UV / ultraviolet for a festival tent

[rmaskey]

Heya, thanks in advance - I know there are a bunch of threads on UV here already but wanted to start a new one as the LED technology seems to have improved a fair bit.

 

I am trying to wash a festival tent with non-visible uv light. It is important for us to use the proper uv spectrum so there isn't any visible light that will wash out our LED installation. There are a couple of photos below of the tent from last year trying to show what we are working with... This year we are adding 18 10w custom RGB LEDs, 1 every half meter to the length of the tent suspended from the bar holding the fabric up. I need to be able to turn the UV on and off rapidly as part of our sequencing for the night.

 

From what I have learnt so far the best wavelengths are sub 395nm and lower produces a more pronounced effect, is this correct?

 

Having done a bunch of research into UV options it seems that the cannons are out of the question as we want to achieve a decent flood of the whole marquee, 5m x 10m and aprox 4m high. So that leaves tubes, CFL bulbs or LED floods...

 

Has anyone experience of using low wavelength uv LEDs such as these - 50w 375nm UV LED flood or 50w 390nm UV LED flood? They also do 10w versions of these lamps. I'd like to work out if there is an advantage to going for the more expensive 375nm versions.

 

I have a custom built relay system which can switch 8x 2A loads so this could be used to control the lights. Is it possible to switch tubes or CFL bulbs on and off rapidly without causing damage?

 

Also is there a big difference in the quality of the available UV tubes?

TLC have them for less than £7 each!! TLC 4ft Tube These guys seem to think there's at £16 is better.... UV Gear 4ft Tube

 

Personally I'm moving towards the LED options as they are tougher and smaller and our kit takes a beating at festivals and clubs. But the tubes work out a lot cheaper and would look good running the length of the tent.

 

Any advice or experience would be most welcome!!

 

Cheers

 

 

 

 

 

 

[TomHoward]

We bought a load of LED 50W floods recently, but rather than buying the coloured versions, we bought the warm white versions in the uk for about a tenner a piece, then bought 50W coloured LED chips from aliexpress or eBay from china for about a fiver a piece and swapped the chips out. I just checked and you can get all sorts of UV spectrum from china.

 

We were trying to use them to uplight trees but we found the power totally inadequate so we swapped to 400W coloured halide floods instead.

 

I still have a ton of floods I didn't get round to swapping the lamps in, and I have some with nicer cable and 16A plugs fitted (the cable the cheap floods came with was shocking) but I think you'll need serious numbers of them to compete with the effect of cannons. The LED isn't really any more efficient than discharge - only when compared to filament lamps.

 

Sorry I just re-read and saw the marquee was 5m x 10m, you might be alright with say 4 or 6 then for a reasonable coverage, maybe you'll get away with less

Also - apologies, I was checking pricing on my phone and didn't quite get it right, the UV chips are significantly more expensive than the coloured, about $50 a piece. Still cheaper than £149 a fitting though.

[timsabre]

The problem with those LED floods of any colour is the extremely wide light output - nearly 180 degrees. So although a lot of light comes out, most of it is wasted going in directions you aren't interested in. UV cannons using halide or CFL lamps however have quite a focused beam so the apparent light output is much better. I think you'd be very disappointed with the output of those floods.

 

I'm not surprised that you couldn't uplight trees with the white ones, metal halide floods are optically much better at directing the light output in useful directions.

[TomHoward]

We were using coloured ones - but the same 50W design. It was terrible, you're right, we'd used them on buildings before with slightly more success but trees were barely any light at all. The beam angle is too wide and the output is really variable between colours.

[adam2]

For area UV lighting I would be inclined to use UV tubes, the cheap ones linked to in the O/P should be fine.

 

Flashing the tubes on/off will drastically shorten the life, but looking at the present low price of replacements this might be acceptable. Use fittings with electronic ballasts as these strike quicker and don't kill the lamps as quickly.

 

 

 

[indyld]

I've found LED UV underwhelming so far. Many units I've seen and used seem to emit quite a lot more visible violet compared to cannon or tubes. Perhaps things are better with dedicated LED fixtures now but at the moment I'm still picking old skool UV sources for decent blacklight effects.

[ImagineerTom]

for covering a large area with UV there's still nothing that comes even close to tubes - It's well worth the cost of adding a reflector behind the tube (otherwise half your light is wasted) and you will be amazed just how much usable light you get out of them. 2 x 6ft tubes with reflectors will completely wash most stages we've encountered so allowing for your reduced throw range I'd suggest 4 x 4ft tubes (with reflectors) right up in the apex of the roof will give you an unbeatable flood throughout the whole tent and you would have change from £100 even if you have to buy everything.

[Jivemaster]

For fixed install long tubes are fine. For a marquee I'd consider CFLs in number to counter the losses due to breakage in foul weather, or by careless installers.

 

SO FAR all forms of "clear" cover I've seen has fluoresced severely and blocked most of the UV. "tube protection" is wire mesh. If tubes win on cost, have a spare or two in a custom box.

[rmaskey]

Thanks so much for all the info guys!!

 

Got the components to assemble two 4ft tubes and will test that this week - hopefully will go for 6x 4ft tubes high up in the roof alongside our own LED lights and a couple of custom built LED uv fixtures using chips we already have to wash the tent and add some punch at the back where there are some sofas.

 

Really pleased the look of the lamps I'm building from stainless steel mixing bowls which direct the light well. Using 380nm LEDs so not much visible light and they throw a LOT further than the tubes.

 

I've not been able to find chrome reflectors for tubes sold individually ... Any suggestions where I might get some?

[xllx]

 

Also is there a big difference in the quality of the available UV tubes?

TLC have them for less than £7 each!! TLC 4ft Tube These guys seem to think there's at £16 is better.... UV Gear 4ft Tube

 

 

I bought some of the TLC tubes recently, and they are absolutely fine. No idea why they are so much cheaper from them than other suppliers. Be warned, that most branches only hold a couple in stock unless you give them a couple of days notice., and they won't deliver them.

[rmaskey]

I bought some of the TLC tubes recently, and they are absolutely fine. No idea why they are so much cheaper from them than other suppliers. Be warned, that most branches only hold a couple in stock unless you give them a couple of days notice., and they won't deliver them.

 

Awesome advice - thanks for the heads up!!

[sunray]

Also is there a big difference in the quality of the available UV tubes?TLC have them for less than £7 each!!

I used TLC UV tubes for a long time IIRC they used to be £1.60!

Reflectors don't need to be massive, I went to a local aluminium stock holder/metal worker and as luck would have it he had some 16 Gauge checker plate off cuts 7"x8ft. He chopped them to 4ft, cut a bit out for the holder at each end then bent from one edge at 1.5"-145' at 2.5"-135' at 4.5"-135' at 5.5"-145' with a hand bender ['=degrees] this made a reflector 4" across and and deep enough to clear the tube with ease.

We tested each version with a flou fitting and this was the 3rd attempt. He made 2 of the final shape and charged me scrap value of checker plate [including spoiled versions which were returned to scrap pile] and 1/2 hour labour, whole visit took less than 20 minutes. I returned a week later for 2 more, visit was about 5 minutes and just charged for materials as previously promised.

I drilled holes using the original lid as a template and screwed it to the flou fitting, pair of lift off hinges and snap catches from Maplins fixed 2 together front to front for storage and transport [looked like a drain pipe with a bit of 2x1.5" timber each side]. My flou fittings had 3 20mm holes in the back for cable access, I drilled and tapped some 1/4" steel plate at M10 then got them spot welded inside to take bolts for hook clamp etc.

Eventually the ali lost it's shine and 10 minutes with a buffing wheel brought them all up to scratch again.

Obviously these were not 'drop it off a lorry' flight cases but a similar unit in a bespoke flight case with spare tube in the lid in foam would work.