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cloudflint
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Avon/Admiralty pattern full face mask

Wed Apr 04, 2012 5:12 pm

Got another bit of kit in the mail. Ive heard these mask where used from the 50's to the late 80's early 90's. The one I just got says 91 on it which leads me to believe it isn't that old so I thought I would put it here :D

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So, does anyone know much about these masks? From what ive been able to find out these masks where used from the 1950's through to the early 90's by the royal navy and others such as police dive units. I believe the skirt on the mask is meant to be filled with water via the wee nozzle on the lower left side. The water that was already in there was pretty rank so i emptied it out and put fresh water in there, does anyone know if your meant to do anything particular to the plug to ensure it stays on?

I got the mask attached to my new mistral without any problems, it fits perfectly so im hopefully going to be able to try it out at the weekend :D

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Re: Avon/Admiralty pattern full face mask

Wed Apr 04, 2012 10:41 pm

I am totally unfamiliar with this mask. Since I cannot see the inside of the mask I am only guessing what is on the other side. Is there a nose block or other device for clearing your ears? I am also wondering if there is any means for defogging it. It appears to me that the mouthpiece is shoved through the "mouth" of the mask. This would eliminate the need for an oral/nasal mask to eliminate CO2 buildup but I think that would eliminate any airflow to the faceplate for defogging it. The face piece of the mask looks flat enough enough...

It is just a wild ass guess on my part but it would seem to me to be a marginal mask that might keep your face warmer but would not be good for a fog-free mask or one that would be good for under water comm unless there is more to the mask than I am aware of. I do like the fact that there is a water filled seal. As a person with a narrow, and once-handsome face, I like the idea of an adjustable seal as some FFM do not work for me. I hope someone with experience with this mask weighs in as all I have done is make some wild conjunctures after consuming a few beers while sitting on my front porch for my yellow hose shipment to get here.

I did just notice the nose clip in the pic just before posting this. While functional this is less than desirable for ear-clearing and one more piece of gear to keep track of. But the nose clip would be useful to keep beer from shooting out of my nostrils and soaking my computer when I read funny posts.

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cloudflint
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Re: Avon/Admiralty pattern full face mask

Thu Apr 05, 2012 8:17 am

The inside of the mask has an internal mouthpiece that connects straight into the port on the front. Since your breath dosen't enter the main airspace of the mask it shouldn't fog up (at least that is the theory!)

I read an interesting article by John Maloney on trying to develop underwater comm systems for police dive units in the 70's (Can be read here if anyone is interested). Apparently at the time most of them where using the admiralty pattern mask with some beginning to use the AGA mask. Since the mask had an internal mouthpiece it wasn't much use for comms so they experimented with an oral/nasal cup to allow the mask to work with comms equipment, but I dont think this modification ever went into production.

My ears generally clear themselves without my having to do anything so I hopefully shouldn't need to wear the nose-clip, I tried it on earlier and it hurts like hell :)

Heres a picture of what the mask looks like from inside. Also a picture of a couple of divers testing out underwater coms with the oral/nasal cup modification!

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Picture from http://www.therebreathersite.nl

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Picture from http://www.dtels.org

regulatorbj
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Re: Avon/Admiralty pattern full face mask

Fri Apr 06, 2012 4:41 pm

The mask was fitted to the RN "Sabra" inverted air set and the SDDE (Surface Demand Diving Equipment) all aluminium construction (Bomb Disposal) from about 1958 to about 1980 the sets all used double hose However the mask the took on a new lease after the Sabra and SDDE sets were superseded being married to the US Divers Conshelf regulator using a mouthpiece adaptor. A nose clip to equalize was all part of the kit If you can get hold a copy of BR155 or BR2805 RN manuals it covers the mask and the sets in great detail.

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YankDownUnder
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Re: Avon/Admiralty pattern full face mask

Sat Apr 07, 2012 11:52 pm

The Avon full face mask was part of the kit for the 'clearance divers breathing apparatus' or CDBA (oxygen or EAN 60/Nitrox), of the late 1950s and the 'underwater breathing apparatus' UBA (oxygen only version). The apparatus can be seen in the Lawrence Harvey film Silent Enemy, worn by Mediterranean Fleet divers appearing as the Italians. However, the mask is not used.

The mouthpiece was available to use when the mask began to fog or CO2 began to build up. A fogging mask is caused by moisture of course, but it occurs simultaneously with the CO2 build up. When diving with an oxygen pendulum rebreather, CO2 builds up in the single hose and it is necessary to exhale deeply to insure the breath is forced through the scrubber. To do this a mouthpiece is needed otherwise you would just exhale into the sea, loosing precious recyclable oxygen.

They were such a good mask that they were also used with the Siebe Gorman Merlin, using the V shaped plastic mouth piece. The Merlin was hookah capable so they were used in dockside and ship side operations. The V shape mouth piece was first designed by Heinke, which merged with Siebe Gorman in 1960. They were used by countries throughout the Commonwealth, including Canada, New Zealand and Australia.

It is possibly the best full face mask ever made, or at least I thought so. I regret selling mine when I sold my CDBA a few years ago. Steve

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cloudflint
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Re: Avon/Admiralty pattern full face mask

Sun Apr 08, 2012 3:10 pm

Cheers for the info guys, ill have to see if I can dig out a copy of those service manuals.

I just spent the weekend diving this mask on my new mistral so I thought I would write up a wee report on it detailing my experiences with it in case its any use to anybody :)

1st dive - Cregan bridge - 55 minutes @ 5msw(16fsw)
My first dive on the mask I filled up the mask skirt fully with water the night before, though some leaked out. The mask was very easy to don even though I was wearing gloves. The mask sealed without me having to faff with anything despite me having a month or so worth of beard.

Impressions upon entering the water was that the field of view was somewhat narrow. At the point where the visor bends the view appears distorted and hazy. There is a long narrow vertical band on each side that you can see clearly out of. The mask was very comfortable on my face, after 50 minutes wearing it I felt no discomfort and the mask left no marks on my face.

The work of breathing was slightly affected by the mask. I noticed when the demand valve was above the level of the mouthpiece the corrugated section of the internal mouthpiece was drawn in before the demand valve cracked. Similarly when the mouthpiece was above the level of the demand valve the corrugated section of the internal mouthpiece was pushed out a bit before air was pushed out the exhaust valve. This was only very slight and after a few minutes I didn't notice it and I never felt that I was particualy struggling for air.

One thing I did notice was that the external mouthpiece had to be angled correctly or the internal mouthpiece tended to kink up which made it difficult to grip in the mouth. I found the ideal angle was about 45 degrees upwards. Wearing the mask to low on the face also seemed to cause the internal mouthpiece to kink up. I eventually figured out that if the point where the outer mouthpiece connects to the main body is to close to you (Caused by wearing the mask to low down) the mouthpiece has to turn through 90 degrees causing it to kink. Similarly having the external mouthpiece to near the horizontal means the internal mouthpiece has to bend in a z shape causing it to kink. Heres a rough diagram to show what I mean:

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Original face picture taken from http://artrush73.hubpages.com

This made a big difference to comfort so id suggest anyone who tries one of these masks take this into account when getting it setup. I suspect if you get the one of these masks with the conshelf adaptor this wouldn't be a problem.

2nd dive - Cregan bridge - 4 minutes @ 5msw(16fsw)
This was a drift dive so gave a good chance to see how secure the mask was. Im pleased to say it didn't come off despite crashing into rocks, getting repeatedly kicked in the face by buddies and being flung around quite a few times. The mask skirt seems a lot bigger than on other full face masks ive seen, this means that even though I had it loose enough that I could tear it off my face with one hand it still sat very securely on my face.

I was concerned that the current might try to tug at the mask but I didn't notice this at all during the dive, despite appearing bulky its surprisingly streamlined!

3rd dive - Ballachulish - 35 minutes @ 30msw(98fsw)
This was my first time going deep on the mask. It behaved its self very well though I did wear the mask to low which meant with it kinked up I couldn't actually grip the inner mouthpiece it was just sitting in my mouth. Coming out of the water after the dive I moved the mask up slightly and this caused the mouthpiece to sit right again.

The mask gave no problems with regards to fogging. I spat on the visor before the dive then dipped it in seawater and it remained clear for the whole dive. More water leaked out of the seal overnight and it was now almost totally empty. On this dive I noticed the mask was not sealing around my beard very well, resulting in me being up to the bottom of my nose in water most of the dive. This wasn't a problem with the internal mouthpiece but it was rather chilly (Water temp 7c/44f).

I had put some black witch around the plug for the skirts filling nozzle but water from the seal is still leaking out around it so I will maybe take the plug off completely then see if I can do a better job of sealing it.

Overall impressions
  • I did not wear the nose plug on any of these dives, I found this allowed me to breathe in through my nose and draw air across the visor. This could be used to clear up any fogging which did occur.
  • Using the mask with a twin hose seems to require a little bit of fiddling with angles and positions to get it nice and comfy.
  • Getting water out the mask with the twin hose on was just a case of leaning back and opening my lips to allow the positive pressure air stream into the mask.
  • With the internal mouthpiece the main airspace of the mask is not affected by variations in pressure coming from the twin-hose unless you want it to be. You can exploit this to clear the mask or suck it tighter against your face.
  • the seal is absolutely brilliant, but only if you actually have water in it!
  • I found it was possible to spit the mouthpiece out, yell at my buddies, then grab the mouthpiece with my tongue and put it back in my mouth.
  • With regards to the above, if the mouthpiece is positioned badly and kinked up it can be quite hard to get it back into your mouth. (Particualy at 30 meters in the pitch black!)
  • Overall I agree with YankDownUnder, its a brilliant mask and surprisingly easy to use!

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BigMike
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Re: Avon/Admiralty pattern full face mask

Mon Nov 12, 2012 10:05 pm

I was able to pick one of these up and your posts were very helpful with my research. I'm trying to find a mouth piece adapter so I can use my rebuilt DA Aquamaster with it. Any idea where I can get one in the states? Any advice is appreciated. Thanks
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DaleC
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Re: Avon/Admiralty pattern full face mask

Mon Nov 12, 2012 11:07 pm

Thanks for the report - very informative.
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cloudflint
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Re: Avon/Admiralty pattern full face mask

Tue Nov 13, 2012 8:14 pm

BigMike wrote:I was able to pick one of these up and your posts were very helpful with my research. I'm trying to find a mouth piece adapter so I can use my rebuilt DA Aquamaster with it. Any idea where I can get one in the states? Any advice is appreciated. Thanks
I don't have a mouthpiece adapter for my mask either so I just clip my twin hose mouthpiece directly onto the front of the mask. This seems to be how its rigged up in most of the older pictures ive seen. Reading regulatorbj's post it seems the mouthpiece adapter only came in when they started using the masks in conjunction with Conshelfs?

I think if I was going to hook up a twin hose with the standard hoses (Instead of the great big rebreather hoses on my new mistral!) id maybe purchase one of the US divers/voit straight mouthpieces and just trim the lip on the mouthpiece a little so I could put it through the hole in the front of the mask and clamp it in?

Thinking about this has just made me think of another question I shall need to find the answer for. On my Merlin the mouthpiece is made of soft pliable rubber with the one way valves being what gives you something solid to clamp down onto when attaching it to the hoses. If this is the case how did they clamp the mouthpiece to the mask!?

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BigMike
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Re: Avon/Admiralty pattern full face mask

Wed Nov 14, 2012 9:37 am

I had the same idea about the straight mouthpiece and have one on order from VDH. I'm wondering how much of a crossover there will be to secure them together. Thanks for the reply and if you find a better solution, please let me know. Thanks, Mike
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cloudflint
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Re: Avon/Admiralty pattern full face mask

Wed Nov 14, 2012 10:48 am

I found the size of the lip inside the mask was the right size that any regulator that will fit a "standard" mouthpiece will fit in it perfectly. I just took some measurements with a ruler and it seems like the straight us-divers mouthpiece should fit in pretty much perfectly. The only possible problem I can see is that the end of the mouthpiece is rounded which might make it a bit wobbly when its being put in though once its secured it shouldn't make any difference I think?

I must admit the first time I put the mask together I was worried about it coming apart on me, I slotted the regulator mouthpiece into the front, slid the internal mouthpiece over the mask lip and the regulator mouthpiece on the inside then just got a quarter inch cable tie and put that over the whole lot on the inside and tightened it up.

I had visions of the internal mouthpiece slipping out or the regulator mouthpiece getting kicked out. The first time I used it however turned out to be in a 7 knot current and at one point I was kicked in the face so hard it made me do a couple of back-flips and it never budged. A few months later when I went to detach the mask from the regulator so I could use a standard mouthpiece again I actually found I could not get the damn thing off! In the end it took me about an hour and a half with some fine clippers working my way through the cable tie trying not to cut the mask in order to separate the damn thing!

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BigMike
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Re: Avon/Admiralty pattern full face mask

Thu Nov 15, 2012 2:57 am

It sounds like it worked better than you thought it would. I'll let you know how it works out once I get the mouthpiece. I'm really looking forward to diving with the Avon mask. Thanks again for the information. I appreciate being able to ask questions like this on the forum.
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cloudflint
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Re: Avon/Admiralty pattern full face mask

Tue Dec 11, 2012 7:45 pm

I finally managed to dive with someone who had a camera while wearing this mask so I thought I would post them up in-case anyone is curious. Scotland being Scotland however the conditions weren't great though being a shallow dive they are the best I have been in in a while!

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