Reg performance after being serviced?

[mohave_steve]

Last weekend I had the privelige of diving with Jupitermaid and NJMike down in Jupiter. The diving was fantastic!! Unfortunately the dives were shorter than I am accustomed to. I was diving 36% nitrox, HP100. On the first dive we dropped straight down to 85' and drifted along the reef holding 80-87'and BT was only 27minutes and I had exhausted my air. During this dive when I drew on my reg it felt like it was "preasure filling" my lungs. I am used to inhaling gradually. On this dive once I started airflow I had little control over how quickly I inhaled. I noticed at the end of this dive and on subsequent dives that my reg performed in the manner I am accustomed when I ascended to 65-70'.

Is this normal performance/behaviour for a reg at this depth?

Could this have affected my air consumption?

This was my first time diving such a "square" profile. In the past I have made many dives where my max depth was 90' but a good bit of the dive was shallower. On these dives I would typically get 40-50 minutes from an AL80 on air.

I neglected to mention that this was my first diving at depths over 60' since I had my reg serviced at my LDS.

 

[Couv]

Hello Steve,

It could be that your regulator has just gone through a sort of "break in" period after service. After service the tech should the time to cycle the regulator enough so that the high pressure and low pressure seats take a "set". Sometime they do not do this and you can get symptoms such as you described. If you asked the LDS for a quick turn/service so you could have your regulator in time for this trip, that is a real possibility. But before I go off on a tangent, help up to help you with a little more information. What make and model first and second stage do you have? Are there any external adjustments, flow vanes, pre-dive switches etc. Chances are your regulator will just need a quick "final adjustment" that the LDS should be happy to perform.

In the meantime, see the sticky thread http://www.scubaboard.com/forums/regulators/260452-regulator-checklist-inspection.html for some info you might find helpful.

Could this anomaly have hurt your air consumption-yes. Any out of the ordinary performance could do that.

Looking forward to your update and the input of others,

couv

 

[halocline]

It sounds like your reg has a little more venturi effect than you want. Some regs will have some sort of venturi adjustment, like the flow cane on most SP regs. If yours does not, or if it's already turned down, you can ask to have the cracking pressure set a little higher.

Unfortunately, some 2nd stages are designed to maximize venturi effect to lower WOB numbers on test machines. Test machines don't really care about the qualitative "feel" of a particular reg, only how much air it delivers at what vacuum level. If you have a reg like that, your choice is either to de-tune it substantially or go in search of something with a more natural feel. The old SP 109 is about perfect in that regard. G250s with the flow vane turned off are very natural too. They both have slightly larger cases than many current high performance regs, which I suppose allows for a slightly more natural expansion of air in the 2nd stage, a couple of millimeters further away from your mouth.

 

[fnfalman]

The average depth of 80+ft isn't exactly chump change either. You may be drift diving, but you're still at depth.

 

[DA Aquamaster]

It would help to know what model reg you have.

 

[mohave_steve]

Scubapro Mk11/R295.

At depth the reg was breathing so aggresively I was virtually unable to control how quickly I inhaled. Kind of like an "on-off" switch.

 

[halocline]

So, no user venturi adjustment. I imagine that the flow vane is "pre set" in the position of most assist.

There might be other issues but that's the one I would guess first. You can ask the tech about it, and have him de-tune the reg a little.

 

[redacted]

I believe the 295 uses a plug in one of the housing ports which will reduce positive pressure breathing. I usually leave it out of my R190 for better performance. Your tech may have left a plug out to improve performance. But if the positive pressure effect is uncomfortable, it should be installed.