Shearwater Transmitters Nitrox vs Air

[Sean Younk]

Hello folks,

I just bought two Shearwater wireless transmitters for my Perdix. The transmitter manual says "WARNING: Transmitters marked EN 250 are certified for use with air only. Transmitters marked EN 13949 are certified for use with Nitrox only."

The Perdix manual says AI, as configured, is good for air and Nitrox up to 40%.

I don't want to buy a set for air and a separate set for Nitrox.

Should I assume these two marked EN 250 are good for air AND Nitrox up to 40% mix, or should I return these and buy a pair marked EN 13949 and use them with air too?

...ore return them and give up on this fancy transmitter idea altogether?

Also, I really bought two so I could monitor my wife's air as well. The manual says they are good for 1 meter of reception. Does this mean my wife's transmitter will only be useful if my wrist is within 1 meter of her transmitter? I saw some of the other models being marketed for up to 10 students in a classroom environment. Is this a completely unrealistic expectation to monitor my wife's air in this manner? Will it reconnect instantly if I swim close to her?

What are you guys finding in the field?

Thank you all in advance.

 

[Marie13]

I use the same transmitters for everything. No problems.

Why do you need to monitor your wife’s air? Yes, your expectation to monitor her air is unrealistic.

 

[Manatee Diver]

The contradicting information is because Europe has some stupid rules on nitrox. Unless you are in Europe, that disclaimer doesn't apply.

 

[Sean Younk]

Hey guys I also posed this exact question to info@shearwater.com and got the following response, (looks like I am almost as good as planned);

Customer Support Representative (Shearwater Research)

Mar 19, 2021, 4:37 PDT

Hi Sean,

Thanks for getting in touch.

The EN markings are European standard ratings. All transmitters that we supply are rated to be used with up to 40% Nitrox.

You can use the transmitter to monitor your buddies air, however the range is limited to 3-5 feet. This means that you would need to be essentially shoulder to shoulder to pick up the signal. If you did separate for a period, the signal would drop, however it would reconnect once your are back within range.

I hope this helps,

Best regards,

 

[Sean Younk]

I also recommended they ad this to the Transmitter manual.

 

[Newdiv]

Keep in mind your battery will drain faster as it will constantly be looking for the transmitter when it disconnects.

 

[Belzelbub]

Does this mean my wife's transmitter will only be useful if my wrist is within 1 meter of her transmitter? I saw some of the other models being marketed for up to 10 students in a classroom environment. Is this a completely unrealistic expectation to monitor my wife's air in this manner? Will it reconnect instantly if I swim close to her?

Yes, this is an unrealistic expectation. Your wife should be competent enough to monitor her own air. If not, she needs more training/practice.

My wife doesn’t dive, but my daughters do. They monitor their own air. When I inquire, they will let me know how much they have left, but I don’t need to monitor them constantly.

I think, that the Garmin transmitter may have the range for what you are trying to, but that’s probably it. The PPS transmitters will probably work if you are diving really close, but it’s probably just as easy to signal a gas check.

 

[ATJ]

Keep in mind your battery will drain faster as it will constantly be looking for the transmitter when it disconnects.

Will it, though?

Note that I'm not having a go at you and I think even the manuals state this but it doesn't make sense.

With PPE transmitters there is no connection/disconnection. The transmitter just broadcasts its ID and pressure and the dive computer just listens for the broadcast. If it receives the broadcast it displays the pressure. If not, it keeps listening for the next broadcast. There's a timeout period and after that period if it hasn't received the broadcast in that period it goes into a warning state. There's a second timeout which puts it into an error state. On my Perdix it flashes yellow after 30 seconds and red after 90 seconds.

The dive computer will be listening no matter whether it receives the broadcast or not. This is much the same as an analog radio. If it picks up the station you get the station playing. If it doesn't, you get static. It shouldn't use any more of the battery if you are picking up the station of getting static.

The only area where you could potentially use more of the battery is if flashing the small area of the display uses up more battery power, but considering the depth, NDL, time, etc. are constantly changing, I don't see this making much difference.

 

[rsingler]

No. Your battery won't discharge faster. It discharges at the same rate once you turn "AI" on. It keeps receiving no matter how many transmitters are transmitting. That doesn't change when one goes out of range. EDIT: I'm wrong.

No. It's not stupid to monitor your buddy's air. Yes, he/she should be competent to conduct the dive. But if there's a significant skills disparity, it's not a bad thing to have a second pair of eyes, so that the less experienced diver can relax a bit more. It doesn't absolve them of the responsibility of tracking their (greater?) air consumption, but it can be a nice teaching tool if the monitoring buddy can signal "check your gauge" if a faster drop is noted. I did that with my buddy, and the signal was absent most of the time (>5-10 ft apart). It popped in often enough to allow an unobtrusive check.

 

[scubadada]

@Newdiv @ATJ @rsingler

I assume this to mean that if the computer is scanning for a paired transmitter that is out or range, that the power consumption will be increased. Shearwater is very responsive to queries, you could email them for confirmation.