School me on tanks and canister lights

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TheCanuck

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Mainly, HP vs LP tanks and what type of canister tanks are available, what are each's strong and weak points. What are decent brands of can lights.
 
I like LP tanks. Easier to get full fills. Easier to PP blend with, and lower pressure means less wear on the o-rings, seats and moving parts of regulators. More capacity for a given pressure and usually cheaper than HP tanks.

Also, they're "3AA" spec, so no worries about failing Hydros, as some "exemption" tanks are known to do. (HP tanks are made on a "special permit" or "exemption" versus the DOT's "3AA" established standard for steel tanks. Though they're not failing right and left, it's more of an issue with HP tanks).

And, (though this is controversial), my LP tanks have the ability to become HP tanks when I need the gas. With the right burst plugs, my LP85s become HP120s. (YMMV) :eyebrow:

For can lights, I like Halcyon or Light Monkey. Both are pretty much the same as far as design, but Halcyon uses NiMH batteries, while LM uses Li-Po batteries, which give a little more burn time, (allegedly). I was gonna get a LM light, but at the time I was looking, Halcyon had a deal where if you bought a light, they threw in the two backup lights (at $185 apiece!) in for free. So I bought the light at near-retail, (got a slight discount 'cause I'm friends with the shop owner), but got nearly $400 worth of backup lights, (which I needed anyway) for free.

If you're not opposed to buying used, you can scour the classifieds here and and elsewhere and sometimes score good deals.
 
So a LP120 has the same quantity of gas as an HP120 but the HP120 requires 3442psi to get it because the tank has a lower volume(smaller than an LP120)?

Getting a full fill isn't a problem.

What about wattage, led or halogen etc.. for can lights?
 
So a LP120 has the same quantity of gas as an HP120 but the HP120 requires 3442psi to get it because the tank has a lower volume(smaller than an LP120)?

Pretty much.

What about wattage, led or halogen etc.. for can lights?

The "standard" minimum for cave diving and such is a 21w HID. I'm not a caver, but I find the 21w to be nice, even in open water, since it can easily be seen. HID v. LED is a common debate, and while LED has a number of advantages over HID, (bulb life, toughness, replacement cost), it can't match the light output, focus and "throw" of a HID, especially when you start getting over 18w or so. For my money, I'll take a 21-35w HID, with an appropriately-sized battery to give me the burn-time I desire. I went with the "mid-size" battery for the Halcyon, (9Ah), which is a good compromise on size and battery output for the 21w light head.
 
Mainly, HP vs LP tanks and what type of canister tanks are available, what are each's strong and weak points. What are decent brands of can lights.

I am a fan of HP tanks. Let's compare HP 100 vs LP 95 (from XS Scuba Worthington Steel Cylinder Specifications ). The HP tank has a higher capacity (99.5 cubic feet, versus 93.3). Although the LP tank is 8.9 pounds heavier (41.9 for LP vs. 33.0 HP), it is only 0.5 pounds more negatively buoyant when empty (-3.0 vs. -2.5). Thus, with the HP tank you start with more gas and can dive with 8.4 pounds less weight on your back/belt (the difference between the two tanks of the sum of the weight and the buoyancy). The same website (but a different page) markets the LP tanks as "offer[ing] lower fill pressures, making them ideal for dive boats and many air compressors." So, if fills are not a problem, I recommend HP tanks.
 
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May I take the opportunity to add to the schooling process? Sorry, I just had too. :D

Firstly "tanks" are used in the armoured divisions to penetrate and destroys "hard points" in the enemy lines. Cylinders are used in scuba and hold your breathing gas.

I am not fond of HP cylinders; they are heavier than LP’s and a low percentage of filling stations are capable of filling them to their potential. A lot of divers prefer the HPs because of potential higher volumes; I would just get a larger cylinder for recreational diving or go twins if plan on tech stuff.

Canister lights are used and have very specific requirements in deep, wreck and cave diving. The popular brands are Halcyon, Dive Rite, Light Monkey and Green Force to name a few. They come in different configuration ranging from 10-21W outputs, have HID or LED bulbs, various sized battery packs, differences in beam angles with focus adjustability (4-16 degrees) and depth ratings. All of these specs have pro and cons so make sure you get what you need. They are very expensive IMO and your really need to have a purpose to buy one or have to no issues with your cash flow to justify spending $$$$$$$$. Dive with different configs to understand pro and cons. Also, don’t let anyone including myself guide you too or away from LED light. I have a 12w Halcyon LED perfect for my needs and very underrated by the HID crowd.
 
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I am not fond of HP cylinders; they are heavier than LP’s and a low percentage of filling stations are capable of filling them to their potential. A lot of divers prefer the HPs because of potential higher volumes; I would just get a larger cylinder for recreational diving or go twins if plan on tech stuff.
...
"May I take the opportunity to add to the schooling process?"
A PST E7-80 (3442 psi) weighs 28 lbs. empty
A PST LP-80 (2400 psi) weighs 34 lbs. empty
A standard aluminum 80 (3000 psi) weighs about 31 lbs. empty
I haven't been in a math class in a very long time but I'm fairly certain 28 is less then 31 or 34. So for equivalent sized tanks the high pressure tank is lighter.
 
......a low percentage of filling stations are capable of filling them to their potential. .......

I don't buy this. Most commercial compressors are more than capable of pumping 3500psi needed to fill a HP cylinder. The fill operator may not take the time time to properly fill the HP cylinder to the specified pressure (too lazy, ignorant, etc..), but this is an operator issue, not an equipment issue in most cases.
 
"May I take the opportunity to add to the schooling process?"
A PST E7-80 (3442 psi) weighs 28 lbs. empty
A PST LP-80 (2400 psi) weighs 34 lbs. empty
A standard aluminum 80 (3000 psi) weighs about 31 lbs. empty
I haven't been in a math class in a very long time but I'm fairly certain 28 is less then 31 or 34. So for equivalent sized cylinder the high pressure cylinder is lighter.

:rofl3:

Let me add two more examples of LP vs. HP cylinders, these are from Fabers, and are current production.

Cylinder Specifications

LP108 vs HP133

LP108:
Internal liquid volume: 1,037 cubic inches
Length: 26.77 inches (does not include valve)
Weight: 41 lbs (does not include valve)
buoyancy: -5.02 to 2.98 lbs (does not include valve)

HP133
Internal liquid Volume: 1,037 cubic inches
Length: 26.78 inches (does not include valve)
Weight 42.7 lbs (does not include valve)
Buoyancy: -9.08 to 1.45 lbs (does not include valve)

LP120 vs. HP149

LP120
Internal liquid volume: 1,159 cubic inches
Length: 29.33 inches (does not include valve)
Weight: 44.0 lbs (does not include valve)
Buoyancy: -4.87 to 4.07 lbs (does not include valve)

HP149
Internal liquid volume: 1,159 cubic inches
Length: 29.53 inches (does not include valve)
Weight: 46.9 lbs (does not include valve)
Buoyancy: -9.41 lbs to 2.35 lbs (does not include valve)

When you are comparing identical size of cylinders, cylinders with the exact same liquid volume, then yes, HP cylinder are heavier both in dryweight and buoyancy, but then you also get a lot more air volume out of them.

Before you buy a steel cylinder, have a talk with the person you are getting your fills from. Most if not all dive shops CAN fill a HP cylinders, but it's up to the shop if they want to fill them to full capacity. I have yet to come across a shop that could not fill a HP cylinder. However, I have come across some scuba parks that would not fill a HP cylinder to rated capacity, but then again, I would not get my cylinders filled from them (annually gas analysis, compressor is in very bad shape, oil all over the place).

Also don't buy an LP cylinder and expect you will be getting HP fills, this is up to the shop doing the fills, if you do get HP fills good for you. If you want HP fills then get a HP cylinder, if you are satisfied with LP fills then get a LP cylinder.

I like LP cylinders because they are easier to correct a nitrox or trimix mix, if a goof is made; HP cylinders not so much. LP cylinders also don't heat up as much. I have notice HP cylinders really heat up after 3,000 psig, so HP cylinders usually need a top off once they cool down. I own both LP, and HP cylinders, but if someone asked me which cylinders, 108 vs. 133, I would take the 133s because I can get a HP fill at my LDS. If you are worried about 3AA or exempt status, then take a hard look at Fabers, they have been around for a very long time, and are not going anywhere. I have not heard of a problem with Fabers when they get a Hydro, just Worthington, and PST (no longer make scuba cylinders).
 
... a low percentage of filling stations are capable of filling them to their potential.

I don't buy this. Most commercial compressors are more than capable of pumping 3500psi needed to fill a HP cylinder. The fill operator may not take the time time to properly fill the HP cylinder to the specified pressure (too lazy, ignorant, etc..), but this is an operator issue, not an equipment issue in most cases.

I don't buy that statement either, since most commercial compressors are rated for 4,500 psig to 6,000 psig, (5,000 psig and 6,000 psig are more common for brand new compressors). I have come across fill operators that were just too lazy to fill a HP cylinder, and did not want to take the time to adjust the regulator, and/or fill slow. Again, talk to your LDS about HP fills.

If your dive shop is using a compressor from WWII, or their compressor has an oil catch can under it, then rethink your choice of dive shop. If you are not sure about a dive shop, ask to see their compressor.
 

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