During operation and debugging, it is inevitable to check and maintain the reverse osmosis. This article details the installation and preparation steps for membrane elements:
I. Preparation of tools for preliminary work
4. Silicone grease lubricant
1) When disassembling and installing the reverse osmosis membrane components, carefully check the upstream water inlet pipeline and remove all dust, grease, metal debris, etc. If necessary, chemically clean the water inlet pipeline and reverse osmosis pressure vessel to ensure that all foreign objects are effectively removed.
This step can be done by dragging and cleaning with a clean mop or large piece of cloth using a rope.
2) Carefully check the water quality. Before installing the element, allow qualified water from the pretreatment system to flow through the membrane pressure vessel for 30 minutes, and check whether the water quality entering the reverse osmosis meets the membrane element inlet specifications, and check for leaks in the pipeline.
3) Remove the end plate and thrust ring of the pressure vessel. The end plate structure may vary depending on the pressure vessel manufacturer; refer to its product diagram when disassembling.
4) Rinse the opened pressure vessel with clean water to remove dust and sediment. If further cleaning is required, make a mop large enough to fill the inner diameter of the pressure vessel, soak the mop in a 50% glycerin aqueous solution, and drag it back and forth in the pressure vessel several times until the inner wall of the pressure vessel is clean and lubricated.
5) Before installing the element, ensure that all parts and chemicals of the installation and operation system are complete and the pretreatment system is operating normally.
6) Only open the packaging and install the membrane element when the system is scheduled to be put into operation immediately; otherwise, the membrane element should be stored in its original packaging.
1) Carefully remove the membrane element from the packaging box and check whether the position and direction of the brine seal on the element are correct (the opening direction of the brine seal must face the water inlet direction; refer to the diagram on the membrane element performance specification, as shown in Figure 6-1).
2) Push the end of the membrane element without the brine seal into the pressure vessel inlet end parallel until the element is about 10 cm outside the pressure vessel inlet end. Note that the element must always be installed from the pressure vessel inlet end, as shown in Figure 6-1.
3) Insert the connecting inner connector between the elements into the element's central water outlet pipe. Before installing the connector, a small amount of silicone-based "O"-ring lubricant (Dow Corning 111 can be used, except in special cases where it cannot be used. DuPont recommends using chemically pure glycerin as the main lubricant for connecting connectors and "O"-rings; glycerin is an FDA-compliant chemical) can be applied to the connector "O"-ring; if not, simply wet it with qualified pretreated water.
4) Carefully remove the second membrane element from the packaging box, check whether the position and direction of the brine seal on the element are correct, carefully hold the element, and insert the inner connector on the first element into the element's central water outlet pipe. At this time, do not let the connecting inner connector bear the weight of the element, and push the element into the pressure vessel parallel until the second element is about 10 cm outside, as shown in Figure 6-2.
Repeat steps 3) and 4) until all elements are installed in the pressure vessel, transfer to the concentrate end, and install the element connector on the central water outlet pipe of the first element, as shown in Figure 6-3. The number of membrane elements that can be installed in a single pressure vessel is determined by the length of the element and the pressure vessel.
Install the thrust ring at the concentrate end of the pressure vessel, as shown in Figure 6-3. Refer to the pressure vessel manufacturer's diagram when positioning the thrust ring. Do not forget to install the thrust ring; failure to install the thrust ring at the concentrate end of the pressure vessel will severely damage the membrane element.
Install the end plate at the concentrate end of the pressure vessel according to the following steps.
7-1) Carefully check the "O"-ring on the element adapter (the transition connector between the element and the end plate, commonly known as a grenade), insert the element adapter into the concentrate end plate, and carefully position the concentrate end plate of the pressure vessel for connection with the external pipeline, aligning the element connector and pushing the concentrate end plate assembly into the pressure vessel parallel.
7-2) Rotate and adjust the concentrate end plate assembly to align it with the external connecting pipe.
7-3) Install the end plate retaining ring according to the pressure vessel manufacturer's diagram.
Push the membrane element from the inlet side towards the concentrate side until the first installed membrane element is firmly in contact with the concentrate end plate.
Install the inlet end plate similarly to step 7). Before installing the inlet end plate, it is recommended to use shims to adjust the gap between the membrane element and the end plate. Installing shims can prevent axial movement and impact between the elements during system startup and shutdown. Refer to the section "Adjusting the axial gap of the membrane element in the pressure vessel" for details.
10) Repeat the above steps to install membrane elements in each pressure vessel and connect all external inlet, concentrate, and product water pipelines.
与步骤 7) 相似安装进水端端板。在安装进水端板前，建议用调整片调节膜元件和端板间的间隙。安装调整片能够防止元件在系统开机和停机时的轴向窜动和元件间的冲击。请参阅<<调整膜元件在压力容器内的轴向间隙>>一节的详细介绍。
10) 重复以上步骤，在每一支压力容器内安装膜元件并连接所有的外部进水、浓水和产水管路。
