Polysulfide sealant polyurethane sealant brief description of the

Sealants are used to fill the gaps ( holes, joints, seams , etc. ) of the material , both bonding and sealing two functions . Polyurethane sealant with silicone sealant,printed cable ties polysulfide sealant sealant composition of the current high-end of the three varieties.
Polyurethane sealant widely used in civil construction, transportation and other industries :
The application of the building - doors and windows , such as glass filled seal ;
In the civil aspects of the application - highways, bridges , runways , etc. caulking seal ;
In automotive applications - window ( mainly windscreen) seal assembly .
Polyurethane sealant has many excellent features ,
Including :
( A ) Performance adjustable range, strong adaptability
( 2 ) good wear resistance ;
( 3 ) mechanical strength ;
( 4 ) good adhesion properties ;
( 5 ) good elasticity , excellent resilience , can be used for dynamic joints ;
( 6 ) good low temperature flexibility ;
( 7 ) good weather resistance, strap seals long service life of 15 to 20 years ;
( 8 ) oil resistance ;
( 9 ) resistance to biological aging ;
( 10 ) affordable.

High performance soft seal butterfly valve

Characterized in that : said seat ring by a T -shaped tamper evident tape ring on both sides of the soft multi-layer stainless steel sheet .
Valve plate and valve seat sealing surface for the oblique cone structure , oblique cone surface of the valve plate welding temperature, corrosion resistant alloy material ; adjusting ring plate fixed on the spring between the platen adjustment screw assembly structures. This structure effectively compensate for tolerances between the sleeve and the valve stem in the medium band and elastic deformation under pressure to solve the two-way valve in the transmission medium of exchange sealing problems exist in the process .
Use of soft T seals on both sides of multilayer stainless steel sheet , with a metal seal and soft seal the dual advantages of both low and high temperatures, both with zero leakage sealing performance . Test proved positive Chi flow state ( medium flow direction and the disc rotation in the same direction ) , the sealing surface pressure is the transmission of torque and media pressure on the valve plate produced by interaction . Forward medium pressure increases, the valve plate oblique cone surface and the valve seat sealing surface squeezed more tightly , sealing the better .
When the counter state, the valve plate and valve seat seal for containers between the drive torque to the valve plate is pressed against the valve seat . With reverse media pressure , the valve plate and valve seat pressure between the units is less than the medium pressure, adjusting ring spring contained in the subject after the deformation energy stored in compensation valve plate and valve seat sealing surface of the clamping pressure play the role of automatic compensation .
Therefore, the utility model, unlike the existing technologies, as the valve plate mounting hardware multi ring, but directly mounted on the valve body , the middle seat in the platen and an additional adjustment ring is a very good way to two-way seal . It can replace the valve, and ball valve .

Porous mechanical seal processing methods Analysis

Mechanical seal mechanical security seals structure of porous structure. Ring seal ring is flat, flat end face of the stationary ring arranged with uniform pores rules to form a porous face. Microporous round hole, oval hole or tapered bore.
Diameter from a few microns to hundreds of microns, hole depth from a few microns to tens of microns, porosity (pore area percentage of the total face area) from 5% to 30%.indicative seals The surface roughness of the porous end with the same stationary ring surface roughness, Ra are 0.01 ~ 0.02μm.
Porous mechanical seal processing methods
Cover depth micron processing flow slots or pores, conventional machining methods are almost powerless. So people explored a variety of processing methods, mainly the following: photochemical etching process (photolithography), EDM (electric etching), electrochemical machining and laser processing method.
Compared to conventional processing techniques, laser processing for a wide range of different materials, different shapes are suitable for machined surfaces with no mechanical deformation of the workpiece, clean, fast, good repeatability and high degree of automation. Obviously, for the porous mechanical seal rings, the other processing methods are powerless, only the use of the laser processing method in order to obtain satisfactory results.
Friction performance test
End load with the seal ring, respectively, and the common seal ring laser processing porous comparison test, two kinds of seal ring face size, surface roughness, end load and speed, etc. are identical test conditions, carbon graphite material of the seal ring sealing ring paired with both tests run. Laser Surface mechanical seal mechanical seal friction coefficient than the average coefficient of friction is much lower. From the friction coefficient of view, high security bolt sealsordinary mechanical seal friction coefficient in boundary friction state, and laser processing porous mechanical seal friction coefficient in mixed and even liquid friction state, therefore, the laser processing of porous seal ring seal rings than ordinary has better friction properties.

About the gear pump mechanical seal requirements

Mechanical seals, also known as face seal (Mechanicalseal), is a dynamic seal rotating shaft mechanical seal performance and reliable amount of leakage, long life, low power consumption. Need frequent maintenance, and can adapt to the production process automation and high temperature, low temperature, pressure, vacuum, high speed, and various corrosive media. medium containing solid particles and other harsh conditions of the hungry sealing requirements. mechanical seal is rely on one or more pairs of lip perpendicular to the axis relative to the end face of the fluid dynamic pressure and the compensation mechanism stretch * (or magnetic) to keep under seal and then combined with the auxiliary shaft seal leakage resistance achieved devices gear pump mechanical seal requirements, mechanical tamper seals and soft packing seal is as follows:
Benefits:
1) reliable sealing, long-term operation in a sealed state is very stable, very small leak, the leak is about 1% of soft packing seal:
2) long life, in oil, water media generally up to 1 to 2 years or longer in the chemical medium generally work more than six months:
3) rub the power consumption, the friction power is only the soft packing seal 10% to 50%
4) essentially no shaft or sleeve wear:
5) maintenance cycle. Face wear can be automatically compensated, under normal circumstances do not require regular maintenance and repair:
6) resistance to shock, vibration of the rotating shaft and the shaft deflection of the sealed chamber insensitive:
7) applies to a wide range of mechanical numbered seals can be used for high temperature, low temperature, high pressure, vacuum, different rotation frequency, and a variety of corrosive media and media containing abrasive seal.

Three eccentric metal seal butterfly valve structural features interpreted

1 , three eccentric multi-level metal seal butterfly valve butterfly plate stacked rings of hard and soft metal sheets , metal seals and elastomeric seals with the dual advantages of both low and high temperatures, both with excellent sealing performance.

2 , the use of three-dimensional eccentric structure , seat and disc almost no friction parts inside the valve when closed almost no damage ; This structure greatly improves the performance of the valve in use . And has a more closed more tightly sealing function .

3 , the stem , the lower part is equipped with bushings , each bushing wear and friction generated is small , this structure can prevent wear and adhesion, but also improve the service life.

4, the valve sealing surface , the use of alloy steel or stellite alloy,barrier security seals  sealing surface abrasion, erosion , corrosion resistance ; long service life.

5 , unique structure , switching torque is small , flexible operation, labor-saving , convenient, high pressure from the media , low-impact , reliable sealing performance . Can be used for opening and closing and regulating equipment .

Soft sealing gate by friction resolve technical design

First, the technical background :

Existing in the body of the valve , the valve cover and the case member are intact , only slight deformation or corrosion of the sealing surface , the valve can not be used . Fix these valves non-professional plant can not, therefore resulting in a great waste . Therefore, the use of units of hope Valve is : seat , the valve plate sealing surface is not easy deformation , corrosion , wearing sealing material can be changed . In opening and closing the valve plate not to have friction with the sealing surface or minimize friction, avoid soft sealing gate various deficiencies .

Second, the purpose of the invention :

Solve the seat and the valve plate sealing surface corrosion or deformation , the valve plate can automatically compensate and close the cover and press the soft sealing gate automatic pressure balance between the problems solved by the soft sealing material sealing surface friction and damage problems due to the valve sealing cap can be changed, greatly increased the use of valves .

Third, the practical range :

Bore φ50-φ400mm, pressure 2.5-4.0MPa, less than 200 ℃ for various liquid at room temperature

Fourth, the technical solutions :

The valves are double parallel gate valve , numbered seals inlet seals, inlet valve plate by a sealing sleeve and unloading force composed mainly sealed gate valve plate . Sealing sleeve and valve plate unloading force synchronous movement but not connected to the pipeline pressure through the valve plate unloading force , leveling arm passed to the exit side of the seat , which will greatly improve the soft sealing surface adhesion. Valve plate outside the set of a corrosion-resistant rubber seal sets. Soft sealing material in the opening and closing process , and the seat to keep a certain distance , the soft sealing material in the absence of friction without folding pressure environment. Gland in the pipeline transportation of the liquid components within the valve isolation , nylon cable tie corrosion and impurities from the liquid blocking . This valve is very easy to replace a sealing material , so the service life is generally more than 5 times the gate valve .

Machine impurities into the seal face wear and tear caused by

The seal face contact and friction is normal, can enter the seal face of the solid impurities are very subtle , it is easy to seal water away , so there is no leakage of the sealing effect . Larger solid particles into the seal face , causing increased wear of the case , are not working properly sealed occur . Divided into the following situations:
( 1 ) In the downtime or maintenance after the initial test , the pipe seal dirty or poor water quality , solid impurities easy access to the seal faces . Therefore, the mechanical seal friction surface wear faster .
( 2 ) double mechanical seal in the sealing water pressure fluctuations , or below the pump , the pressure inside the pump body with chemical impurities into the medium from the inner end face of the seal chamber , some impurities remain in the sealed end face , resulting in increased wear and tear , single-acting mechanical seal built , due to media pressure fluctuations , seal face into the possibility of impurities is much smaller than the double-end , relatively longer life expectancy.
( 3 ) due to various reasons impurities into the seal face . Early peroxide mechanical seal face severe wear , wear mechanism from view, the main particle abrasion , adhesion wear only take place in a particular case , so we only discuss the wear particles . Peroxide particles wear rate is high , greatly reducing the service life of mechanical seals . Wear particles not only soft sealing ring ( graphite ring ) wear , but also hard seal ring ( mainly carbide ring ) wear particles generally worn surface has obvious rules nicks and grooves. The essence of wear particles in the vertical component of the hard particles under the action of the friction surface piercing , while under the action of the tangential component of the relative movement, so that the friction surface micro- machining process and plow . Wear particles and the hardness of the material not only than the pressure on the end face , and the microstructure of the material and the test temperature , load and stress the nature of the size , the size and hardness of the abrasive and chemical properties of the friction surface and other factors.
Friction pairing material hardness difference , tamper seal tape a great impact on the wear particles . Friction large difference in hardness , wear particles appear much less the case , friction and wear rate is also small ; but the hardness difference is small , the more wear particles occurs . The main reason is because when particles invade friction , high hardness in the ring , only embedded in graphite or graphite ring on the ring groove on wiping the hard ring is not bruised, but also to maintain the original finish , over a period of time the particles may also be sealed water washed away. The particles invade the friction surface , moving ring hardness is low, due to the hard ring is scratched , the effect of vibration and eccentric , such as rasp file graphite ring , causing serious wear and tear. Meanwhile abrasions ring itself is also growing . After running-in , snap ring groove surface and the surface of the graphite ring concentric grooves gradually coincide , then the leakage reduction .
In addition , stationary ring or ring leakage inlet end , if the chamfering is too large, larger particles can also lead into the friction surface along the slope , causing premature wear .
For special circumstances , tamper evident label special measures should be adopted , in the car or the initial sealing water is quite poor , in order to avoid premature wear of the mechanical seal failure , end than the pressure to increase the use of temporary practice , you can receive significant effect , due to increase spring pressure and no significant increase in friction wear particles contrary avoid early wear and extended service life.

Centrifugal pump mechanical seal failure causes

1, the static ring sealing surface leakage
Main reasons are: face flatness, roughness does not meet the requirements, or surface scratches ; face between particulate matter , resulting in both ends of the surface can not be the same run ; installed in place , incorrectly.
2 , the compensation ring seal leak
Main reasons are: gland deformation, uneven preload ; installed incorrectly ; seals do not meet quality standards ; ring selection is wrong.
Actual results showed that most parts of the failure of the sealing element is dynamic and static ring end face mechanical seal centrifugal dynamic and static ring face is a common failure occurs cracking phenomenon for two main reasons :
① sealing surface when installing the gap is too big , too late to rinse away the heat generated by friction ; flushing fluid leakage from the sealing surface clearance to go , resulting in overheating and damage to the end face .
② liquid medium vapor expansion , so that both ends of the surface by the vapor expansion force to separate , when the two sealing surfaces when bonding force , resulting in destruction of the lubricating film facing surface overheating.
③ poor lubricating liquid medium , together with the operating pressure overload, the two sealing surfaces trace rotation is not synchronized. Such as high speed pump speed is 20445r/min, central diameter of the sealing surface 7cm, pump operation after the line speed up 75m / s, when there is a lag can not track the rotating sealing surface , the sealing surface is damaged resulting in instantaneous temperature .
④ sealing fluid orifice or filter is clogged , causing water shortage, so that the mechanical seal failure.
In addition , the sealing surface slippery surface ditch , face a gap of bonding lead to failure of the sealing element ,nylon cable ties two main reasons:
① dirty liquid medium , a small hard particles , people at high speed sliding sealing surface , the end surface scratches and failure.
② poor coaxial transmission parts pump , the pump is turned face each revolution is shaking friction once, moving ring running track misalignment , causing vaporization face , overheating wear.
③ liquid medium caused by the frequent occurrence of hydraulic characteristics of pump vibration , resulting in the sealing surface dislocation and failure.
The sealing element is a liquid medium corrosion, stress concentration , with soft and hard materials , erosion , secondary seal O-ring , V -ring , is not compatible with the liquid medium concave ring , deformation, surface damage can cause failure of the mechanical metal cable ties , so form of damage to its comprehensive analysis to identify the root cause , to ensure the long-running mechanical seals .

Polysulfide sealant range of applications

Although polysulfide sealant expensive, application subject to certain restrictions, but because it has a variety of excellent physical and chemical properties, so in a variety of major projects on both widely used.
1 , the construction industry : a large building roof seal. Such as the Three Gorges Left Bank Power House roof,container security seals the roof of Chairman Mao Memorial Hall , Tiananmen roof.
2 , hydraulic : Shanxi Yellow River Diversion Project , the Three Gorges permanent lock of expansion joints, Guangdong Dongjiang-Shenzhen Water Diversion Project .
3 , the airport road : western suburbs of Beijing airport renovations , Zhengzhou airport , airport Zhangjiakou part of the project .
4 , sewage treatment plants : According to incomplete statistics, 80% of domestic sewage treatment plant expansion joints are sealed using polysulfide sealant .
5 , Metro and Tunnel : Beijing subway station Andingmen waterproofing , Tiananmen East Station roof are sealed with a polysulfide sealant .
6 , aerospace industry: aircraft fuel tanks, cockpit seals ( military products ) .
7 , the automotive industry : car door shock seal.
8 , petrochemicals : gasoline, kerosene , diesel fuel storage tanks of various anti-corrosion seal. meter seals Chemical product storage tank seal , such as Power Group PAC workshop Jiaozuo Chemical storage tank is the crystallization of our sealant, a long time in about 80 ℃ and acidic environments, has been more than six months found no leaks phenomenon .
9, the electrical and electronic industry: such as refrigerators, freezers glass doors.

Slag pump mechanical seal

Slag pump is a gear pump , the mechanical seal device and discuss problems , also called seal mechanical seal , he is relying on springs and seals in the pressure of the media twisted the ring and stationary outer ring contact pressing force occurred on the right , is that the two end faces tight fit. Face a very thin oil film between the stick ,high security seal when the media after great resistance to prevent liquid leak , in order to reach the goal sealed , while the ring and stationary ring has a smooth probation . Adapt well to complete no leak .
Mechanical seal features: slag disposal pump mechanical seal problems and discussion of the mechanical seal primary strengths are sealed securely in an application cycle, leaked rarely ; probation long life, you can usually use five years ; maintenance cycle. But the mechanical seal structure is complicated, built-in , repairing mechanical seal pump should stop crashes often heavy workload . Thus , to ensure reliable mechanical seal work , delay the use and life of the mechanical seal is very important.
Mechanical seals in their daily operations , prone to many problems. Mechanical seals to attack the primary problem is the amount of leaked tolerance and temperature is too high, touch the mechanical seal gland, If you can not stay on top , to clarify the temperature is too high. Leaked amount should not exceed 60 drops each side / min.wire seals If a linear flow , then clarified excessive leak can be sure they can look operation ; if outward injection , you should immediately check the downtime

Factors affecting the performance of the valve seal

Assessment of the valve is the valve sealing performance merits of the main indicators of quality . Valve sealing performance mainly include two aspects, namely, leakage and leakage . Endoleak refers to the closure member between the valve seat and sealing of the media reach , assessment criteria within the country there are two missing . One is the State Technical Supervision Bureau released in December 1992 , June 1, 1993 began the implementation of a national standard GB/T13927-1992 " universal valve pressure test ." This standard is used with reference to the international standard ISO5208-1982 " industrial valves valve pressure test " developed ; another was issued by the Ministry of Machinery Industry JB/T9092-1999 " valve testing and inspection ," This standard is referenced API598- 1986 " valve inspection and test " developed . GB/T13927-1992 for general industrial valves inspection ; JB/T9092-1999 industrial valves for the oil inspection . Leakage refers to the parts of the stem packing leak , the leak in the flange gasket and valve parts casting defects caused due to leakage, leakage is simply not allowed. If the media is not allowed into the atmosphere , then the leakage of seal leakage than the inner seal more important. Therefore, the valve sealing performance should lead to the manufacturer 's attention.
Factors affecting the performance of the main valve seal are: ① sealing surface quality ; ② sealing surface width ;plastic padlock security seals ③ valve before and after the valve pressure difference ; ④ sealing surface material and its processing status ; ⑤ media properties ; ⑥ surface hydrophilicity ; ⑦ seal film presence ; ⑧ closed parts of rigidity and structural characteristics .
⑴ quality sealing surface of the valve sealing performance of the sealing surface of the valve seat and the closure member is in contact with each other to shut down part. When the sealing surface pressure at 40MPa or less, the quality of the sealing surface of the valve sealing performance play a decisive role . This is because : When the sealing surface pressure is small, low surface roughness , the leakage is increasing rapidly . When the sealing surface pressure is large, the surface roughness on the leakage has been significantly reduced .
⑵ width on the valve sealing surface of the sealing performance of the sealing surface width determines the length of the pores . When the width is increased, fluid movement along the pores stroke lengthened to increase the resistance movement . Can be reduced to increase the width of the sealing surface pressure in the valve erosive wear . Increase the width of the sealing surface , it will cause leakage increased in proportion to the stroke length , and thus be able to proportionately reduce leakage. But the sealing surface width increases , in the same sealing force , vehicle seals the sealing pressure than decreases, but also make the possibility of leakage increases. Therefore, the increase can not be unlimited sealing surface width.
⑶ valve before and after the valve differential pressure on the valve sealing performance is analyzed theoretically , valves before and after the valve pressure difference is proportional to both the amount of leakage . But tests proved : in other conditions are the same , the leakage volume growth is increasing pressure differential over . Leakage between the pressure difference can be approximated by the following formula : G = M (N △ P2 + S △ P) where : M, N, S - constant coefficients, which depend on the material , the sealing surface processing quality , the sealing surface pressure and other conditions ; △ P - pressure differential.
⑷ sealing surface materials and their processing status on the valve sealing performance of the sealing surface materials and their processing status of the valve leakage have a great impact . As the remaining gap between the seal faces depends on the sealing surface micro-roughness , so that , if the use of steel materials, seals, resulting in sealing of the same , there must be greater than the pressure , the value must exceed brass system value than the pressure seal . The sealing surface of the processing state , such as a peak distortion , and sealing the gap size changes and other phenomena occur on the metal surface , it is clear that the performance of the surface properties of the base material have significant difference . Induced changes in the machining surface can affect the thickness of 50μm. Grinding the base metal is not exposed . Work is different from the metal surface tissue matrix organization . Geometry and material properties and microstructure geometry compared to little effect . Differences in the performance of metal , usually less than other factors . Sealing surface when working under low pressure conditions , the situation is more prominent. When the pressure ratio is higher than 40MPa , the surface roughness of the sealing performance is reduced , and the impact of the material is increased.

Spiral Labyrinth Seal

Spiral labyrinth seal is used in industry long ago, and it is different from the spiral seal in that: the axis of the helical groove machined surface , the holes in the sealing collar is made also vehicles , and has opposite the shaft screwed to the shaft and screw suites stark turbulent flow . Additionally , labyrinth seal spiral screw velocity higher than the sealing screw , which turbulent flow conditions for low viscosity liquids. cable marker ties Spiral laminar flow conditions generally used for sealing large -viscosity liquid ( such as viscosity liquids than water ) .
How it works: In between the screw and the threaded sleeve work space, the liquid in the collar two tooth surfaces and screw two tooth surfaces bounded by a number of cellular space . Screw and the gap between the threaded sleeve surface was grooved annular cylinder . Fluid through the vortex formed when the threads , the direction of flow in the opposite direction . As the screw fluid flow around a momentum exchange results , security seals screw the energy to liquid. Helix and threaded sleeve with the liquid interaction that results in through the gap between the screw and the threaded sleeve surface frictional force is generated in the name of boundaries . Friction generated by the liquid in between the screw and the threaded sleeve pressure .

Several sealing material on Q

1 fluorine rubber and nitrile materials What is the difference ?
Answer : Viton and NBR rubber seals are commonly used materials . As for petroleum based hydraulic fluids nitrile better compatibility , as a sealing material has good stability ,metal security seals the price is cheap, so in the hydraulic , pneumatic seal widely used. Viton is the best overall performance synthetic rubber sealing rubber . Carbon atoms, fluorine rubber, a fluorine atom primary key replacement, stable molecular structure . Its heat resistance, good chemical stability. Therefore, in high temperature applications and special occasions more media .
(2) What is the rubber material elongation ?
A: The elongation rate is the reciprocal of stiffness of a material index , the amount of materials used in the natural state of tension length ratio expressed as a percentage . Material allows elongation is not in permanent damage or permanent deformation occurs before the maximum elongation.
3 What rubber material breathable ?
A: refers to the gas permeability of the material in pneumatic sealing and vacuum -sealed material should be noted that this performance .
4 sealing material FPM, FKM What is the difference ?
Answer : FPM is ISO 1629 abbreviation of fluorine rubber , FKM Viton is ASTM 1418 in the name abbreviation . FPM and FKM are referring to the same kind of Viton, wording is different because the European and American English are spelled differently .
5 braided packing material type which of these categories ?
A: Many types of woven material , according to the material of natural fibers, mineral fibers,barrier security seals synthetic fibers, ceramic and metal fiber four categories.
6 often said that self-healing is the kind of material ?
A: Flexible graphite .

How to eliminate the external conditions on the effects of mechanical seals for pumps

The pump mechanical seal is used, not only to consider the mechanical seal itself, influencing factors, tamper evident seals but also to consider a variety of mechanical seals external factors .
1 large measure to eliminate channeling shaft
Rational design of axial force balancing device , eliminate the axial channeling . To meet this requirement , for multi- stage centrifugal pumps, ideal design is twofold: one is to balance the axial thrust bearing plate plus , the balance disc balance the axial force , the axial thrust bearing on the shaft for axial limit ; balancing drum plus the other is an axial thrust bearing , the balance drum axial force balance out the most , and the remaining axial force by thrust bearings bear , while the axial thrust bearing for the shaft axis to the limit . The second scheme is the key to the rational design of balancing drum so that it can really balance out most of the axial force. For other single-stage pump in a pump and other products, are designed to take some measures to ensure that the amount of the mechanical shaft seal channeling the required range.
(2) Measures to eliminate the axial force is too large
Rational design of axial force balance mechanism , so that it can truly and fully balance out the axial force to the mechanical wire seal to create a good condition. For some plants , petroleum, chemical and other fields important products , in the factory before the test must be done to detect and Taiwan and Taiwan issues and solve problems. Some pumps can be important to design a rotor axial measuring ring , on the size of the axial force at any time to monitor , identify problems and timely solutions.

Heat pumps and cooling pump eight differences

Heat pumps and cooling pump eight differences are as follows :
A heat pump models are generally expressed by the letter R , cold oil pump with the letter J represents waterproof labels.
2 , heat pumps pump with vertical segmented , and cold pump pump with horizontal split , some heat pump to prevent the pump centerline structures.
3 , the heat pump orifice ring gap bigger. Cold oil pump is smaller.
4 , the average heat pump seal oil seal agencies note , and cold pump not inject .
5 , the heat pump timber multi- carbon steel , alloy steel , and cold pump can be made ​​of cast iron .
6 , the heat pump bearings, bearing boxes, packing boxes mechanical seals require water cooling , and cold pump can not use .
7, the heat pump needs to warm up before the start , but with cold pump , the cooling pump is unnecessary .
8, the use temperature of 200 degrees Celsius for the cold pump, 200 degrees Celsius for the heat pump identification cable ties.

Rotating cell to ring mounting method

Installation Instructions:
1 cusp requirements deburring, vehicle seals chamfering blunt or install seals case of thread, requiring additional protection to prevent damage to seals.
(2) Any rust , dirt , debris or foreign particles must be removed.
3 not allowed to use the tools with sharp corners .
4 Before installation , cylinder, rotary shaft and seals need to apply oil or grease . If grease, its composition does not contain solid additives ( such as molybdenum disulfide, zinc sulfide or the like ) .
5 . PTFE slip ring can be in oil or water heated to 80 ~ 120 ℃, PTFE slip ring expands , it is easier to install on the piston or rod .
Mounting shaft rotary Grameen circle :
Shaft rotation Grameen ring is usually installed in a closed groove :
1 . The first O-ring into the groove , while pressing the PTFE slip ring heart shape , but be careful to prevent breakage
(2) the state of the pressure on the slip ring PTFE O- ring , and then a rod ( usually with 10 ~ 15 °) direction of the arrow Flatten PTFE slip ring , to restore the original size security seals .

Select two aspects of imported bearings mechanical seal structure

Bearing structure type mechanical seal selection is an important step in the design cycle , you must first be investigated : ① operating parameters of the medium pressure , temperature, shaft diameter and speed . ② the concentration of dielectric properties , viscosity, corrosion , with or without solid particles and fibrous impurities are easily vaporized or crystallization . ③ host work characteristics and environmental conditions continuous or intermittent operation ; mainframe installed in the indoor or outdoor ; atmosphere surrounding the nature and temperature changes. ④ host allowable leakage seal leakage direction ( internal leakage or leakage ) requirements ; life and reliability requirements. ⑤ host sealing structure or size. ⑥ operation and production process stability .
1, according to the operating parameters p, v, t Selection
Where p is the pressure of the medium at the sealed chamber , according to the size of the p-value can initially determine whether to select balanced structure and the degree of balance . NSK Bearings for medium viscosity, good lubricity , p0.8MPa, or low viscosity, poor lubricating medium , p0.5MPa when the structure is usually used unbalanced . p-value exceeds the above range , you should consider using balanced structure. When p> 15MPa , generally single face -balanced structure is difficult to achieve sealing requirements , then you can use multiple tandem seal .
Refers to the average diameter of the circumferential sealing surface velocity , depending on the value of the size of the elastic member to determine whether the rotation with the shaft , which uses a rotary spring or spring static structure , generally <20 ~ 30m / s in a rotary spring can be higher speed conditions, the rotating parts can lead to strong vibration unbalance mass , preferably spring stationary structure. If p and values ​​are high, considering the selection of hydrodynamic structure.
t is the seal cavity medium temperature , FAG bearings based on t determine the size of secondary seal material, the sealing surface of the cooling method and its auxiliary systems. Temperature t in the range of 0 ~ 80 ℃ , secondary seal is usually chosen nitrile rubber O-ring ; -50 ℃ t <150 ℃, according to the strength of corrosive media , the choice of fluorine rubber, silicone rubber or Teflon molding packing ring: temperature < -50 or t150 ℃ , the rubber and PTFE will produce low or high temperature aging embrittlement , metal bellows structure can be used at this time . Medium turbidity higher than 80 ℃, in a sealed area is usually necessary to be considered at high temperatures , the cooling time must take appropriate measures .
Second, according to media characteristics selection less corrosive media
Usually use the built -in mechanical security seals , SKF bearing its face the stress state and the direction of media leaks than the external and reasonable. For strongly corrosive media , the more difficult the selection of the spring , the choice of external or PTFE bellows type mechanical seal , but generally only applicable p0.2 ~ 0.3MPa range.
Easy to crystallize , easy coagulation and high viscosity medium , large springs should be used rotating structure. Because small spring easily be blocked solids , high viscosity media make small spring axial compensation movement blocked.
Flammable, explosive, toxic media , in order to ensure that the media does not leak , you should use a sealing liquid ( liquid separation ) of the double-end structure .
Press the dielectric properties of the selected operating parameters and the structure is often only a preliminary program , INA Bearing ultimately determine the host must also consider the characteristics and the sealing of some special requirements. For example, the rocket engine seal life just a few minutes , but requires a short time absolutely does not leak .nylon cable ties Sometimes hosts on the ship in order to obtain a more efficient space , the size of the seal and mounting position are often made ​​very demanding , and if the drain pump on submarines , submarine ups and downs in the process, the pressure varies widely and so on. In these cases , it is not the conventional structure of the selection criteria , and must be specially designed for the specific conditions , while taking the necessary complementary measures.

Pump Mechanical Seal Overhaul Mistakes

1 greater the amount of spring compression seal better. In actual fact , the spring compression excessive friction can cause rapid wear , instantly burning ; excessive compression of the spring to lose the ability to adjust the ring face , resulting in seal failure.
2 ring seal Fig tight as possible . In fact, ring seals tight harm than good. First exacerbate inter- ring and sleeve wear, premature leakage ; Second, increasing the axial adjustment ring , the resistance movement , frequent changes in operating conditions can not make timely adjustments ; Third spring fatigue easily damaged ; four is to make the ring seal deformation, affecting the sealing effect.
3 stationary ring seal tight as possible . Stationary ring seals basically at a standstill , the effect will be relatively tight seal better, but too tight is harmful. One cause static ring security stickers due to excessive deformation, affecting the sealing effect ; Second, the majority of graphite stationary ring material , generally more brittle , excessive force can easily cause fragmentation ; three is to install , difficult to remove , easy to damage the stationary ring .
4 Impeller lock nut tight as possible . Mechanical seal leakage , the leakage between the sleeve and the shaft ( shaft between the leak ) is relatively common . Generally, the impeller shaft between the leak is not locking the lock master , in fact, lead to leakage between axes many factors , such as the failure of inter-axis pad , offset , there are impurities between axes , with the shaft and sleeve at a larger shape bit error , the contact surface damage , there is a gap between the shaft parts , threaded shaft is too long , and this will lead to leakage between the shafts . Lock nut locking pad between axes can only lead to excessive premature failure , contrary moderate lock locked mother , so that the shaft between the pads always maintain a certain degree of compression flexibility in operation will be automatically timely lock nut locking , so that the shaft is always in a good inter- the sealed state .
5 The new better than the old . In contrast, using the new mechanical seal better than the old , but the new mechanical seal quality or choice of material is not the time , with the larger size of the error will affect the sealing effect ; and permeability in the polymerization medium, the stationary ring without excessive wear, or not to replace as well. Because static ring stationary ring seat for a long time in a quiescent state , the polymer and impurities deposited as a whole, played a good seal.
6 overhaul better than not split tamper seal. Once the mechanical seal leakage will be eager to overhaul , in fact , sometimes sealed and not damaged , simply adjust the working conditions or the seals can be adjusted to eliminate leakage. This way to avoid waste and to verify their ability to judge the fault has accumulated experience in maintenance to improve the quality of maintenance .

Reactor with a mechanical seal principle introduced

Mechanical seal is by one pair or several pairs perpendicular to the axis relative to the sliding face in the fluid pressure and compensation institutions elastic ( or magnetic ) to keep under seal affixed to achieve the merger with auxiliary shaft seal leakage resistance device .
Common mechanical seal structure consists of stationary ring ( stationary ring ) 1, the rotating ring ( ring ) 2, the elastic element 3, the spring seat four , set screws 5 , 6 secondary seal rotating ring and the stationary ring seal 8 and other auxiliary components , anti-rotation pin 7 is fixed to prevent the gland 9 stationary ring is rotated . Rotating ring and the stationary ring often also according to whether they have the ability to compensate for axial cyclic or compensation is also referred to as compensation .
Mechanical seal possible leakage of fluid channels are A, B, C, D four channels.
C, D leakage channels are stationary ring and the gland , the gland seal between the housing , the two are static seal .ss cable ties B channel between the rotary shaft sealing ring and , when Friction and wear , it can follow the compensation ring only for a small amount of movement in the axial direction , in fact, still a relatively static seal .
Therefore, these leak paths are relatively easy closure. The most commonly used static sealing rubber O-ring or PTFE V-ring , and as compensation or stationary rotating ring ring ring secondary seal , sometimes using both elastic elements feature rubber, PTFE or metal bellows structures.
A channel is a rotating ring and the stationary ring opposite end faces sliding Lamination dynamic seal , it is the mechanical seal device of the main seal , mechanical seal in determining the performance and life of the key. Thus , the processing requirements of the seal face is high , while the sealing end faces in order to maintain the necessary lubrication film , the system must be strictly the end surface of the cavity pressure per unit area , the pressure is too large, difficult to form a stable lubricating film , will accelerate the end wear ; pressure is too small , increase of leakage . Therefore, to obtain good sealing performance and enough life , in the design and installation of mechanical seals , we must ensure that the pressure per unit area of ​​face value in the most appropriate range.
Mechanical seal with relatively soft packing seal , has the following advantages:
① reliable sealing in a long period of operation, the sealed state is very stable, very small leakage , wire seals according to rough statistics, the leakage is typically only soft packing seal 1/100 ;
② long life in oil, aqueous medium, generally up to 1 to 2 years or more, usually in the chemical medium can be more than six months ;
③ friction small power consumption of the mechanical seal is only soft packing seal friction power of 10% to 50%.

Chemical pump mechanical seal options introduced

No leakage is always the pursuit of chemical equipment , it is this requirement led to the application of magnetic pump expanding . However, truly no leakage is still a long way to go, such as magnetic pump containment shell life issues, pitting the material problems of static trailer seals sealing reliability issues and so on. Now on some basic aspects of seal briefly as follows:
A seal forms for static sealing , it is usually only two forms of gaskets and seals , and O-ring seals Youyi most widely ; For dynamic sealing , chemical pumps rarely used packing seal, mechanical seal based , mechanical seals have single face and double face , balanced and unbalanced type of points , balanced for high pressure sealing medium ( usually refers to pressure greater than 1.0MPA), double end mechanical seal is mainly used for high temperature , easy to crystallize , there viscosity, containing particles and toxic volatile media , double end mechanical seal should insulating liquid is injected into the sealed chamber , the pressure is generally higher than the medium pressure 0.07 ~ 0.1MPA.
2 , the sealing material chemical magnetic pump static sealing materials commonly used Viton, PTFE used under special circumstances materials ; mechanical seal ring material movement configuration is more critical , and not on the best carbide cemented carbide ,vehicle seals high prices on the one hand , the hardness difference between the two is not too unreasonable , so it is best treated differently according to media characteristics .

Asphalt pump mechanical seal repair errors introduced

1, the ring seal tight as possible . Asphalt pump stationary ring seals basically at a standstill , the effect will be relatively tight seal better, but too tight is harmful.
One cause static ring seals due to excessive building deformation, affecting the sealing effect ; two is mostly static ring material with graphite . Generally more brittle , excessive force can easily cause fragmentation ; three is to install , difficult to remove , easy to damage the stationary ring .
2, the new better than the old . Relatively new asphalt pump mechanical seal better than the old , but the new mechanical seal quality or choice of material is not the time , with the larger size of the error will affect the sealing effect : and permeability in the polymerization medium, such as non- stationary ring excessive wear, or not replaced as well. Because static ring stationary ring seat for a long time in a quiescent state , the polymer and impurities deposited into one. Played a better Plastic seal.
3 , static overhaul than never dismantle good, asphalt pump mechanical seal leakage will occur once the rush to overhaul . In fact , sometimes sealed and not damaged , simply adjust the working conditions or the seals can be adjusted to eliminate leakage. This way to avoid waste and to verify their ability to judge the fault has accumulated experience in maintenance to improve the quality of maintenance .
4 , impeller lock nut tight as possible . Asphalt pump mechanical seal leakage , the leakage between the sleeve and the shaft ( shaft between the leak ) is relatively common , generally believed that the impeller shaft lock nut ask leak did not lock their buying lead to leakage between axes many factors , If lapse between axes pad , offset shaft ask there impurities, with the shaft and sleeve at a larger form and position errors , contact surface damage. shaft there is a gap between the various components ; shaft threaded shaft is too long , and this will lead to between the leak. Lock nut locking pad between axes can only lead to excessive premature failure , contrary moderate lock locked mother, so always keep a pad shaft ask Piece Goods compression elasticity, in operation lock nut locking automatically timely , so that the shaft is always in a good inter- the sealed state .
5 , ring seals tight as possible , in fact, detrimental tight ring seals . First exacerbate the wear ring and sleeve between leakage ; Second, increasing the axial adjustment ring , the resistance movement , frequent changes in operating conditions can not make timely adjustments ; Third spring fatigue easily damaged : four is to make the move ring security stickers deformation, affecting the sealing effect.
6, the greater the amount of spring compression sealing the better . Its buy Otherwise, spring compression excessive friction can cause rapid wear , instantly burning ; excessive compression of the spring to lose the ability to adjust the ring face , resulting in seal failure.

Characteristics of the various types of sealant summary

Sealant definition:
Typically bituminous , natural resins or synthetic resins such as natural rubber or synthetic rubber or dry dry viscous material as the base material , with talc , clay , carbon black, titanium dioxide and inert fillers such as asbestos , then add plasticizers, solvents , curing agent and catalyst is made.
Sealant Category:
Can be divided into elastic sealants, liquid sealing gasket and sealing putty three categories.
Sealant Application:
Widely used in construction , transportation, electronic instrumentation and components of the seal.
Sealant by use classification :
1 Building Sealant
Such sealants for building a variety of sealing seams or holes to prevent gas , liquid, solid through and prevent displacement of structural materials in the structure is destroyed, wire seals and thus play a thermal insulation, sound insulation, waterproof, dustproof , anti-gas , fire , corrosion , vibration and prevent accumulation of foreign joint function .
2 automotive sealant
Automotive sealant is a modern car engine repair emergence of new sealing material , automotive sealant variety, it can be applied to different parts of the car . For example, it can be a good solution to car engine leaking oil spills and leaks and other issues.
3 electrical insulation potting sealant
In order to ensure the motor , electrical components and electrical properties of stable and reliable mechanical strength required between the conductors , the gap between the insulation and the outlet lead security seal labels.
4.Packing Sealant
Sealing an important part of the packaging . Sealing a direct impact on packaging effect , packing and storage life , and even affect the credibility of the packaging .