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Remote tire pressure monitor

N

Nick Leonard

Member
Has anyone found a remote tire pressure monitoring system with sensors that will work on our tires? Most senders appear to be quite large and I'm not sure that they will fit inside the wheel fairings.

It would really be nice to be able to see actual tire pressures rather than guessing if the tire looks low enough to have to check, which is always a pita.
 
That's really interesting. I can leave the receiver on the wall in the hangar and glance at it during pre-flight...

Is anyone using these? Do they work well? How heavy are the sensors, do they fit in the wheelpants?
 
My experience with a monitor

I thought that would be a great idea. I ordered and installed a similar unit on my car first to try it out.

First I was concerned by the large cap size for our restricted area and the fact that they are always pressurized so if damaged somehow you lost all your air.

Turned out that they don't turn on until the car gets over 20 mph for a minute or two which was not what I wanted. I wanted instant reading to be part of pre-flight.

For me desired would be small caps with a leak failsafe and a remote reading stationary, say a handheld display that you can turn on and will read air pressure as part of pre-flight
 
Looking at Amazon, there are plenty of examples. However, I am wondering exactly how they work.

The valve is normally pressured closed so there would be no pressure to read at the cap. It seems to me that these devices must somehow depress the valve stem so that they are pressurized. That means you are relying on the seal around the cap and the valve stem to stop the tyre going flat.

Or am I missing something....?
 
Judging tire pressure on preflight

Over 20 years I've learned I can KINDA judge tire pressure by the size of the tire's contact patch on the hangar floor.

And I've wondered if it would be practical to make a go/no-go gauge that would slip under the pant like a chock and let you know if the tire was getting deflated enough to require airing up. Seems like the thickness could be calibrated against known pressures, and slid under the pant on a selfie-stick type of telescoping wand so you wouldn't have to get on the ol' knees.

Maybe "A couple printed ideas" could make a set for Amanda to sell :D

I'd do mine on a table saw with rip fence, I guess.
 
Bill Boyd said:
SNIP

And I've wondered if it would be practical to make a go/no-go gauge that would slip under the pant like a chock and let you know if the tire was getting deflated enough to require airing up. Seems like the thickness could be calibrated against known pressures, and slid under the pant on a selfie-stick type of telescoping wand so you wouldn't have to get on the ol' knees. SNIP
Click to expand...

Exactly correct. Make up a couple of PVC ?U? shape chocks and get them to just slide in when the tires are at pressure. If a tire is even a little low the chock will not slide in. As a side benefit you get a set of lightweight chocks.

At tire change you may need to adjust to the new tire.

Simple, cheap, easy.
Carl
 
I?m looking to switch to nitrogen, but haven?t found an aviation source near me yet. Probably need an FBO that services Jets. There are a good number of higher end car dealerships that provide the service, but I?m not pulling my tires off.

Nitrogen is a bit better, more stable in varying temps IMO.
 
I bought a large cylinder for nitrogen several years ago at my local welding supply (East Bay Welding, if you happen to live near me). I think it was about $200 at the time. And that last time I swapped it out, it was something like $40. The benefit being I get a new (er) tank every time I swap it out. It holds about 235 cu ft of nitrogen, which got me through a couple years with my Baron (N2 struts, prop bladders, tires), but now that I only use it for tires, it's probably a 4-5 year supply...just in time to get a newer tank.

I do the same thing for oxygen as well.

I find that my tire pressures rarely drop more than 2 pounds over the course of the month with N2.
 
rongawer said:
I find that my tire pressures rarely drop more than 2 pounds over the course of the month with N2.
Click to expand...
I am always amused by claims that N2 leaks out slower than air.
If that were true, after repeated adding pressure all tires would become pure N2, as the other molecules like O2 would be those leaking out, purifying the contents of your tire. With Leakguard tubes from Desser, I typically add air every 2-3 months, airing to 2-3 psi above specified, so that at next fill they are maybe 2-3 psi below desired.
Nitrogen is desirable for temperature stability, expanding and contracting less than air, and desirable to minimize corrosion risks. But certainly not worth the cost if just filling tires.
 
Given that a tubes permeability to Nitrogen is less then other gases, per the link to the paper in a previous post, wouldn't all of our tires be almost pure Nitrogen as was suggested. The compressed air we fill our tires with is low humidity by virtue of being compressed and starts out as 78% Nitrogen. As the other gases leak out and we refill the tire wouldn't it get to be a higher and higher percent of Nitrogen?
 
Kellym said:
I am always amused by claims that N2 leaks out slower than air.
If that were true, after repeated adding pressure all tires would become pure N2, as the other molecules like O2 would be those leaking out, purifying the contents of your tire. With Leakguard tubes from Desser, I typically add air every 2-3 months, airing to 2-3 psi above specified, so that at next fill they are maybe 2-3 psi below desired.
Nitrogen is desirable for temperature stability, expanding and contracting less than air, and desirable to minimize corrosion risks. But certainly not worth the cost if just filling tires.
Click to expand...

Glad your amused. However, nitrogen molecules are physically larger than oxygen and therefore leak slower threw rubber. Leakguard tubes are good because of the smaller membrane size the inhibits both oxygen and nitrogen leakage, however in natural rubber, oxygen will leak down faster than nitrogen...it?s not a myth, it?s physics.

The main reason for nitrogen in aviation is explosivity and moisture aborption; nitrogen does not and oxygen does - google accidents from many years ago that drove this.
 
No question the physics exist, but is the quantified effect relevant?

rongawer said:
Glad your amused. However, nitrogen molecules are physically larger than oxygen and therefore leak slower threw rubber. Leakguard tubes are good because of the smaller membrane size the inhibits both oxygen and nitrogen leakage, however in natural rubber, oxygen will leak down faster than nitrogen...it?s not a myth, it?s physics.

The main reason for nitrogen in aviation is explosivity and moisture aborption; nitrogen does not and oxygen does - google accidents from many years ago that drove this.
Click to expand...

Since the law of partial pressures would apply and effusion coefficient of N2 is about 3X that of O2 but the partial pressure of O2 is 1/3 that of N2 does that not mean the rate of mass effusion of each is about the same in the tire?? So as a practical matter, it seems to be of little consequence, amusing or not.

While self ignition is a real possibility as many tires operate this hot, but does an RV tire do this? Is that more likely than a guy that just does not set his tire pressure. We aren't running 115psi like a G550.
 
BillL said:
Since the law of partial pressures would apply and effusion coefficient of N2 is about 3X that of O2 but the partial pressure of O2 is 1/3 that of N2 does that not mean the rate of mass effusion of each is about the same in the tire?? So as a practical matter, it seems to be of little consequence, amusing or not.

While self ignition is a real possibility as many tires operate this hot, but does an RV tire do this? Is that more likely than a guy that just does not set his tire pressure. We aren't running 115psi like a G550.
Click to expand...

Self ignition is an issue on large commercial airliners. The accident of 1986 Mexicana Boeing 727 precipitated the regulation requiring nitrogen in certain aircraft, mostly part 121. Certainly not an issue for GA generally. Nitrogen in GA tires is more a novelty, but there is a factual reduction in leak rates. Bicyclists that run 100 psi air (78%N2) in their thin wall tires will have about 10-15% loss of pressure over 7 days, whereas 100% nitrogen will be about 1/2 that empirically speaking; which is why its pretty popular among bicyclists to use N2. This is a great home experiment project...

Moisture absorption and leak rate is why certified propeller and aircraft manufacturers specify it for use in propeller control and unfeathering accumulators. But is it worth going out and buying nitrogen equipment just to air up your tires? I don't think so. But if you have it, use it.
 
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Leak stop tubes will get you through any reasonable amount of time. You really should be removing your wheel pants and checking your tires for damage, and your other components like wheel pant brackets, brakes and hardware at least that often anyway.
Don?t put off these inspections because you don?t want to take an hour to pull off the wheel pants every few months.
 
Leakstop tubes do the job for certain, but they're also $120 each compared to $75 for a standard tube.

For me, I check my tire pressure with a digital gauge on my inflator more often than once a month, so pulling the trigger to add couple pounds is inconsequential to me, making the extra $45 per tube, times three tubes, not worth the extra cost to me.

As I think about it, I go through tires about once a year (lots of flights...), so the cost of my nitrogen tank and inflator is paid back in roughly two years. Something to consider.

As has been noted in other threads on VAF, making a small port in your wheel pants with either a pop-off cover, or even a fancy schmancy push-to-open cover, makes checking tire pressure fairly effortless.
 
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