Do you trust your SPG?

[bubbletrubble]

Originally Posted by mksmith713

Also, is there a way to calibrate SPG's to make them accurate?

Your LDS repair shop will not be able to do this calibration, although they may be able to state how accurate and precise your SPG is. Technically, the factory that manufactured the SPG could carry out this calibration. Considering the cost of labor, the factory would just junk your SPG and give you a new one.
Practically speaking, if you're uncomfortable with the accuracy of your SPG, you should just buy another one.

[bubbletrubble]

Originally Posted by acamato

Accuracy is defined as the conformity of an indication to its true value. Accuracy is a percentage of the full range. For example, a gauge that has a scale of 0-3000 psi with an accuracy of ±1% would mean that the gauge is accurate to within ± (plus or minus) 30 psi.

@acamato: Using your example with gauge accuracy stated as +/- 30 psi, the accuracy of extremely low pressure readings will be limited by the resolution of the "needle" scale being used. Many brass-and-glass SPGs only have four hash marks below 500 psi. My Suunto-brand SPG doesn't have any hash marks below 500 psi.

[BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)]

Your life does *not* depend on the SPG reading, it depends on having breathing gas while under water.

It's documented that people have gon OOA with their SPG reading just fine and it's well known that people dove and some still dive without SPGs

You might consider learning how long you can dive on a full tank at different depths and treat your SPG with skepticism if you've been down a long time and it's still reading high.

Here's what I want in an SPG: Show when I have a full tank and when I have an empty tank and be reasonably linear (i.e. proportional) in between. If it does that I don't care whether it reads pressure in psi, bars, smoots per acre, or ears per square nose.