Aqua Lung Titan free-flow

[Chris Richardson]

I have an Aqua Lung Titan (bought second-hand so unsure of year of manufacture) that went into free-flow @ 33m. What would cause this to happen? The octo was fine @ this depth though so was it a setting on the dv that caused this? What exactly does the little adjuster do on a second stage and what is the ideal position for it? Cheers

 

[wnissen]

That regulator is good to a minimum of 50 meters so it's definitely not the depth. The manual also discusses what to do with the switch. To jump ahead it should be set in the '+' position while you're breathing off of it. Free flow at the surface is common and mildly irritating, but I would be scared as hell if my reg was free-flowing at depth. That is a great way to empty the tank within a minute. Despite ones intuition the low-pressure port can put out a larger volume of gas than the high-pressure port.

The only correct answer here is to get it serviced, unless you look inside and there's some piece of debris clearly keeping the "demand valve" open. Then think about how you would respond if it happens in the future. Here's a thread on freeflows that has some suggestions. Techs are typically very good at servicing regs but even they can't predict every way a reg can fail. They're supposed to fail open (free flow), so at least that part was right. How did you respond on your dive? Glad it was not a major problem.

 

[DogDiver]

Get it serviced

 

[John C. Ratliff]

Okay, you are in the UK, and it's winter. So I'm assuming that you are diving in pretty cold water. It sounds to me like you had a freeze-up situation develop, and servicing the regulator won't change that. It will happen again under similar circumstances. It sounds like your regulator was doing fine until it started free-flowing at 33 meters (about 108 feet depth).

Please look over this publication by Dive Lab about regulator freeze-up. Here is part of what they say in this report:

2.5 Regulator Freezing in 50°F (10°C) Water: So how does ice form in the second stage if you are not diving in water much colder than 50°F (10°C)? Simple! When the high pressure air passes through the first stage regulator, the rapid drop from high pressure to low pressure causes a dramatic temperature drop. This pressure drop is basically how your refrigerator and air conditioner work, the temperature drop is fairly linear, the higher HP pressure the greater the drop in pressure and the colder the air gets at the second stage. Now increase the flow and it gets even colder. If you can keep your breathing rate at the low to moderate breathing rates (15 - 30 lpm flow) the risk of ice formation is less and you will minimize the potential for second stage freezing. See: Table 4 page 16. The temperature / breathing tables show how extreme the cooling can get.
https://divelab.com/download/proced...ubaRegulatorFreezing-ChillingFacts-4-9-14.pdf

So take a look at this and see whether it matches what happened to your Aqualung Titan. That regulator is a great regulator, with great breathing characteristics, but those very characteristics can influence the temperature change in the second stage, and make ice formation happen more easily.

The depth can affect this freeze-up situation, as more volume of air is passed through the valve. Remember the universal law:

P1V1/T1 = P1V2/T2 (the temperature is not degrees C or F, but rather degrees K or R.

If you flow a greater volume of air, it will affect the temperature.

There is another thread here on Scubaboard which discuss this. Here's one post:

JimmyC: Rivers, Aqualung North America recommends you not use it in water colder than 50 degrees as it may freeze up. If it is an LX it will have the ribbed heat exchanger on the 2nd stage. It would help you out to install the Enviro kit as mentioned as it will give you a better edge against the cold.
Question about Aqualung Titan and water temperature

What exactly does the little adjuster do on a second stage and what is the ideal position for it? Cheers

That knob will allow you to adjust the spring tension on the second stage valve, thus increasing ore decreasing the effort required to open the valve. Screwing it in increases effort, and screwing it out can decrease that effort to the point where it will leak air a bit. But this would not affect the process by which a regulator second stage freezes.

SeaRat

 

[Belzelbub]

That knob will allow you to adjust the spring tension on the second stage valve, thus increasing ore decreasing the effort required to open the valve. Screwing it in increases effort, and screwing it out can decrease that effort to the point where it will leak air a bit. But this would not affect the process by which a regulator second stage freezes.

I could be wrong, but I don’t believe the Titan 2nd stage has the breathing adjustment knob. I think it only has the Venturi switch.

OP, the Venturi switch is generally used in one of two positions. Dive and pre-dive, or as they are often maybe + and -. In pre-dive position, the regulator is less likely to free flow. In the dive position, surface free flow is more likely, but usually not a problem at depth. The purpose of this switch is to make breathing easier as the airflow in the dive position helps keep the valve open.

The valve SeaRat mentioned is another valve on many regs, and that valve does affect the effort required to open the valve, while the Venturi affects the effort required to keep the valve open.

 

[John C. Ratliff]

I could be wrong, but I don’t believe the Titan 2nd stage has the breathing adjustment knob. I think it only has the Venturi switch.

OP, the Venturi switch is generally used in one of two positions. Dive and pre-dive, or as they are often maybe + and -. In pre-dive position, the regulator is less likely to free flow. In the dive position, surface free flow is more likely, but usually not a problem at depth. The purpose of this switch is to make breathing easier as the airflow in the dive position helps keep the valve open.

The valve SeaRat mentioned is another valve on many regs, and that valve does affect the effort required to open the valve, while the Venturi affects the effort required to keep the valve open.

Belzelbub,

You are correct, the Titan has only a Venturi adjustment. My mistake was simply looking at a photo of the Titan, and making an assumption. Apparently the Aqualung Legend ACD dose have this type of adjustment, in addition to the Venturi adjustment. The 2006 Aqualung catalog states:

--Diver-controlled Venturi Adjustment Switch (VAS) reduces sensitivity to free flow on the surface and provides maximum airflow at depth.

I will look more closely in the future, but thank you again for the correction.

SeaRat

 

[herman]

Troubleshooting from a distance is difficult at best but we need a bit more info just to get close. What exactly are you calling a free flow? A very slight leak or a full bore flow of gas, they are very different but are both technically free flows but are very different. We also need to know the model of the reg, looking at the manuals, the Titan series had both balanced and unbalanced second stages. Also did the free flow continue or stop as you changed depth. I could go on but I think it's clear, a simple "it free flowed, what was wrong" is way too general description to make any useful diagnosis.

 

[Chris Richardson]

Thanks guys. I took the regs in this weekend for a service so we'll see what that turns up when collecting them.

Cheers Belzelbub for the info on the venturi adjustment switch. So ideally have it fully on '-' when @ the surface and them flick it over to '+' when going down and staying @ depth?

herman: it was indeed a full bore flow of air that just vented out of the dv but oddly stopped when ascending to 28/30m so surely it must be something pressure related?

 

[Chris Richardson]

Okay, you are in the UK, and it's winter. So I'm assuming that you are diving in pretty cold water. It sounds to me like you had a freeze-up situation develop, and servicing the regulator won't change that. It will happen again under similar circumstances. It sounds like your regulator was doing fine until it started free-flowing at 33 meters (about 108 feet depth).

John, it was 21°C on the surface and 8°C @ 33m. It was mid July here in the UK so I'm the middle of summer.

 

[Belzelbub]

So ideally have it fully on '-' when @ the surface and them flick it over to '+' when going down and staying @ depth?

That is correct. I usually flick to + when I begin my descent, then leave it there. I’ll only switch back during the swim back to the boat if my reg free flows.