This instrument is made for measuring atmospheric pressure with the scale in hPa and the venier which can read to 1/10 mm. Since this precision fortin. INTRODUCTION. The Fortin barometer is the most widely used type and can be found in many industrial laboratories, workshops, classrooms and. A wooden wall plaque supports a brass outer casing which protects the glass barometer tube and wood and leather cistern. A brass screw provides the means .

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A Zirconium Oxide Detector for Oxygen. Traditionally, barometer thermometers are mounted with their bulbs within the frame of the barometer so that the thermal time-constant of each is about the same. Mercury barometers must be firmly supported, made vertical and given forin to adopt ambient temperature before attempting to use them.

The height of the mercury barometet is read from the scale on D using the vernier V. Calculation of pressure from Fortin barometer readings where: A Fortin barometer is usually also provided with a gimbal mount to that it may be maintained vertical.

If the mercury is to be reused is should be cleaned. Fortin barometers should be used with their axis of rotation vertical – such that a setting of the mercury surface to the fiducial point remains correct after axial rotation through any angle.

The availability of a good vacuum pump makes other methods possible. The brass housing is placed once again over the barometer fortij and secured to the cistern with the long brass bolts.

A ring G is provided by which to hang the instrument. Restoring and Using a Fortin Barometer The Fortin Barometer is the most widely used, and generally most accurate barimeter mercury barometers and while fodtin use of mercury is still permissible, will remain the primary absolute instrument for calibration fortni and in all circumstances where a dependable, precise measurement of atmospheric pressure is required.

More Like This Show all results sharing this subject: The stopcock is then opened and the barometer pumped down for an hour. The cistern C has a lower brass section containing a leather bag, the capacity of which can be adjusted by the screw W.


With all the mercury removed, the components of the barometer can be carefully cleaned. Proper setting can be aided by making small ‘pecking’ head movements to ensure that both cursor edges just meet the meniscus. Controlling a Peltier Cryostat. NPL’s commercial services are built on years of leadership in accuracy, innovation and scientific research.

Before travelling, the base of the reservoir is raised using the adjusting screw until both reservoir and tube are filled with mercury. The space above the baormeter in T contains a Torricellian vacuum. Tube T is some mm in length and is supported by the top plate of the cistern C, by corks B, and by a slot not shown in barmoeter top of the brass scale housing D.

The correct sequence for measuring pressure with a Fortin or Kew Pattern barometer is:. Commercial Services NPL’s commercial services are built on years of leadership in accuracy, innovation and scientific research. The whole is arranged so that it is possible to read the vertical distance between the forrtin of the ivory pin S and the lower edge of the vernier V.

Publications Our library of publications, posters, training and other useful resources. The cistern and baormeter section of the barometer tube after removal of the barometer tube housing.

The Barometer tube should be cleaned with nitric acid using the technique described under Restoring a Fitzroy Barometer. The stopcock on the trap is opened momentarily to remove some air from the barometer tube. The screw Y is then used to bring the lower edge of the Vernier V to a point exactly level with the top of the mercury meniscus. In use the vertical tube T and the cistern C are filled with mercury.

Fortin barometer – oi

The vacuum presents a challenge both from the point of view of the difficulty in establishing it and from the difficulty of verifying its quality. The evacuation is carried ount in stages: The trap fills with mercury during this process. Here you can find out more about the interesting things we do, science outreach activities you can get involved in or take a look at some of our educational resources. Oxide and dust have to be removed and this can be done using a hypodermic syringe to draw the mercury away from the dross.


At the upper end of the instrument, the barometer tube T passes into the brass scale housing D. Simple device used for filling barometers using a vacuum pump. This requires care and precautions to be taken for the collection of mercury and the safe handling of it. A McLeod Vacuum Gauge. Mercury barometers have a temperature coefficient of nearly 0.

The two barimeter holding the brass housing are slackened and the brass housing carefully raised thus exposing a section of the barometer tube still resting in the baroometer.

Refilling the barometer is an operation which requires great care if it is to be accomplished correctly and the resulting barometer is to read accurately. The barometer tube needs to be filled with mercury and inverted and its lower end opened under the surface of the mercury in the cistern.

Fortin Barometer

The major disadvantage gortin the cistern and the mercury it contains require frequent cleaning to maintain the instrument’s accuracy. In other mercury barometers air pressure is calculated from the distance between the level of the mercury in the reservoir and in the tube.

How do I use barometef Fortin or Kew Pattern mercury barometer? The screw W is adjusted until the surface of the mercury just touches the point of the ivory pin.

If the surface is bright and the setting correct, the tip of the point will appear to coincide with its reflected image in the mercury surface. Fortin barometer Fortin bafometer Fortin barometer Fortin barometer Fortin barometer Fortin barometer Fortin barometer.

Experienced consultants and project managers draw upon a unique combination of industry know-how and world-leading scientific discovery to deliver real-world business solutions and enable innovation and secure competitive advantage. Arrangement used for filling barometer with a vacuum pump. Air bubbles, moisture and mechanical difficulties all conspire to give a batometer result a boarometer which reads too low. Users without a subscription are not able to see the full content.

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