1. Pipe: The pipe material should be non-toxic engineering plastic or stainless steel. The characteristics of stainless steel materials are:
a. Chemically inert after passivation;
b. Easy to disinfect;
c. Wide operating temperature range.
The diaphragm valve uses a diaphragm to isolate the medium from other components of the valve, and makes the passage tight, simple, smooth, and less susceptible to contamination. It is convenient to clean the passage and replace the diaphragm, so it is often used in water production projects.
2. Pipe connection and pressure test joint: Stainless steel pipe should be welded by hot-melt argon arc welding, the inner wall should be smooth, the welding quality should be checked, the number of welding should be recorded, and X-ray film should be made. Since the pipeline is difficult to film in the technical interlayer and takes the form of filming first, the automatic argon arc hot-melt welding machine is generally used. According to the equipment manual, the welding control parameters, such as current magnitude, frequency, etc., are determined first, and then the welding parameters are used to weld several Connector, film before installation (such as unconditional can send outside film), if it meets the requirements, it can be controlled in the welding parameters during installation, which can ensure the weld is smooth, and then use deionized water to test after welding. The test pressure is 1.5 times the working pressure, and no leakage is acceptable.
3. Pipe cleaning, passivation, disinfection, stainless steel pipe treatment (cleaning, passivation, disinfection) can be roughly divided into purified water cycle pre-flushing → lye circulating cleaning → purified water cleaning → passivation → purified water again flushing → discharge → Several steps such as pure steam sterilization.
a. Purified water circulation pre-flushing: prepare a liquid storage tank and a water pump, and connect with the pipeline to be passivated into a circulation passage, inject enough normal temperature purified water into the liquid storage tank, circulate with a water pump, and open the drainage after 15 minutes. The valve is discharged while circulating, and it is better to install a flow meter;
b. lye cleaning: prepare sodium hydroxide chemically pure reagent, add hot water (temperature not lower than 70 ° C) to prepare 1% (volume concentration) lye, cycle with pump for no less than 30min, then discharge ;
c. Flushing: adding purified water to the storage tank, starting the water pump, and opening the drain valve to discharge until the resistivity of the water at each outlet point is consistent with the resistivity of the water in the tank, and the discharge time is at least 30 min;
d. Purification:
(a) 8% acid solution is prepared from purified water and chemically pure nitric acid, and discharged after being circulated for 60 minutes at a temperature of 49-50 ° C;
(b) or 3% hydrofluoric acid, 20% nitric acid, 77% purified water to prepare a solution, the solution temperature is 25-35 ° C, cycle treatment 10-20min and then discharged;
e. Initial flushing: rinse with normal temperature purified water for not less than 5 min;
f. Final rinse: rinse again until the resistivity of the inlet and outlet purified water is consistent;
g. Pure steam sterilization: Pass clean steam into the entire stainless steel piping system, and rinse at least 15 minutes for each point of use. The above cleaning, passivation, disinfection processes and their parameters should be recorded.