Cause Of Valve Leak
Valve leakage in life, production is very common, light will cause waste, or bring danger to life. Such as tap water valve leakage, heavy will lead to serious consequences, such as chemical industry toxic, harmful, flammable, explosive and corrosive nature of the leakage, serious threats to personal safety, property safety and environmental pollution accidents. An electric butterfly valve depends on external force rotation drive to open and close the valve, are designed with a sealing device used in the packing culvert with a certain number of packing ring, so as to achieve the sealing effect, but what is the sealing situation? Valve packing leakage is one of the most prone to leakage fault in the valve, but there are roughly two reasons.
一, Leakage at the sealing packing
Corrosion Of One Aspect Of The Reason
Corrosion conditions are as follows:
1.The natural oxidation corrosion of the valve stem, electric butterfly valve due to the table at the stem packing is oxidized, the generation of ferric tetroxide (rust) off, resulting in the stem thinning, caused by leakage;
2. Leakage caused by chloride corrosion of asbestos packing;
3. Corrosion of stainless steel by graphite packing;
4. The corrosion of the valve stem by the medium.
二, For Packing Reasons
The Main Fillers Used NOW
1. Asbestos: Because the asbestos material has chloride ions to the valve stem corrosion, in addition, asbestos contains carcinogenic substances, harm human health, the state has adopted to parts of the product has been banned or less used.
2. Synthetic resin and synthetic fiber, tax planning and consulting some limits on the scope of use this kind of product, such as the use of pure PTFE temperature to 150 ℃ or less and filled PTFE 250 ℃ or less and PTFE particles filler compensation performance is poor, also is only applicable to low pressure valves, four fluorine fiber, carbon fiber or both mix packing, and the price is too high, bad promotion;
3.The expanded graphite will undergo severe electric chemical corrosion.
