Meeting of the minds

[SUNNYDAYS]

I have a hypothetical situation and wanted to see what the answer would be.

If you had 1 high pressure bed and one 160 new era lamped bed and they both metered the same, would the tanning results be the same or not?

All meter readings 5.0, 6.0 and 7.0 are identical.

I was just wondering if the the method of delivery would effect the tanning results or how long the tan would last.

[TonyG]

I would think that if the output (watts/centimeter squared (someone correct me on this) were the same for EVERY wavelength (nanometer?), then the two units would produce an identical tan.

If that is correct, then a body would get the same tan from a $10,000-$15,000 VHR machine as from a $30,000 HP machine. I don't have HP, but I would doubt that this is possible. A 1000 watt lamp must output more than a 160 watt lamp!

[Don]

An excellent question!

1. All meter readings 5.0, 6.0 and 7.0 are identical.

First of all, let's look at the 7.0 (MED/hour) readings. If they were identical, i.e., the Te (4.0 MED) times were the same, they would have equal erythemal (sunburning) power. A 12 minute Te time is the same no matter the irradiance source.

Next, even if the 5.0 and 6.0 readings were the same, you won't know if there are important differences in the spectral distribution. For that, you need a spectroradiometer so that you can measure the irradiance at 1.0 nm increments. Every salon should have a set of hand-held radiometers for quality control purposes but they are not recommended for comparing one sunlamp to another sunlamp and especially not for comparing one irradiance source to another irradiance source.


2. If you had 1 high pressure bed and one 160 new era lamped bed and they both metered the same, would the tanning results be the same or not?

While new-era sunlamps have "narrowed the gap" between low pressure and HID/hp tanning (a 160w new-era lamp is about equal to a 600w-700w HID/hp lamp for tanning power), a 160w LP lamp doesn't have the tanning power of a 1000w/1400w HID/hp lamp.

Therefore, even though the meters may read the same, the HID/hp sunbed (assuming it has 1000w/1400w sunlamps) will have more tanning power than a 160w new-era LP sunlamp equipped sunbed.

For those "techies" out there who are curious why this is true, it is because the 1000w/1400w HID/hp sunlamps have more photons in the 400 nm - 430 nm wavelength area than does any LP sunlamp (traditional or new-era) and we now know that although these wavelengths don't have enough erythemal power to cause sunburning, they have enough power to tan.

There is, however, a good way to prove to yourself that the HID/hp sunbed has more tanning power than the 160w sunbed equipped with new-era sunlamps, even if you don't have a spectroradiometer.

Tan in both of them yourself.

[solarmeter®]

Wow - that IS interesting. The "gap" in this case has narrowed indeed. Father tan would be worried!

Regarding the tanning power.... I would have to assume the HP lamps are not 1000W - 1400W because they would read lot's higher on a 5.0 meter than any 160W new era tube would. What wattage are they?

The best VH* new era 5.0 readings I've seen are ~75 mW/cm² at body position with good canopy illumination geometry. Most HP readings are above 100... with BIG wattage systems nearing 200.

It would be cool if Don could run a spectrogram on the two units and overlay the graphs. The "shifting" of the UVB photons must be somewhat similar for both the 6.0 AND 7.0 meters to read the same. HID/HP output is more "spikey" than LP... but the meters tend to smooth out the spikes and resolve the irradiance into a total single number.

I would think in this particular instance the two units will tan about the same. I looked at a log plot of the 5.0 meter sensor response; it IS picking up out to 420nm 3 decades down and goes totally blind at ~435nm 4 decades down.... (fyi for Don - I can fax you the log plot if you want).

[Father Tan]

Good stuff, BUT tan time must also come into play. Many of the 360 HP units are a 12-15 minute session. MOST of the New Era equipedt units are a 10-12 minute session.

Also I would think ALL HP units have a lower TT time then a New Era lamp. Now take a 160W New Era lamp with a 15 minute session and we are talking. The Sungate will meter in the 80's-90's with a new era lamp. Then again it is a 10 minute session.

Still a DECENT gap from what I have seen in the real world. A 10-12 minute bed with New Era lamps still tans differently then a HP unit.

[Don]

Scott:

You are absolutely correct.

I've been "playing" with a 160w new-era sunlamp with a 20 minute Te (4.0 MED) time and I can tell you that when you go 16-18-20 minutes, you get a tan VERY close to a 1000/1400w HID/hp tan.

Of course, in our "fast food" culture, not everyone wants to go longer than 12 minutes.

[SUNNYDAYS]

I was not talking about any beds in particular just got to thinking about this the other day.

Don
I was wondering if what FT had to say was correct that the TT would be quicker in the high pressure lamp just because of the fact that it is a high pressure lamp.

[solarmeter®]

Not if they actually read the same on a 5.0 meter.... say 90 like Father Tan has seen. The magical TT times should be nearly the same.

I'm sure Don may beg to differ however. *(^_^)*

I still say the big HP's with 1000-1400W will always read higher than any tube lamps and will have a shorter TT time too.
.

[uv2021]

Don ,I thought at one point you were saying that although the photons that are emited from new era lamps were in the same zone as hp lamps ,that they were not as "dense" therefore even thogh readings may be similar the "quantity" of photons being denser resulted in more opportunity to strike a melanosome.

[solarmeter®]

Not knowing what Don will say.... yet .... I submit that if the readings per square centimeter are identical then the quantity AND the density are also the same.

What you are saying would apply to "UV flux" ...the crazy units Cosmedico uses to measure lamp output in "watts of UV". Then the density of LP flux is less than the density of HP flux. But meters don't measure flux.. they measure output per unit area. So do spectralradiometers.
.

[engfant]

also you are metering the tube lamps in the middle which is the strongest part of the tube lamp. HP beds are more even as there are not getting weaker towards the ends of the beds....right? maybe?

[Don]

You can have two irradiance sources with exactly the same total W/cm^2 reading and each of them could have completely different Tt (tanning power) readings.

You have to know how many photons you have in each wavelength in order to compare one irradiance source with another irradiance source.

It is not only "how many" photons there are (which is what Steve's meter reads) but also "where they are positioned" (which is what my spectroradiometer reads) that is important.

What you can do to "estimate" the tanning power is subtract the Model 6.0 (UVB + UVA2) from the Model 5.0 (Total Irradiance) reading and this will give you a pretty good handle on the "tanning power" of your sunbed.

And, if you also have a Model 7.0 (MED/hour) meter, you can also "estimate" the erythemal (sunburning) power of your sunbed.

Remember, it's not what you have, it's how you use it-LOL.

[Drew]

Robbie , read this. It will cost you millions in lost revenue.