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Mechanical seal common sense
Releaseman:Yeziliang      Browse number:625Times    Key Words:Mechanical seal common sense     Time of issue:2010-12-30

1, mechanical seal sense mechanical seal principle of work
            Mechanical seal is to rely on a pair of perpendicular to the axis or more relative sliding of end in fluid pressure and compensating unit of elastic (or magnetic) under the action of keep stick merger match with assisting sealing and achieve resistance leakage of shaft sealing device.

 2, mechanical seal material selection of commonly used
             Water, Normal temperature, (dynamic) 9CR18, 1CR13 surfacing cobalt chromium cast iron; tungsten, (static) leaching resin graphite, bronze, bakelite.
             The river (including silt); Normal temperature, (dynamic) and tungsten carbide (static) tungsten carbide
             Seawater, Normal temperature, (dynamic) and tungsten carbide 1CR13 surfacing cobalt chromium cast iron; tungsten, (static) leaching resin graphite, tungsten carbide, metal ceramics;
             After hot water 100 degrees, (dynamic) and tungsten carbide 1CR13 surfacing cobalt chromium cast iron; tungsten, (static) leaching resin graphite, tungsten carbide, metal ceramics;
            Gasoline, oil, liquid hydrocarbon, Normal temperature, (dynamic) and tungsten carbide 1CR13 surfacing cobalt chromium cast iron; tungsten, (static) leaching resin or sn-sb alloy graphite, bakelite.
            Gasoline, oil, liquid hydrocarbon, 100 degrees, (dynamic) and tungsten carbide 1CR13 surfacing cobalt chromium tungsten, (static) leaching bronze or resin graphite.
            Gasoline, oil, liquid hydrocarbon, Containing particles, (dynamic) tungsten carbide, (static) tungsten carbide.

3, sealing the sort of material and purposes
            Sealing material should satisfy the sealing function requirement. Due to the sealed different media, as well as equipment of different working conditions, sealing materials have different requirements of the adaptability. To the seal material requirements are generally:
             1) material density is good, not easy leak medium,
             2) have the proper mechanical strength and hardness.
             3) compressibility and elasticres ilience, permanent deformation is small;
             4) under the high temperature not soften, does not decompose temperature, no hardening, not brittle cracking,
             5) corrosion resistance, good performance in acid, alkali, oil, and other media can long-term work, the volume and hardness change small and non-adhesive in metal surface;
            6) small friction coefficient, good abrasion resistance,
            7) with seal face combination of softness,
            8) aging resistance, durable,
            9) processing manufacturing convenient, price cheap, based on the easy.
             Rubber is the most commonly used sealing material. Except rubber outside nv, sealing material and graphite etc, ptfe and various sealant, etc.

 4, mechanical seal the installation and use of technology essentials
           1), equipment pivotal radial beat should acuities 0.04 millimeter, axial channeling momentum not allow greater than 0.1 mm,
           2), equipment of the sealing parts when installation should keep clean, seal components should be cleaned, the seals intact, prevent impurities and dust into the sealing parts,
           3), in installing a process strictly touch attack, knock, lest make the mechanical seal breakage and seal failure;
           4), when installed in and sealing phase contact surface should be clean of layer of the tu yi JiXieYou, so we can smooth installation;
           5), the installation of static ring gland, tighten the screw must dint even, guarantee the static ring feedback.the axis line of vertical requirements;
           6), after installation by hand to promote acting-ring, can make acting-ring on the shaft flexible mobile, and have certain and elastic.
           7), after installation by hand shaft axis, axis should be no weight feeling;
           8), equipment in operation before must be filled with medium, in order to prevent dry friction and make the seal failure;
           9), to easily crystallized, particulate medium, medium temperature "for 80OC when, should adopt corresponding flush, filtration, cooling measures, various auxiliary devices, please refer to mechanical seal related standards.
          10), when installed in and sealing phase contact surface should be clean of layer of the tu yi JiXieYou, we must pay special attention to JiXieYou choices for different assisting sealing material, avoid to cause o-rings th1t oil inflation or accelerated aging, causing seal failure in advance.

 5, mechanical seal. What are three seal points, and the three seals point of sealing principle
              Acting-ring and static sealing ring between by elastic elements: (spring, corrugated pipe, etc.) and seal the liquid pressure in the relative motion acting-ring static contact (ring) on end to produce a proper compaction force (than pressure) make two bright and clean, flat end closely 6-colours, Maintain a layer between devicees extremely thin, liquid membrane and achieve sealing effect. This layer membrane possess liquid dynamic pressure and static pressure, it plays the balanced pressure lubrication and end of the role. Two end is required a high-gloss flat is to give the tip-to-face create perfect joint and make than pressure evenly conditions, which is relatively rotating seal. ???

 6, mechanical seal sense mechanical sealing technology species
             The current with new materials and process all kinds of mechanical seal of the new technology, progress faster, has the following of mechanical seal of new technology. Seal face slotting sealing technology in recent years, the mechanical seal of the seals on opened various flow trough, in order to generate fluid dynamic and static pressure effect, and is under constantly updated. Zero leakage sealing technology in the past always think non-contact and contact-less mechanical seal impossible to achieve zero leakage (or no leakage). Israel USES slotting sealing technology, puts forward zero leakage non-contact mechanical seal face new concept, and has been used in nuclear power plants lubrication pump. Dry running gas seal technology of this kind of seal is used for sealing technology will be slotted vapor seal. Upstream pumnping sealing technology namely using seal surface flow downstream trough will open a small leak fluid pumps back upstream. The above categories of seal structure features are: use shallow groove, and film thickness and flow groove depth belong to the micron-grade, and USES the lubricating slots, radial sealing dam and circumferential sealing seal and bearing composed weir part. Can also open slot seal is slotted plane seal and bearing combination. Its advantage is less leakage (or even no leakage), membrane large and thick, eliminate contact friction, power consumption and little calorific value. Thermal fluid dynamic pressure sealing technology is to use the various shapes of deep groove, sealing surface flow caused by the partial thermal deformation, in order to generate fluid dynamic wedge effect. This has the hydrodynamic pressure of carrying capacity of sealing, called thermal fluid dynamic wedge seal.
              Bellows seal technology can be divided into molding metal bellows and welding metal bellows mechanical seal technology.
              Many end face sealing technology into double seal, middle ring seal, sealing technology. Another PingHangMian sealing technology, monitoring seal technology, combined sealing technology, etc.

 7, mechanical seal sense mechanical seal flushing plan and characteristics
              Flush the aim to prevent impurities accumulate, prevent airbag integrating formation, maintain and improve the lubrication, when rinses temperature is lower, both cooling effect. Flush the way are mainly as follows:

            A, flush
                   1, is flush

                  (1) features: use to work of host was sealed medium, by pump outlet through the pipe into seal chamber.

                 (2) : used for cleaning fluid, P1 slightly greater than P into, when high temperature or impurity, may in piping Settings cooler, filters etc

                2, backwash

                 (1) features: use to work of host was sealed medium, by introducing the pump outlet seal chamber after rinsing through the pipe flows back to pump inlet.

                 (2) : used for cleaning fluid, and the P into three. Fully flush

                 (1) features: use to work of host was sealed medium, by pump outlet through the pipe into seal chamber, rinse again after the concession road flows back to pump inlet.

                (2) application: cooling effect is better than the former two for cleaning fluid, and P1 and P into and P out inferiorly close.

               Second, the flush
              Features: introducing the system and sealed media compatible clean fluid to seal chamber flushing.
              Application: outside rinses pressure shall than sealed media big 0.05-0.1 MPA, suitable for medium for high temperature or solid particles occasion. Rinses flow should guarantee take away heat, still need to meet the needs of washing, won't produce on the seals of erosion. Therefore, to control seal chamber pressure and flush flow, general cleaning rinses velocity should be less than was/S, Contains particles pulpous state liquid shall be less than 3M/S, to achieve the above velocity value, rinses and seal chamber pressure should be "the difference in value of 0.5 MPA, generally take 0.05-0.1 MPA, double seals advisable to 0.1-0.2 MP. Rinses enter and exhaling seal chamber of the orifice position, should be installed in the seals nearby, and should near acting-ring side, in order to prevent graphite ring eroded or uneven deformation caused by temperature difference for cooling, and impurity accumulation and coked etc, can use tangential introduction or multi-point flushing. When necessary, rinses can be hot water or steam.

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