About Flowmeter

8/22/2019 About Flowmeter

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Flow Meters / Rotameter

Flow meters: Alat yang digunakan untukmengukur laju alir gas atau cairan

Flow: Volume cairan yang melewati titik

tertentu dalam waktu tertentuFlow Rate.


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FLOW

Laju Alir dipengaruhi oleh viskositas dandensitas.

Pada saat aliran rendah: Viskositas

Pada saat aliran tinggi: Densitas.

So,each type of gas requires diff.

calibrated flow tube. The flow tubes designed for one gas

should not be interchanged with anotherhypoxic mixtures.


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Flow tube :Conical glass tube.

Low flow tube graduated/100

ml/min. up to one liter High flow tube

graduated/1L/min.up to 10L/min.


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Control knob :when it is turnedneedle valve is opened.

Gas flows into the bottom of the flow tube& moves upward around the bobbinupward force pushes the bobbin up in the

tube .


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Float (bobbin)

It may be balls or cylindrical with slots inits upper part & tapered base to make it

to rotate in the gas stream . Non spinning bobbin that may indicate O2

is flowing while the bobbin is stucked with

no adequate flow hypoxic mixture.


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Peralatan rotameter


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The density of a gas is dependent on theambient pr .

Large diff. in atmosph. Pr. alter the calibrat.offlow tube .

At high altitudes with hypobaric condit.Flow meter setting is less than the actual

At hyperbaric condition flow setting is more thanthe actual hypoxic mixture


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The spinning movement of the bobbin can beaffected by dust , dirt & static electric charges .

Static charges can be dealt with by bimetallicstrip .

Dirts & dusts by air filter proximal to the needlevalve.

Slots on the bobbin to spin resist the effect ofstatic charges & dust.


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The twist required to turn the knobs mustbe sufficient to prevent accidental

readjustment from casual knock . If axial push _ pull forces are applied to

the needle valve spindle the flow change

must not exceed 10% .


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In modern anesth. ,there is interconnect. OfN2O & O2 flowmeters to ensure delivery of aconc.of at least 25% O2 .

There are 2 systems :-1. Pneumatic syst. ORMC (designed by

Drager).

2. Chain _link 25 proportion (by Ohmeda )


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1. The flow tube for oxygen has been on theextreme rt. Side O2 is the last gas to beadded to the fresh gas supply.

2. A color _coded flow control knob is locatedunder its respective flow tube.


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3. A color_coded cylinder pr. gauge for the gasentering the flowmeter & located under itsrespective flowmeter.

4.

A plastic screen used to prevent damage to theflowmeters.

5. In some machines , protective bar placedinfront of the flow meters to protect from

accidental bumping.


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6. Lighting system for the flow meter is valuablewhen the op.room light is dimmed .

7. Flow tube pin _indexing syst. to prevent

interchange of flow meter units hypoxicmixture.


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O2 flow can not be completely turned off. Aminimum flow rate of 200_450 ml/min isdelivered to provide sufficient O2 for the basalmetabolic needs by :

1. Applicat. Of resistor in the oxygen pipeline.

2. OR/stop screw on O2 control valve.


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The control knob of O2 has esp. shape:

Octagonal

Greater diameter

Project beyond the other knobs


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1. Electronic flow meter

a. Oscillations of pr. Drop across an orifice isproportional to the flow rate

b. Thermister flow meter :

Gas flow affects thermocouple attached to eitherend of flow tube


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2. Coxter flow meter

3. Bubble flow meter

4. Rotor meter Wrights spirometer

5. Pneumotachographs (Vitalograph)

6. Ultrasonic flowmeters

7. Electronic magnetic flowmeter


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About Flowmeter

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