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LOW pressure gauge

David Nadle
David Nadle Member Posts: 624
$80 for a compound digital gauge, +/- 14.50 psi.

http://pewa.panasonic.com/acsd/sunx-sensors/products/dp-100.php

I might try one...if I do I'll post the results. My original 0-30 gauge doesn't budge.

Comments

  • archibald tuttle
    archibald tuttle Member Posts: 1,085
    LOW pressure gauge

    While I expect that the mercury vaporstats are long proven accurate if the leveling arrow is observed in mounting, can anyone recommend a low range pressure gauge to be used in concert with vaporstat to monitor system pressure over the cycle?

    I'm imagining maybe a 2PSI gauge would put 1 PSI at half the gauge range, or ???? depending what is available, e.g. might have to settle for 5PSI although I can't even find any of those quickly on the net, or experience anyone has had with gauges of even lower range than 2PSI.

    Thanks,

    Brian
  • Dave_4
    Dave_4 Member Posts: 1,405
    Perhaps...

    Thinking "inches of water column" rather than "pounds per square inch" may be the "search" criteria bringing the most appropriate "hits"?

    28" w.c. still equals ~1 p.s.i.
  • tim smith
    tim smith Member Posts: 2,752
    Compound vacuum gauge

    If I remember right they not only have vacuum but they go up to a lb or 2. Check them out.
  • archibald tuttle
    archibald tuttle Member Posts: 1,085
    vacuum / inch gauge

    who is "they"?

    Winters only lists a 0-15 or a vacuum gauge at least in looking at their web listings.

    When I searched for W.C. gauges I found stewartusa.com which appears to list in a clunky .pdf some gauges that are in the 1 to 2 psi (15 to 60 w.c inches).

    Also found somebody selling 30 w.c. " gauges on ebay for 24.99 a pop which I would have bought one right away but it is also a 14.95 shipping rip.

    Thanks for the hint on searchin on w.c.

    I also plan to call Stewart on Monday.

    Brian
  • FredR
    FredR Member Posts: 62
    Low pressure gauge

    dwyer-inst.com

  • archibald tuttle
    archibald tuttle Member Posts: 1,085
    dwyer, etc. temperature ratings

    Fred,

    Dwyer's got the goods. Thanks for the link. Also found:

    http://www.coleparmer.com/catalog/product_index.asp?cls=47625

    they are cheaper ($28 vs. $34 or 42 depending which Dwyer gauge you choose) but they appear to be not quite as accurate although I don't quite know how to read the accuracy specification which looks like this 3-2-3%. I don't know if this means most of the time its 3% or what or why there are three numbers. Maybe that means Monday, midweek, and Friday manufactured units. I don't know.

    Dwyer lists an LPG4 series with accuracy as 1.5% (They also have an LPG-3 series with 1% accuracy that is cheaper, go figure but not as many ranges to choose from. The really cool thing about the LPG 4 series for anyone still operating in vacuum/vapor is that they have relatively sensitve gauges that run from low vacuum to low pressure, e.g. LPG4-D9522N Low pressure gage, range -40-0-60" w.c. (-10-0-15 kPa). $42.50 . Maybe I missed something in my reading of 'the lost art' but I never did quite figure out the operating vacuum reading for most of the average vacuum system, but you would need 10" mercury vacuum to get the boiling point down to 192 and Dan speced some systems going as low as 160 degrees boiling point, so the -40" w.c. is only going to take you to about -3" of mercury. But it might be useful as a diagnostic for radiator or even system wide for vapor systems dipping slightly into vacuum. Of course there are plenty of folks who make -30" hg - 0 - 30 psi gauges, but your accuracy is going to be much less.)



    I digress, the real issue with all these gauges I've found is that they all have about a 150 degree temp limit. While I assume that is ambient, at least one of them indicates that this is a process limit as well. If that means a limit on the measured media, are we SOL here. Anybody using these on steam. Would a pigtail syphon help. I can't imagine that the media temp wouldn't ultimately exceed 150, but maybe that is a conservative rating. Or maybe they really do mean ambient. or ????
  • FredR
    FredR Member Posts: 62
    Dwyer Gauges

    Dwyer has some good help at customer service:

    1-800-872-9141

    The syphon loop is required for steam.
  • Brad White
    Brad White Member Posts: 2,398
    Brian

    I found a couple of Winters gauges, 0-32 ounces with (IIRC) compound feature for vacuum down to 15" Hg.

    These ran about $130 (again, IIRC). I ordered both even though one is spoken for. Maybe above your price range but they are available. I will let you know how they work.

    Siphon loops are essential on steam instrumentation. An impulse dampener is another thing I am considering.

    These gauges are for steam and I will see if they give a temperature limit (which if 150 would say "ambient" to me.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • scrook_2
    scrook_2 Member Posts: 610
    low pressure gauges

    See:
    "Low-Pressure Diaphragm Gauges" at: McMaster-Carr

    http://www.mcmaster.com

    They have 2.5" in lb/sq. in., oz/sq. in., & inch H2O for $50

    or at:
    Small Parts Inc.
    http://www.smallparts.com/

    Same thing, but only $33-$38

    or Google "Low-Pressure Diaphragm Gauges" for other manufacturers/vendors

    Tee the gauge w/ the 0-30 PSI. Too bad they don't make 0-3-30 psi retarded gauges for steam heat boiler applications.

    Not sure I'd use Dwyer's *Magnehelic* gauges for *this* application though, but they are nice gauges for draft, air filter pressure drop, and other low/manometer level measurements
  • scrook_2
    scrook_2 Member Posts: 610
    3-2-3% gauges

    A 3-2-3% gauge is +/-3% in the first quarter of the scale, +/-2% in the middle half of the scale, and +/-3% in the last quarter of the scale. It is assumed that nominal system pressures will be around 1/3 to 2/3rds the full scale rating of the gauge. You don't want to go too close to full scale, lest you go over and damage the gauge (hence a 30 psi gauge on a 15 psi relief) boiler, nor do you want to be in the low end of the range or you lose precision/accuracy of reading (as happens running at only 0-1.5 psi for one pipe steam on the 15 psi rated boiler!).

    The other common spec (and not *just* for pressure gauges) is %FS or "% of Full Scale": this means ANY reading is +/- the percentage of the full scale rating, e.g. a 30 psi 3%FS gauge is +/-0.9 psi for *any* reading, 1 psi +/-0.9psi, 20 psi +/- 0.9psi, etc. so it's best to be in the upper half of the scale (just, as before, don't *exceed* full scale, bu tyou see the trouble trying to accurately measure 0-1.5 psi on a 30 PSI boiler gauge!).
  • Eric Tardif
    Eric Tardif Member Posts: 38
    Noise - New one needed?

    If there's a noise like steam escaping coming from the pressure gauge, should I get a new one? It's a newly installed steam boiler using the pressure gauge from the old boiler. So the gauge is probably at least 25 years old.
  • Brad White
    Brad White Member Posts: 2,398
    Noise is not normal.

    I would pass my hand or a mirror around it to make sure, but if in doubt, a new gauge, siphon tube and gauge cock (valve) will be short money for the peace of mind.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • Eric Tardif
    Eric Tardif Member Posts: 38
    The guage is connected directly to the boiler -

    is that normal? It doesn't seem to have a valve or a siphon tube.

    Is it suppose to look like this even though there's no control (scroll to middle of webpage):
    http://www.nationalboard.org/NationalBoard/CommissionedInspectors/InspectorGuides/CInsp_Guide_Operating_Controls.aspx

    Does it need the gauge?
  • Brad White
    Brad White Member Posts: 2,398
    By Code, Yes

    The boiler does need a pressure gauge by code at a range of twice the operating pressure (0-30 for a 15# boiler). Nothing says that this gauge has to be particularly useful either in range or mode of installation.

    Keep it and properly install another of appropriate scale is what I would do.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • Eric Tardif
    Eric Tardif Member Posts: 38
    It seems ok now

    I haven't heard the hiss lately. So I'll leave it alone for now. Thanks for your help.
This discussion has been closed.