cg43
Senior Diver
Posts: 91
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Post by cg43 on Nov 4, 2023 13:30:32 GMT -8
Hello
Let's look for the compensation .
I will use the part's nummbers from the new version because they are better to indentify .
For understanding the funktion it's better to look at the old version witch is more simpel .
As written before there is a differenc in the working hp area's of part 15 (floating valve eat) .
Result , the tank pressure moves up part 15 against the force of spring 10 and spring 11 .
The upper end of both springs press against part 9 (guid plate) .
The rising force caused from spring11 pressing the metering valve seat (part 12) against part 15
is compensated by the highter opening force caused from the highter tank pressure .
Designed well such an valve works very well . It has the big advantage that the floating valve part (15)
only moves during changes in hp pressure and not in every breathing period .
It's an not dynamig moved compensated valve . Thats very fine for the sealing O rings .
The old version has an disadvantage .
During floating valve seat(part 15) comes up the lift washer (part 7) do the same .
The lever' get lose and the diaphrahm has to go down to kompensate this .
The new version avoid this because the fulcrum tube (that is the supportpoint for the leavers) goes up too .
Greetings Rainer
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Post by vance on Nov 4, 2023 14:46:11 GMT -8
Hi Ranier,
Thanks for the explanation. I have studied what you've written while consulting the diagram. There are some questions I have.
This regulator has not had a big presence on this or any other vintage scuba site that I know about. It would be very cool to be able to get these regs working again, like we did with the Healthways Scuba.
I don't think there has been another regulator as different as this one discussed on this site, and it would be great if we could provide people who are interested in rebuilding one enough information about it to do so.
I will send an email to you to discuss!
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Post by snark3 on Nov 4, 2023 14:51:24 GMT -8
Apparently, the first production models had a mushroom valve in the center of the diaphragm. From CG-45: 1954 - Northill Air Lung: The first two numbers of the serial number indicate the year. The label is green, Northill Company and Garrett Corporation are listed with a patent number, and the label was attached using adhesive The internal metering valve (high pressure valve assembly). is held in place with a “C” (or Truarc) clip, and all internal working parts are made of polished brass with the exception of the springs. The main inhalation diaphragm is made of thin rubber and yellow fiberboard riveted together and in the center is a mushroom exhaust valve. The reserve assembly has a cast “limit lever sleeve.” The lever itself is made from stamped-out sheet metal and is held in place with a C (or Truarc) clip. The corrugated hoses are held in place using brass bands, and the mouthpiece is a cast fitting, which carries a push-button cut-off valve and removable mouthpiece. (NEDU report 1954).Huh. Mine is a 1956 model, as the first digit of the serial # is the year of manufacture. I have a '55 and a '57. One of the has a "P" between the year and the 4 digit serial number. The P stands for something although I don't remember what |
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Post by vance on Nov 4, 2023 19:14:15 GMT -8
Apparently, the first production models had a mushroom valve in the center of the diaphragm. From CG-45: 1954 - Northill Air Lung: The first two numbers of the serial number indicate the year. The label is green, Northill Company and Garrett Corporation are listed with a patent number, and the label was attached using adhesive The internal metering valve (high pressure valve assembly). is held in place with a “C” (or Truarc) clip, and all internal working parts are made of polished brass with the exception of the springs. The main inhalation diaphragm is made of thin rubber and yellow fiberboard riveted together and in the center is a mushroom exhaust valve. The reserve assembly has a cast “limit lever sleeve.” The lever itself is made from stamped-out sheet metal and is held in place with a C (or Truarc) clip. The corrugated hoses are held in place using brass bands, and the mouthpiece is a cast fitting, which carries a push-button cut-off valve and removable mouthpiece. (NEDU report 1954).Huh. Mine is a 1956 model, as the first digit of the serial # is the year of manufacture. I have a '55 and a '57. One of the has a "P" between the year and the 4 digit serial number. The P stands for something although I don't remember what Does your P model have a sheet metal reserve lever? |
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Post by vance on Nov 5, 2023 7:50:01 GMT -8
I have Ranier on the hook via email, hoping he'll be able to clarify the operation of the Northill for me. Thanks, Ranier!
I'm pretty sure I understand it in general, but there are some murky spots, especially concerning the "floating valve seat assembly" #15.
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Post by vance on Nov 5, 2023 7:53:55 GMT -8
Bill, the missing lever on the Northill you're looking at could be a problem. If it had a sheet metal version, that wouldn't be so bad, but the cast levers have internal ramps that would be very difficult to reproduce.
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Post by antique diver on Nov 5, 2023 11:17:30 GMT -8
Bill, the missing lever on the Northill you're looking at could be a problem. If it had a sheet metal version, that wouldn't be so bad, but the cast levers have internal ramps that would be very difficult to reproduce. That missing part is the only thing that had kept me from trying to acquire the Northill in the past. Hopefully I can make a replacement part that will look sort of OK. I think I will go ahead and try to work out a deal on it next time I go to service the owner's compressor. Not sure when that will be needed, but it's only about 50 miles away. |
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Post by nikeajax on Nov 5, 2023 11:48:48 GMT -8
Bill, it looks like you might be able to make a silicone-mold rather easily if you were able to borrow that piece: it could be cast in resin that is reinforced with wire.
Conversely, you could probably machine most of the part and make a mold of the part with the lobes/cams (?) that you'd glue onto the rest of it: the resin for this could have metal filings added to it for strength, like they do with JB Weld.
Also, the resin can be colored too, so as to make it less obvious/noticeable...
JB
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Post by snark3 on Nov 5, 2023 13:12:05 GMT -8
I have a '55 and a '57. One of the has a "P" between the year and the 4 digit serial number. The P stands for something although I don't remember what Does your P model have a sheet metal reserve lever? No the one with the "P" has the same reserve lever as the other one. I thought I read someplace but I can't remember where the "P" stood for a regulator that was intended for sale to the Public as opposed to a government/Military/NEDU reg. But I can't remember where I read this so I can't double check it. |
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Post by snark3 on Nov 5, 2023 13:15:10 GMT -8
Here's something for the "things that make you say hmmmmmm" file. I was looking foe clarification on the "P" over at the CG-45 website when I came across No 1957 Northills have been seen or are known to exist. I've got one.....hmmmm
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Post by vance on Nov 5, 2023 14:44:36 GMT -8
Here's something for the "things that make you say hmmmmmm" file. I was looking foe clarification on the "P" over at the CG-45 website when I came across No 1957 Northills have been seen or are known to exist. I've got one.....hmmmm Interesting! Here's something else that's interesting. This is one of the Northill inventors posing with what looks like an early single hose version. I love the shower tap valve handle:  There's a Spanish saying I love. "No tiene dos dedos de frente." He doesn't have two fingers of forehead, meaning what you'd figure. Este tipo tiene cinco dedos de frente! |
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Post by vance on Nov 5, 2023 15:59:42 GMT -8
I ran this description of the Northill regulator's basic operation past Ranier. I added some detail that he provided and I think it's correct, although there are probably corrections that will have to be made.
Anyone is free to add, or correct. You'll want to consult the diagram and parts list.
The Northill has a balanced, single stage, downstream valve.
Unlike most other DH regulators, the chamber below the main diaphragm is the exhaust side. It is mostly isolated from the intake chamber of the regulator, but it is not sealed.
When the diver breathes in, suction from the exhaust hose pulls the diaphragm down and depresses the 3 levers.
The downward movement of the diaphragm lifts the valve retainer #6 upward via the levers at washer #7, while simultaneously pressing the fulcrum tube #13 downward at the lever pivot points.
Lifting the valve retainer #6 upward compresses spring #11, and pressing the fulcrum tube #13 downward allows spring #10 to expand.
Compressing spring #11 lifts the metering valve #12 off the seat, and expanding spring #10 pushes the floating valve seat #15 away from the metering valve.
Both actions serve to open the valve by moving the valve and seat apart.
When the valve is open, HP air from the tank pushes (fairly forcibly, I'd think) through the intake side of the regulator and delivers air to the diver via the intake hose.
I hope that's clearer than mud!
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Post by vance on Nov 9, 2023 8:58:04 GMT -8
I'm still working on the Northill reserve. I learned from Roberts that the reserve stem is "actuated" by air pressure. When the tank is turned on, the stem is pushed outward and engages the ramps in the handle. That's why it's floppy when the regulator is not under pressure.
I still need some o'rings that fit, so I'm stalled for the moment. The regulator leaks air all over the place, so there's some troubleshooting to do. I'm heading out of town for a week or so, so no chance to get anything done on it until I get back.
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