Utilities

<p>The selection of mechanical filters is based on the total water intake of the system to select the size and combination of filters.</p><p>One mechanical filter is not enough to choose multiple parallel uses and the number of spares. For example, according to the water recovery rate of the reverse osmosis system, The ratio of the water output to the system is the total water intake of the system.</p><p>The packing in the mechanical filter is composed of many refined quartz sands with different particle diameters in strict order from large to small. Although a good quartz sand gradation filter is formed when it is first put into use, the filtering effect is often not very good. It is because the filter did not form a &ldquo;bridging&rdquo; at the beginning. The so-called &ldquo;bridging&rdquo; refers to an interception net composed of suspended solids in the water. The intercepting net intercepts suspended solids of the same particle size and then intercepted a smaller particle size Suspended matter. Form a reverse particle size filtration process that first intercepts sizeable particulate matter and then intercepts small particulate matter.</p><p>&nbsp;</p><p>Once the filter forms a &ldquo;bridging&rdquo; the filtering effect is perfect. As the time of operation increases, the filtering accuracy becomes higher, and the interception net becomes thicker. The inlet and outlet pressure difference becomes larger and larger. When the pressure difference reaches, 1kg/ cm2 should be back washed for the filter. In the process of backwashing, it is best to be equipped with compressed air to scrub the quartz sand. The general engineering experience is that the mechanical filter with a diameter of less than 2500mm does not need compressed air. And the mechanical filter with a diameter of more than 2500mm The core of the device needs to be scrubbed with compressed air to achieve a satisfactory cleaning effect. The backwash flow rate is generally 3-4 times the design capacity of the filter.</p><p>Old-fashioned mechanical filters mostly use large pebbles as the base cushion. The bottom is evenly punched with water-permeable holes with a convex steel plate to make the water distribution uneven. It is easy to produce a large center filter rate and a small edge filter rate. When the filter is backwashed, a mixed layer of quartz sand will occur. In this way, the filter material will inevitably leak into the downstream pipelines and precision filters, posing a severe threat to the precision filters and reverse osmosis devices.</p><p>&nbsp;</p><p>After continuous practice and experimentation, many manufacturers have improved the water distribution device of the mechanical filter, using a porous plate with a particular form of ABS water cap. This kind of ABS water cap has the function of different bidirectional output. As a result, the output is small during operation, and the backwash output can be increased several times. Thus, make the water distribution of the filter more even during the positive washing, more thorough backwashing, and greatly improve the water quality.</p><p>To prevent fine sand from penetrating the filter during operation or backwashing, the penetration gap of this kind of ABS water cap is very small, generally around 0.1-0.2mm. It is worth noting that in filling the filter filler, a certain amount of water must be injected into the filter to prevent the large quartz sand from crushing the ABS water cap. In installing the water cap, do not wear hard shoes to avoid stepping on the ABS water cap. The mechanical filter is equipped with a backwash water inlet limit butterfly valve to control and adjust the backwash water flow and backwash intensity. The filter layer should be expanded by 15-25%, and the strength of the backwash compressed air is generally 10-18L/cm2. If there is no compressed air, consider using a Roots blower.</p>