6 factors affect the vacuum insulating glass quality
Vacuum insulating glass,is becoming the new trend for building envelope.Architect and designers like this low thermal transmittance,high sound acoustic performance,and thin energy efficient glass product for their newest brilliant projects.
Recent years,more and more factories invested in vacuum insulating glass production and claim to have the highest quality,but how to judge the quality of vacuum insulating glass? This posts will analysis the factors affecting vacuum insulating glass quality to help you selecting the best VIG products.
Factors affect vacuum insulating glass quality
The thermal insulation performance is decided by the the vacuum degree and the low-E coatings.
For most glass factories, double silver low-E is widely used with similar emissivity, then vacuum degree becomes the deciding factor affecting the final vacuum glass U value.
Each factory develop their own vacuum glass production lines while the vacuum degree is different.
Simulation based on Window 7.5 shows VIG U value is 1.13w/m2.k with 10-2Pa, 0.51W/m2.k with 10-3Pa and 0.44 with 10-4Pa.That’s the reason why many manufacturers manage to produce VIG with 0.4W/m2.k and some others 0.7W/m2.k,sometimes the vacuum degree is unstable which cause unstable U value even though it’s produced in the same line.
HaanGlas produce the vacuum insulating glass at 10-4 high vacuum degree and our 10.3mm VIG with double silver low-E steady state U value test result is 0.47W/M2.K.
Tempered vacuum glass or annealed glass?
Since its innovation in 1993,vacuum glass production technology developed very slow and had almost all glass were anneal vacuum glass,It’s limited by the edge sealing technology.Till now,many international brands still produce anneal VIG ,which has limited application .
Tempered vacuum glass has 3-5 times higher strength than normal float VIG.Its mechanical strength ,impact resistance ,and wind resistance enable the architects to apply them on more industry,especially glass facade,greenhouse glass, BIPV ,and replace triple glazing glass used in passive houses,etc.
Different from others,HaanGlas not only produce fully tempered vacuum insulated glass,but also has minimum thickness 6.3mm.To cooperate the large area glass facade requirement,our recommended Max size for different vacuum glass thickness are below:
3+0.3V+3 tempered vacuum glass: 1000 *1500mm
4+0.3V+4 tempered vacuum glass: 1500*2500mm
5+0.3V+5 tempered vacuum glass: 1700*3200mm
Edge sealing technology.
Edge sealing technology for vacuum insulating glass can be classified into 2 types: Glass powder solders and low temperature metal edge sealing.
Sealing with glass solders is the earliest and most traditional edge sealing technology,it’s now used by most vacuum glass manufacturers worldwide.The disadvantage of this technology is,during sealing process,the solder must be heated to combine 2 pieces glass,which will affect the already tempered glass to anneal again,glass edge strength will decrease by 15-25%.
To solver this problem,many manufacturers will temper the glass in high compression status,then after sealing,the edge compression will decrease to normal level.
But this won’t solve the problem- uneven glass strength,the uneven glass strength will cause high glass breakage ratio.
Another edge sealing technology is low temperature edge sealing.It’s sealed by low temperature metal materials,typical manufacturers are Land glass and HaanGlas.After several years market promotion and projects all over the world,Landvac has proved the high quality of metal edge sealing technology.
Same as Landvac,HaanGlas vacuum insulating glass is also sealed with low temperature metal edge sealing technology under 250℃，the low temperature keep even glass strength and ensure low spontaneous breakage ratio.
Even glass strength.
Despite above mentioned glass edge sealing technology affect the overall glass even strength,other notches or holes on glass also affect glass strength as well.
Some manufacturers products has evacuation holes to eliminate the air inside the vacuum space,then seal the hole.Some products even place the evacuation holes at glass edge,whether it’s holes or notches,will cause concentrated strength at the holes and cause higher breakage ratio after installation.
Another factor affecting the strength is the micro supporting pillars,the misplacing or duplicated pillars will increase the contact area between glass and the pillars,so glass will has high breakage ratio if the pressure on certain pillars,especially when the pillar is in Cylindrical shape.
HaanGlas eliminated these factors affect glass quality: HaanGlas vacuum glass has no evacuation holes as the edge sealing is finished in the high vacuum condition, edge sealing and vacuum process is finished in the same time,while others need to seal glass first and then make it vacuum space.
Micro supporting pillars,Each HaanGlas supporting pillars consist 3-5 round balls with even smaller dimension and smaller contact area with the glass.
Glass lifetime is decided by the edge sealing performance,and the gutter to absorb moisture penetrate into the glass after years.
Some manufacturers make it stripe shape along the glass edge and some others make it round shape.
1.Based on same quantity,round ones has smaller area than stripe ones.
2.Whether it’s round or strips,processors has to have groovs on glass surface,the bigger groove,the higher spontaneous breakage ratio during tempering.
3.Each factory has its technology and production method,just depend on whether customers like it or not..
HaanGlas vacuum insulating glass use 12mm gutters to absorb the moisture and prolong the lifetime of VIG to 25years and even longer,after 25 years,the vacuum degree may degree and slight dew points may appear,this won’t affect the overall thermal and acoustic performance.Beside that ,HaanGlas offer 15 years warranty.
The most widely used low-E coatings in VIG products are high transparency 1.16 coating,when applied in 6-16AR-6 insulated glass,glass U value reach 1.16W/M2.K.But the most important is its high light transmittance.
While each project is different,especially in hot areas which require low transmittance and even low-E coating on body tinted glass to achieve lower SC and SHGC.
HaanGlas is more flexible in the coating selection,we offer more than 100 different low-E coatings options for your project,same as Insulated glass products,whatever you can apply in insulated glass,we can apply it on vacuum insulating glass as well.
HaanGlas is your turnkey vacuum insulating glass manufacturer,kindly contact us if any requirement.