Fermentation tank is divided into two types of valves:
According to the cleanliness of valves, the valves used in various factories are generally divided into two categories: one is mainly used for opening and closing, either fully open or fully closed; the other is used for throttling control, such as flow, pressure and temperature regulation.
Utility pipeline of fermentation tank:
Gate valves, ball valves and butterfly valves of water, steam and air utility systems are mainly used for opening and closing, while globe valves and butterfly valves are used for throttling control. Valve selection is mainly based on the cost of installation and maintenance, little or no need to consider the cleanliness of the valve.
Common faults and preventive measures of fermentation tank valve:
1. Leakage of stuffing box
The reasons are as follows: ① the packing does not adapt to the corrosiveness, temperature and pressure of the working medium; ② the wrong filling method, especially the whole packing coiled in, is most likely to cause leakage; ③ the machining accuracy or surface finish of the valve stem is not enough, or there is ovality or notch; ④ the valve stem has pitting corrosion, or rust due to lack of protection in the open air; ⑤ the valve stem is bent; ⑥ the packing makes the valve stem smooth If it is used for too long, it will be aged.
2. Leakage of closing parts
There are two types: one is the leakage of sealing surface, the other is the leakage of sealing ring root. This kind of leakage is often encountered when we overhaul equipment and pipelines, which will prolong the overhaul time or affect the production unit.
3. Valve rod lifting failure
① Excessive operation causes thread damage; ② lack of lubrication or lubricant failure; ③ stem bending and twisting; ④ insufficient surface finish; ⑤ inaccurate fit tolerance and too tight bite; ⑥ stem nut inclination; ⑦ improper material selection, such as stem and stem nut are the same material and easy to bite; Ⅷ thread is corroded by medium (refers to the valve with Non rising stem or stem nut at the lower part); Ⅸ open air The valve lacks protection, and the stem thread is covered with dust and sand, or rusted by rain, dew, frost and snow.
4. Gasket leakage
Main reasons: the gasket is not corrosion-resistant, does not adapt to the working temperature and pressure, does not adapt to the temperature change of high temperature valve.
5. Valve body cracking
It's usually caused by freezing. When the weather is cold, the valve shall be provided with heat preservation and tracing measures, otherwise the water in the valve and connecting pipeline shall be drained after shutdown (if there is a valve bottom plug, the plug can be opened for drainage).
6. The hand wheel is damaged
Impact or long lever force operation. Avoid long bar force operation and impact.
7. The packing gland is broken
When compressing the packing, the force is not uniform, or the gland is generally defective in cast iron. To compress the packing, rotate the screws symmetrically. Do not deviate. When manufacturing, we should not only pay attention to large parts and key parts, but also pay attention to secondary elements such as gland, otherwise the use will be affected.
8. The connection between valve stem and valve plate fails
The gate valve adopts many forms of connecting the rectangular head of the valve stem with the T-shaped groove of the gate. Sometimes the T-shaped groove is not machined, so the rectangular head of the valve stem is worn faster. Mainly from the manufacturing aspect to solve, but also can carry on the repair processing to T-groove, let it have a certain degree of finish.
9. The gate of double gate valve shall not be pressed tightly
The tension of the double gate is produced by the top wedge. For some gate valves, the top wedge material is poor (low grade cast iron), and it will be worn or broken soon after use. The top wedge is a small piece with few materials. It can be made of carbon steel and replaced with the original cast iron.
Technical reference:
Specification: dn20-150, 1 ″ - 6 ″;
Standards: DIN, SMS, ISO;
Material: SUS304, SUS316L;
Application: beer, dairy, beverage, pharmaceutical.