30-Minute stagnation time sampling

Measures for individual houses consist of lead pipe replacement and flushing before drawing water for eonsumption. The effect of the first measure ean be established using 30-minute stagnation-time sampling and proportional sampling. To assess the efifeetiveness of flushing, the fully flushed protocol can be applied. 

This example shows that the differences in monitoring costs are considerable. The composite flow proportional sample, as expected, is the most expensive. For the costs of one COMP sample, three properties can be sampled using RDT Obviously the 30-minute stagnation time makes 30MS protocols expensive. 

Type 1 or type 3 can describe results from CRECEP, TZW nanofiltration filtrate, WRC, Kiwa and LHRSP. Peak contamination (type 3) appeared in the first weeks in 30-minute stagnation samples (no data exist for longer stagnation times during the first month). After about 2 months operation, copper concentrations decreased to a minimum with some variation which could be explained (probably) 1 changes in water quality (pH, temperature, oxygen, etc.). 

The simulation of 30MS samples is the same as for 6 hours stagnation sampling, except that the stagnation time is 30 minutes and the standard used is 10 pg/1. 

Winter et al. [119, 120] studied phase changes in the system PS/PVME under planar extensional as well as shear flow. They developed a lubrieated stagnation flow by the impingement of two rectangular jets in a specially built die having hyperbolic walls. Change of the turbidity of the blend was monitored at constant temperature. It has been found that flow-induced miscibility occurred after a duration of the order of seconds or minutes [119]. Miscibility was observed not only in planar extensional flow, but also near the die walls where the blend was subjected to shear flow. Moreover, the period of time required to induce miscibility was found to decrease with increasing flow rate. The LCST of PS/PVME was elevated in extensional flow as much as 12 K [120]. The shift depends on the extension rate, the strain and the blend composition. Flow-induced miscibility has been also found under shear flow between parallel plates when the samples were sheared near the equilibrium coexistence temperature. However, the effect of shear on polymer miscibility turned out to be less dramatic than the effect of extensional flow. The cloud point increased by 6 K at a shear rate of 2.9 s. ... 

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