Zebralight quality??

[De-Lux]

Well, we were trying to explain to you how the mentioned testing standards work in real life, but you two obviously have no interest in listening.

Testing standards? Lack there of maybe. Apparently the IP68 spec standard is nothing more than a "cop out" for flashlight manufacturers. I have no problem with a light not being water proof but it should be clearly stated if so. In this case it is not clear at all.

So, other than giving flashlight manufactures something to hide behind, what is the point of the IP86 "standard"?

 

[Marduke]

what is the point of the IP86 "standard"?

The point of the IP68 standard is to give a maximum delta P and time condition for testing of that component.

Sorry to disappoint, but that does NOT describe an actual depth rating at which that component can be used.

 

[Marduke]

I do not believe he made a good effort, he stated an opinion that the IP ratings does not mean what it says, but he proved no links to any documents that supported his opinion.

It's not opinion. Pressure is pressure. How you get there in real use depends on MANY other aspects besides just depth.

 

[De-Lux]

Sorry to disappoint, but that does NOT describe an actual depth rating at which that component can be used.

So, then why is it that in Europe, they are obligated to give an actual depth rating at which that component can be used in regards to the IP68 standard? Do we use an amended version of the IP68 "standard"? We must use the complacent American version of the standard.

 

[Marduke]

So, then why is it that in Europe, they are obligated to give an actual depth rating at which that component can be used in regards to the IP68 standard? Do we use an amended version of the IP68 "standard"? We must use the complacent American version of the standard.

Again, I think you are confused. There is a BIG difference between the rating which a product can withstand, and which a product can be used.

It is also possible to underrate a product to IP standard to a usage depth instead of a max delta P condition. Since this rating is conservative, it is technically correct and perfectly acceptable.

It could also be the case of certain companies with uniformed management who cannot understand the spec to incorrectly interrupt the requirement as a usage standard. Since this is conservative, no one is going to tell them it's wrong.

This is exactly why high end watches quote atmospheres or torr or bars of pressure instead of depth. The users of these high end product understand that that pressure WILL occur at a depth LESS THAN the static pressure associated with the specification. They also understand that to maintain the appropriate factor of safety, that the "usable" depth is further decreased.

 

[HKJ]

It's not opinion. Pressure is pressure. How you get there in real use depends on MANY other aspects besides just depth.

It is yours opinion, please find some other reliable source that explains why a norm that states "immersion beyond 1 m" does not require immersion beyond 1 m. No dynamic pressure, we are talking about still water, not moving water or objects.

 

[Marduke]

It is yours opinion, please find some other reliable source that explains why a norm that states "immersion beyond 1 m" does not require immersion beyond 1 m. No dynamic pressure, we are talking about still water, not moving water or objects.

Huh?

The entire point is that 1m depth in testing does NOT equate to 1m depth of usage. The pressures don't match.

As shown earlier, you can be at 0m depth, where a simple raindrop can equal 300m of pressure for a brief instant.

 

[HKJ]

Huh?

The entire point is that 1m depth in testing does NOT equate to 1m depth of usage. The pressures don't match.

In my books they do, but I will prefer to have some safety rating. Try reading about ISO6425 for divers watches. They test at 125 meter for 100 meter.

As shown earlier, you can be at 0m depth, where a simple raindrop can equal 300m of pressure for a brief instant.

I do not really believe you calculations and the guy that wrote the above wiki article does only add 5 meter dynamic pressure for fast swimming and mentions something about an urban myth and dynamic pressure.

 

[De-Lux]

Here is a quote from Barbarin in regards to this very subject.

In Spain and in Europe the norm is very clear. IP 68 followed by a number and "m" means how deep it will keep the IP68 characteristics. (example IP68 200 m) This followed by a M letter also means that the properties will be kept while moving parts are actuated.

This being said, Zebralight should not claim IP68 standards and "3 meters for 30 minutes". They should state one or the other. Not both. Hense the confusion.

 

[Marduke]

I do not really believe you calculations and the guy that wrote the above wiki article does only add 5 meter dynamic pressure for fast swimming and mentions something about an urban myth and dynamic pressure.

Don't believe me? Do them yourself and see what you get...

 

[De-Lux]

As shown earlier, you can be at 0m depth, where a simple raindrop can equal 300m of pressure for a brief instant.

Dude, where are you getting your info? 300 meters? 900 feet? Are you high?

 

[Marduke]

Dude, where are you getting your info? 300 meters? 900 feet? Are you high?

I previously linked it above. Since some people seem to have a hard time looking up in threads, I have posted it again to save you the trouble.
http://www.candlepowerforums.com/vb/showthread.php?p=2925629#post2925629

 

[De-Lux]

I previously linked it above. Since some people seem to have a hard time looking up in threads, I have posted it again to save you the trouble.
http://www.candlepowerforums.com/vb/...29#post2925629

Can you send me a link to a post that was written by someone other than yourself?

 

[Marduke]

Can you send me a link to a post that was written by someone other than yourself?

Sure
http://www3.interscience.wiley.com/journal/119580205/abstract?CRETRY=1&SRETRY=0

http://www.publish.csiro.au/paper/SR01112.htm

http://www.tucson.ars.ag.gov/unit/Publications/PDFfiles/MAN_2.pdf

Natural raindrops range from 2-6mPa impact pressure. I calculated a large free falling raindrop. Smaller raindrops product less pressure because of a slower speed (2mPa), and wind driven large raindrops can produce an even higher pressure (6mPa).

 

[HKJ]

Don't believe me? Do them yourself and see what you get...

Considerable less, more like 0.5 meter of water, but then I also uses another formula:
http://en.wikipedia.org/wiki/Dynamic_pressure

 

[Marduke]

Considerable less, more like 0.5 meter of water, but then I also uses another formula:
http://en.wikipedia.org/wiki/Dynamic_pressure

The pressure created by a raindrop impact is not a case of dynamic pressure, which requires moving flow.

An equation doesn't do you much good if you don't know how and when to apply it.

View my above posts....

 

[De-Lux]

What you fail to realize is that the type of pressure a rain drop produces is not the same as the pressure created by being submerged. A rain drop will not cause the pressure within the torch to change. It will not cause any gasses within the torch to compress. That being said, your rain drop example is not relevant. You see, pressure is not pressure as you so ignorantly stated earlier in your post!

 

[HKJ]

The pressure created by a raindrop impact is not a case of dynamic pressure, which requires moving flow.

Then I would expect the pressure from a raindrop to be even less.

But we are talking about putting something under water, i.e. the pressure that we are interested in, is the dynamic pressure from moving water and the formula I linked to does that.
This also shows that the wiki article I linked to probably is very correct in stating that maximum dynamic pressure when swimming is less than 5 meter water pressure.
And the conclusion from that, is that dynamic pressure does not have a big effect on anything just because it is dipped in 10 cm water.

An equation doesn't do you much good if you don't know how and when to apply it.

View my above posts....

Of the 3 links, only one works and does not mention anything about the pressure of raindrops.

 

[Marduke]

What you fail to realize is that the type of pressure a rain drop produces is not the same as the pressure created by being submerged. A rain drop will not cause the pressure within the torch to change. It will not cause any gasses within the torch to compress. That being said, your rain drop example is not relevant. You see, pressure is not pressure as you so ignorantly stated earlier in your post!

Pressure is pressure, so yes, it is the same.

No external pressure will cause the light internal pressure to change. It would have to crush the light to do so. A high delta P will simply find the weakest point of failure.

The only difference, as I stated, is the area and time of action, which does play a part. But pressure is still pressure.

 

[Marduke]

Then I would expect the pressure from a raindrop to be even less.

Based off what? Gut feeling? Common sense?

But we are talking about putting something under water, i.e. the pressure that we are interested in, is the dynamic pressure from moving water and the formula I linked to does that.
This also shows that the wiki article I linked to probably is very correct in stating that maximum dynamic pressure when swimming is less than 5 meter water pressure.
And the conclusion from that, is that dynamic pressure does not have a big effect on anything just because it is dipped in 10 cm water.

Add 5m + 10cm for me, and compare that to 1m 😗

Of the 3 links, only one works and does not mention anything about the pressure of raindrops.

I fixed the 3rd link. All three sources state the same. The first link states it right out front in the abstract, the other two cite it in the body.

Results indicated maximum stresses of 2–6 MPa acting for about 50 microseconds on the perimeter of a circle corresponding with the shape of the initial rebound corona.