1. Unit conversion for the dimensions, pore size, diameter, area, and water production of imported reverse osmosis membranes?

Answer: In water treatment processes, length units are generally expressed in mm (in = inch, ft = foot): 1in = 25.4mm, 1ft = 304.8mm, 12in = 1ft;

Reverse osmosis membrane pore size: 10-6in = 2.54 x 10-6mm;

Area: 1ft2 = 144in2 = 929 x 10-4m² = 92903mm², 1 in2 = 6.45 x 10-4m² = 645.2 mm²;

Flow rate: UK gpd (gal/d, gallons/day) = 4.546L/d = 5.26 * 10-5L/s; US gpd (gal/d, gallons/day) = 3.785L/d = 4.381 * 10-5L/s;

Pressure: 1b/in2 (psi, pounds per square inch) = 0.0703kgf/cm², Legal unit: 1pa = 1N/m², 1Mpa = 106pa, 1psi = 6.895kpa = 6.895 x 10-3Mpa; When the reverse osmosis can withstand a pressure of 600psi, it is 4.14Mpa. 1bar (commonly known as 1 kg) = 0.1Mpa; 1mmHg = 0.1333kpa; Free chlorine content < 1ppm, i.e., free chlorine < 1mg/L.

2. Temperature conversion? (Thermodynamic temperature, Celsius temperature, Fahrenheit temperature)

Answer: Thermodynamic temperature (K) = Celsius temperature + 273.15; ℃ = 5/9 (℉ - 32), ℉ = 9/5℃ + 32;

How to obtain relative humidity using dry-bulb and wet-bulb thermometers; it can also be found in tables.

3. Conductivity correction?

Conductivity correction can be performed using 0.01mol/L and 0.02mol/L potassium chloride solutions. Specific method: Place the conductivity electrode to be calibrated in a 0.01mol/L or 0.02mol/L potassium chloride solution, maintain the potassium chloride solution at different temperatures using a precision constant temperature water bath, compare the measured conductivity with the table below to determine the electrode constant of the unknown constant electrode, and also perform verification.

Conductivity (uS/cm) of potassium chloride solutions of different concentrations and temperatures

When measuring conductivity, try to keep the temperature close to 25℃ for easy comparison.

Online conductivity meters can also be used as process control signals to regulate the amount of chemicals. For example, when adding ammonia to pure water to increase the pH value to prevent corrosion, the pH signal cannot be used to keep the water pH between 8.8-9.4 or 9.0-9.6. However, the change in water conductivity can easily control the addition of ammonia. When controlling the amount of sodium tripolyphosphate added to boiler water, when the boiler conductivity ≤10uS/cm, the phosphate is 0.3-2.0mg/L. It is better to use conductivity control than phosphate meter control.

Components to be installed:

1. Remove the end plate and thrust ring from the system pressure vessel.

2. Rinse the opened pressure vessel with clean water to remove dust and sediment.

Note: 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 until the inner wall of the pressure vessel is clean and lubricated.

3. Insert the membrane element from the inlet side of the pressure vessel without the brine seal ring, pushing it in about halfway.

Note: It is stipulated that the element must be installed from the inlet side of the pressure vessel.

4. Confirm that the direction of the brine seal ring on the element stressor is correct. That is, the opening direction of the seal ring should face the inlet direction.

Insert the connecting joint between the elements into the central water outlet pipe of the element. Before installing the joint, a small amount of glycerin can be applied to the O-ring of the joint (except in special cases where it is not allowed).

5. Install the second element and connecting joint in sequence, carefully hold the element to prevent the connecting joint from bearing the weight of the element, and push the element into the pressure vessel until about half of the element is exposed outside.

6. Repeat steps 4 and 5 until all elements are installed in the pressure vessel. The number of elements in a single pressure vessel is determined by the length of the elements and the pressure vessel.

7. Install the thrust ring at the concentrate end of the pressure vessel and locate the thrust ring according to the diagram of the pressure vessel manufacturer.

8. Install the end plates at both ends of the pressure vessel according to the following steps:

a) Carefully position the concentrate end plate of the pressure vessel, align the element and push it into the end plate assembly, carefully place the O-ring on the transition joint (adapter) between the element and the end plate, and insert the transition joint into the element to avoid twisting or turning the O-ring.

b) Rotate and adjust the end plate assembly to align with the external connecting pipe.

c) Install the end plate retaining ring according to the diagram of the pressure vessel manufacturer.

d) Push the RO element from the inlet side to the concentrate side.

e) Before installing the inlet end plate, it is recommended to use shims to adjust the gap between the element and the end plate. This step can help prevent the element from moving and impacting each other during system startup and shutdown.

f) Install the elements in each pressure vessel in the system in the same way as steps a) to e).

9. Connect all external pipelines.

Disassembly of elements:

1. First, remove the external hard pipes at both ends of the pressure vessel. If necessary, refer to the diagram of the pressure vessel manufacturer. Number all the removed parts and place them in order.

2. Remove the vessel end plate assembly from both ends of the pressure vessel.

3. Remove the RO element from the pressure vessel from the water inlet end, one element at a time. When an element is removed from the pressure vessel, it should be caught immediately to prevent damage to the element or injury to personnel.