Pressure-time measurement

Hauver concluded that pressure-time measurements with a sulfur transducer in contact with detonating Baratol gave clear evidence of an initial pressure spike, and lends addnl confirmation to the hydro-dynamic theory of deton proposed by von Neumann and others. The sulfur transducer appeared capable of good resolution over that portion of the pressure-time curve corresponding to the reaction zone, and may offer a method for investigating the reaction process Refs 1) S. Joigneau J. Thouvenin, "Electrical Conductivity of Sulfur Under the Action of a Shock Wave , CR 246, 3422-25 (1958) 2) G.E. Hauver,... 

The same general point can be made but with greater force on the type of experiment in which a single physical property characteristic of the reaction system as a whole is measured at a series of times (e.g. pressure-time measurements in... 

Nagase and Tanaka [29] studied the decompositions of [Cr(NH3)5]X3 compounds (where X = Cl, Br, T and NCS ) using isothermal pressure-time measurements. The values of (shown in brackets) for the stepwise substitution of the ammonia ligand by chloride were ... 

The fire hall is related to the chemical reaction along with and after the detonation. The after huming takes place after the detonation gas was generated that leads to the blast wave. Blast is a longitudinal compression wave much faster than the speed of soimd. Side-on local pressure-time measurements show that... 

Reservoir pressure is measured in selected wells using either permanent or nonpermanent bottom hole pressure gauges or wireline tools in new wells (RFT, MDT, see Section 5.3.5) to determine the profile of the pressure depletion in the reservoir. The pressures indicate the continuity of the reservoir, and the connectivity of sand layers and are used in material balance calculations and in the reservoir simulation model to confirm the volume of the fluids in the reservoir and the natural influx of water from the aquifer. The following example shows an RFT pressure plot from a development well in a field which has been producing for some time. 

The electrical Itw-pressure impactor (ELPl) has been developed, using the Berner-type multijet low-pressure impactor stages. The cut sizes of the seven channel system range from 0.030 to 1.0 pm. Real-time measurements can be achieved due to the instrument s fast time response. The schematic representation of the impactor construction is shown in Fig 13.44. 

Ahlvik, Peter, Leonidas Ntziachristos, forma Keskinen, and Annele Virtaiien. Real Time Measurements of Diesel Particle Size Distribution with an Electrical l.ow Pressure Impactor. SAL Technical paper 980410. Reprinted from General Emissions (SP-13.3,5). lnternation.al Congress and Exposition, Detroit, February, 23-26 (1998). 

Results have been presented on one experiment. It involved a 5.659-m vessel containing 1000 kg of butane with a fill ratio of 39%. The vessel s contents were heated to 99°C, which is near but still below the supetheat-limit temperature, producing an internal pressure of 14.6 bar gauge. Vessel failure was then initiated. Measured pressure-time histories indicated that a number of separate pressure pulses occurred. They are plotted in Figure 6.6 as the overpressure-time relationship measured at 25 m from the vessel. 

Impulse A measure that can be used to define the ability of a blast wave to do damage. It is calculated by the integration of the pressure-time curve. 

The recommended full load AP is 490 psi. When the pressure is measured inside the drill collars and below the motor, AP can be determined. The flowrate is also known and the hydraulic power can be calculated in real time ... 

The quantity consumed or produced is conveniently expressed in partial pressure units if the substance is a gas. Concentration units are convenient if the reactant or product is in solution. The time measurement is also expressed in whatever units fit the reaction microseconds for the explosion of household gas and oxygen, seconds or minutes for the burning of a candle, days for the rusting of iron, months for the rotting of wood. 

The route from kinetic data to reaction mechanism entails several steps. The first step is to convert the concentration-time measurements to a differential rate equation that gives the rate as a function of one or more concentrations. Chapters 2 through 4 have dealt with this aspect of the problem. Once the concentration dependences are defined, one interprets the rate law to reveal the family of reactions that constitute the reaction scheme. This is the subject of this chapter. Finally, one seeks a chemical interpretation of the steps in the scheme, to understand each contributing step in as much detail as possible. The effects of the solvent and other constituents (Chapter 9) the effects of substituents, isotopic substitution, and others (Chapter 10) and the effects of pressure and temperature (Chapter 7) all aid in the resolution. 

Understanding the production process involves knowing the function of each step to be covered by the Q system. Typical issues that must be discussed include the different process steps, the functions of each step, the measurable technological parameters such as time, temperature, and pressure, the measuring units present, the available analysis techniques and tools, and the way the process is orgaifized (continuous, batch, convergent, divergent, etc.). 

Adiabatic heat storage or accumulation tests are performed to obtain data on temperature-and pressure-time behaviour of a substance at quasi-adiabatic conditions. Where heat dissipation by evaporation is anticipated, the measurements have to be performed in a closed system. If this is not the case the experiment may be carried out in an open system. 

Adiabatic calorimetry. Dewar tests are carried out at atmospheric and elevated pressure. Sealed ampoules, Dewars with mixing, isothermal calorimeters, etc. can be used. Temperature and pressure are measured as a function of time. From these data rates of temperature and pressure rises as well as the adiabatic temperature ri.se may be determined. If the log p versus UT graph is a straight line, this is likely to be the vapour pressure. If the graph is curved, decomposition reactions should be considered. Typical temperature-time curves obtained from Dewar flask experiments are shown in Fig. 5.4-60. The adiabatic induction time can be evaluated as a function of the initial temperature and as a function of the temperature at which the induction time, tmi, exceeds a specified value. 

The measured NMR signal amplitude is directly proportional to the mass of adsorbate present, and the NMR signal versus pressure (measured at a fixed temperature) is then equivalent to the adsorption isotherm (mass of adsorbate versus pressure) [24-25]. As in conventional BET measurements, this assumes that the proportion of fluid in the adsorbed phase is significantly higher than the gaseous phase. It is therefore possible to correlate each relaxation time measurement with the calculated number of molecular layers of adsorbate, N (where N = 1 is monolayer coverage), also known as fractional surface coverage. 

Robert Boyle (1627-1691) studied the effect of changing the pressure of a gas on its volume at constant temperature. He measured the volume of a given quantity of gas at a given pressure, changed its pressure, and measured the volume again. He obtained data similar to the data shown in Table 11-1. After repeating the process many times with several different gases, he concluded that... 

S.M. Marcus and R.L. Baine, Estimation of bias in the oxidative induction time measurement by pressure DSC, Application note TA-228, TA Instruments, Inc., New Castle, DE, USA. 

Figure 1. Representative plots from 46 low-pressure impactor measurements, illustrating aerodynamic size (Dp) distributions of Pb-212 and Pb-214 (R = radioactivity), (a) type results occurred 46% of the time, (b) 39% of the time, (c) 8.7% of the time, and (d) 6.5% of the time. Lower Dp limits are arbitrary.

An HM-HEC monolayer at the air/aqueous interface was formed by adsorption from an aqueous solution of the polymer placed in the Langmuir trough overnight. In "stress-jump" experiments, HM-HEC monolayers were placed under rapid compression to a large degree and surface pressure was measured as a function of time after compression was stopped. (The compressional "jumps" required a minute or two to complete, and in some cases were on the order of the polymer monolayer relaxation times. See later section for discussion). In hysteresis experiments, the adsorbed monolayers were subjected to continuous compression-expansion cycles at a specific speed, while surface pressure was determined as a function of surface area. 

Milton et al. [1.136] used this methods and refer to it as manometric temperature measurement. They used times of pressure rises of up to 30 s. During this time, the ice temperature will increase, mainly due to continued heat flow. Therefore, an equation has been developed to transform the experimental pressure data, including three other corrections, into the true vapor pressure of the ice. If the valve is closed for only a very short time, < 3 s, and the pressure is measured and documented 60 to 100 times/s, these data can be recorded as shown in Fig. 1.78.1. The automatic pressure rise measurements (1) can then be plotted... 

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