Azbil KFLB User manual

OM2-5260-2100
Liquid Level Detectors
(Meter Bodies)
Model KFLB
User's Manual

NOTICE
While the information in this manual is presented in good faith and
believed to be accurate, Azbil Corporation disclaims any implied
warranty of merchantability or fitness for a particular purpose and
makes no express warranty except as may be stated in its written
agreement with and for its customer.
In no event shall Azbil Corporation be liable to anyone for any indirect,
special or consequential damages. is information and specications
in this document are subject to change without notice.
© 2013 - 2020 Azbil Corporation. All Rights Reserved.

i
Table of Contents
GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. Types of Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
3. Instructions for Instrument (Transmitter or Controller) to be Used in Conjunction . . . . . . . . 1
4. Combination of Float, Bonnet, and Chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
STRUCTURE OF METER BODY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
1. Torque Tube Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Operating Principles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. High Damping Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Operating Principles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
INSTALLATION METHOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1. External Chamber Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Internal Chamber Type * . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Tightening Torques of Chamber Flange Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Installing the Float . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Dashpot Pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. General Precautions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
OPERATION AND MAINTENANCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
1. Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2. Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1
GENERAL
1. Description
The liquid level (density) meter body is installed with flanges on the side or top of an open or
closed tank. The meter body detects the top level, boundary level, or specific-gravity of liquid
contained in the tank into buoyancy of a float. The buoyancy is converted into torque by a
torque tube an the torque force is applied to a pneumatic signal transmitter (Model KFLB)
or to a controller (Model KFL). The meter body is directly coupled to the instrument. The
detecting section is comprised of a meter body, a chamber, and a bonnet.
2. Types of Meters
Type/Specific-gravity Range Instrument Used in
Conjunction
Operator’s Manual Used
in Conjunction
Torque tube type, medium specific-gravity
range
KFLB_ _ -61 OM2-6220-0000
Torque tube type, low specific-gravity range KFLB_ _ -62
3. Instructions for Instrument (Transmitter or Controller) to be Used in
Conjunction
Refer to the operator’s manuals mentioned in Section 2. These manuals cover the operating
principles, replacement procedures of service units, and calibration and adjustment
procedures of the instruments.
4. Combination of Float, Bonnet, and Chamber
The float diameter and length differ by the specific-gravity range and measuring range, and
the sizes of the bonnet and chamber to be used in conjunction differ accordingly.

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STRUCTURE OF METER BODY
1. Torque Tube Type
1.1 General
The structure of the torque tube assembly is as shown in Fig. 1.
Fig. 1. Structure of the Torque Tube Assembly
1.2 Operating Principles
One end of the torque tube is fixed to the housing and the other end is coupled to a torque
arm which is supported with a knife edge fulcrum. A float is hung at the end of the torque
arm, keeping the torque tube constantly in a twisted state.
As the liquid level rises, a buoyancy force in the upward direction is exercised on the float.
This force is fed via the torque arm and knife edge to the torque tube in the direction that its
torque is reduced. The torque in the form of the rotating angle of the torque rod is fed to the
transmitter.

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2. High Damping Type
2.1 General
The structure of the meter body is as shown in Fig. 2.
Fig. 2. Structure of the Meter Body
2.2 Operating Principles
As the liquid level rises, the upward buoyancy force exercised on the float increases. This force
is fed via the float lever and diaphragm to the strap in the downward direction. Then the force
is fed via the torque arm, in the form of the rotary angle of the torque rod, to the transmitter.
A bellows and a spring is connected to the strap. The bellows has two chambers, which are
filled with seal liquid and are connected with a restriction for damping adjustment. The spring
balances out the weight of the float so that no excessively large force is applied to the torque
tube.

4
INSTALLATION METHOD
1. External Chamber Type
The float chamber must be installed in such manner that, as the liquid level in the tank
changes for the full measuring range, that in the float chamber also changes for the full
measuring range. The connection method between the tank and the float chamber is as shown
in Fig. 4A. It is most recommendable to provide stop valves in the connection pipes between
the tank and the float chamber in order that the float chamber can be completely isolated from
the tank for calibration and maintenance service.
When the liquid level changes very rapidly, it is recommendable to provide an oscillation
prevention restriction in the pipe which connects the tank to the float chamber.
It also is recommendable to provide a drain valve at the bottom of the float chamber so that
the liquid level in the float chamber is readily adjustable for instrument calibration.
The float chamber and the connecting pipes should be protected with heat insulator when
there is a possibility of increase in viscosity of the measured liquid in the float chamber due to
cooling or when heat loss is required to be prevented.
2. Internal Chamber Type *
The internal type of float should be installed as shown in Fig. 4B. When there is a possibility
of agitation of the measured liquid, side plates or guide plates should be provided as shown in
Fig. 4B. in order to prevent sway of the float.
*Note: For the side mount type, the flange section is delivered with a protector fixed with
two sets of bolts and nuts. Remove the protector before installing the flange section.

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3. Tightening Torques of Chamber Flange Bolts
The sizes of bolts and the tightening torques of the bolts after replacing the gaskets with
new ones should be as shown in the below table. When the flange and/or bonnet of a used
instrument are removed by removing their bolts, their gaskets should be replaced with new
ones. Note that leak may result if the old ones are re-used.
Fig. 3. Flange Section
Bolt Size Tightening Torque (N·m)
A M14 130±20 {1326±204 kgf·cm}
B
300 or less M14 130±20 {1326±204 kgf·cm}
600 M20 250±20 {2549±204 kgf·cm}
C
3B, 4B
150 M16 150±20 {1530±204 kgf·cm}
Other than
the above M20 250±20 {2549±204 kgf·cm}
4. Installing the Float
Normally *, the float is delivered separately from the instrument (including the meter body).
*Note: Except the floats which have been approved for high pressure chambers and whose
lengths are not greater than 2 meters .
Of the torque tube type of instrument, the float hanger may be hung in either direction on the
arm pin. Of the high damping type of instrument, however, it must be hung from the outer
side.

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5. Dashpot Pin
A pin is provided at the cap section of the dashpot of the transmitter beam in order to prevent
leak of dashpot oil. When operating the instrument, remove the dashpot pin.
6. General Precautions
Install the instrument to the process in the direction that the instrument is positioned
vertically.
The allowable ambient temperature range of the instrument is -30 to +80 degrees C. Protect
the instrument within this temperature range.
The stop valves and mating flanges shown in Fig. 4 must be provided by the process side (by
the customer). The instrument supplied is up to the flange of the meter body (chamber).
Fig. 4A. External Chamber Type