What is the sensor lifespan for a helium analyzer?

[walkonmars]

Just wondering what the lifespan of a sensor from a helium analyzer is?
I'm suspecting much longer due to the detection method used is thermal conductivity or heat capacity (instead of a galvanic cell).

Also, for oxygen, we use air as our calibration bump gas. Do you need a bump gas for helium as well?

Thanks,
-T

 

[Camerone]

Usually about five years, but it depends on the sensor. I've gotten six or seven out of them, but officially the one I have is five. Helium can and will diffuse through the glass of sensor (tiny little molecules...) which causes it to no longer be a good reference sample on those thermal sensors...

You don't need a bump gas on helium... the measurement of thermal conductivity compares it against a sealed cell's conductivity in pure helium, and the imbalance tells you the approximate helium concentration in the sample.

 

[walkonmars]

Thanks, That is good to hear. I posted some question on another section and the point came up that I'm going to need an analyzer sooner or later. Prices are a bit painful in spite of the longer lifespan. Thanks, -T

 

[Camerone]

You don't "need" an analyzer for helium unless you're trying to continuously blend through a compressor. Buying the helium from a traceable source and good hygiene plus junior-high chemistry and math skills will get you everything you need. (Breathing the sample on land, plus a good oxygen analyzer will tell you if you're in the neighborhood or royally screwed up.) It's a good check to have one, and it makes life convenient, but most of us who have been doing this for a long time started before these were relatively affordable.

If you're concerned about lifespan, the ultrasonic analyzers require only that the relatively inexpensive oxygen cells ($75-ish) get changed annually, as the sensor's operating principle is completely different than the reference-cell/heater version. The helium side requires a good O2 cell so it's math works, but the helium "bits" lasts indefinitely, as it's a speed of sound measurement with a transducer/mic. They're as good as the sealed-cell version for this purpose.

If you're concerned about the cost of an analyzer, you really should not be diving helium in the first place.

 

[walkonmars]

You don't "need" an analyzer for helium unless you're trying to continuously blend through a compressor. Buying the helium from a traceable source and good hygiene plus junior-high chemistry and math skills will get you everything you need. (Breathing the sample on land, plus a good oxygen analyzer will tell you if you're in the neighborhood or royally screwed up.) It's a good check to have one, and it makes life convenient, but most of us who have been doing this for a long time started before these were relatively affordable.

If you're concerned about lifespan, the ultrasonic analyzers require only that the relatively inexpensive oxygen cells ($75-ish) get changed annually, as the sensor's operating principle is completely different than the reference-cell/heater version. The helium side requires a good O2 cell so it's math works, but the helium "bits" lasts indefinitely, as it's a speed of sound measurement with a transducer/mic. They're as good as the sealed-cell version for this purpose.

If you're concerned about the cost of an analyzer, you really should not be diving helium in the first place.

Thanks,

I would like to trouble you for a few ultrasonic analyzer models/part#'s, if I may.

Yes, I agree it is not required and with the convenience of blending software available online or even with free basic dive computer software (Suunto, Dive Rite, etc) the He analyzer can be just a quick safety check.
The reason I considered purchasing one was started in another thread concerning blending on a boat for multi-day trips. Boats would discourage us taking a half dozen cylinders for personal use. An alternative considered and suggested by contributors was to bring only two or three cylinders and blend on-board the boat with our own transfill whip. Then let the boat top off my cylinders after I transfer gases to use cylinders. There is question whether or not boat operators will look kindly to topping off your tanks without the ability to analyze what is in them. They have no idea what I have in my cylinders as I walk on the boat and then I ask them to top off and take my word that I have done mixing my calculations correctly. This way I can show them exactly what we end up with.
I am not a boat operator but I would personally not allow a passenger to do transfill mixing by asking me to provide him/her my compressor gas and allow them to dive with it on my boat without proving to me what is in their tank.

I probably mis-spoke about the cost issue. I just don't want to buy equipment I don't need or won't use. I'm an early 40's average working stiff and I can really start to buy junk and clutter the apartment. I dive the south California coast and boat trips (single and multi-day) average $170 per day. The helium in a 25/30 costs me around $45 so three tanks of trimix is still less than the daily cost for the boat. Local shops charge 3 times that for helium.
I analyze oxygen only but deeper dives for trimix are most available by boat charter.

As I mentioned in another thread, I want the helium for the reduction of narcotic effects in the 100-130ft range and not as a tool for diving very deep (150ft+range) At those depths, I function normal but have very fuzzy memories afterward. I'll likely use trimixes more normoxic rather than rich in O2 as well.

Thanks,
-T

 

[Camerone]

I would like to trouble you for a few ultrasonic analyzer models/part#'s, if I may.

Google "DiveSoft" and you will find what you're looking for. It's really about the same price point as the thermal sensor ones (or close enough that no one should care.) Just be careful if you use it and make sure you do not get water into the lines at all... let's just say that one comes from some friends' experiences...

I am not a boat operator but I would personally not allow a passenger to do transfill mixing by asking me to provide him/her my compressor gas and allow them to dive with it on my boat without proving to me what is in their tank.

I do this often, but I usually show up with a small Jetsam baby booster pump, rebreather, and a single 80 of some reasonable helium mix, where I'm just topping off my own diluent... the boat just ends up giving me air for drive gas on the booster, or I scavenge the dregs from the bubble blowers' remnants.

As I mentioned in another thread, I want the helium for the reduction of narcotic effects in the 100-130ft range and not as a tool for diving very deep (150ft+range) At those depths, I function normal but have very fuzzy memories afterward. I'll likely use trimixes more normoxic rather than rich in O2 as well.

To each their own. On the rebreather, for the last decade or so, I generally have my dil loaded with 18/45 no matter what the dive (unless I need something hypoxic), because the cost of a 19cu ft bottle fill when I'm filling at home from a T cylinder is insignificant in the grand scheme. On open circuit, I don't think it'd be worth it to spend the money for something as shallow as 130 feet. I, like you, appreciate the clear head helium adds in the deeper end of recreational ranges, but it's not worth what OC would run to fill it.

Have you considered just doing this the easy way with a set of doubles? Start with a very rich mix and blend down during the day by topping with air? No need to bother arguing with the boat operator as to what you're trying to blend -- just don't bother mentioning it, as it's none of their business, and no one pumping air is going to bother you to check air... Not only is it a safer configuration for deeper diving, but it's a hell of a lot more stable in the water than a single tank, and the equipment placement on your body is so much better.

 

[lucca brassi]

CZ rules productor page NRC International vs CZ page Set Blender Max - Detail - DIVESOFT.CZ for 369 € difference ...

US sensor : Product line

PS: In theory :because that sensor calculates ratio between mixture of TWO !(important ) known gases by difference in travel time of sound wave you could made DIY your own US sensor from some US distance measuring unit and put it on the tube ( https://www.youtube.com/watch?v=EfU6SlrOndc ) but you have to observe difference of time pulses on oscilloscope unit for start you would also need precise measured mixture of gases for calibration .
You would also need stabile temperature inside ( just insulation from outside temperature ) and constant pressure (calibration points )

Usually about five years, but it depends on the sensor

don't understand that at all . What have He diffusion with ultrasound or temp . ( you have two quarz ''beepers'' or you have in second option some precize and fast temp sensor )

Talking for myself from pure technical aspect .

 

[walkonmars]

I see...sonic detection.
Yes, trimix for the occasional use and when detail planning is available. Not so much for exploration and new sites.
Likely for wrecks or a familiar site I want to have sharper memory and dexterity.
Thanks.
-T