IP Gauge Reading

[rsingler]

On the bench, I use a 0-300 psi digital pressure gauge with 0.25% accuracy. Cost about $250 WITHOUT a calibration report, but I figure with that degree of accuracy, the actual value will be close enough for scuba.
Cole-Parmer Digital Pressure Gauge, 0-300 psi, 3" Diameter, 1/4" NPT(M) from Cole-Parmer
I just cross-compare with my junk gauges from Home Depot or Lowe's, and mark the midrange deviation on the face. As you all know, it's the consistency that's important for tracking need for service, rather than an absolute value +/- 5 psi. For that, any $10 junk gauge is just fine.
But it is reassuring to know the real number from time to time. As you've observed, the manual air-filled gauges are all over the place.

 

[tbone1004]

similar to @rsingler I use a cheap analog gauge to get it "close" and "stable", once I validate that because it is easier to read a moving analog gauge than a digital one, I pop my good digital one on and set the actual IP.

That said, with balanced seconds especially, as long as you are within 5-10psi it's close enough. You'll get the cracking pressure set and as long as it doesn't move, it's close enough. The Poseidon Jetstream and Xstreams are a bit more picky because of the servo valve, but even 5psi in either direction for them is close enough