Pressure measurments 0-1" H2O

[OldSchl]

What do you use for 0-1"H2O calibrations and what is the accuacy of you standard? I have a hook gage.  I'm looking for some more accurate.

[MIRCS]

The schiewn

[scottbp]

We use a Dwyer Microtector model 1430 electronic point gauge. It's range is from 0 to 2" H2O, with an accuracy of ±.00025" w.c.

http://www.dwyer-inst.com/htdocs/pressure/Model1430Price.cfm

[OlDave]

I've got both the 1430 microtector and a 1420 hook gage. Personally I don't trust the 1430.

I've polished the point numerous times and it still seems unrepeatable. Got any suggestions scottbp? And I'm also skeptical of its "stated" accuracy. Does yours have an accredited calibration? If so by who? Maybe I will dig mine out of the closet if I can get it traceable and working to my satisfaction.

[WestCoastCal]

We've struggled with this area of measurement for years.   We have the FPG 8601, DH Instruments, with accuracy of ±(0. 020 Pa + 30 ppm) 0 to 60 inH2O range, obviously built to match the schwein, at least in range.

[scottbp]

I've got both the 1430 microtector and a 1420 hook gage. Personally I don't trust the 1430.

I've polished the point numerous times and it still seems unrepeatable. Got any suggestions scottbp? And I'm also skeptical of its "stated" accuracy. Does yours have an accredited calibration? If so by who? Maybe I will dig mine out of the closet if I can get it traceable and working to my satisfaction.

Actually, I'm not the one who uses it on a regular basis, I'm more into the electrical/electronic side of the house. I know it is in our inventory, though, and the few times I used it years ago I had limited success calibrating a digital manometer that had a 0 to 1" w.c. sensor with about a .1% accuracy, I think. We calibrate it in-house by pulling the micrometer head and using T.O. 33K6-4-105-1, but everything has to be completely leak free when put back together, it has to have very clean juice inside, and all the tubing and fittings have to be completely leak free when testing otherwise it'll never have repeatable readings. Good luck with that one...

[OlDave]

Interesting. The micrometer head in my 1430 is a standard 0.001 in. micrometer head. Looks like a Starrett though it's etched with Dwyer. And the copy of 33K6-4-105-1 that I have lists the accuracy spec as ±0.001 inches.

The 1430 accuracy specification is based on the premise that:
1. The micrometer is accurate to ± 1/8 of a division, and
2. That you can repeatably READ 1/8 of a division.

Two words....Bu.. Sh..!!

You usually don't see a micrometer head that has an error of that magnitude, but I have seen it, and 33K6-4-105 sure doesn't test it to that level of accuracy. So you see where my skepticism about Dwyer's claim of ±0.00025 in. w.c. accuracy for the 1430 comes from.

[OldSchl]

Interesting.  The micrometer head in my 1430 is a standard 0. 001 in.  micrometer head.  Looks like a Starrett though it’s etched with Dwyer.  And the copy of 33K6-4-105-1 that I have lists the accuracy spec as ±0. 001 inches.

The 1430 accuracy specification is based on the premise that:
1.  The micrometer is accurate to ± 1/8 of a division, and
2.  That you can repeatably READ 1/8 of a division.

Two words. . . . Bu. .  Sh. . !!

You usually don’t see a micrometer head that has an error of that magnitude, but I have seen it, and 33K6-4-105 sure doesn’t test it to that level of accuracy.  So you see where my skepticism about Dwyer’s claim of ±0. 00025 in.  w. c.  accuracy for the 1430 comes from. 

I couldn't figure out how they got that accuracy for the 1430 either.

[skolito]

they do not cal the hook gage they cal the mics.

Mitutoyo does the same thing its a way to play with numbers to make it look more accurate than it is
Like some low end DMM'S Accuracy of ±0.005% of Reading dc PLUS 47 LSD which if you add that up its ±.5% of Reading


as for low pressure readings I use an ashcroft ate 100 and a aqs-1 10 in H2O module ±0.06% of F/S