The generic low pressure gauges (and even a Taprite) I've been getting lately for spunding valve builds have been lousy at the lowest pressures, failing to register anything (i.e. reading 0) when there is in fact up to 3 PSI (above atmospheric) on them. Maybe I've just had a run of bad luck. Anyone (@billandsuz) know of a brand/model of currently available low pressure gauges that work well at very low pressures?
This is what I use. Difficult to measure 1 psi but at or above 2 psi it's seems okay (if you look closely you can see it's non-linear from 0 - 5). Large dial (2.5") for the visual challenged and liquid filled. Get 'em at . . . where else . . . Amazon: FWIW, typical accuracy of commercial gauges is optimized for middle of range and slightly less accurate at the extremes (0 and Max). Ideally the "middle" of range is where you would like to operate. The gauge above is available in the 0 - 15 range and if you look hard there are even some that go as low as 0 - 3 . . . that would help with low-end accuracy. If you truly want to set and hold 1 psi you'll need something industrial/lab grade and probably not from the big A. For bottling I use 1 - 2 psi and find it easiest to set by "listening" to the flow of gas. But my ears are better than my eyes, YMMV. For spunding I'm guessing you want something accurate at the low and intermediate level . . . tough request. More minutiae: https://www.instrumart.com/pages/539/pressure-gauge-accuracy-grades
I agree that the standard equipment pressure gauges are rather poorly made. What do you expect for $5? They are just good enough. If you want to measure very low pressure, or vacuum, the best piece of equipment is a Magnehelic. Dwyer makes them and there are pages in the Grainger catalog. Not terribly expensive either. These gauges are ubiquitous in process equipment and pretty impressive with very good accuracy. If you are interested, the mechanism is kind of cool too. Not sure if you can get them to read psi since the usual specification is inches of water column, but it is an easy conversion. 1" w.c. = 0.036 psi, so you should be getting as accurate a reading as you would ever want. You could also rig up a U tube manometer. That was state of the art in DaVinci's time but still useful. Very simple and dead nuts accuracy. Does not break. Consider taking into account your elevation above sea level as well. Depending on where you are it could make a bit of difference, but usually it is an academic variation. Cheers Vike.
Somewhat related to this topic... if I buy a new pressure Gauge and install it, is there anything special to calibrate it? Or just some pipe tape and wrench it in and it’s all set ?
Looks like the 2.5" dial has better accuracy in addition to being easier to read.....based on the description of an elsewhere source: "Display accuracy is + or - 2.5% of full scale value for the 1.5" (40 mm) and 2" (50 mm) gauges, and + or - 1.5% of full scale value for the 2.5" (63 mm) and 4" (100 mm) gauges" ETA - looks like VM is trying the same one I linked........
There is no calibration required. Even if you were able to calibrate the dial you would need a reference standard to match it to. The use @VikeMan needs is a bit different. For most everyone confirming the correct pressure is applied is all that is required, and we get what Taprite includes on their regulator. A $5 crappy pressure gauge. The regulator itself is not terribly robust to be honest, especially at low pressures. It's just a diaphragm and a spring after all. Taprite is a decent product but regualtors are one of the weaker links in the whole shebang. There are much more robust regulators available, from welding suppliers for example and they do occasionally show up on commercial systems but even then it is over kill. Cheers
