UV lamp outputs

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kendragon

kendragon

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Mar 23, 2009
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I'm in the process of measuring fluence rate of lamps made in USA and China. MicroWatt/cm^2 will be measured from a digital light meter. Four different sizes of each will be observed. What will take the longest is the building of the test stand.
This should tell us if there are any differences in output for the same wattage bulbs. I'm betting the US bulbs will have better efficiency.

Phase II would be to confirm dose with a digital flow meter.

Will update when ready.

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the output of uv lights is also influanced by the length of travel through the water, 185nm uv light, which is a little more efficiant than 254nm but doesnt travel through water nearly as well as the 254nm. also a polished stainless steel housing will reflect the uv light inside the chamber alot better then pvc or plastic housings, which the uv can degrade over time.

can i ask why you need to be so exact on your uv doseage? a proper sized uv light working at 40mJ/cm2 Dose will sterilize 99.9% of the water that passes through, oxidizing all the carbon containing organizms, including good bacteria. this is what is used on our ultrapure water system at my work to produce sterile water for manufacturing, something that is not needed in the aquarium world at all.
 
This should be interesting. As mentioned the dwell time is a factor, but that should be easy to figure with flow rates and volume of the housing.
 
Stay tune
 
frickr said:
the output of uv lights is also influanced by the length of travel through the water, 185nm uv light, which is a little more efficiant than 254nm but doesnt travel through water nearly as well as the 254nm. also a polished stainless steel housing will reflect the uv light inside the chamber alot better then pvc or plastic housings, which the uv can degrade over time.

can i ask why you need to be so exact on your uv doseage? a proper sized uv light working at 40mJ/cm2 Dose will sterilize 99.9% of the water that passes through, oxidizing all the carbon containing organizms, including good bacteria. this is what is used on our ultrapure water system at my work to produce sterile water for manufacturing, something that is not needed in the aquarium world at all.
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Not all bulbs are the same. There are good bulbs and bad. The dose program take lamp efficiency into account. Not all 25W lamps put out the same. So how do you know? You don't. You believe what they tell you or you measure it. Which is what I'm going to do in this thread.

Polished chambers are not practical for aquaria because of the organic buildup on the walls. They are mainly used for medical or processing. I agree plastic chambers are not good however, most PVC chambers are built of UV stable PVC. Stainless is the best if you can afford it.

UV dose has to be exact for the target organism. The keyword is "properly sized". So many times I see reference to a chart to pick a UV which is bad practice because not all bulbs and chambers are the same. This to me is a shotgun approach or a shot in the dark. Aquarium/pond water is actually harder for UV because of clarity which affects the refractive index. Pond water is assumed 85percent T whereas medical water is 100percent T. Over and under sterilized water defeats the whole purpose for a UV on a tank. With a flow meter one can fine tune the dose. How many people control flow? Large public displays require a dose of 50mJ/cm2. Ocean research request 105mJ/cm2.

I truely believe most people don't know what they have except they just hope it works. Hopefully, this thread will help.
 
I started setting up with the sensor 1 meter away from the lamp. The meter keep reading 0 so I decided to take the reading at 3" away.
Here's what I got (all readings in microW/cm2):

12" bulb USA 120 China 140

18" bulb USA 110 China 90

36" bulb USA 140 China 120

48" bulb USA 130 China 100

Both USA and China bulbs are built to the same spec and wattage for the particular length. The USA bulbs are within spec which leads to believe the China bulbs lack quality control.
To validate my conclusion a larger sample size should be done but I don't have the time so I'm going to call it good.
What's in your UV?
 
Chinese manufacturing as a whole la is quality control.
 
interesting to say the least!!
 
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