• Welcome to ScubaBoard

  1. Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

    Benefits of registering include

    • Ability to post and comment on topics and discussions.
    • A Free photo gallery to share your dive photos with the world.
    • You can make this box go away

    Joining is quick and easy. Login or Register now by clicking on the button

Helium in Commercial Diving

Discussion in 'Commercial Divers' started by CAPTAIN SINBAD, Mar 29, 2021.

  1. Akimbo

    Akimbo Just a diver Staff Member ScubaBoard Supporter

    10,713
    9,012
    Here is the link if anyone else is interested.


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

    upload_2021-4-28_14-24-4.png

    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?
     
    Pressurehead likes this.
  2. Superlyte27

    Superlyte27 Cave Instructor

    # of Dives: 5,000 - ∞
    Location: Florida
    4,101
    3,216
    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.
     
    Akimbo likes this.
  3. Searcaigh

    Searcaigh Chromodoris gordonii Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Dubai, UAE
    6,432
    5,366
    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 likes this.
  4. Akimbo

    Akimbo Just a diver Staff Member ScubaBoard Supporter

    10,713
    9,012
    @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.
     
    Searcaigh likes this.
  5. lowwall

    lowwall Contributor

    # of Dives: 200 - 499
    Location: Chicago
    1,612
    1,635
    So you had to go outside for a smoke?
     
  6. Heliumthief

    Heliumthief Contributor

    # of Dives: I'm a Fish!
    Location: Scotland
    81
    49
    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...
     
  7. Akimbo

    Akimbo Just a diver Staff Member ScubaBoard Supporter

    10,713
    9,012
  8. Akimbo

    Akimbo Just a diver Staff Member ScubaBoard Supporter

    10,713
    9,012
    That's how we used the Nikonos film camera. I took this shot looking up at the bell at just under 290M in 1972.

    upload_2021-4-2_12-16-36-png.651428.png

    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.
     

Share This Page