The sealing structure and type
The sealing structure and type
1,inflow and outflow
According to the direction of media leaks divide into inflow and outflow.
Inflow : Media in radius direction leak from face 's peripheral to the inner.
Outflow: Media in radius direction leak from face's inner to the peripheral.
The direction of inflow leak is contrary to the centrifugal direction ,centrifugal force preventing fluid leak ,so the inflow leak volume is smaller than outflow. therefore, when there is solid particle in the media ,we should choose the inflow .this can prevent the solid particle into seal face.
2,built-in and outside fitted
According to the spring if contact with media divide into inside and outside mounted.
Inside mounted is the spring into the media ,Such asCR 58U,59U,M7N,68series,491, 591,9T mechanical seals.
outside mounted is the spring is out of the media.
Outside mounted 's characteristic: generally speaking most of mechanical seal's parts are not contact with media. they're expose outside of the device. Ease to observation, repair and install .but for outside media structure ,the media's effect is contrary to spring force, when the media press has fluctuate or higher, spring energy is not bigger, spring unstable situation will arise so that happen leak . when the media press is lower, for spring force is no change ,the seal face load increase, especial at low voltage startup, there is no liquid film between the seal faces. Easily bruised seal faces.
Inside mounted the force is better .when open the device ,the media press is lower, a small spring force can make the seal face close. It's easy to form liquid film of seal faces at lower press . the inside mounted face pressure increase with the media pressure. Therefore increase the reliability for seal.
3,balance and unbalanced
Mainly divide into the loading degree on the face effect by medium.
4,Rotariry and stationary type
According to the spring 's movement divide into rotary and stationary type .
Rotary type: spring and axle structure is simple and small radial dimensions.
Under high speed conditions, spring and other rotating parts generated a lot of centrifugal force. dynamic balance have a bigger requirement .some of media will easy crystallization after strong mixing .in this case choose static type is more appropriate.
5,single spring and multi–spring
Single spring is only one spring install with axle in mechanical seal device.
Such as CR17D,41,80,120,M2N,24,BIA,JC1,MG912 mechanical seals.
Multi-spring is there are many springs following circular distribute uniform.
Such as CR 58U,58B,59U,59B,8T,9B,U1002 mechanical seal
Normally a lesser load and mass produce it's better to choose single spring seal .
Small –batch produce and when used under strict conditions can use multiple spring seal.
6,single face ,double face and multi face
According to the logarithm of friction surface divide into single face ,double face and multi face.
Single face :only have one seal face in mechanical seal .
Such as CRMG1 elastomerbellowseal ,M7N,M2N,JC21,24,155,250,950,US2,68.491,58U,59U,560A,502,Cartex-SN GU1,GU2 cartridge seal,609,680 metal bellow mechanical seals.
Double face :there are two seal faces in the mechanical seals and both of them stay in same liquid pressure.
Such as :Burgmann type M74A,M74D.560C,GUO Cartridge seal,
There are more than 2 seal faces in mechanical seals and the press in the seal cage is progressively lowering.
Judging from the structure, sing face is more simple than double face. it's more easy in manufacture and assembly and disassembly. also have a widespread use.
Double faces need to another device for the liquid to the seal cage generate sealing and lubrication effect. single face seal apply to general occasions, double seal face apply to strong corrosion ,high temperatures ,suspended particles and fibers in the media, gas media, flammable and explosive media, volatile and low viscosity medium ,high vacuum, precious materials, demand media and air cut off and leakage cases are allowed.