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.