Franken-Son: Rippin' out the Guts

Franken-Son Page 1: Rippin' Out the Guts!

No joke, the very first job is to remove EVERYTHING from the inside of the shell, with the exception of the counterlung. When I say "Rip out it's guts", I MEAN it.

All of the internal bracketry is held in with aircraft-style rivets. To remove them, you centerpunch the head, and drill the rivets out. This takes an hour or so, and the result is what's seen here: One naked IDA-71 chassis.

Here's the bottom of the counterlung. We have (2) sets of scrubber ports, and two other fittings. The fitting on the left is the direct access port to the counterlung, where we'll feed 02 later. The right port feeds the auto-add valve, which is where we'll feed diluent.

The original piping is removed, and laid on the bench. We'll need those fittings later.

The excellent original 2-port quick disconnect will also be saved. I'm sure it'll come in handy on some other project, but it's days in this IDA-71 chassis are over.

Here's a view of the auto add-valve inlet port. It's a Russian fitting, but that's not a problem as we'll see later.

Why did we remove the scrubber and cylinder bracket? Because it's not located on the centerline of the chassis, that's why. In the original system, there are two scrubbers, and one 02 cylinder which is located on the right side of the rig. I wanted to use 2 cylinders, meaning that the center scrubber is the one that will remain while the left scrubber is removed, and in order to have the center scrubber really centered, the brackets need to be removed and relocated about an inch to the divers left side. A little hacking with a saw and some stainless steel machine screws and that's done with ease.

Now we have a scrubber and cylinder bracket set that does us some good.

At first I wanted to use the 6 ft/3 cylinders for diluent and 02, but decided that they would not provide a usable advantage over the original Franken-Rig. The only advantage was that the valves and regulators could be enclosed by the shell, but this offers some disadvantages as well, for routing drysuit hoses, as well as providing access to the on/off knobs.

I ended up using a pair of 13 ft/3 cylinders that I got from OMS. If you look, you'll see that I used valves that were originally designed as a double manifold, so that the two cylinders are a mirror image of each other.

With the relocated bracket installed, the 2 cylinders and the scrubber fit perfectly. A little sheet-metal trimming to allow the valves to protrude through the bottom of the rig and that part's finished.

Thinking ahead to later needs of PP02 measurement, 2 P-Connectors were then installed into the counterlung.

Since I'll only be using one scrubber, brass caps were installed on the unused scrubber ports.

Here the plugs are shown installed to blank off the right scrubber.

Looking down between the scrubber and the cylinder, we can see the Russian connection to the auto-add valve.

To adapt to that, I sourced some 6 mm tube to 1/4 National Pipe fittings from Swagelok. Cutting the original tubes and then installing the fittings from Swagelok took just a few minutes. You can see that i then installed Buoyancy Compensator inflator quick-disconnect fittings onto the Swagelok fittings, so that I have a convenient way to hook up the pneumatics later.

Here the modified pipes have been reinstalled and are waiting for the pneumatic system to be plugged in.

That pretty much completes the chassis modification, now all we need to do is to add the other subsystems.

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		No joke, the very first job is to remove EVERYTHING from the inside of the shell, with the exception of the counterlung. When I say "Rip out it's guts", I MEAN it. All of the internal bracketry is held in with aircraft-style rivets. To remove them, you centerpunch the head, and drill the rivets out. This takes an hour or so, and the result is what's seen here: One naked IDA-71 chassis.
		Here's the bottom of the counterlung. We have (2) sets of scrubber ports, and two other fittings. The fitting on the left is the direct access port to the counterlung, where we'll feed 02 later. The right port feeds the auto-add valve, which is where we'll feed diluent.
		The original piping is removed, and laid on the bench. We'll need those fittings later.
		The excellent original 2-port quick disconnect will also be saved. I'm sure it'll come in handy on some other project, but it's days in this IDA-71 chassis are over.
		Here's a view of the auto add-valve inlet port. It's a Russian fitting, but that's not a problem as we'll see later.
		Why did we remove the scrubber and cylinder bracket? Because it's not located on the centerline of the chassis, that's why. In the original system, there are two scrubbers, and one 02 cylinder which is located on the right side of the rig. I wanted to use 2 cylinders, meaning that the center scrubber is the one that will remain while the left scrubber is removed, and in order to have the center scrubber really centered, the brackets need to be removed and relocated about an inch to the divers left side. A little hacking with a saw and some stainless steel machine screws and that's done with ease.
		Now we have a scrubber and cylinder bracket set that does us some good.
		At first I wanted to use the 6 ft/3 cylinders for diluent and 02, but decided that they would not provide a usable advantage over the original Franken-Rig. The only advantage was that the valves and regulators could be enclosed by the shell, but this offers some disadvantages as well, for routing drysuit hoses, as well as providing access to the on/off knobs.
		I ended up using a pair of 13 ft/3 cylinders that I got from OMS. If you look, you'll see that I used valves that were originally designed as a double manifold, so that the two cylinders are a mirror image of each other.
		With the relocated bracket installed, the 2 cylinders and the scrubber fit perfectly. A little sheet-metal trimming to allow the valves to protrude through the bottom of the rig and that part's finished.
		Thinking ahead to later needs of PP02 measurement, 2 P-Connectors were then installed into the counterlung.
		Since I'll only be using one scrubber, brass caps were installed on the unused scrubber ports.
		Here the plugs are shown installed to blank off the right scrubber.
		Looking down between the scrubber and the cylinder, we can see the Russian connection to the auto-add valve.
		To adapt to that, I sourced some 6 mm tube to 1/4 National Pipe fittings from Swagelok. Cutting the original tubes and then installing the fittings from Swagelok took just a few minutes. You can see that i then installed Buoyancy Compensator inflator quick-disconnect fittings onto the Swagelok fittings, so that I have a convenient way to hook up the pneumatics later.
		Here the modified pipes have been reinstalled and are waiting for the pneumatic system to be plugged in.
		That pretty much completes the chassis modification, now all we need to do is to add the other subsystems.