Helium in Commercial Diving

[Akimbo]

There’s quite a good ‘animation’ from a company called Nsea on the internet, for their TUP system which used to work in the southern sector of the North Sea.

Here is the link if anyone else is interested.

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Thanks. That looks a lot like the small portable sat systems of the 1970s and 80s.

Considering that they are decompressing divers out after each lockout, I wonder how they justify a hyperbaric lifeboat requirement? Is it really any different than using Sur-D-O2? Divers can't get out of the deck chamber too early without getting seriously bent, regardless if they are using Sur-D-O2 or a closed bell.

Handling bells over the side is nasty business in the North Sea. Wasn't the last one the Wildrake? For other readers, see A Fantastic Adventure Book About Commercial Diving - Into the Lion's Mouth

On the other hand, it is probably not much worse than launching an open bottom bell over the side. Do you see many work/supply boats with moonpools?

 

[Superlyte27]

I would enjoy seeing some photos if you get the chance. Are these bounce systems portable/using vessels of opportunity or integrated into smaller DSVs?

I did an HeO2 sat at 50M and switched to open circuit air in the water. This was on the Andrea Doria in 1973. Our gas supplies and budget were low and our push-pull system (conceptually like the Divex today) was leaking. We didn't even notice the difference between air and Helium except the heat transfer and our voices.



Was that limit imposed by OSHA (Occupational Safety and Health Administration for non-US readers)?

I’m not sure. I think the limit was to stay under 1.6ppo2. The only time it was ever an issue was a tall water tower. You know how inland is, they do some sketchy crap because the oversight is so much less.

 

[Searcaigh]

At some point when I get back to Scotland I need to have all my 35mm slides scanned of the systems on the DSVs I worked on (Drive Performer and British Providence).

Drive Performer had a DRASS system rated for 300m
British Providence had an Aqua Logistics system.

I've just found some notes in my log of a recovery of a British Telecom plough in the English Channel where we started with a storage depth at 35m and excursion depths of 40-50m

 

[Akimbo]

@Heliumthief

Off topic: What kind of keyboard and mouse are you using in the chamber (hardwire USB or Bluetooth wireless)? If wireless, do they hardwire a Bluetooth antenna through an electrical penetrator?

Related Questions:

• Are there any electrical devices that they make you stop using when you get shallow/into the combustion zone?
• What other electrical devices do they let you use (besides built-in comms and gas sensors)?
• Can you use modern digital cameras in the chamber? Early LED displays with flexible membranes would be pressed in and make it unreadable. I never ran across any solid state devices or standard components like resistors and capacitors that weren't pressure tolerant.

For other readers:
Any electrical devices that are capable of producing a spark were prohibited from inside any chamber when the percentage of Oxygen (not PPO2) was high enough to support combustion (4.5% as I recall). This has been the case since the chamber fire at NEDU in the 1960s. There is also concern over many battery types due to outgassing. Simply putting these devices in a one atmosphere housing is more complicated than you would expect because of Helium permeability through transparent materials, which is why Helium relief valves are on watches used for sat diving.

I couldn't take an electric razor in the chamber due to sparking and the battery. The Navy chambers had a special 120VAC connector in the chamber for some medical equipment in the early days but the power was shut off when we entered the fire zone. For example, they would draw blood and spin samples down in the chamber trying to figure out what sat diving was doing to the body. Sending saturated blood out through the utility lock would turn it to red foam full of exploded cells.

 

[lowwall]

Any electrical devices that are capable of producing a spark were prohibited from inside any chamber when the percentage of Oxygen (not PPO2) was high enough to support combustion (4.5% as I recall). This has been the case since the chamber fire at NEDU in the 1960s.

So you had to go outside for a smoke?

 

[Heliumthief]

In all chambers here there’s Bluetooth keyboards (with touchpad for the mouse stuff) with either 12v Monitors or projector outside, screen inside. Razors, toothbrush etc. Not a problem, send them out to be charged.we’ve just been trialling a remote medical system which goes through the bulkhead to a defibrillator, with a laptop inside which can take BP, sp02, pulse, ECG, camera etc.
Digital cameras aren’t a problem- if we have to use them at relative depth, we’ll have them in the wet pot to stabilise, then put them in the U/W housing there or in the bell- meaning you could take pics at 109m, but the housing only needs to take 20-odd meters pressure (from bell to bottom).means you can use a dirt cheap Sony cybershot or similar in a standard scooby doo housing instead of one of the old bulletproof NikenosV film cameras....real boon being able to review the pics as you take them, instead of the nervous wait for film to be developed...
Some companies have laptops with batteries removed wired in for each bunk, guys take solid state hard drives in to ‘personalise’ them, or many have WiFi hard drives outside you can log onto..
Phones are just cheap cordless phones, with rechargeable batteries so when it runs down, you can send out old ones and get new ones in...every company has slightly different procedures but generally don’t be stupid is a good rule of thumb...

 

[Akimbo]

So you had to go outside for a smoke?

You can stay inside and smoke... yourself to a crisp.

See: Hyperbaric and hypobaric chamber fires: a 73-year analysis

 

[Akimbo]

Digital cameras aren’t a problem- if we have to use them at relative depth, we’ll have them in the wet pot to stabilise, then put them in the U/W housing there or in the bell

That's how we used the Nikonos film camera. I took this shot looking up at the bell at just under 290M in 1972.

We also shot thousands of stills with a housed super-wide Hasselblad and a 70mm film back to document various bits at Ekofisk. We had to keep the strobes outside the bell and plug the sync cord with an EO connector. Helium will infiltrate the Xenon tubes, plus the outgassing problem of the Ni-Cad batteries. The first commercial ROVs only had 400 lines of B&W resolution.

 

[Heliumthief]

Nice pic! ‘homeward bound’!

it’s really pretty amazing how much has changed with that technology in the last decade or two. Nowadays even a fairly run-of-the-mill hat camera can take very hi definition footage. A few years ago, I was on an inspection campaign with a lot of MPI, remedial grinding etc. and the Inspection controller would send us down the digital camera in its housing, just because that was what was done, but he said most of the pictures he used were actually stills taken from the hat camera feed, they were of such good quality...

 

[Akimbo]

Nowadays even a fairly run-of-the-mill hat camera can take very hi definition footage.

I expect that 8K will be the standard very soon for hat cameras through ROVs. Do you know if you are running 1080p or 4K now?

For other readers, here is an image that illustrates the difference.