Flushing time

The relaxation time V/Q is therefore the mean residence time of the species i in the reservoir. This parameter does not depend on the nature of the species as long as the species is non-reacting In particular, V/Q is also the water residence (or renewal or flushing) time. For this reason, it will be denoted th. 

Figure 13.2 Permeate concentration as a function of flush time after membrane stand-by (250 ppm micro Siemens per centimeter feed conductivity). Courtesy of Jonathan Wood and UltraPure Wafer Journal, wwiu.ultrapureiuater.com, March, 2009.

Moore, W. S., Blanton,., and oye, S. B. (2006). Estimates of flushing times, submarine groundwater discharge, and nutrient fluxes to Okatee estuary. South Carolina. J. Geophys. R s 111. 

Large-scale purification of americium, curium, and californium with pressurized cation exchange has been planned at SRP for many years (1). Initial work involved SRP batch extractions to isolate a crude actinide-lanthanide fraction followed by solvent extraction and ion exchange in the SRL high level caves (1J. For large-scale purification, a single step was substituted for batch extraction and solvent extraction. Plant Purex solvent (30 vol % tri-n-butyl phosphate in n-paraffin) was used to minimize flush time and cross-contamination of solvent. 

Intermittent stream addition is often exploited to achieve merging zones [106], to speed up the flushing time in a flow analyser [107] or to implement multi-analyte determinations [108]. At the confluence point, the sample/carrier stream concentrations undergo sudden variations caused by the addition of the merging stream (Eq. 3.10). Consequently, the Schlieren effect can manifest itself as a spurious transient signal, usually observed before sample arrival in the detector flow cell. This effect is more likely to occur in highly versatile flow systems such as multi-commuted flow systems [109]. 

Sea, the estimate was 0.3molNirf2y-1 (Simpson Rippeth, 1998). These estimates are in line with newer field measurements of denitrification (Lohse etal., 1996 Trimmer etal., 1999). Hydes etal. (1999) used the NERC-NSP data from January 1989 to show that the concentration of P predicted, from a concentration-salinity relationship, at the salinity of source waters at the shelf break, matched the observed concentration. However, the predicted concentration of nitrate was significantly lower than at the shelf break. The nitrate deficit in the southern North Sea was equivalent to a denitrification rate of 0.25 mol N m-2 y-1, assuming a flushing time of one year for the North Sea. 

The time t, is the flushing time for the box, that is, the time required by the airshed to clean itself after emissions are set to zero. Note that the concentration evolution of... 

The time tr is the flushing time for the box, that is, the time required by the airshed to clean itself after emissions are set to zero. Note that the concentration evolution of the inert species in (23.8) is the sum of two contributions the initial condition contribution that decays exponentially with characteristic time tr — 10 h, and the contribution due to emissions and advection. For t r, exp(—t/tr) — 0 and the inert species reaches a steady-state concentration... 

Flushing time The time required for an existing body of water to be exchanged with surrounding water. 

Deposition potential/initial potential/final potential (V) Flushing time duration (s)... 

Flushing times were of 1 or 2 minutes at a flow rate of 300 litres per hour, which gives a volume of 5 or 10 litres for eaeh flushing period. 

Heating and cooling of the membrane are carried out under nitrogen atmosphere, as suggested by the producers. In order to reduce the flushing time with... 

A major and important use of mixers is to ensure minimum exposure of the melt to shear and high heat, so that, with heat-sensitive melts, less stabilizer is needed. With these devices, a moderate pressure drop and melt uniformity are achieved in a short process time. The mixers can be placed adjacent to a die, to provide the least flush time between material changes. 

Flushing time, the interval between achievement of the maximum analytical signal and baseline restoration, is typically 12-120 s. The next sample can therefore be introduced without a long delay time and this permits a high sample throughput, typically 30-300 h This is particularly advantageous in relation to, e.g., repetitive measurements, simultaneous determinations, titrations, standard additions, and quality control. 

Column m(rI) Required re-equilibration volume Flushing time for 5-8 at... 

The purge vessel is made of Duran (Pyrex) glass [20 mm outer diameter (o.d.), 20 cm length] and accommodates a glass frit at the bottom (Schott, pore size Gl) the top S cm are widened to 40 mm o.d. to prevent bubbles entering the helium outlet. The above dimensions (ca. 50 mL internal volume) are chosen to minimize purge gas flushing time and are suitable... 

The reason for this is that portable units do not have the capacity to provide the required 15 minutes of flushing time per the ANSI standard. For example, a one gallon portable eyewash unit is only going to supply the required flow rate for approximately 2 V2 minutes. Even a 4.5 gallon portable unit would provide a longer flushing time, but still not at the required 1.5 liters per minute (0.4 gallons) for 15 minutes. And eyewash bottles have a much smaller capacity. 

The on-line flush takes place when the RO skid is returned to service. The objective of the flush is to remove particulates and salts that have settled on the membrane surface while the skid was off line as well as to bring down the concentration of the RO permeate. Figure 13.2 shows the concentration of the RO permeate as a function of flush time after stand-by (assumes a feed water conductivity of 250 micro Siemens per centimeter). Typically, pretreated feed water is used for the flush there is no need to use higher-quality water for this flush. Pressure is generally at nominal operating condition, and any permeate that is generated is sent to drain. 

Dijt et al. [10] determined the hydrodynamic thickness of a PEO layer on a glass capillary by streaming potential measurements. The capillary was first saturated with polymers at a concentration of 100 g m after which pine solvent was flushed through the capillary. In Fig. 12a the hydrodynamic layer thickness 8j is plotted as a function of the flushing time for different molar masses. A substantial... 

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