Talk:Pressure measurement

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Manometer Types[edit]

according to me there are five types of manometer
1. Simple Manometer Can measure negative presures too .A improved version of piezometer (fig is shown on the page )
2. micro manometer
more sensitive
3. inclined tube manometer
micro manometer with inclined tube or simple manometer with inclined tube
4. Differential Manometer
measure pressure difference between two pressure sources
5. Inverted tube manometer
used to measure low pressures and more sensitive for low pressures.
124.125.21.85 14:02, 17 January 2007 (UTC)

Organization and definitions[edit]

I think this page needs to be reworked. "manometer" typically only refers to devices that use a fluid column to measure pressure. I suggest re-titling the page, maybe "Pressure Measuring Devices," then restructuring the article. Break it up into 1. Manometers (include piezometer tube, u-tube manometer, and inclined tube manometer), and 2. Mechanical and Electronic Pressure measuring devices (Bourdon gage, and other electronic pressure transducers). —The preceding unsigned comment was added by Simsea (talkcontribs) .

I'm not sure about that. According to Webster's dictionary, mano means sparse, and manometer would be any device to measure low pressure or low pressure differential. Vacuum companies like MKS and Varian use the word manometer for many of their ion gauges, Piranis and capacitive membrane gauges, and they may be right. Maybe we should merge the vacuum gauge article into this one, and add a disambiguation note at the top for liquid column manometers. And we already have a pressure gauge page, so we definitely shouldn't add a new "Pressure Measuring Devices" page. -Yannick 02:36, 19 February 2006
The etymology's misleading. When invented and named in the early eighteenth century manometers were thought to measure the rarity or density of air. Later it was realised that they were measuring fluid pressure differentials. NebY 19:07, 15 July 2006 (UTC)
In the UK the use of "manometer" has changed to encompass other pressure measurement devices, following European usage. Wikipedia's descriptive, not prescriptive, so the article is correct in this. NebY 19:07, 15 July 2006 (UTC)

I disagree with merging pressure gauge into manometer because manometer specifically refers to pressures below atmospheric, whereas most pressure gauges measure pressures above atmospheric. Maybe you could make a better case for merging in the opposite direction, manometer into pressure gauge, but I would still disagree with that because there are many significant design characteristics of vacuum gauges that merit a seperate article. I do still support, and have tagged, a merge from vacuum gauge to manometer, pressure measurement possibly presented as a type of pressure gauge.--Yannick 17:30, 6 August 2006 (UTC)

Very few of the liquid-column manometers I used to design and manufacture were used for vacuum measurement. They were used for setting gas pressures, testing pressures in underground phone cable ducting, monitoring pressure differentials across filters, measuring fluid flows in conjunction with orifice plates (and venturis, nozzles, pitot tubes and control valves), testing radome integrity and a myriad other uses, but hardly ever vacuum. NebY 16:49, 15 August 2006 (UTC)

I think this area is in a bit of a mess and could do with a damn good tidy. We need a single 'launch' article for gas/liquid pressure measuring devices, with one-paragraph descriptions of all types of gauges, plus main articles on each of the gauge types. So, I suggest we merge Manometer, Vacuum gauge, and Pressure gauge. The final title is a secondary concern, as long as redirects are in place. Mr Stephen 08:35, 7 August 2006 (UTC)

I do certainly agree that these pages need more work, as all articles do in their infancy. I'm quite knowledgeable with vacuum gauges/manometers and would like to do some serious work on them, but I think we should first try to agree on the number of articles, titles, and scope. When we put off those decisions for too long, we wind up having to move or copy material around from one article to the next, and that creates a lot of stylistic patch-up work.--Yannick 17:59, 7 August 2006 (UTC)

Sorry, I though I had posted here, but it was on my sandbox. I see we have Vacuummeter too. I assumed the structure of the main article would be something like this:

  • Pressure gauges
    1. Ionization gauges
    2. Pirani / thermocouple (etc) gauges
    3. McLeod gauge
    4. Liquid-column manometer
    5. Bellows
    6. Diaphragm deflection
    7. Bourdon gauge
    8. Piezoelectric crystal gauges
    9. Piezoresistive gauges

Any missing? Mr Stephen 23:03, 13 August 2006 (UTC)

Uh - how about: piezoresistive gauges (all the silicon types) vibrating cylinders (Solartron) —The preceding unsigned comment was added by 67.78.68.5 (talkcontribs) .

piezoresistive yes, they belong in (added). "Vibrating cylinders" are new to me, any pointers? Mr Stephen 15:40, 15 August 2006 (UTC)

Deadweight testers, one of the two basic standards. (Liquid-column manometers are the other). Rather less significant are resonant-wire transducers. NebY 17:07, 15 August 2006 (UTC)

In my experience, deadweight testers are used to calibrate pressure gauges, rather than as a gauge in themselves, but they deserve a decent article. A resonant-wire transducer is a type of diaphragm deflection gauge, no? Mr Stephen 22:18, 15 August 2006 (UTC)
Yes, deadweight testers are used to measure pressure but not usually called pressure gauges. I suppose I assumed the scope of the article was to be all pressure measurement technology. So, should it be called Pressure Measurement reather than Pressure Gauges? Doesn't the resonant-wire transducer's diaphragm only deflect in failure mode? cf US Patent 4,165,651. NebY 09:09, 16 August 2006 (UTC)

Two points on article structure:

  1. The classification of gauges should be grouped by type, and should be ordered from simplest or most common to most complicated and exotic.
  2. Classification is only part of the article. We also need to talk about absolute vs. gauge, dynamic pressure and transients, calibration, etc.

Here's a more comprehensive structure we could use, assuming that we are merging everything under the title of pressure gauge:

Overview

  • Zero reference
    • absolute
    • gauge
    • differential
  • Dynamic pressure (vs. total pressure)
    • Pitot-static tubes
  • Applications
  • Classification
    • Hydrostatic
    • Elastic
      • Bellows
      • Bourdon
      • Diaphragm shape
        • Flat
        • corrugated
        • flattened tube
        • capsule
      • Secondary transducer
        • resistive (strain gauge)
        • inductive
        • capacitive
        • piezoelectric/piezoresistive
    • Thermal conductivity
      • two wire
      • Pirani (one wire)
    • Ionization gauge
      • Hot Cathode
      • Cold Cathode
  • Calibration
    • Dead weight tester
    • McLeod
    • mass spec + ionization
  • Dynamic transients
  • History

I haven't worked with piezoelectric/piezoresistive gauges except as secondary transducers on a diaphragm. Do they really have a standalone form like that "vibrating cylinder" mentioned by the anonymous contributor above? Also the Vacuummeter article seems to use a lot of classifications that I don't recognize. Can someone fit them in?--Yannick 22:53, 15 August 2006 (UTC)

Four quick comments:

  1. Yes, standalone piezoresistive transducers are used (we used to use them in our products). Sensortechnics have a wide range. But I've never come across a vibrating cylinder device.
  2. Do we need to discuss how the pressure is generated? Most pressure measurement devices don't distinguish between dynamic and total pressure.
  3. Technically most devices measure differential pressure, those called absolute using a vacuum as the reference pressure and those called gauge using the atmosphere.
  4. Should the title be Pressure Measurement rather than Pressure Gauges? NebY 09:09, 16 August 2006 (UTC)

For the sake of consensus, I weakly support merging the whole lot under the title of Pressure measurement as suggested by NebY. I used to want separate articles for manometers and pressure gauges, but I think I see the logic of a complete merge under this comprehensive title, as long as it's something neutral like Pressure measurement. Mr. Stephen has said above that he supports a complete merge and doesn't care as much about the title, so I think we have consensus on this:

Merge Manometer, Vacuum gauge, Vacuummeter and Pressure gauge to Pressure measurement--Yannick 01:46, 22 August 2006 (UTC)

Agree Mr Stephen 08:00, 22 August 2006 (UTC)

That looks like a consensus. So should we create Pressure Measurement with a skeleton structure, fill it in, then remove Manometer etc - or rather would one of you that has more Wiki experience than I like to lead? NebY 07:35, 28 August 2006 (UTC)

Pumps used as gauges[edit]

The vacuum gauge article that I merged here had some weird stuff about pumps used as gauges. I moved it here instead of the main article:

Turbopump - Make the output a dead end and measure current for a given rotations/s.

Membrane pump - Measure membrane displacement to measure the pressure difference between two spaces.

Ion getter pump - This gauge is named the Penning gauge. It measures the current.

--Yannick 12:27, 4 September 2006 (UTC)

Talk:Pressure Gauge[edit]

Both of those pictures of the mechanics are horribly overexposed to the point where they are basically unusable. Does anyone have any alternatives? -lommer 03:54, 22 Apr 2004 (UTC)

Replaced with an improved image of the mechanical details, write me if you want a new shot for printing, etc. Leonard G. 19:37, 22 Apr 2004 (UTC)

Vacuummeter types[edit]

As discussed above, I didn't know what to do with many of these types on the Vacuummeter article, so I'm dropping them off here for someone else to mess with:

A Vacuummeter is a device to meter pressure below atmospheric pressure

Types:

  • viscosity
  • commpresion
  • electromagnetic
  • ion
  • ionization
  • glow discharge
  • alphatron
  • balometric strip
  • thermalvacuum
  • magnetic

--Yannick 12:54, 4 September 2006 (UTC)

Picture captions questioned[edit]

I'm not sure about the captions on two of the pictures. The "Pile of aneroid bellows in a barograph" has shadows that make me suspect it is really a pile of corrugated pressure capsules. The "Membrane-type manometer" does not show any inner workings, and dial gauges are more commonly based on Bourdon tubes. Can anyone confirm these captions or offer more information?--Yannick 00:31, 6 September 2006 (UTC)

I'm accustomed to referring to the latter as "Diaphragm pressure gauges"; they can be configured for differential pressure and fitted with a direct-reading flow scale for use with a specific orifice or other DP flow measurement device for which flow varies as the square root of pressure. One manfacturer providing further information is Bailey & MackeyNebY 09:14, 9 September 2006 (UTC)
Do you mean the latter or the former? The website you linked has small low resolution pictures of diaphragm gauges that seem to have a wide pressure chamber just below the dial where the diaphragm is located. The picture in our article does not illustrate the pressure chamber, and in fact seems to narrow directly down to a pipe thread. Your website also offers much more information and options for Bourdon gauges, suggesting this type is more common for dial gauges. I usually only see diaphragm gauges in electronic instruments because diaphragms have a more linear calibration than Bourdon, but are more susceptible to backlash in a mechanical amplification.--Yannick 03:33, 10 September 2006 (UTC)
My question about the "pile of aneroid bellows" has been settled by the recent image update which provides a better explanation of the image source. The french wikipedia description, (which predates my question,) calls this a "pile of capsules."--Yannick 02:21, 13 September 2006 (UTC)

Pressure Formula[edit]

Under the section "liquid column" the caption to the manometer is "The difference in fluid height in a liquid column barometer is proportional to the pressure difference. " The equation is then H=\frac{P_a-P_o}{\rho}. Shouldn't the equation be H*g=\frac{P_a-P_o}{\rho}? This is my first edit so I didn't want to go ahead and do it on the article. Nyr56 20:56, 14 September 2006 (UTC)

Ah, it depends on the units. If the pressures are in psi, and the density is in pounds per cubic inch, then the equation is right. In some systems (eg SI) you are right. If we are working in mmHG/torr, neither is right. Have we got a decent 'proportional' sign in the maths editor? Mr Stephen 21:28, 14 September 2006 (UTC)
Good point, I figured I was missing something. In that case, this would probably be more appropriate: H \propto \frac{P_a-P_o}{\rho} Nyr56 23:18, 14 September 2006 (UTC)
I agree with Nyr56's original formula. If you keep track of units and do proper conversions it is always correct, even if you are working in torrs, and it provides more information than a proportionality statement. The old formula happens to be correct because g = \frac{1 \mbox{ lb(force)}}{1 \mbox{ lb(mass)}} = 9.8 \frac{\mbox{kg} \frac{\mbox{m}}{\mbox{s}^2}}{\mbox{kg}} I will change it.--Yannick 02:40, 15 September 2006 (UTC)

Industrial applications[edit]

I'll have to track down some references but it should be mentioned that the Bourdon-style gauge may be the most common type, with hundreds of millions of instances in use everywhere from tire inflators to power plants. A comparative discussion of the limitations of each type of measuring device would be helpful (costs, precision, measured fluids, range of application) -some of the vacuum types already show usual pressure ranges. Bourdon tubes go up from a few to tens of thousands of PSI, for example. Capacitive types are very common in industry as transducers for process control, as are silicon strain gauge types. Differential types for use with flow measuring orifices and Venturi tubes. Direct-reading (non-electronic) instruments vs. electronic pressure transmitters. Lots to add. --Wtshymanski 21:09, 18 September 2007 (UTC)

I think it would be really difficult to get verifiable information on how common the different types are. Personally, I suspect that piston-type tire pressure gauges would win the popularity contest over Bourdon types. But I agree with you that there's lots to add.--Yannick 22:48, 18 September 2007 (UTC)

shouldn't any gauge that measures any unit of vacuum/pressure be on the same page. A vacuum is only very low pounds per squere inch based on a zero reference or it is mearly a negative number on a relative gauge. All we are talking about is scale. a manometer is a pressure guage that measures the pressure by measureing the weight of the column of air above it based on a reference weight on top of the column pushing down, this can be acheived in many different design methods. Hence, all manometers are pressure guages but all pressure guages are not manometers. So the pages for vacuum, pressure and all other types of pressure guages should be under the same article and reference in the table of contents, they all measure the same thing right? Brad —Preceding unsigned comment added by 68.54.220.29 (talk) 00:26, 26 September 2007 (UTC)

Isn't that currently the case?--Yannick (talk) 15:26, 19 July 2008 (UTC)

Comment by Anon[edit]

Moved from article. The second paragrpah should at least start in a different way. Maybe it´s refering to a variation OF the the McLeod gauge. 201.213.220.35

Redhead gauge, Nude Gauge, MAN-o-meter?[edit]

Redhead gauge? Nude Gauge? MAN-O-METER? Who are you trying to fool? I'm going to mark this article as Adults Only, unless you at least add a note on how to pronounce manometer: ma-NOM-e-ter or MAN-o-meter, please use IPA too ☺. Jidanni (talk) 02:36, 14 June 2008 (UTC)

These are the accepted terms for these devices, and Wikipedia is not censored in any case.--Yannick (talk) 15:26, 19 July 2008 (UTC)

Spinning Rotor Gauge[edit]

"Most ion gauges come in two types: hot cathode and cold cathode, a third type exists which is more sensitive and expensive known as a spinning rotor gauge, but is not discussed here."

There are only two types of ion gauges, SRGs have nothing to do with ionization. They work purely mechanical. 141.84.69.20 (talk) 22:17, 21 July 2008 (UTC)

Penning pressure gauge: In the text it is stated that the arrangement of magnetic field and electrodes is such that the ions have a pathlength of meters. This is incorrect. The arrangement is such that the electrons have a very long pathlength. In fact the arrangement is such that the electrons cannot reach the anode (+) unless they collide with gas atoms. So the plane of the anode ring is perndicular to the magnetic field. At both sides of the ring there is an anode plate. Kind regards, Karel van der Mast, kvdmast@solveigh.com — Preceding unsigned comment added by 77.169.8.250 (talk) 09:59, 15 December 2011 (UTC)

Units[edit]

The following sentence: "Thus a vacuum of 26 inHg gauge is equivalent to an absolute pressure of 30 inHg (typical atmospheric pressure) − 26 inHg = 4 inHg." seems slightly unacceptable to me. It should be expressed in (k)Pa. The inHg units could be added in parenthesis (if still useful for those who use those units). --Mojca Miklavec (talk) 08:08, 15 September 2013 (UTC)