Comparison of sodium silicate and phosphate for controlling lead release from copper pipe rigs
Bibliographic record
Abstract
This study compared sodium silicate and zinc orthophosphate for their ability to decrease lead and copper release from pilot-scale premise plumbing in low alkalinity (<5 mg/L CaCO3) water. The study used pipe loops (to age the water) connected to copper pipe rigs. The copper pipe rigs were constructed using 50:50 lead:tin solder, which provided the only source of lead. Three different treatments were compared, using the same source water: phosphate (0.8 mg-PO4/L at pH 7.3), sodium silicate with pH control (18 mg-Si/L at pH 7.3), and sodium silicate (18 mg-Si/L at pH 6.3). Lead and copper levels (both total and dissolved) were measured following the copper pipe rig after two different stagnation times (24 h, 30 min). The phosphate treatment consistently resulted in significantly lower lead release compared to sodium silicate at the same pH of 7.3. The phosphate treated pipe rigs released 12 μg/L and 2 μg/L lead following the 24 h and 30 min stagnation times, respectively. The sodium silicate with pH control system released 46 μg/L and 6.7 μg/L lead following 24 h and 30 min stagnation time, respectively. The sodium silicate treated pipe rigs released 27.4 and 4.6 μg/L lead following the 24 h and 30 min stagnation time, respectively. The phosphate treatment also consistently released less copper than both the sodium silicate with pH control treatment and the sodium silicate treatment. However, more lead particles were observed in the phosphate treatment compared to either of the sodium silicate treatments. The difference in performance between the sodium silicate corrosion inhibitor at two different pH levels, suggests that the performance of sodium silicate could be further optimized.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".