Pirelli Explorer Maior

[Joris Vd]

I was wondering if anyone had ever dived the Pirello Explorer two stage regulator with the weird bellow?

I've looked for one for ages but have always missed out on the bid when there was one passing buy on ebay.

The real question would also be: is it properly diveable? How is wob etc? And what do you guys think of the design of the reg, ingenious or borderline idiotic?

Credit for the photo goes to the website cg-45.com

 

[axxel57]

Interesting Design, but sorry, I don't know anything about that reg.....

 

[John C. Ratliff]

I read many, many years ago that this Pirelli Explorer was used on a very deep dive (don't remember the depths, but well over 250 feet). Apparently, it allowed a slight rebreathing of the diver's last breath, which conserved air a bit. The duckbill valve being away from the diaphragm could cause some free-flow issues in certain positions. The reason for the bellows being on the chest and the short duckbill is to minimize the water pressure differential between the diaphragm and the outlet of the duckbill. If it was placed correctly, it would balance, but only in certain positions. I have never dived one. I think my LDS has one on display, and will look next time I go in.

I have no idea of WOB, but I'm assuming that it was worse than single hose regulators, even tilt valve single hose regulators. But the fact that bellows were used means that the initial part of the inhalation would be nearly effortless (rebreathing part of the last breath), but then would kick in with harder breathing.

Concerning the design, this was one of many attempts to overcome the Coustea-Gagnan patent on the exhaust of the Aqualung. By placing the exhaust away from the diaphragm/billows, there was no question that it did not violate the Cousteau-Gagnan patent in any respect. Take a look at these patents:

The first ones are not apparently for underwater breathing apparatus.
Google Patents

US3348538A - Breathing apparatus exhalation valve with suction control - Google Patents

US3348538A - Breathing apparatus exhalation valve with suction control - Google Patents

This one apparently is the basis for the Pirelli apparatus:
US3085571A - Underwater respiration apparatus - Google Patents

SeaRat

 

[Mike Lev]

I have one. Have never tried it. Maybe this summer in the pool. They go for good money.

 

[Goonzodiver]

This type of regulator should be remembered for two reasons:
* it is a regulator ["Maior" and "Standard" models] which contains in the second stage a soda lime filter, similar to the early rebreathers (or ARO), but without the oxygen bottle. The exhaled air was then reused after being purified in the second stage, which therefore also acted as a "lung bag". This filter was not present in the "Minor" model, much simpler than "Maior" and "Standard".
* it was successfully used in the diving record at -131 meters (i.e. ~ 430ft) with compressed air made by Olgiai, Falco and Novelli in 1959. Although Novelli (who had invented together with Buggiani the regulator and organized the event!) forgot to punch the plate to demonstrate the descent, Olgiai and Falco punched the plate successfully. Therefore we can still speak of a certified diving record with compressed air at -131 meters. For this reason, since then many coral collectors in Italy have used this type of compressed air regulator, since they often had to reach considerable depths of the order of 80-100 meters to collect red coral.

 

[Goonzodiver]

Article about the depth record (-131mt) with compressed air , from "Mondo Sommerso", 1959

 

[Angelo Farina]

It was a trick for making the mixture "leaner", reducing the risk of oxygen toxyicity.
In my opinion this made that record at 131 meters "spurious", as it was not "in air", but using an OC rebreather using air as a diluent.
Personally I think that the real record with pure air and normal regulator is still detained by Raimondo Bucher and his wife Luciana Civico, 102m, Maldivaru, Maldives, April 1986.

 

[Goonzodiver]

It was a trick for making the mixture "leaner", reducing the risk of oxygen toxyicity.
In my opinion this made that record at 131 meters "spurious", as it was not "in air", but using an OC rebreather using air as a diluent.
Personally I think that the real record with pure air and normal regulator is still detained by Raimondo Bucher and his wife Luciana Civico, 102m, Maldivaru, Maldives, April 1986.

Whether the record of Olgiai, Novelli and Falco was obtained with "pure compressed air" or not, is debatable, I agree.
It remains true that, despite being an open circuit rebreather, no gas was used, other than compressed atmospheric air.
But it is not disputable that the design of this regulator is not idiotic (as was said above), but absolutely brilliant.

 

[Angelo Farina]

Whether the record of Olgiai, Novelli and Falco was obtained with "compressed air" or not, is debatable, I agree.
But it is not disputable that the design of this regulator is not idiotic (as was said above), but absolutely brilliant.

Actually this regulator paved the road to the development of military-grade semi-closed rebreathers, which culminated in the development of apparatus currently employed by Italian Comsubin, the SIEL Caimano IV SC.
I had the honour of testing this apparatus at SIEL 6 years ago, and to perform the noise assessment at Varignano a few months later...
The principle of operation is basically the same.

 

[Goonzodiver]

It was a trick for making the mixture "leaner", reducing the risk of oxygen toxyicity.
In my opinion this made that record at 131 meters "spurious", as it was not "in air", but using an OC rebreather using air as a diluent.
Personally I think that the real record with pure air and normal regulator is still detained by Raimondo Bucher and his wife Luciana Civico, 102m, Maldivaru, Maldives, April 1986.

As regards the performances of Raimondo Bucher and Luciana Civico, although I admire these two great divers infinitely, it must be said that only the record (1962) at -80 meters of Luciana Civico with compressed air is certified and Raimondo Bucher's certified records are only in freediving.
Although there are still living witnesses for the -102 meters record at Maldives, that "record" is not certified.
Instead I mention Dick Birch and Roger Hutchins in the Bahamas in 1962 (-141mt) who did not have "special" regulators and finally Dan Manion who in 1993 reached -155mt.

But all this takes us away from the discussion on the brilliant design of the Pirelli Explorer, which risks being forgotten.