Cargo pressure

So Cargo balls are supposed to be inflated at 3.5 psi but atmospheric pressure is ~14. Am I missing something?

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It means relative to atmospheric pressure.

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Known as “gauge pressure”, as opposed to “absolute pressure”

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I’m curious about how much pressure variation affects handling. Should probably go from 2.5 to 4.5 for testing, especially with how poorly most gauges handles pressure that low.

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I was thinking the same thing as I was inflating our balls (which I did pretty much on the “inflate them until the wrinkles come out of the surface” plan.) I’m not sure I have a gauge that will read that low a pressure accurately. I’m going to try the bounce test from the game manual too, but this may be one of those problems that crops up the whole season. Fortunately, the balls themselves are pretty stiff and small variations in inflation pressure may not be as critical as what we had with the Deep Space cargo.

Mountain bikers use some pretty low tire pressures compared to road bikers. This one has the lowest full scale pressure that I could find (15 psi) so 3.5 psi is still just around 13 % of full scale. It’s better than using a gauge with a full scale of 100 psi or greater.

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That may need a weird adapter. Presta valves are different than the kind that most ball adapters work with.

My bike pump can’t go lower than about 10.

One of our mentors had a Milwaukee compressor that had a digital gauge that went that low.

Yes. I have a Ryobi version. I think it can go that low. I am going to check tomorrow.

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This adapter might help.

Nope nope nope nope don’t do it. I have the same one (m12 compact inflator) and it’s an easy +/- 2 psi depending on a bit of everything. Some of them even read atmospheric as 3 psi out of the box.

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I think bounce test is pretty much the best applied way to meet the field expectation for the cargo. I added a little testing place for it with 2 pieces of tape under a shelf/bar. So I can touch the shelf, and see if the ball returns between the tape or not.

The ball is not perfectly rigid, but most all the squishiness is gone.

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I am thinking something like this may be more accurate, but a bit pricey.

Electric Ball Pump,Smart Air Pump Portable Fast Ball Inflation with Accurate Pressure Gauge and Digital LCD Display for Football Basketball Volleyball Rugby (2 Needle and 1 Nozzle)

I am going to discuss this with our athletic director as well. It is essentially an indoor soccer ball I think.

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Might want to try the athletic director?

Moroso makes a 15 psi pressure gauge used for drag racing slicks, but the “zero” end of it is rather iffy. And digital gauges…where you can’t see what it’s seeing…also rather iffy.

Catapult ftw.

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Yep. Thanks. Darn autocorrect.

We bought this one today at Meijers. We’ll be trying it out tomorrow.

Team Update 2 indicates this (https://soccer.epicsports.com/prod/14762/champion-sports-pressure-gauge.html) is what official events will be using

With the two CARGO balls supplied in the KOP, we are finding inconsistencies in section 5.7.

Specifically, a ball inflated to 3.5 PSI (using the specified gauge listed below) is less than 9.3 inches in diameter.

A much bigger problem is that there appears to be insufficient pressure to close the valve when the ball is inflated less than about 5 PSI. When we use the specified official gauge to bleed it off to 3.5 PSI, it will deflate on its own to around 2 PSI.

We haven’t tried the bounce at 3.5 PSI - we were getting the described bounce height when inflated to 6 PSI (still under 9.5" diameter).

Anyone else seeing the same things?

image

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Does your gauge read “zero” when it’s not connected to a ball?