Parking In The Sun - Can It Shatter Windscreen ?

[eyepea]

Can parking in the sun with all shutters up cause the windscreen to shatter due to build up of air pressure inside a car ?

(I think effects of parking under the sun, w.r.t paint, damage to plastic interior parts etc was discussed in a previous post. But I don't recall the above concern being discussed. Any links, pls give).

Someone mentioned that when a car was parked all day long under the hot sun, suddenly the windscreen had shattered. No hard object falling on the windscreen had been noticed. At the garage it has been told that this is due to parking under the sun with all shutters up and the air pressure building inside the car.

I cannot ascertain the truth of this as the person who told me had heard it from another.

1) Is something like this possible or it may be just B.S ?

2) If all shutters are up, and supposing the cabin air intake is set to recycle, does it effectively seal the cabin or restrict air flow to such an extent such that there can be a pressure build up as claimed?

3) Long time back, I got the windscreen replaced in a car. After the new windscreen was put, and the glue or what ever was left to dry, the bass kept the shutters down saying if shutters are up, the hot air pressure inside will push the windscreen out before the glue hardens. Is there any truth in this ?

4) Supposing there was a small crack or something on the windscreen, is it possible for sufficient air pressure build up to shatter a windscreen ?

Thanks!

[Sifaan]

Can parking in the sun with all shutters up cause the windscreen to shatter due to build up of air pressure inside a car ?

(I think effects of parking under the sun, w.r.t paint, damage to plastic interior parts etc was discussed in a previous post. But I don't recall the above concern being discussed. Any links, pls give).

Someone mentioned that when a car was parked all day long under the hot sun, suddenly the windscreen had shattered. No hard object falling on the windscreen had been noticed. At the garage it has been told that this is due to parking under the sun with all shutters up and the air pressure building inside the car.

I cannot ascertain the truth of this as the person who told me had heard it from another.

1) Is something like this possible or it may be just B.S ?

2) If all shutters are up, and supposing the cabin air intake is set to recycle, does it effectively seal the cabin or restrict air flow to such an extent such that there can be a pressure build up as claimed?

3) Long time back, I got the windscreen replaced in a car. After the new windscreen was put, and the glue or what ever was left to dry, the bass kept the shutters down saying if shutters are up, the hot air pressure inside will push the windscreen out before the glue hardens. Is there any truth in this ?

4) Supposing there was a small crack or something on the windscreen, is it possible for sufficient air pressure build up to shatter a windscreen ?

Thanks!

Let's say inside air temp is 25 Celsius (298 Kelvin) and the temperature goes up even 20 degrees to 45 Celsius (that's 318 Kelvin). Increase in air pressure would be 6.7% (gas pressure is approx. proportional to absolute temperature) - assuming the car is perfectly airtight. I very much doubt if a thick glass like a windscreen can shatter due to such small pressure difference.

I think even this level of difference won't happen because the extra pressure would compress seats (so volume would increase and pressure would decrease) and/or there would be ways for air to leak out.

[Watchman]

a car aint airtight. hundreds of places air can leak in/out

[jdnet]

while I doubt you could build up pressure in a car, excess heat, alone, could cause a glass to break IF it already has a small crack. the expansion and contraction of the glass could turn a a pretty large one. I have had this happen in cold weather. I had a crack the size of an eraser on a pencil, the first day of cold weather turned it into a crack significantly larger than it's original size and over the weeks it cracked from one corner of the windshield to the other.

[Killer-B]

while I doubt you could build up pressure in a car, excess heat, alone, could cause a glass to break IF it already has a small crack. the expansion and contraction of the glass could turn a a pretty large one. I have had this happen in cold weather. I had a crack the size of an eraser on a pencil, the first day of cold weather turned it into a crack significantly larger than it's original size and over the weeks it cracked from one corner of the windshield to the other.

Not what you could expect in a tropical country.

[SeanD]

QUOTE (Killer-B @ Sep 5 2010, 08:26 PM) <{POST_SNAPBACK}>

Not what you could expect in a tropical country.

Actually, I've had the exact same happen in severe heat, where a neglected crack from a flying pebble on the highway in cold weather lead to the exact same thing happen during the summer Granted this was in a part of the world where summer temperatures regularly hit 43-45 celcius, and the sun was the strongest I've ever felt. This is not something I've experienced even in the hottest parts of Sri Lanka at the hottest times of the year. In any case, as was mentioned above, cars are not airtight, and if this was a common occurrence it should have been remedied in the last 50 years or so.

[harshansenadhir]

cars aren't built to be airtight. If you observe the boot space carefully you'll notice there are one way flaps to let go of additional air comes into cabin space, such as closing a door very fast. This flap helps in stabilizing cabin pressure, no hanky panky high tech, simple rubber flap opens one-way. However, there can be instances where our maka baas fellows have meddled with these (such as, closing of fresh air-intake to increase efficiency of A/C, closing down every possible hole when doing some tinkering) might end up making a cabin area little air tight. You would feel a sudden pressure on your ear(s) when closing a door of such vehicle.

However, even with such modifications, pressure built up inside the cabin won't be high enough to crack a windscreen.

[topgear]

A weird thing happened to a relative's van a few months ago. The front right shutter was malfunctioning so the van was sent for repair. when the van came back home and parked, not 5 minutes passed but we hear a loud noise of shattering glass. The shutter that had been repaired had just exploded. for no real reason. no one threw a rock at it or anything. it just happened. Even the driver was freaked out.

We suspected a heat build-up could have caused this. But then, how hot should it get for glass to burst like that!

[Killer-B]

Actually, I've had the exact same happen in severe heat, where a neglected crack from a flying pebble on the highway in cold weather lead to the exact same thing happen during the summer Granted this was in a part of the world where summer temperatures regularly hit 43-45 celcius, and the sun was the strongest I've ever felt. This is not something I've experienced even in the hottest parts of Sri Lanka at the hottest times of the year. In any case, as was mentioned above, cars are not airtight, and if this was a common occurrence it should have been remedied in the last 50 years or so.

again, not what you could expect in Srilanka

[Watchman]

A weird thing happened to a relative's van a few months ago. The front right shutter was malfunctioning so the van was sent for repair. when the van came back home and parked, not 5 minutes passed but we hear a loud noise of shattering glass. The shutter that had been repaired had just exploded. for no real reason. no one threw a rock at it or anything. it just happened. Even the driver was freaked out.

We suspected a heat build-up could have caused this. But then, how hot should it get for glass to burst like that!

if the vehicle was brought home and parked; and the driver got down, the preasure would have equalized with the atmosphere. And 5 mins is NOT enough for the air in the van to naturally heat up to such a temp (even if we presume that the van is airtight) and cause the glass to burst.

I presume the shutter repair was done and the glass was nto properly fitted. This probably applied some stredd/force on one single point of the glass causing it to stress/compress more due to all the vibrations while being driven back, and just snapped...

[SeanD]

A weird thing happened to a relative's van a few months ago. The front right shutter was malfunctioning so the van was sent for repair. when the van came back home and parked, not 5 minutes passed but we hear a loud noise of shattering glass. The shutter that had been repaired had just exploded. for no real reason. no one threw a rock at it or anything. it just happened. Even the driver was freaked out.

We suspected a heat build-up could have caused this. But then, how hot should it get for glass to burst like that!

Well the side windows are of tempered glass but is not laminated (i don't think) unlike the windscreen, so when it meets with an impact it does not just cave in like the windscreen but will literally explode into shards. Since you say the front shutter was sent for a repair it's very possible that the glass had some error in it in the first place, and they did something that changed the amount of stress on the shutter when putting it back in and it was at the point of fracture due to door closing/street vibration. Given the exact right circumstances I guess there is then the chance that the thing can explode the way it did. Kinda like a glass breaking if you set it down too hard on the table. Or perhaps it was at the edge of breaking when an insect collided with it or the neighbour shot a BB gun at it Maybe someone else has a better explanation but I've never heard of this happening and that would be my guess.

Edited September 6, 2010 by SeanD

[topgear]

the glass shattering when the vehicle was moving is understandable but I couldnt understand how it shattered after the vehicle was parked. I forgot to ask my relative if he found the reason behind this. Must ask him next time I see him.. Coz it's not something that happens everyday ne!

[Sylvi]

the glass shattering when the vehicle was moving is understandable but I couldnt understand how it shattered after the vehicle was parked. I forgot to ask my relative if he found the reason behind this. Must ask him next time I see him.. Coz it's not something that happens everyday ne!

Members,

Windshield Glasses Crack normally when there is a Crack ( Star or Chip) on same and the cracked legs of the crack can extend due to weather conditions like heat of the mid day or you drive to a rain after driving under hot sun shine that is because sudden changes of the temperature of the Windshield glass this happens only on safety glasses.

I have never come across due to Air pressure build inside of the car parking under hot sun conditions.

Normally when you park under hot sun during 10.00 AM to 3.00 PM in old cars where there is corrosion under the bonded end of the glass a line will start and than can extend to the center of the Windshield glass.

All Windshield glasses are made with safety Glasses and fitted on to Automobiles by reputed manufactures in the Automobile industry. I have come across some Chinese New Vehicle Imports with Tempered glasses and few Japanese new exports to Srilanka 15 years ago had Tempered glasses and Srilankan replacements. Due to the cost of Safety glasses.

Above is my Experience for last twenty two Years in Windshield glasses.

Wijesinghe.

[hakjay]

QUOTE (Killer-B @ Sep 5 2010, 02:56 PM) <{POST_SNAPBACK}>

Not what you could expect in a tropical country.

If it were the case, the windscreen business in countries like Dubai will be booming