Hello,
What are the best used regulators?
Any of the higher quality regulators perform just fine. The main difference is parts availability.
- What is exactly is a Conshelf? From my reading, it appears to be the first stage manufactured by US Divers later bought out by Aqualung (1960's) which also bought out Apeks? If Conshelf refers to just the first stage then why are not discussions based on just talking about first stages. Are the discussions using a short hand whereas it is understood that conshelf regulators mean only the first stage. If so, this is confusing for a newbie as we generally think of a set(1st stage, 2nd stage and even perhaps console). The conversations seem to be conflating first stage and 2nd stage. Is this done because the 2nd stage of the US Divers/Aqualung basically has not changed much over the years(see first thread below on Why is the Conshelf so reliable). Besides the difference between plastic and chromed brass(which provides a somewhat wet feel that some prefer as there is no dry mouth) the 2nd stage has not really changed. Is this correct? Would the same be the case for the first stage?
Generally regulators have been (and still are) sold as sets. A "Conshelf" regulator is a set consisting of a 1st stage and one or more 2nd stages.
The waters are muddied by the fact that Aqua Lung used the same 2nd stages on several of their products, including the Calypso, Aquarius, and many others. They also used several different 2nd stages over the product life of the Conshelf.
- Are there versions on the conshelf first or 2nd stage that one should avoid
The most useful versions for actual diving are the Conshelf XIV and later because the Conshelf XII and earlier versions don't have enough LP ports. They also cannot accept a DIN conversion The differences between the XIV and later models have to do with port configuration. Some versions have an oversize LP port (marketing gimmick) that requires an adapter or can be blocked off. Most versions use the smaller HP port (same size as the LP port), but can accept an adapter or custom HP hose. I find that the XIV has the best port placement overall even though it requires an adapter for the HP hose (or a custom hose), but the later ones work OK too.
The "supreme" version adds an environmental seal, more on this below. There are also DIN versions. While it is possible to convert non-DIN to DIN, the parts to do so are no longer available.
Any of the early second stages that have the exhaust valve in the middle of the diaphragm should be avoided by anyone but collectors because important parts are no longer available.
I avoid the plastic second stages mainly out of personal preference. Since most regulator sets on the market were originally sold when only one second stage was used, it is sometimes necessary to combine sets to create something useful. I also replace all hoses and usually replace the SPG.
- Is the conshelf environmentally sealed for colder diving? At what temperature would one need an environmentally sealed first stage? Are 2nd stages ever environmentally sealed? I read in the forums that one person had his first stage seize up/stop working at 50 degrees.
There are three versions of the "supreme" or environmentally sealed Conshelf. The original one fills the spring chamber with silicone oil and has a solid secondary seal. The EFA "external fine adjust" also fills the spring chamber with silicone oil, but has a hole in the secondary seal allowing an adjustment screw to protrude so that the IP can be adjusted without removing the seal (which is a messy process). I have one of each. There is also a dry seal kit.
I dive extensively in cold water and find that the Conshelf regs perform fine regardless of whether they have an environmental seal.
The environmental seals complicate service but not severely. It is possible to convert from environmentally sealed, to non-sealed, and back, by exchanging a handful of parts including the spring, spring housing, adjustment screw, secondary seal ring, and so on.
I find that the 2nd stages perform well in cold water and believe that the metal housing contributes to this, even though there is an absence of solid test data.
They aren't any better than anything else. The reason they have a strong following is that they are abundant and have good parts availability.
