Page 5 of 5

Posted: Sat Apr 07, 2007 9:45 am
by Craig_Bridge
Replacement tungsten bulbs are fairly easy to find:
http://bulbster.com/lightbulbs/sm1460x-p-890.html
http://www.jkllamps.com/store.cfm?Product_ID=1630&page=details.cfm
Before ordering, take a look at the existing bracket assembly and determine that these are the correct bulb mountings. Various companies sold different replacement bracket/bulb/socket assemblies for their replacement parts. If these fit your existing brackets, then you will pay more to ship 4 bulbs than for the bulbs themselves!

The N-905-LB (lamp with bracket assembly) goes for around $45 + shipping http://www.novabiotech.com/lampprices.html

Louise gave you most of the precautions for handling these bulbs, but I re-iterate: These Tungsten bulbs are extremely high wattage bulbs for their size and get extremely hot and are very sensitive to dust and finger prints. DO NOT USE medical gloves when handling these as they often contain latex dust or other powder to make them easy to put on. Clean cotton work gloves or microfiber gloves used in film processing are better. Unlike projector bulbs that have a coated safe place to hold them, these do not. Before opening the new bulb package, wipe down and use some canned air to blow out the dust from the instrument.

Posted: Sat Apr 07, 2007 11:11 am
by Louise
Craig_Bridge wrote:Replacement tungsten bulbs are fairly easy to find:
http://bulbster.com/lightbulbs/sm1460x-p-890.html
http://www.jkllamps.com/store.cfm?Product_ID=1630&page=details.cfm
Before ordering, take a look at the existing bracket assembly and determine that these are the correct bulb mountings. Various companies sold different replacement bracket/bulb/socket assemblies for their replacement parts. If these fit your existing brackets, then you will pay more to ship 4 bulbs than for the bulbs themselves!

The N-905-LB (lamp with bracket assembly) goes for around $45 + shipping http://www.novabiotech.com/lampprices.html

Louise gave you most of the precautions for handling these bulbs, but I re-iterate: These Tungsten bulbs are extremely high wattage bulbs for their size and get extremely hot and are very sensitive to dust and finger prints. DO NOT USE medical gloves when handling these as they often contain latex dust or other powder to make them easy to put on. Clean cotton work gloves or microfiber gloves used in film processing are better. Unlike projector bulbs that have a coated safe place to hold them, these do not. Before opening the new bulb package, wipe down and use some canned air to blow out the dust from the instrument.


I agree that ordering a new bulb is a good idea- the spec 20 is a really nice tool for a school to have. Since the solutions have already been made, I don't think a new bulb will help for this project, since even with overnight shipping the earliest they will arrive is Tuesday.

As for gloves, I think (but could be wrong) that most places have moved away from powdered gloves, particularly powdered latex (due to allergies). Unpowdered nitrile gloves are really common and widely used everywhere I have been, and fine for this purpose.

Craig and I have emphasized safety because this can be dangerous. This isn't really any more dangerous that the chemicals you have already worked with. I've changed many lamps of this type and the majority of times there are no issues. I've had lamps explode (due to a defective batch of lamps we purchased) and I have a healthy respect for the damage they can do. As long as the box holding the lamp is closed when you power up, if the lamp explodes the damage is limited to what is in the box. Other than that one run of bad lamps, I've never had problems with lamp changing. But I work slowly, carefully, and I always wear the appropriate safety gear. (I highly recommend long sleeves and long pants too.) Again, only enter the lamp chamber when you are certain the power is off (and I prefer unplugged) and the lamp has cooled.

Louise

Posted: Sun Apr 08, 2007 10:19 am
by vanillabean16
yeah, i talked with my teacher, and we came to the conclusion that the lamp is dead. she also agreed that given the age of the spec 20 and the fact that it is NEVER ever used, buying a bulb specifically to use for about 2 hours would be pointless... and the school isn't to good about lending money. to any department.
so i'm going to go with my next best bet.. a colorimeter. if that doesn't work, i quit.
but thanks! :)

Posted: Sun Apr 08, 2007 10:28 am
by Louise
vanillabean16 wrote:yeah, i talked with my teacher, and we came to the conclusion that the lamp is dead. she also agreed that given the age of the spec 20 and the fact that it is NEVER ever used, buying a bulb specifically to use for about 2 hours would be pointless... and the school isn't to good about lending money. to any department.
so i'm going to go with my next best bet.. a colorimeter. if that doesn't work, i quit.
but thanks! :)


well, don't quit! You can rank them by eye.

The lamps themselves are not that expensive, about $5 each. It is just when the lamp assembly is incuded that is cost $45.


Louise

Posted: Wed Apr 11, 2007 5:25 pm
by vanillabean16
ok so i have the colorimeter. its a Hach DR/890 colorimeter. i figure it HAS to be able to measure total transmittance, right? i just have to figure out how....

Posted: Wed Apr 11, 2007 5:56 pm
by Louise
vanillabean16 wrote:ok so i have the colorimeter. its a Hach DR/890 colorimeter. i figure it HAS to be able to measure total transmittance, right? i just have to figure out how....


Is this it?
http://www.hach.com/hc/search.product.details.invoker/PackagingCode=4847000/NewLinkLabel=DR&frasl%3B890+Portable+Colorimeter

From that page, under FAQ...


Absorbance or %T measurements with DR/820, DR/850, or DR/890

Problem Description:
How do measure Absorbance or %T with the DR/820, DR/850, or DR/890 Colorimeter?

Problem Solution:

Enter the first two numbers of the wavelength you wish to use as the program number. Then press the ABS %T key to change between absorbance and % transmittance.

The DR/890 Colorimeter has wavelengths of 420, 520, 560, and 610 nm. Press PRGM, then 42, 52, 56, or 61 to measure absorbance at 420, 520, 560, or 610 nm with this instrument.


You can try the 520 nm light. I don't know how well it will work.


Louise

Posted: Sun Apr 15, 2007 1:13 pm
by vanillabean16
well, thats that! i'm all done!
today i used the colorimeter to measure the samples. They all turned some shade of pink, which was good.
Here are the averages of the 4 readings of each in %T.
Green Tea: 45.02
Green w/ Skim: 61.03
Green w/ Whole: 38.2
Black: 49.92
Black w/ Skim: 64.41
Black w/ Whole: 35.2
so as the paper said, pink color is formed in the presence of flavonoids. So more pink color (and more flavonoids) results in less transmittance, which makes sense comparing Green tea to green tea with skim, and black tea to black with skim. The whole milk samples are weird though.. they were pretty cloudy so im assuming thats why they have such low transmittance readings. So i can't really use them.
But overall, the results are good enough to conclude from. Don't add milk to your tea. :)

But basically, i just want to say (again) that i am so so soo thankful that you helped me with this, as someone to bounce ideas off of. i would have made a LOT of mistakes if it hadn't been for your advice, and i really appreciate everything. This project would have been nearly impossible without your help. So, thank you for all the time you spent with me on this.. it was time well spent, i must say!

sincerely,
emily.

Posted: Sun Apr 15, 2007 3:53 pm
by Louise
vanillabean16 wrote:well, thats that! i'm all done!
today i used the colorimeter to measure the samples. They all turned some shade of pink, which was good.
Here are the averages of the 4 readings of each in %T.
Green Tea: 45.02
Green w/ Skim: 61.03
Green w/ Whole: 38.2
Black: 49.92
Black w/ Skim: 64.41
Black w/ Whole: 35.2
so as the paper said, pink color is formed in the presence of flavonoids. So more pink color (and more flavonoids) results in less transmittance, which makes sense comparing Green tea to green tea with skim, and black tea to black with skim. The whole milk samples are weird though.. they were pretty cloudy so im assuming thats why they have such low transmittance readings. So i can't really use them.
But overall, the results are good enough to conclude from. Don't add milk to your tea. :)

But basically, i just want to say (again) that i am so so soo thankful that you helped me with this, as someone to bounce ideas off of. i would have made a LOT of mistakes if it hadn't been for your advice, and i really appreciate everything. This project would have been nearly impossible without your help. So, thank you for all the time you spent with me on this.. it was time well spent, i must say!

sincerely,
emily.


Glad thinks worked out. I'm not surprised about the cloudiness of whole milk...

Let us know how the science fair goes!

Louise (who drinks black tea, no milk)

Posted: Tue May 01, 2007 3:13 pm
by vanillabean16
Well, the science fair is DONE!! Whew.
aaannddd....

i won first place in the chemistry category!

I am so happy! And of course, everyone here, especially Louise, was a huge help! I doubt i could have done ANY of it without your advise. And just look where it got me, first place! You should be proud of yourselves. I appreciate it soooo much. I really don't know how to thank you.

But thanks for absolutely everything. You were wonderful to have :)
-Emily.

Posted: Tue May 01, 2007 3:51 pm
by Louise
vanillabean16 wrote:Well, the science fair is DONE!! Whew.
aaannddd....

i won first place in the chemistry category!

I am so happy! And of course, everyone here, especially Louise, was a huge help! I doubt i could have done ANY of it without your advise. And just look where it got me, first place! You should be proud of yourselves. I appreciate it soooo much. I really don't know how to thank you.

But thanks for absolutely everything. You were wonderful to have :)
-Emily.


Congrats! First place! Glad everything worked out- you certainly had some bad luck with the spec20... You should be proud of yourself too. You picked a really difficult experiment, and used some pretty sophisticated chemistry and instumentation. You also did a ton of trials, which is always a good thing, despite how much time it takes. We had the easy part- sitting around, drinking tea (with out milk!), and making suggestions! :D

Louise