Yokogawa RAGN - Manual (Page 8)

<1. INTRODUCTION>
1-4
IM 01R01B10-00E-E 2nd edition: November 01, 2011-00 All Rights Reserved. Copyright © 2011, Rota Yokogawa
A Rotameter measures the flow of liquids, gases and steam by using a float inside a conical tube.
The gap between the tube and float is larger at the top to allow a greater flow to pass through the meter. As gravity
works in a vertical orientation so the tube needs to be vertically oriented.
Rota Yokogawa developed the free rotating float which stabilises its position in the centre of the cone to provide a
more stable flow measurement.
The medium passes through the metering tube from bottom to top and consequently rises the float until there is an
annular gap between the inside surface of the metering tube and the float and equilibrium of the following forces
has been achieved.
Buoyancy / Gravity / Friction force
The Rotameter principle is one of the oldest and mature principles in flow measurement. This mechanical principle
is as simple as it is reliable. The flow is indicated by the top of the float and can be read from the standard scale on
the metering tube. The RAGN can be equipped with limit switches option /GR2 to /GR8 and /GM1 to /GM5.
All units are calibrated with water or air by the manufacturer. By adjusting the calibration values to the measured
substance’s state of aggregation (density, viscosity), the flow rate scale for each measuring tube can be determined.
When the process conditions have changed the scale is not accurate any longer and the glass tube needs to be
replaced.
1.2 General description
This manual describes installation, operation and maintenance of the RAGN. Please read it carefully before using
this device.
Further, please note that customer features are not described in this manual. When modifying specifications,
construction or parts, this manual is not necessarily revised unless it can be assumed that these changes will
impair RAGN functions or performance.
All units are thoroughly tested before shipping. Please check the received units visually to ensure that they
have not been damaged during transport. In case of defects or questions please contact your nearest
YOKOGAWA service centre or sales office. Please describe any defect precisely and indicate model code as
well as serial number.
YOKOGAWA refuses any liability for units which have been repaired by the user without prior consent and do
not meet the specifications as a consequence.
1.3 Principle of measurement
1.4 Intended use
The RAGN is designed for the continuous flow measurement of liquids or gases and can be used in all industries.
Typical applications are:
- Visual fluid monitoring
- Industrial gas measurement
- Controlling of water circuits
F
G
= F
F
+ F
B
= Equilibrium
R
10
20
30
40
50
60
70
80
90
100l/h
Equilibrium
F
G
F
B
F
F