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SurfLung
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Fill Whip Idea

Wed Sep 25, 2019 5:48 pm

My Fill Whip Idea...
Image
- The Back Pressure Regulator (BPR) I tried to mount directly onto the filter tube of my little Aerotecnica compressor (JIC connector) proved a little too heavy for the JIC joint and eventually the joint connector broke. The JIC connection is on a little 1/8 inch NPT and I think it was designed to handle the weight of a fill whip hose and no more.
- I looked at the manual for my other compressor (RIX SA3) and it positioned the BPR on the end of the fill whip with a gauge and bleed valve. So, I thought that might be a better way to include a BPR in my Aerotecnica system.
- The original Aerotecnica fill whip is nothing more than a yoke and a gauge... There isn't even a bleed valve. As the manual says, the compressor was designed to fill one tank at a time. So when you get to the desired pressure, you close the tank valve, open the drain valves, and turn off the compressor. Everything is depressurized at that point and the tank can be disconnected from the fill whip.
- The fill whip I put together above adds the benefit of the BPR for better efficiency in moisture removal and filteration, but it also serves as a one way check valve. So, the bleed valve is necessary to relieve pressure between the BPR and the tank before disconnecting.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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captain
Plank Owner
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Re: Fill Whip Idea

Thu Sep 26, 2019 10:07 am

I would use a short length of hose between the filter to take the strain off the fitting and BPV and then the fill whip. What material was the fitting made of. I have found stainless steel does not like vibration and will eventually crack and fail. Carbon steel or brass is a better choice.
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SurfLung
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Re: Fill Whip Idea

Fri Sep 27, 2019 9:17 am

captain wrote:
Thu Sep 26, 2019 10:07 am
I would use a short length of hose between the filter to take the strain off the fitting and BPV and then the fill whip. What material was the fitting made of. I have found stainless steel does not like vibration and will eventually crack and fail. Carbon steel or brass is a better choice.
I think it WAS stainless. Anyway, the latest configuration in the picture (above) worked great last night when I used it to top off a single 38 and a set of Twin 72s. Here's my procedure:

After connecting the whip to the tank, I start up the motor and close the drain valves. At this point the BPR on the end of the whip is holding back pressure until it reaches 1800 psi. You can detect when 1800 psi is reached by simply leaving the bleed valve open (on the whip). When the BPR reaches 1800 psi, air will start coming out of the bleed valve. At that point, I simply close the bleed valve and open the tank valve and start filling the tank.

When the tank is full, I close the tank valve, open the bleed valve and open the drain valves... Then just turn the motor off.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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captain
Plank Owner
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Joined: Mon Jul 04, 2005 11:32 am
Location: LaPlace, LA

Re: Fill Whip Idea

Fri Sep 27, 2019 11:45 am

I would almost guarantee the failure was related to the stainless. I have had two personal experiences with vibration and stainless steel failure
On my old Harley shovel head engine there is a 6" long 1/8" oil line that connects from the head to the crankcase. The original is chromed steel. I replaced it with stainless. Shortly there after it started leaking. It had cracked inside the fitting just above the ferule. I replaced it with another piece of stainless tubing and it did the same thing. I went back to the original steel tube and never had the problem again.
The same thing happened with a 5" length of of stainless steel 3/8" pipe I used when modifying my Luchard compressor. After a few hours of operation it cracked at the threads where it screwed into the 2nd stage head. Having not learned the lesson from my Harley I replace it with another piece of stainless and it did the same thing. I replace it with a piece of cheap black iron pipe and have yet to have a problem.
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SurfLung
Master Diver
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Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
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Re: Fill Whip Idea

Fri Oct 04, 2019 11:48 am

Tank Checkers are Perfect for this...
- The USD Tank Checkers that are so plentiful and cheap to buy are actually perfect for modifying into Fill Whips, Cascade Whips, and Tank Balancers. Before I got my compressor, I made a Cascade Whip for filling my Twin 38s from AL80s. Here's a photo...
Image
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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