The "R" port on my 1st stage?

[Barnacle B]

I once knew what the "R" marking on one of the low pressure outlets of my 1st stage of my regulator was all about. Can't remember now. Can anyone HELP?

 

[b1gcountry]

What kind of reg is it?

 

[ae3753]

Do you have a Mares regulator?

If so, the following from one of their manuals is what you're looking for (emphasis is mine):

DFC System
The exclusive MARES DFC system featured on the Ruby first stage minimizes the intermediate pressure drop which occurs in all
regulators during the inhalation phase (Fig. 4). This phenomenon is all the more marked when higher airflow is demanded of the regulator.
The DFC system substantially reduces breathing effort and inhalation resistance, especially during deep dives and under demanding
conditions. The Ruby first stage incorporates the DFC system on the preferential LP port for the primary second stage, whereas the
operation of the other low pressure ports (for octopus, inflator, etc.) is standard.

 

[Barnacle B]

I have this "R" on my Posiden and Oceanic 1st stages. I remember reading what this was for in the manuals, but...................You see my home was broken into and my regulator bag which held all my manuals was stolen. They dumped 3 sets of regs and 2 computers on the floor and took the bag. Unfortunatly my dive log was taken as well. Hundreds of dives and collected info gone.

 

[keyshunter]

On an Oceanic, the "R" port is supposed to have the most direct airflow and is where they say to connect the primary second stage. On my CDX5, the "R" was toward the back (tank side) of the first stage and I did not like the routing, so I moved to the front port and noted absolutely no difference in breathing.

 

[Brewone0to]

Same thing for poseidon 1st stages.
Connect your Primary 2nd to this port.

I would imagine that this could become
quite important for cold water diving especially.

 

[captndale]

As you draw air through the first stage the intermediate pressure drops due to the friction through the regulator. This drop in intermediate pressure slightly increases the work of breathing through the second stage. In order to overcome this tendency for the IP to drop as air flows through the system, some manufacturers icorporate a venturi path into the design or their first stage. This boosts the IP as flow increases. The problem is that the venturi can usually be incorporated into only one of the available low pressure ports, so the manufacturers usually mark that port with a unique symbol.