Chinese 40W 365nm compact E27 lamps legit?

[Avalon]

Hello. I seen chinese small E27 mercury vapor UV compact lamps that claim to have up to 40W power being sold on Ebay and Aliexpress. Some even claim 60W. For comparison lamps sold in EU that are 120cm long and thicker are rated 36W.  Chinese do have habit of scamming,claiming for example equivalent wattage to incandescent bulbs. Of course what matters is real UV output but sellers do not provide any more details than wattage. Is it technologically possible for small lamps to output so much ultraviolet?

 

https://www.ebay.com/itm/175620949202?hash=item28e3d304d2:g:KpMAAOSwQ61j8mVV&amdata=enc%3AAQAHAAAA4Ko5uzHlS1OH36XGYWEehHKC%2B0rE8OcDncbTn4aGFi1tPoMzNPuE4h6UZk%2BFBSk%2BYlNufDWS2MRdyQ574Lq4zBROEln%2B2rLFUUzEv%2B3fuv6BcKuM1qlnIYSZzEzl7bmmcdctRI5TwEBwwnBO2XFsDJKd4PKMW8jthWdDt9JbtM5HKzkOj8pXNWSzU%2FySyITU6DxPitwETruCyzdrmjnxURjj7tvBZvkFc0UUgBTFMKOFlLUItPjatLMObcfGQj6ylWMP5nyvCXHmml9fVcfX9OaL2cXGSWV0supdf0v4JYkE|tkp%3ABFBM7uKd5NNh

[KaJashey]

They don't look to be a quartz style light (those are clear) nor really germicidal. I'm highly skeptical. Looks like they are selling a blacklight and making up copy to sell it.

[Avalon]

Most likely it's Wood's glass. Wouln't make sense just for 365nm spectrum. I really hope that compact lamp like these could output more UV than those bulky lamps on budget. 

[photoni]

@Avalon It looks the same as my Fluorescent Wood 20W 220V
the emission spectrum confirms that it produces a lot of light 365 nm
The word "germicidal" seems wrong to me.

 

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[lukaszgryglicki]

I've bought only once from China - I was stupid.

It was a KrCl lamp supposed to emit 222nm - all it emits is a buzzing, seems broken and the cost was $260... not that low, but still too low for real KrCl lamp that is actually working. No idea why I believed it, of course now money is gone and they stopped responding.

 

[dabateman]

Yep the Wattage is wrong. Those are small fluorescent black lights. Its possible that they maybe pushing 60W or 40W, but it will all be heat and not tons of UV light.

I got three pack of Sunlite 20W black fluorescent bulbs,  rated as equivalent to 75W and its 365nm output is similar to a 365nm led bulb. But it has a broader UV light output and its quite nice to avoid the monochrome UV look.

 

[Avalon]

Are those lamps also really 365nm? Yes, mercury lamps tend to produce broader UV spectrum than LED's.  I need two powerful lamps to lit painting/artwork investigation, 365nm is ideal for inducing old varnish fluorescence. As alternative I considered also buying chinese 36W 365nm E27 LED lamps and then fitting with ZWB2 2mm filters but not sure what quality I could expect: https://www.ebay.com/itm/394277413198?var=662791823265

 

Nichia 3W 365nm LED's do produce more UV and less visible light than chinese 3W but at much higher cost.

[lukaszgryglicki]

The best option (IMHO) is to buy low pressure mercury lamps - they do emit a lot of UV-C 254nm - up to 70% of their rated power - you can find bulbs rated 30W and you can assume 20W will be UV-C 253.7nm... they come with E27/E26 too. Some even emit 184nm that produces ozone.

https://en.wikipedia.org/wiki/Mercury-vapor_lamp

 

 

[Andy Perrin]

10 hours ago, photoni said:

@Avalon It looks the same as my Fluorescent Wood 20W 220V
the emission spectrum confirms that it produces a lot of light 365 nm
The word "germicidal" seems wrong to me.

 

.

 

Based on those results it sure looks like a 365nm lamp. If that's how they advertised it, it's fine, but obviously it is not germicidal. There is nothing wrong with 365 if you want 365nm! 

 

1 hour ago, lukaszgryglicki said:

The best option (IMHO) is to buy low pressure mercury lamps - they do emit a lot of UV-C 254nm - up to 70% of their rated power - you can find bulbs rated 30W and you can assume 20W will be UV-C 253.7nm... they come with E27/E26 too. Some even emit 184nm that produces ozone.

https://en.wikipedia.org/wiki/Mercury-vapor_lamp

 

Most of us on this forum do NOT want UV-C bulbs...you and Colin are some of the exceptions. People reading this from outside should know that UV-C is wicked dangerous and not needed for the "normal" UV-A photography that is most of what we do around here. 

[colinbm]

2 hours ago, lukaszgryglicki said:

The best option (IMHO) is to buy low pressure mercury lamps - they do emit a lot of UV-C 254nm - up to 70% of their rated power - you can find bulbs rated 30W and you can assume 20W will be UV-C 253.7nm... they come with E27/E26 too. Some even emit 184nm that produces ozone.

https://en.wikipedia.org/wiki/Mercury-vapor_lamp

 

 

You have not mentioned the dangers of UV 254nm.

[dabateman]

3 minutes ago, colinbm said:

You have not mentioned the dangers of UV 254nm.

Its also very dangerous for old art work,  which wil be the subject. 

I am not sure what would be the safest light for the artwork,  but you can getsome nice large 365nm leds in E26/E27 format. 

[Andy Perrin]

Honestly, any exposure to UV is a problem for old art, but I guess sometimes people weigh the knowledge gained versus the damage from a small exposure. I am sure some materials can withstand UV better than others, so checking in the conservation community might be a good idea before going ahead with a project.

[lukaszgryglicki]

OK, I didn't know that UV-C 254nm will be dangerous to art - nice to know. Thanks for the info.

 

[colinbm]

I think Lucas needs to be moderated, he is too contemptuous of UVC.

[JMC]

13 hours ago, lukaszgryglicki said:

The best option (IMHO) is to buy low pressure mercury lamps - they do emit a lot of UV-C 254nm - up to 70% of their rated power - you can find bulbs rated 30W and you can assume 20W will be UV-C 253.7nm... they come with E27/E26 too. Some even emit 184nm that produces ozone.

https://en.wikipedia.org/wiki/Mercury-vapor_lamp

 

 

Do you have a reference for that? The info I've seen was that they were about 30-40% efficient, and of that 30-40%, 90-98% would be the UVC lines - https://uvlampconsulting.com/wp-content/uploads/2017/08/the-analysis-of-modern-low-pressure-amalgam-characteristics-fred-van-lierop.pdf

[Avalon]

13 hours ago, lukaszgryglicki said:

The best option (IMHO) is to buy low pressure mercury lamps - they do emit a lot of UV-C 254nm - up to 70% of their rated power - you can find bulbs rated 30W and you can assume 20W will be UV-C 253.7nm... they come with E27/E26 too. Some even emit 184nm that produces ozone.

https://en.wikipedia.org/wiki/Mercury-vapor_lamp

 

 

UV-C would be harmful and of little use in art investigation. I'm aware some minerals and pigments do exibit fluorescence in 254nm radiation but in art work investigation 365nm is mostly used.

 

I probably going to use those 365nm 36W  LED lamps sold on Ebay that come with built in lens and fit them with cheaper 20mm diameter filters. Not sure if ZWB2 filter is best idea.

[colinbm]

ZWB1 will be the filter to use with the 36w 365nm LED lamp.
It cuts off at about 380nm to eliminate any visible light & has some cutting any IR leak.

 

[lukaszgryglicki]

3 hours ago, JMC said:

Do you have a reference for that? The info I've seen was that they were about 30-40% efficient, and of that 30-40%, 90-98% would be the UVC lines - https://uvlampconsulting.com/wp-content/uploads/2017/08/the-analysis-of-modern-low-pressure-amalgam-characteristics-fred-van-lierop.pdf

I don't have any references other than the seller's - so probably they lie again. Anyway, we already know that UV-C won't be usable here, so just ignore me.

 

[lukaszgryglicki]

5 hours ago, colinbm said:

I think Lucas needs to be moderated, he is too contemptuous of UVC.

what do you mean by that? I'm not aware of any ban regarding speaking about UV-C - this is, in the first place, UV forum so I don't feel like any UV-related content is banned or tabu.

[colinbm]

1 minute ago, lukaszgryglicki said:

what do you mean by that? I'm not aware of any ban regarding speaking about UV-C - this is, in the first place, UV forum so I don't feel like any UV-related content is banned or tabu.

I am very concerned for any nieve readers that don't see any warnings about the dangers when UVC is mentioned.
This thread was about an inquiry about the suitably of a 365nm UVA lamp, then you are recommending they get a very dangerous 254nm UVC lamp & even suggest a extremely dangerous 185nm which produces ozone !
This is all very dangerous advice & worse that it carried no warnings.
That is just my opinion.
 

[JMC]

20 minutes ago, lukaszgryglicki said:

I don't have any references other than the seller's - so probably they lie again. Anyway, we already know that UV-C won't be usable here, so just ignore me.

 

Ok, thanks.

[Avalon]

3 hours ago, colinbm said:

ZWB1 will be the filter to use with the 36w 365nm LED lamp.
It cuts off at about 380nm to eliminate any visible light & has some cutting any IR leak.

 

Thanks for advice. What thickness I should choose?

[colinbm]

17 minutes ago, Avalon said:

Thanks for advice. What thickness I should choose?

Mostly 2mm is used.

[ulf]

1 hour ago, Avalon said:

Thanks for advice. What thickness I should choose?

The thickness is very essential when discussing filter.

Thank you for finally bringing that up with your question.

 

My advice is that in most cases a ZWB2 would work slightly better that a ZWB1 as it's peak transmission is closer to 365nm, but it must be 2mm thick.

 

By the way those 365nm 36W  LED lamps sold on Ebay are not actually real 36W.

The "36W" is only a false Chinese marketing statement W-number. 

 

A few of the ones claimed to be 15W (falsely) are rather good LED lamps consuming 7-8W and emitting something like 30% as UV-Light.

https://www.ebay.com/itm/204042005899 Select the 15W option here.

They are already equipped with 2mm ZWB2 filters.

 

36W is simply not possible without very big heat sinks or fan cooling that you never see on those reasonably cheap lamps.

I know that there has been opinions  about this on the forum, but they are not correct.

 

This is my professional field as a senior electronics design engineer.

I have made product designs of professional UV illumination equipment with similar types of LEDs and batteries that are used in the torches. 

 

---

Lately very many here has omitted stating the thickness when discussing filters, just naming the glass material.

 

For filters like UV-Pass and BG glass types ZWB1, ZWB2... BG39, QB39, BG40, S8612 etc the glass thickness used is just as important as the glass material!!!

Glass type + Thickness gives an indication of the filtering performance.

Without thickness information any advice is rather useless and vague.

 

Compare to water and depth, together with a statement like "You will will drown if you stand in water".

That statement will be true only if you wear very heavy shoes and the water reaches above your mouth.

Thus standing in water is not always deadly.

 

Please, please everybody, include some estimated glass thickness when discussing filter performance of filter materials without a well defined cut off like long pass filters.

Not doing so is sloppy.

End of rant.

 

 

 

[Avalon]

ZWB2 2mm seems to be best and cheapest option. ZWB1 gets really expensive so I'm glad to hear it's not the best choice.

 

That 36W lamp seems to be made of 3W LED's. There are 12 LED's so at least input power might correct. Question is how much UV they really output. Obviously energy is ineficiently being wasted as heat and visible light. I plan to use two 36W lamps with 60 angle lens so that is already a lot power. I'm thinking for settling for 21W lamps. They do have aluminum passive coolers and I will run them long enough to take photos.

 

Also want to know if PMMA lens good for 365nm? Plastics do tend to yellow and become opaque after long exposure to UV. So is it worth investing into glass or silicone lens? That's assuming they can be found for sale and fiting 3W LED's.