Filter gravel for water supply
Filtered gravel is one that can sufficiently support the sand layer in the filtration pond and can perform stable and efficient cleaning, and is specified in 1.1 main component, 1.2 quality (physical properties) and 1.3 quality (leaching property). Must fit.
1. Main component and quality
1.1 Main component
Filtered gravel is a rounded stone with rounded corners that is obtained by crushing naturally occurring rocks by natural action. Its main components are oxygen and silicate.
1.2 Quality (physical properties)
Quality (physical properties) shall be tested according to JWWA A 103-4: 2006-2 6.4.1-6.4.3 and shall comply with the provisions of Table 1.
1.3 Quality (exudability)
Quality (exudability) shall be tested according to JWWA A 103-4: 2006-2 6.5 and shall comply with the provisions of Table 1.
● Table 1-Quality
|item||Quality regulations||Applicable test clause|
|Physical properties||Cleaning turbidity (degree)||30 or less||JWWA A 103-4:6.4.1|
|density（g/cm3)||2.50 or more in a saturated surface dry state||JWWA A 103-4:6.4.2|
|Hydrochloric acid solubility (%)||3.5 or less||JWWA A 103-4:6.4.3|
|Exudative||taste||Not abnormal||JWWA A 103-4:6.5|
|Saturation (degree)||0.5 以下|
|Turbidity (degree)||0.2 or less|
|Iron and its compounds (mg/L)||0.03 or less|
|Manganese and its compounds (mg/L)||0.005 or less|
2. Appearance and dimensions
Appearance shall be tested according to JWWA A 103-4: 2006-2 6.6.1 and comply with the provisions of Table 2.
The dimensions shall be tested according to JWWA A 103-4: 2006-2 6.6.2 and comply with the provisions of Table 2 and the requirements set by the purchaser.
● Table 2-Appearance and dimensions
|item||Appearance and dimensions||Applicable test clause|
|appearance||appearance||Hard and rounded, with little content of flats, impurities, clay, fragile particles, etc.||JWWA A 103-4:6.6.1|
|Size||Shape of gravel particles (%)||The shape of the gravel particles should be 5 times or more the major axis and 2 or less in mass ratio.||JWWA A 103-4:6.6.2|
|Mass ratio of particle size (%)||The particle size of the filtered gravel shall be 15 or less in total, which is the sum of the mass ratio of the particle size below the design minimum diameter and the particle size above the design maximum diameter for each layer.|
Quote: Japan Water Works Association Standard JWWA Water Supply Filter Material A-103: 2006-2
Revised on March 30, 2006
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