Filter tests collapse test

Figure 11 Plots comparing results of water and SLF leach tests performed on settled dusts generated by the WTC collapse. One part dust is added to 20 parts water or SLF at 37 °C and mixed for 24 h, with the leachate filtered (<0.45 p,m) and analyzed. The composition of the SLF used in the extraction is a variation on the recipe provided by Bauer et al (1997) pH 7.4 Na—150.7 mM Ca—0.197 mM NH4—lOmM Cl— 126.4 mM SO4—0.5 mM HCO3—27 mM HPO4— 1.2 mM Glycine—5.99 mM Citrate—0.2 mM. Other metals shown in the SLF blank were contributed as trace constituents of the various chemical reagents used to make up the fluids.

A continuation of the pressure drop test, now using contaminated fluid, at the flow rate expected for the filter in use, will allow the differential pressure to rise (given a pump capable of achieving the differentials) to the point where the element is caused to fail or collapse. 

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