Recommendations for digital IP gauge?

[Fibonacci]

I've got a couple of good quality analog 0-300 psi IP gauges but would like to get an accurate digital model as ONE reference tool.
There are a lot of cheap Chinese digital gauges on the market, but with tools I like to buy good quality... and just cry once!

I've narrowed it down to the following US Manufacturers (+ rubber boot where available)
Dwyer Instruments 0-300 PSI, DPGA-10 (+/- 1%)
Series DPGAB & DPGWB | 0.5% Digital Pressure Gage is easy to use unit at prices comparable to mechanical gages. This product comes with a protective rubber boot to protect against short drops and rough handling. | Dwyer Instruments

SSI MGA-300-A-9V-R (+/- 1%)
https://www.ssi-sensors.com/perch/resources/documents/ps-an5mga-9v-product-overview.pdf
SSI MG-5-A-9V-R (+/- 0.25%)
https://www.ssi-sensors.com/perch/resources/documents/ps-an4-mg-9v-product-overview.pdf

Ashcroft DG2551N1NAM02L300#- (+/- 0.5%)
2074 Digital Pressure Gauge .25% accuracy

Seems most manufacturers recommend an IP target of say 135psi +/- 5psi (which is +/- 3.7%)
The exception appears to be Poseidon, which apparently MUST be set accurately to the manufacturer's specifications for reliable performance.

My question is how accurate does a SCUBA IP gauge really need to be?
Prices are reasonable at the +/- 1% accuracy level but really take off for +/- 0.25% accuracy.
Any other suggestions gratefully received

 

[Perryed]

I don`t know. For me when the IP range is 125-140 PSI analogue is fine. Save the bucks and go with the slightly lower accuracy.

 

[chris kippax]

I use Stauff gauges at work and they are dear but good.
STAUFF: Digital Pressure Gauges SPG-DIGI and Accessories

 

[herman]

Accuracy is not really that critical as most regs have a fairly wide "acceptable" range. I am more worried about changes in IP as opposed to the actual number. If my IP is 135psi when I set it, I want to see it at 135 when I check it later, weather it's actually 130, 135 or 140 is not nearly as important as it is the same as last time. It's much more important that the reg lock up at the same pressure rather than what the exact value is.

 

[Schwob]

Not in the know for what you are looking for, but also wondering (and hoping to learn from it):
Why digital?
Why 300 psi?
Why does it need which acuracy?
Why wouldn't +/- 2% FS with properly selected FS do just fine as long as it repeats?
I mean are you calibrating other gages or setting IP and monitoring for creep?
I.e. this gage at +/- 0.5% of 160 PSI FS is about as accurate for what you are looking for as one at +/- 0.25% of 300PSI FS, is graduated in 1 PSI steps, costs $107 (and I still wouldn't know why that accurate):
McMaster-Carr

 

[runsongas]

@Schwob the dwyer dpgab-09 is 118, not really much different than the 107 for that analog gauge. it really comes down to personal preference which you prefer to use.

@Fibonacci +/- 1% is fine for gauges that go up to 200 psi or so. even a poseidon will not be very affected going between 123 and 125 psi.

 

[Bigbella]

One thing to consider with digital gauges -- something which is rarely mentioned in catalogues -- is a greater requirement for calibration; and those devices themselves don't come cheaply, especially when you're aiming for a .25% margin or error. It's a similar issue for digital scales.

My test bench has all analog gauges -- and I wouldn't trade them.

If you're insistent, a couple of gear-head colleagues like this item; and it won't cost you that plump red kidney:

Digital IP Gauge with Purge Button and Back Light

 

[Fibonacci]

@herman agree consistency of IP lockup is more important than meeting a specified IP figure...

BUT how much of the apparent IP drift is due to analogue gauge hysteresis vs an actual problem with the first stage?
The Role of Repeatability & Hysteresis in Bourdon Tube Pressure Gauges

Each one of my analogue gauges reads sightly differently when pressurised off the same tank, and each one may or may not return to the same point during cycling.

So hopefully, having an accurate digital gauge reduces one variable at least...

 

[Bigbella]

Each one of my analogue gauges reads sightly differently when pressurised off the same tank, and each one may or may not return to the same point during cycling.

So [I]hopefully,[/I] having an accurate digital gauge reduces one variable at least...

I hate to tell you; but the same is true, during cycling, of digital gauges as well as analogue. I have seen drifts of between .2 - .35 bar (the latter, being about 5 psi), even with some of the most "expensivist" of equipment . . .

 

[dlofting]

@herman agree consistency of IP lockup is more important than meeting a specified IP figure...

BUT how much of the apparent IP drift is due to analogue gauge hysteresis vs an actual problem with the first stage?
The Role of Repeatability & Hysteresis in Bourdon Tube Pressure Gauges

Each one of my analogue gauges reads sightly differently when pressurised off the same tank, and each one may or may not return to the same point during cycling.

So hopefully, having an accurate digital gauge reduces one variable at least...

I do my own reg maintenance but am far from an expert....but I've seen IP drift using an analog gauge and it's pretty obvious.