I have an SPG and Depth Guage which I keep clipped out of the way as my computer is air integrated. But having those guages really came in handy when my computer failed at 27m

Cut low pressure hose will empty the cylinder faster - just saying. Liked the curaway - nice and simple. Cheers.

@kevindavison6019

3 жыл бұрын

Lake Hickory Scuba channel did a video on this a couple of years ago where they cut the hoses on a sample tank in a pool and timed the air release it was very informative.

Like the new intro. Short and sweet.

I have a set up with the traditional spg and depth gauge for public safety diving and then I have just the spg for every other diving that I do. Love the videos and advice from the channel.

I especially like the animated cutaway drawing showing the mechanism: perfect! But for the stickler, especially those of us taking our metric gauges on holiday, 3000 psi is actually 207 Bar. Wouldn't it be so nice if one day the US could go metric on cylinder capacity, pressure and depth to make their mental arithmetic as easy as ours?

@KimonFrousios

3 жыл бұрын

Technically, BAR is not the S.I. unit for pressure either. That role belongs to the Pascal. But 23,200,000 Pascal is an inconvenient mouthful compared to 232 Bar... And "metric" tanks are not any more convenient. 80cf refers to the air contained (at 1atm pressure), so in metric it would be 2265,35 liters which is much worse for mental math. If anything, the american way of measuring air volume instead of tank volume, skips a step ahead in calculating how long your air will last. As long as pressure is standardized (american 3000psi, european 230bar (although usually 210)), there is not reason at all to bring the tank volume into the calculation.

@timgosling6189

3 жыл бұрын

@@KimonFrousios True, Bar is not SI. But in 'metric', a 12 litre tank contains 12 litres at 1 Bar. At 200 Bar it contains 2400 litres. You can do it in your head. An 80 cuft tank only contains 80 cuft at 3000psi (actually about 11 litres at 1 atm) so the mental gymnastic are instantly worse. Similarly, pressure at depth increases by 1 Bar per 10 metres. If my SAC is 15 l/min it pretty easy to work out I'm breathing 60 l/min at 30m etc etc. I guess you get used to the US system but there is a reason it's been dumped in engineering and science.

@bloodymarvelous4790

10 ай бұрын

@@KimonFrousios Can't agree with your mental gymnastics there. Unless you're calculating with RMV, the volume of uncompressed air, compressed into the physical volume of your cylinder isn't part of your calculations. Most divers work with SAC rates, which uses pressure/time instead of volume/time because you're SPG is reading pressure, not volume. Air integrated dive computers will also give you your SAC rate, and not your RMV. Now, if you ARE using RMV, then all you need to do in metric is multiply your SAC by the physical volume of your cylinder. Your SAC is 1.2 bar/min? Your cylinder is 11 liter? Then your RMV is 13.2 l/min. It's that simple. In imperial your RMV is your SAC multiplied by the capacity of the cylinder, divided by the maximum working pressure.Your SAC is 17 psi/min? You're diving with Al80's? Then your RMV is 17 * 80 / 3000, which is erm... uh... hang on, let me get a calculator... 0.46 cf/min. So how does that relate to how long you can stay underwater? In imperial, at a depth of 80 feet, you're breathing 80/33 + 1, which is erm... that's 80 * 3 = 240 / 100 = 2.4 + 1 = 3.4x more air than at the surface. At a SAC rate of 17 psi/min, that's about 60 psi/min. You've got 2,200 psi left and want to end the dive at 500 psi, that's 1,700 / 60, which is a little under 30 minutes remaining, let's make it 25 to be sure because of all the rounding errors. While in metric, if you're at a depth of 24 meters, you're breathing depth/10 + 1, which is 2.4 + 1 = 3.4x more air than at the surface. At a SAC rate of 1.2 bar/min, that's about 4 bar/min. You've got 150 bar left and want to end the dive at 50 bar, that's 25 minutes of dive time remaining. Metric is far easier to work with in every way. Pressure underwater is depth/10 instead of depth/33. RMV = "SAC * Cylinder size" instead of "SAC * maximum cylinder capacity / rated pressure", and this cascades into pretty much every other SCUBA formula you can think of.

@KimonFrousios

10 ай бұрын

​@@bloodymarvelous4790 Measuring your air in tank volume vs pressure has NOTHING AT ALL to do woth using imperial VS metric units. One can just as easily say they have 11L of air instead of 80cf, or they could say they have 3000psi of air instead of 210bar. The units don't change the fact you are measuring an entirely different property. Yes, depth to pressure conversion is easier in metric, but that is a coincidental property of water, not a design advantage of the metric, and in any case was not what the original comment was about. Yes I like RMV, because SAC rates are not comparable across dives with different rental tank sizes, RMV is. From an RMV I can calculate the SAC for any given tank, instead of needing to have a SAC reference value for each possible tank volume. And RMV is a more direct indication of how temperature/exercise/stress affect my air consumption.

Excellent video James, really enjoyed this one. I especially liked that you showed how the bourdon tube works

Thank you for the great info you regularly portray. Was just modifying my pony bottle set up and was informed about/purchaded a very small SPG that attaches directly to the first stage (no hose needed). It can be set up to directly face the diver (me). I learn something new the more I dive :)

Another great video James. What the Americans don’t know, was that when us Brits got kicked out after the War of Independence, we left a little time bomb. It was called the Imperial system. Feet, inches, pounds, hundredweight, tons and psi. All horrendously complicated compared with the Metric system, which, in the UK for the most part we use.

Good morning, I love your videos, and I am thankful for them. One comment, counterintuitively, a full LP hose rupture is catastrophic (as in you have 2 to 3 minutes on a full tank before you are out), but not a HP. This is due to the bore size of the hose. There are a few YT videos actually demonstrating this.

great, straightforward video. thanks.

Nice content - quick and clear. I like your new intro!

It has probably been commented on earlier... but here is my take .. 1:44 the incredibly small hose is THE safety feature to prevent major gas loss in the event of a hose rupture or SPG " falling off" or other failure beyond 1st-stage reg. The bourdon tube only needs to sense pressure, flow is unnecessary hence tiny hole to let pressure equalise both sides ( indicating pressure). The bore of the hose is relatively much larger or it would be too stiff for useful human interaction. For sure the apparent flow of gas on hose failure would be ALARMING and a real dive ending moment, but as previously commented by other IP hose failure would discharge your cylinder faster at depth. Side note: as the spg is connected directly to sense cylinder pressure it is irrelevant (to rate of gas loss) what depth it occurs... more directly on cylinder pressure trying to escape [higher pressure - higher rate]. Keep the content coming... clear and succinct info.

The only reason I carry an analog depth gauge is for safe ascent in event of computer failure. Sure, there's my buddy's computer, and I can send up a DSMB to use the line as reference, but a gauge is just simpler. Simple is good when things go wrong.

@colelawton4901

Жыл бұрын

Ascend slower than your bubbles and you'll be fine

@jamiemorris7688

Жыл бұрын

Agreed, I have AI on my computer so 99% of the time the guages aren't touched. I confirm the cylinder pressure on my computer concurs with the gauge then it's tucked away. But I have had a computer failure and I appreciated a depth gauge when that happened.

Amazing video and impressive graphics and animations. I had no idea how the SPG actually worked. Aloha

Great video as always. Can’t wait to get back in water.

Great video...i like carrying a spare spool piece...quicker and easier to change out so I don’t miss a dive...

Thanks for another great video James and Happy New Year. Could you give us your thoughts on sidemount versus backmount for recreational divers? I see sidemount classes increasingly being offered but not clear on the benefits for rec divers or if it’s just something new for instructors to sell in addition to the mandatory sea kelp ID speciality. 🤙

@lukem2889

3 жыл бұрын

I second this

I have been considering the Cressi Digi 2 digital pressure gauge. What are your thoughts? Thanks

Nice star of life on the wall

Hey James! Are most of the o-rings for the SPG pretty standard in terms of size? If I wanted to check my save a dive kit to ensure that I have correct o-rings, would you recommend I pull the SPG apart to see what size the rings are?

Simpler the better 👍 agree no more depth gauges

Had a good laugh at "party blowers"

Hi James. I am Giani and i need your opinion about the Cressi digi2 gauge pressure. wWhat do you think? Is better a traditional gauge or a digital...? Thank a lot.

Hello mate, just identified you on KZread; liked and subscribed. Wonderful video.Question: what kind of other servicing and maintenance do we need to do to our Single Brass & Glass gauges? I've just moved from a 2 console recreational gauge to a single Brass & Glass with the same interest as you. Despite periodically changing the swivel pin, do I have to look upon other factors like lubricating the mechanism inside? Thank you in advance. Tipping my hat to you from Kuala Lumpur.

Hello James. Fanks for the vid on SPGs. Just wondered if you would mention the age old, redundant teaching about facing the gauge away from your face whilst turning on the pressure?

@bloodymarvelous4790

10 ай бұрын

Yeah, don't do it. There is a fail-safe over-pressure protection which vents out the hole in the back of the SPG. If anything's going to explode from the SPG in case of a catastrophic failure, it's going to come out the back.

I like tripple gauge hoses with spg depth and compass just incase of a failure on my computer

Hi James, love your channel! Great video. Just one thing, I don’t agree with the “great big explosion causing catastrophic gas loss due to it being a hp hose” comment. High pressure hose failures are not as catastrophic as a low pressure hose failure. The pin hole diameter of the hose inherently reduces the volume of air going through the hose while increasing pressure. Hence the name. So air will leak out but at much much slower rate giving you plenty of time to safely ascend, most of the times.

@bloodymarvelous4790

10 ай бұрын

Lake Hickory SCUBA did a test by completely cutting through the hoses. Cutting a regulator hose gave you roughly 3 minutes before the tank was empty. Cutting a HP hose took almost an hour to drain the tank.

@softgrapes

10 ай бұрын

@@bloodymarvelous4790 yeah my point exactly

Any recommendations on how to select a quality gauge? I’ve been told most manufacturers are all using components from the same few suppliers so they’re mostly all the same. Just buy them in black and metric and you’re doing the right thing.

@centermass3454

2 жыл бұрын

I was going to buy the Apeks, now what should I buy ?

good video james! one question i cant find the answer is why the spg goes (in bar) to 400 if bottles are filled to 200, i guess with a twin set the spg still will tell 200 no 400 for the two tanks. Thanks!

@kimdrikkjaerlaursen6879

3 жыл бұрын

The 400bar I so you can use it on 300bar bottels, and a spg Loses its precision if it runs to max on the scale therefore the top 20% help to ensure the precision for a longer time.

I got a digital one as a used purchase. Didn't know any different as newbie. Not sure if this was any better.

KISS philosophy is better. If you have a puncture on the hp hose you´re going to lose air in less amount than in low pressures hose, why? the manometer (HP) needs pression, not volume to read/works properly. The loss of gas is less than a second stage (check the hole). I enjoy your videos, and everybody makes mistakes ;) .Greetings from the NW coast of Spain

Great video, thanks. 2 questions though: 1) is brass and glass worth the extra money compared to plastic face? For recreational divers. 2) I find my 2 inch gauge big and heavy, but am concerned going smaller will be harder to read. I don’t want to spend time trying to read my gauge. What are your thoughts.

@scubacro5758

Жыл бұрын

the plastic one will be scratched more easily, the protective rubber seals on the SPG only collect sand and salt around brass on glass looks much nicer, the weight is irrelevant while diving and the glass is more resistant to scratches put a boltsnap on the spg and hook it somewhere so it doesn't drag on the bottom

Hey love your video content..I am also interested in the digi2..any thoughts James.

@mariagarciagarcia5391

3 жыл бұрын

You mean the Cressi? I’m also interested!

@shanefalkenberg7532

3 жыл бұрын

Yes

Can you use a tech gauge as your spg when rec diving? Any negatives?

Nicer new intro!

Hey James - Thanks for the great video as always. Do you use an analog SPG when you're using air integration on your Garmin Descent? Trying to decide if the redundancy is a good backup/safety measure, or if it's unnecessary. Thanks!

@popeye808

3 жыл бұрын

James actually answered this, but it was tucked away in a video. He DOES use an analog SPG, as he said in the other video, if the battery in the transmitter goes out without warning, the analog is there. Older transmitters would die without warning, newer ones give you warning. Aloha!!

Excellent Video... One question, is about replacing O-rings. You did not mentioned the need for Viton/equivalent for Nitrox divers. I personally only carry Viton O-rings now.

@jeffworst9939

3 жыл бұрын

You make a good point but I think it would be more appropriate for a video on O-rings. I've talked to lots of people and it's kind of controversial if Viton O-rings (i.e., O2 compatible) are needed for Nitrox (i.e., below 40%). Some say yes and others no. I agree with you and simply use Viton since it's not that much more expensive. I've got more important things to worry about than saving a few bucks on O-rings.

I've had 2 spg-related problems, and in both cases the hose was the issue. On one, a run of hoses attached to scubapro spgs were found defective. I'd suggest periodic hose replacement.

Thanks

What about digital gages like the cressi digi2 ??

which brass and glass spg do you recommend please?

I also just watched your video on air integration, and was wondering how important that is, and if just having an dog is enough, as I'm planning on buying my first dive computer, Shearwater peregrine, but it doesn't have that air integration feature. Thanks in advance!

@bloodymarvelous4790

10 ай бұрын

You don't need air integration, but it's nice to have. Your computer can calculate your gas time remaining, your SAC rate, and of course warn you when you're getting low on gas. That does come at a significant cost though. If you want an air integrated Shearwater computer, you're now looking at more than double the price of the Peregrine, and that's not including the transmitter. With the transmitter you're looking at 3x the price of the Peregrine. Is having air integration worth another $900~$1,000 to you? An analog SPG is fine, and even with an AI computer it's still recommended to have an analog SPG anyway. If you're planning to get into technical diving, then a Teric, Perdix or Petrel is worth considering, and air integration only requires investing in a transmitter at that point. But then again, technical divers usually don't bother with air integration. They prefer analog gauges.

nice, i have seen these small spg that look like they fit at the ends of hoses. are those tec specific or sidemount gauges

@KimonFrousios

3 жыл бұрын

Don't *all* SPGs fit at the end of hoses?

@ishmaelcastillo6236

3 жыл бұрын

@@KimonFrousios obviously. should have been more specific, the one i was looking at looked like an end cap but it was a small spg about nickle size in diameter.

Hey James! I got the Apeks Tek 3 regulator set. It didn’t come with an SPG/HP Hose. I just tried to put one on from my other reg sets and holy snap the HP Port diameters are different. Which HP Hose/SPG do you use on the the Apeks Tek 3?

@bloodymarvelous4790

10 ай бұрын

Apeks uses the 7/16" connector for the HP ports, and 3/8" for the IP ports. That's pretty standard across the industry.

I was always taught the SPG, should it fail, was very unlikely to result in catastrophic loss of air due to the pin hole source from the first stage??!!??

Hi James, I have a SPG question. I started diving with UTD and removed the DC with the boot from my SPG(Mares Mission 2) , NOW it's a tiny unprotected SPG, I fear i will bump it and break it. Is it ok that this SPG that usually has a boot now does NOT? will a mares tiny SPG survive long without a boot? ...... Maybe a question for Brien, he's the mares guy. Thanks James Cheers

@bloodymarvelous4790

10 ай бұрын

Your SPG will be fine. It's a little more fragile than a brass-n-glass SPG, but it won't break when you bump it. Just don't step on it, or drop something heavy on it. It is a good idea to tie a bolt snap to it, so you can attach it to a D-ring. That way you won't risk it snagging or dragging.

I don't think that catastrophic gas loss is really a thing with a spg. Perhaps a nice addition is the amount of time it takes for a scuba tank to be empty if something like that happens at different depths.

Any ball park figures regarding how long an SPG should last (i.e., roughly how many dives)... or do I just keep an eye on it and make sure that it still reads zero on the surface?

@DiversReady

3 жыл бұрын

You should get easily 400 dives out of an SPG as long as you don't knock it around too hard.

What size of gauge should we consider 52mm or 63mm or does it just come down to preference and your eyesight?

@DiversReady

3 жыл бұрын

Personal preference and eyesight, for sure.

About a compass, I see some companies selling these super strong magnetic devices for quick disconnects. Wouldn't these interfeer with the compass, especially if you had several magnets?

@bloodymarvelous4790

10 ай бұрын

Yes, they will always interfere. They will also interfere with compasses in dive computers. And even when you have the magnet on your right hip, and your compass on your left wrist stretched out in front of you. The magnet will cause a deviation on your compass.

What if my Miflex HP hose doesn’t have the pin hole size port ?

@bloodymarvelous4790

10 ай бұрын

Then it's either not a high pressure hose, or it's not a hose. Or you need to see an optician.

So do you dive with a backup computer to be fully redundant during a dive ?

@jeffworst9939

3 жыл бұрын

I'm pretty sure he does for tech dives. SOP is for tech divers to have two computers for redundancy... usually two Shearwaters.

@scmsean

3 жыл бұрын

@@jeffworst9939 Actually a lot of tech divers are against dive computers. I know doing GUE they won't even let use them. Shearwater is required to be in gauge mode.

@jeffworst9939

3 жыл бұрын

@@scmsean True. There is sort of a spectrum along which tech agencies fall regarding computers. If you're going to always dive in gauge mode, not sure why it's worth it to spend $$$ on a Perdix. Just get a bottom timer and depth gauge. We've all got to make our own choices.... hopefully informed ones.

@scmsean

3 жыл бұрын

@@jeffworst9939 When I'm on vacation, I don't dive with it like that. Most places require a dive computer. I have a teric as well as backup on vacation. But when I'm diving with GUE, I have too.

@jeffworst9939

3 жыл бұрын

@@scmsean That makes sense.

🔝

love analogue gauges! anyone has idea how reliable are digital gauges?🧐

@bloodymarvelous4790

10 ай бұрын

Pretty much the same, as long as your battery doesn't run out during the dive. The nice thing about an analog gauge is that you don't need to process numbers. 1100, is that good or bad? Should I be thinking about ascending for my safety stop? On an analog gauge you see the needle getting close to the red zone. It's easy to understand. On the other hand, when a digital gauge fails, it's immediately apparent. It's either not displaying anything or it's displaying gibberish. A failed analog gauge might have a stuck needle. You'll need to check again in a few minutes, and remember whether it's displaying a different value or not, to know if it has failed.

Hey James, Great video! Couple of points to add ( in my opinion ). 1. Rubber boot traps salt water and might cause corrosion faster. 2. You forgot to mention about over-pressure rubber plug at the back of SPG. While tank opening some folks have a tendency to turn SPG in a such way this plug might fly straight in their face in unlikely event of SPG failure.

@bloodymarvelous4790

10 ай бұрын

Correct. I was taught to turn the SPG face away from mine, so in case of a catastrophic failure my face wouldn't be peppered with glass shards. But the over-pressure fail safe is at the back of the SPG, which I'm now pointing at my face.

No, thank you for that

Another great video. The background music is annoying and distracting, though.

Looking at the comments about Bar vs. Pascal: Einstein, Heisenberg, Pascal and Newton are playing hide and seek. Einstein covers his eyes and begins counting. While Heisenberg and Pascal run off and hide, Newton takes out some chalk and marks a square on the ground with a side length of exactly 1 meter, then sits down inside the square. When Einstein is finished counting and sees Newton sitting on the ground, he yells, "Ha, I've found you, Newton!". Newton however replies, "No you haven't! You've found Pascal! (Where is Heisenberg? We're not certain.)

"SPG is necessary for any dive" because battery low in dive computer does not work.

It would be helpful to not have music playing in the background.

Why do tech divers only wear black?

@diveinstructordaniel1095

3 жыл бұрын

Becouse Its cool 😎

@joakimdiver1120

3 жыл бұрын

If its not black, its broken😎

@jamiemorris7688

Жыл бұрын

I have legitimately seen a guy with a black DSMB. Pretty sure he got it for a laugh but they literally exist out there