and all these components contribute to the over-all mean values Fh(t) and F (t). 

In 1972 a paper on venting by Huff 2J documented concerns that many designers suspected that to truly be safe the vent sizing of many systems should be based on assuming two-phase flashing flow in the vent system. A two-phase flow vent method developed by Huff was compared with Boyle s all-liquid method, and values from the FIA chart in Figure 2. It can be seen that under many conditions, previous methods were not... 

The values of some properties will be dependent on the method of measurement for example, surface tension and flash point, and the method used should be checked, by reference to the original paper if necessary, if an accurate value is required. 

Porter and Wilkinson(56) measured the rates of quenching for a variety of triplet donors with triplet acceptors at room temperature in fluid solution by flash photolysis. The appearance of the triplet-triplet absorption spectrum of the acceptor and the simultaneous disappearance of the donor triplet-triplet absorption spectrum provided unequivocal evidence for the triplet-triplet energy transfer process. Table 6.5 provides some of the quenching rate constants reported in this classic paper. 

Under appropriate conditions, dichloroethylene, previously thought to be nonflammable, can cause a fire hazard [1], Addition of a hot liquid to the cold solvent caused sudden emission of sufficient v apour to cause a flame to flash back 12 m from a fire. Although the bulk of the solvent did not ignite, various items of paper and wood in the room were ignited by the transient flame [2],... 

Dry mixtures of barium phosphinate and potassium chlorate bum rapidly with a feeble report if unconfined, but even under the slight confinement of enclosing in paper, a sharp explosion occurs. The mixture is readily initiated by sparks, impact or friction. A mixture of calcium phosphinate, potassium chlorate and quartz exploded during mixing. Mixtures of various phosphinates and chlorates have been proposed as explosives, but they are very sensitive to initiation by sparks, friction or shock. Admixture of powdered magnesium causes a brilliant flash on initiating the mixture. 

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