Pressure release valve

FIGURE 27.5 Friction valve (pressure release valve or pressure reduction valve) for pressure reduction and pressurized water release. 

The microwave power could be adjusted in order to allow constant pressure within the vessel. A incorporated pressure release valve permits to use this experimental device routinely and safely. Furthermore, an inert gas as argon could be introduced within the reactor to avoid sparking risk with flammable solvents. This experimental device is able to raise temperature from ambient to 200 °C in less than 20 s (pressure is close to 1.2 Mpa and heating rate is close to 7° s 1). The RAMO system has been designed for nanoparticles growing and elaboration [59-62]. The RAMO system is a batch system. It could be easily transpose to continuous process with industrial scale (several hundred kilograms by seconds). 

Sulfate scaling poses a special problem in oil fields of the North Sea (e.g., Todd and Yuan, 1990, 1992 Yuan et al., 1994), where formation fluids are notably rich in barium and strontium. The scale can reduce permeability in the formation, clog the wellbore and production tubing, and cause safety equipment (such as pressure release valves) to malfunction. To try to prevent scale from forming, reservoir engineers use chemical inhibitors such as phosphonate (a family of organic phosphorus compounds) in squeeze treatments, as described in the introduction to this chapter. 

B. 1,4-Cyclohexanedione. The purified 2,5-dicarbethoxy-l,4-cyclohexanedione (170 g., 0.66 mole) (Note 5) and 170 ml. of water are placed in a glass liner (vented) of a steel pressure vessel of 1.5-1. capacity (fitted with a pressure-release valve). The vessel is sealed, heated as rapidly as possible to 185-195°, and kept at this temperature for 10-15 minutes (Note 6). The reaction vessel is immediately removed from the heater, placed in a large tub of ice water, and cooled to room temperature. The gas pressure then is carefully released. The resulting yellow to orange liquid is transferred to a distillation flask with the aid of a minimum volume of ethanol, and most of the water and ethanol is removed under reduced pressure by means of a rotary evaporator. The flask is attached to a short heated column fitted with a short air condenser. The remainder of the water and ethanol is removed under reduced pressure, and the 1,4-cyclohexanedione is distilled, b.p, 130-133° (20 mm.). The product solidifies to a white to pale-yellow solid, m.p. 77-79°, deld 60-66 g. (81-89% yield from 2,5-dicarbethoxy-l,4-cyclohexanedione). The compound may be conveniently recrystallized from carbon tetrachloride (7 ml. per gram of dione) the purified product is obtained as white plates, m.p. 77-79° (90% recovery). 

Fig. 3 Apparatus for high pressure hydrogenation. A, autoclave B, hydrogen inlet valve C, pressure release valve D, pressure gauge E, heating mantle F rocking device.

The reaction is carried out in a well-ventilated hood to remove excess acetylene. All subsequent operations are also carried out in the hood because the product of the reaction has an objectionable odor. The acetylene used is passed through a train consisting of an empty 300-ml. bottle, a 300-ml. bottle containing 150 ml. of concentrated sulfuric acid (through which acetylene passes by means of a gas dispersion tube), a pressure-release valve, and another empty 300-ml. bottle. 

Carlisle (Ref 3) reported an expln occurred when its soln in acct was coned in a glass-lined steam jacketed vessel. The cause of this expln was not detd but examination of the subst showed that it was slightly flammable bur did not explode when unconfined. Therefore, on heating in a closed system a pressure release valve should be provided... 

The p-jump unit produced by Hi-Tech Limited (PJ-55 pressure-jump) is based on a design by Davis and Gutfreund (1976) and is shown in Fig. 4.7, with a schematic representation in Fig. 4.8. A mechanical pressure release valve permits observation after 100 /us. There is no upper limit to observation time. Changes in turbidity, light absorption, and fluorescence emission can be measured in the range of 200-850 nm. The PJ-55 is thermostated by circulating water from an external circulator through the base of the module. The temperature in the cell is continuously monitored with a thermocouple probe. A hydraulic pump assembly is used to build up a pressure of up to 40.4 MPa. A mechanical valve release causes the pressure build-up to be applied to the solution in the observation cell. The instrument has a dead time of 100 /us. A fast response UV/fluorescence... 

Figure 4.8. Schematic representation of the pressure-jump apparatus of Davis and Gut-freund (1976). The instrument is composed of the following components A, observation cell B, hydraulic chamber C, absorbancy photomultiplier D, thermostatted base E, quartz fiber optic from light source F, quartz pressure transducer for the triggering of data collection G. hydraulic pressure line H and I, observation cell filling and emptying ports J, fluorescence emission window K, bursting disc pressure-release valve L, mechanical pressure-release valve M, trigger mechanism N, reset mechanism O, value seat and P, phosphorbronze bursting disc. (Reprinted with permission of the publisher.)...

Between the feeding system and the reactor there is a view port that is used to ignite the bed and acts as well as a safety pressure release valve. 

While the load was falling, the pressure release valve failed and fluid was lost from the loop (overnight). The crack was found to have stopped growing, as witnessed by the increase in load. Qualitative estimates indicated that the cessation of crack growth occurred when the liquid level dropped below the level of the crack. Note that the steam pressure was such that capillary condensation should have maintained an environment within the crack. Since this early observation, the importance of the coupling between the internal and external environments has been confirmed by other experiments, particularly those of Manahan et al. [52], and Zhou and coworkers [53]. 

Although Rebecca designs her pressure release valve to allow gas to escape when the pressure reaches 1000 kPa, she hopes it will never need to be used. To avoid the release of gases, she informs the rest of her team that they should be careful to design the process to keep the temperature well below 1295 °C. 

Prepare the air pressure line. If this is not available, cut an 8 to 9 ft length of 8 mm plastic tubing into three nearly equal length pieces. Connect each piece to the same T. Connect one open end to the bottom of a burner. This is to be the pressure release valve. Connect one open end to the air line. The air line outlet should have a needle valve attached to it to adjust the air flow. The third open end is to be used to force the solvent through the column. 

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