mix and match 1st & 2nd stages ?

[wetlettuce]

Hi

Is it possible to mix and match 1st and 2nd stages ?

I ask because I have a aqualung Legend LX and first stage as a primary. I am going to by another for the secondary but for the moment I want to use a Mares Orbiter secondary.

The first stages are similar types being diaphragms.

Is it possible ? I've tried them in the pool and they work OK but how about at 20metres ?

Kindest Regards

Andy

 

[pescador775]

The main issue with secondaries is freeflow. If the buddy stage works in the pool it should be serviceable on deep dives. There are some weird combinations with Swedish regs which are potentially unsafe due the type of valving in the second stage but even that is not a consideration with buddy stages. Generally, these things will work well even if the supply pressure is not exactly spec. Sometimes they work better where having a slightly lower than spec supply pressure will reduce freeflow and freezing. That doesn't appear to be the case here as the Legend has fairly high stage pressure. Most auxilliary seconds are designed with low venturi effect and stiff valve springs to make them stable. Some have a plug in the mouthpiece to keep out sand and prevent freeflow. However, lacking this, it sounds like your setup is satisfactory for the time being.

 

[Diver0001]

wetlettuce once bubbled...
Hi

Is it possible to mix and match 1st and 2nd stages ?

I ask because I have a aqualung Legend LX and first stage as a primary. I am going to by another for the secondary but for the moment I want to use a Mares Orbiter secondary.

The first stages are similar types being diaphragms.

Is it possible ? I've tried them in the pool and they work OK but how about at 20metres ?

Kindest Regards

Andy

It is possible but you have to keep two things in mind

1) the IP (intermediate pressure)

2) overbalancing.

Not all regs can work on the same range of IP and even if you have a second made for the same range of IP you'll probably need to fine-adjust it to work with a 1st stage for which it wasn't adjusted during it's last service. In most cases mixing and matching isn't a big deal as long as you tune the 2nds to the first you're using.

IN your case, however, you have something else to think about. The Legend LX is "overbalanced" when fitted with an ice-kit. This means that the IP will actually increase a little bit more than ambient when you decend (about 110% of ambient). The net result is that the 2nd stage needs to be balanced too or it could start to flow when you take it to depth. The Mares reg you mentioned isn't balanced which could theoretically lead to a mild free-flow if you go deep enough. You probably have to go really deep to get this to happen but even at that I don't like the idea and I wouldn't advise it.

R..

 

[wetlettuce]

Hi

Tried it yesterday in a balmy 8 degrees C.

Two dives to 20 metres and it worked fine.

Thanks for the advice though. Another Legend is on the way !

Kindest Regards

Andy