Foam generators

Additives are used to provide a specific property. For example, a wax provides mb resistance in the printed film or a surfactant reduces foam generation in the fountain. 

Wetting times of /V,/V-dimethy1-/ -alkyl amine oxides as a function of the alkyl chain length show a minimum with dimethyl dodecyl amine oxide (Table 3). Foam generation of dimethyl-/ -alkylamine oxides solutions show a maximum when the alkyl group contains 14 carbons. 

For small instaUafions, column foam separators are more suitable. Waste flows downward in the column whereas gas spargers, located at the bottom, give countercurrent flow. The foam generated is carried upward to a foam breaker and coUector. 

Before welding is allowed on tanks that have contained heavy oils, the tanks should be filled with inert gas or with fire-fighting foam generated with inert gas, not with fire-fighting foam generated with air (see Section 12.3.2). Filling the tank with water can reduce the volume to be inerted. 

Detergency may be defined as the removal of dirt from solid surfaces by surface chemical means [29], and may be related to several surfactant properties, including wetting and rewelting ability, foam generation, and surface and interfacial tension. It has long been observed... 

There is good correlation between the concentration giving the maximum surface dilatational viscosity and that giving the best foam performance. The nonylphenol 10 EO is a low-foaming nonionic surfactant with a maximum foam height of 150 ml in this test, whereas AOS produced 670 ml of foam. Figure 12 clearly shows that there is an optimum surfactant concentration for a dynamic process such as foam generation. 

AOS surfactant concentration was 0.50% wt in deionized water. Aqueous phase pH was 8.5. The headspace was flushed with nitrogen. All samples were equilibrated at test temperature for 24 h prior to shaking the sample tubes for 1.0 min to generate the foam. Times given are elapsed time from the termination of foam generation. 

Figure 9. Stabilizing effect of methylcellulose on foams generated by a suspension of effervescent antacid granules containing magnesium trisilicate and aluminum hydroxide...

Figure 9 illustrates the stabilizing effect of methylcellulose on the foams generated by a suspension of effervescent antacid granules containing magnesium trisilicate and ammonium hydroxide. Samples 1 and 2 are identical, except for 0.01% of methylcellulose contained in sample 1. The foam in sample 1 (methylcellulose) is stable even after 5 minutes, while the sample without methylcellulose has virtually no foam after 30 seconds. 

G. S. Stepanova, Y. G. Mamedov, I. A. Babayeva, A. A. Mosina, T. L. Nenartovich, and A. A. Li. Thin under gas oil rims— new technology for efficient oil production using foam generating oil/water polymers. In Proceedings Volume, number 050. 9th EAGE Impr Oil Recovery Europe Symp (The Hague, Netherlands, 10/20-10/22) Proc, 1997. 

Why does the density of a polyurethane foam generated from a slab process generally decrease as the water content of the system increases ... 

Foam generated in porous media consists of a gas (or a liquid) dispersed in a second interconnected wetting liquid phase, usually an aqueous surfactant solution (1). Figure 1 shows a micrograph of foam flowing in a two-dimensional etched-glass porous medium micromodel (replicated from a Kuparuk sandstone, Prudhoe Bay, Alaska (2)). Observe that the dispersion microstructure is not that of bulk foam. Rather discontinuous... 

Another thick walled cylindrical, stainless steel, vessel(4 in Figure 1), inside diameter 0.03 m and inside length 0.075 m also capable of withstanding an internal pressure of 5250 p.s.i.g. is mounted close to the inlet feed of the high pressure test cell. Cores or sand packs can be installed within this vessel, which serves as a foam generator. 

Gas can be supplied to the foam generator or to the test cell from a rodded cell(5 in Figure 1), a stainless steel cylinder, inside dimensions approximately 0.5 m long and 0.04 m diameter, mounted with its axis vertical, and designed for an internal working pressure of 6000 p.s.i.g... 

Foam created in the foam generator is fed directly to the inlet of the test unit in the test cell, and the pressure drop developed by its flow through the test unit is measured by means of a differential pressure transducer, not shown in the figure, connected between inlet and outlet, and provided with by-pass and isolation valves for protection against accidental overloading. 

Determination of the rodded cell rod position, as a function of time(Figure 2 shows a typical set of results), permits computation of the volumetric gas flow rate into the foam generator. 

Figure 3. Typical plot of data output from the rig, showing values of the weight of effluent from the capillary test unit as a function of time, during an experiment. The portion of the curve from B - C shows the efflux of surfactant solution from the foam generator which precedes gas break-through. Portion C -D< shows the efflux of foam of increasing quality. At times larger than D only "dry gas, without liquid phase, emerges.

Figure 3. Foam generators and placement for a forest, grassland, or other outdoor scenario.

Figure 4. Schematic of foam production Tanker-stored water using an eduction system (I) or a premix stored in a tanker (II) may be used for foam generation using a water-driven fan (A) or a screened nozzle (B).

This idea has been utilized in elaboration of similar mixture of alkaline hydroperoxide with foam-generating detergents recently [10] but with a lower efficiency (tested only on GD - DI50 12.9). It is obvious that such emulsion cannot be used for primary decontamination in the first line due to a very limited stability (in the order of hours only) and also due to unsufficient effectiveness against HD. Such emulsion has thus limited utility. It could be used as a means of choice in stationary facilities to utilise its excellent effectiveness against V agents. 

The continued use of ABS in some small markets, for example the South East Asia region, despite the advantages offered by LAS in terms of performance characteristics such as foam generation and detergency [75,76], seems to be linked to political situations (oleochemical producer pressure) rather than to any other economical justification. 

The air foams generated by AFFF solutions possess a lowviscosity and have fast spreading, leveling and self-sealing properties. Like other foams, AFFF acts as a surface barrier to limit fuel vaporization and exclude air. To ensure extinguishment, the foam blanket should cover the entire surface of the spill or fire. 

Foams can be generated either in situ or above ground and injected into the contaminated zone. With in situ foam generation, no volatile organic compounds would be created. 

Foam Generators Devices for mixing chemical or mechanical foam in proper proportion with a stream of water to produce foam. 

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