Gear pump mechanical seals appear more damage, the common forms of damage mainly corrosive damage, thermal damage and mechanical damage. Among them, the corrosion damage is more harmful. Due to the special structure of the mechanical seal and the different working environment and conditions, the corrosion damage is also varied.
　　
Mechanical seal corrosion:
　　
Non-metallic ring corrosion
　　
First, graphite ring corrosion. Impermeable graphite impregnated with resin ring, the sun pump experts believe that its corrosion for three reasons: First, when the end surface overheating, the temperature is greater than 180oC, impregnated resin to break away from the graphite ring, the ring wear resistance decreased; If the improper choice of impregnated resin, it will occur in the chemical changes in the medium, but also to reduce wear resistance; Third, the resin impregnation depth is not enough, when worn to impregnated layer, wear resistance decreased. Therefore, the establishment of sealed cooling system, select the corrosion-resistant impregnated resin, impregnated with high pressure to increase the impregnation depth is very necessary.
　　
Second, the graphite ring oxidation. In the oxidizing medium, the end surface in the dry friction or cooling is poor, the temperature of 350 ~ 40o ℃ can make the graphite ring and oxygen react, produce CO, gas, the end face can be roughened, or even rupture. Non-metallic rings in the chemical medium and stress at the same time, it will rupture.
　　
Third, Teflon (F4) seal ring corrosion. F4 filled with such as glass fiber, graphite powder, metal powder to improve its temperature resistance, wear resistance. F4 ring filling corrosion mainly refers to the selective filling corrosion, dissolution or deterioration damage. For example, in hydrofluoric acid, the glass fiber molecules are hot-corroded and sunshine pump experts think what should be filled should be determined as the case may be.
　　
Metal ring corrosion
　　
First, the surface of the uniform corrosion. If the metal ring surface contact with corrosive media, and the metal itself is not corrosion-resistant, it will produce surface corrosion, the phenomenon is leakage, early wear and tear, damage, sound and so on. Uniform corrosion of metal surface with film and no film in two forms, no film metal corrosion is very dangerous, the corrosion process to a certain speed, which is mainly caused by the selection error. Film corrosion, the passivation film usually has the protective effect of the characteristics, but the material used in the metal seal ring, sunshine pump experts believe that the surface of the passivation film such as stainless steel, cobalt, chromium and other damage in the end surface friction in Hypoxic conditions is difficult to generate a new film, so galvanic corrosion worse.
　　
Second, stress corrosion cracking. Metal corrosion and tensile stress at the same time the role, the first cracks in the weak area, and then to the depth of development, resulting in rupture, known as stress corrosion cracking, the choice of surfacing cemented carbide and cast iron, tungsten carbide, titanium carbide seal ring, Prone to stress corrosion cracking. Seal ring cracks are generally radial divergent, can be one or more. These cracks communicate the entire seal face, accelerating the wear of the face and increasing the amount of leakage.
　　
Gear pump safe operation
　　
1. Gear pumps and jacks to use the provisions of the oil number working oil, generally No. 10 or No. 20 mechanical oil, hydraulic properties can also be similar to other similar oil, such as transformer oil. Sunshine pump experts believe that the oil poured into the tank must be filtered. Gear pump should not work under overload, safety valve pressure to be adjusted according to equipment rated pressure, non-arbitrarily adjusted.
　　
2. Tubing under working pressure to avoid bending. Connect the gear oil pump and jack of the fuel tank should be kept clean, do not plug it with screws, to prevent sediment into the gear pump and jack exposed nozzle to be sealed with nuts to prevent dust and debris into the machine. Daily run out, the gear pump should be wiped clean oil grease on the silk cloth on the grease.
　　
3. High-pressure gear pump operation, the oil control valve should be loosen, and then start the gear pump until the normal operation of empty load, and then close the return valve, gradually screw into the valve stem to increase the load and Note pressure gauge pointer is normal.
　　
4. Grounding power supply, the chassis must be grounded, check the line insulation, before commissioning.
　　
5. Oil-resistant rubber hose must be high pressure, the working pressure shall not exceed the rated oil pressure gear or the actual work of the maximum hydraulic pressure. The tubing length should not be less than 2.5m. When a gear pump driven two jacks, tubing specifications should be consistent.
　　
6. Gear pump stop working, the oil return valve should be slowly loosen until the pressure gauge slowly back to zero before lifting the jack pipe joint nut. It is forbidden to change the tubing or pressure gauge during load.
　　
7. With dual-acting jack pump gear to use two simultaneous transmission double gear pump is appropriate.
　　
Mechanical seal corrosion:
　　
Non-metallic ring corrosion
　　
First, graphite ring corrosion. Impermeable graphite impregnated with resin ring, the sun pump experts believe that its corrosion for three reasons: First, when the end surface overheating, the temperature is greater than 180oC, impregnated resin to break away from the graphite ring, the ring wear resistance decreased; If the improper choice of impregnated resin, it will occur in the chemical changes in the medium, but also to reduce wear resistance; Third, the resin impregnation depth is not enough, when worn to impregnated layer, wear resistance decreased. Therefore, the establishment of sealed cooling system, select the corrosion-resistant impregnated resin, impregnated with high pressure to increase the impregnation depth is very necessary.
　　
Second, the graphite ring oxidation. In the oxidizing medium, the end surface in the dry friction or cooling is poor, the temperature of 350 ~ 40o ℃ can make the graphite ring and oxygen react, produce CO, gas, the end face can be roughened, or even rupture. Non-metallic rings in the chemical medium and stress at the same time, it will rupture.
　　
Third, Teflon (F4) seal ring corrosion. F4 filled with such as glass fiber, graphite powder, metal powder to improve its temperature resistance, wear resistance. F4 ring filling corrosion mainly refers to the selective filling corrosion, dissolution or deterioration damage. For example, in hydrofluoric acid, the glass fiber molecules are hot-corroded and sunshine pump experts think what should be filled should be determined as the case may be.
　　
Metal ring corrosion
　　
First, the surface of the uniform corrosion. If the metal ring surface contact with corrosive media, and the metal itself is not corrosion-resistant, it will produce surface corrosion, the phenomenon is leakage, early wear and tear, damage, sound and so on. Uniform corrosion of metal surface with film and no film in two forms, no film metal corrosion is very dangerous, the corrosion process to a certain speed, which is mainly caused by the selection error. Film corrosion, the passivation film usually has the protective effect of the characteristics, but the material used in the metal seal ring, sunshine pump experts believe that the surface of the passivation film such as stainless steel, cobalt, chromium and other damage in the end surface friction in Hypoxic conditions is difficult to generate a new film, so galvanic corrosion worse.
　　
Second, stress corrosion cracking. Metal corrosion and tensile stress at the same time the role, the first cracks in the weak area, and then to the depth of development, resulting in rupture, known as stress corrosion cracking, the choice of surfacing cemented carbide and cast iron, tungsten carbide, titanium carbide seal ring, Prone to stress corrosion cracking. Seal ring cracks are generally radial divergent, can be one or more. These cracks communicate the entire seal face, accelerating the wear of the face and increasing the amount of leakage.
　　
Gear pump safe operation
　　
1. Gear pumps and jacks to use the provisions of the oil number working oil, generally No. 10 or No. 20 mechanical oil, hydraulic properties can also be similar to other similar oil, such as transformer oil. Sunshine pump experts believe that the oil poured into the tank must be filtered. Gear pump should not work under overload, safety valve pressure to be adjusted according to equipment rated pressure, non-arbitrarily adjusted.
　　
2. Tubing under working pressure to avoid bending. Connect the gear oil pump and jack of the fuel tank should be kept clean, do not plug it with screws, to prevent sediment into the gear pump and jack exposed nozzle to be sealed with nuts to prevent dust and debris into the machine. Daily run out, the gear pump should be wiped clean oil grease on the silk cloth on the grease.
　　
3. High-pressure gear pump operation, the oil control valve should be loosen, and then start the gear pump until the normal operation of empty load, and then close the return valve, gradually screw into the valve stem to increase the load and Note pressure gauge pointer is normal.
　　
4. Grounding power supply, the chassis must be grounded, check the line insulation, before commissioning.
　　
5. Oil-resistant rubber hose must be high pressure, the working pressure shall not exceed the rated oil pressure gear or the actual work of the maximum hydraulic pressure. The tubing length should not be less than 2.5m. When a gear pump driven two jacks, tubing specifications should be consistent.
　　
6. Gear pump stop working, the oil return valve should be slowly loosen until the pressure gauge slowly back to zero before lifting the jack pipe joint nut. It is forbidden to change the tubing or pressure gauge during load.
　　
7. With dual-acting jack pump gear to use two simultaneous transmission double gear pump is appropriate.
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