Sunday, October 21, 2012

Gill Pressure Ports

A barometer reading is sensitive to the wind. A sensor input directly exposed to the wind can lead to variations of 2 or 3 mb with strong wind gusts [1], and the effect depends on wind angle as well as wind speed. Even with a sensor indoors or below decks with a leaky seal to the outside, you will see variations of up to a mb with outdoor gusts [2].  Warships and first responder vessels all have to have pressurized pilothouses, so the barometer must be read from a lead to the outside, usually just a small Tygon tube.

Here is a version from RM Young [3]. This one sells for about $140.  Very simple; no moving parts; but the engineering that goes into them is not so simple and has evolved over the years, starting in the mid 70s. They are now often called a Gill Pressure Port, in honor of the inventor Gerald C. Gill who developed it for what is now called the National Data Buoy Center.

We have tracked down his original extensive technical report on the development of this device [4], which we will make into a pdf ebook that is inexpensive and easy to access. (For now it is too big, and takes some cleaning up.)

The history of this device is quite fascinating, and seems to be an example of some lack of communications between researchers–at least several of the key players do not reference each other during the days of its development.  See for example the early work of Miksad [5] and a related  patent app [6] filed in 1989, canceled in 1996... maybe there is a story there as well!

As should not be surprising, the best of the devices comes from Paroscientific, our neighbors just across the bridge in Redmond, WA. They are the world leader in all matters relating to high accuracy barometric pressure measurement. [7]  Paroscientific has somewhere online at their website a report of the testing of this device, but we have not found this yet.

And we should of course mention Vaisala, the world leader in production of the full range of weather instrumentation, which has a top of the line model as well [8]. These devices are often refereed to as static pressure ports, without reference to Gill, but it seems he was a pioneer in the development of the engineering.

For completeness,  note that the pressure port requirement has applications in other areas, such as pressure drop measurements in air conditioning conduits where there is a varying wind flow through the system [9].

THIS ARTICLE IS A WORK IN PROGRESS. IF YOU HAVE AN IMMEDIATE NEED FOR MORE DETAIL, LET US KNOW AND WE WILL PUSH IT UP THE LIST. FOR NOW I JUST WANTED TO COMPILE THE PIECES WE HAVE SO WE HAVE A REMINDER TO MAKE THE GILL EBOOK... which is in keeping with one of our ebook goals, to preserve obscure but important texts that somehow Google did not do for us. Ed. note: we published this one in 2019. see below.


[1] Guide to Meteorological Instruments and Observing Practices, WMO-8 (related section cited in [7], below. Many copies of the full document online.)

[2] The Barometer Handbook
[3] RM Young model 61002

[4] Development and Testing of a No-moving-parts Static Pressure Inlet for Use on Ocean Buoys, Gerald C. Gill 1975-76. 120 pages.  Now available as a Kindle ebook.

[5] An Omini Directional Static Pressure Port, Richard Miksad, 1975-76

[6] Pressure Port Patent app (I do not know where we found this. It was part of the research for the Barometer Handbook. It at least shows the insides of one design, as does the Gill original article. We will, of course, never see the insides of the RM Young or Paroscientifc models online, unless we buy one and take it apart.)

[7] Paroscientific precision pressure port model 8007 (manual)

[8] Vaisala Static Pressure Head SPH10 / SPH20

[9] An Inexpensive Method for Measurements of Static Pressure Fluctuations, Liberzon and Shemer, 2009


SpB said...


I realize this is a rather old post...but it is a very interesting post (and your blog is amazing!)...I've been working on static pressure measurements recently and is there any way to get a PDF of the report by Gerald Gill...if not, I'll try and look at it via the kindle app. Thanks so much for finding this! A summary of our recent work on static pressure can be found here:

cheers! SpB.

Anonymous said...


there is Master Thesis by a Finnish student from 1999. He analyzed the static pressure ports of Gill and Qualimetric on the market and developed with Vaisala the static pressure head SPH10/20. The thesis was written at the Institute of Aeronautics of Technical University of Helsinki. The pressure port was tested in a wind channel. The name of the author is Pekka Palomäki. When I contacted the library of this university, they send me his thesis as PDF within minutes. German Weather Service made a scientific comparison of various pressure ports in 2008. Only their own probe was better :-)

Best regards

David Burch said...

Thanks very much for that valuable information. If you have a copy of that report to share, please let us know at We will check out the Vaisala instrument as well.

SpB said...


Here is a PDF of a WMO report by a German group in 2012 that compares four different static pressure heads (including the Vaisala model SPH-20):

I never had any luck getting the Gerald Gill report as a PDF (but I was able to look at via Kindle)....I will also try to find the 1999 thesis by Palomaki.....thanks for sharing this info!



David Burch said...

Thanks very much. That is an interesting article. We will pass it on to our students.