AFLOWT LV Series User manual

ULTRASONIC LEVEL GAUGE
AFLOWT LV
VERSION
LV-2xx
INSTALLATION MANUAL
9001:2008
Saint-Petersburg, Russia

2
TABLE OF CONTENTS Page
INTRODUCTION.....................................................................................................3
1. SAFETY INSTRUCTIONS...................................................................................4
2. PREPARATION FOR MOUNTING......................................................................5
3. MOUNTING CONSIDERATIONS........................................................................6
4. MOUNTING THE LEVEL GAUGE.......................................................................7
4.1. Types of acoustic systems.....................................................................7
4.2. Mounting acoustic systems....................................................................7
4.3. Mounting modules..................................................................................8
4.4. Wiring the Level gauge..........................................................................8
5. START-UP PROCEDURES..............................................................................10
5.1. Initial configuration...............................................................................10
5.2. Configuring the Level gauge installed on the object under control.......11
5.3. Special-purpose configuration .............................................................13
6. DISMOUNTING.................................................................................................15
APPENDIX A. Acoustic systems.................................................................16
APPENDIX B. Methods for mounting acoustic systems..............................25
APPENDIX C. Wiring diagrams..................................................................31
APPENDIX D. Report on mounting and start-up procedures......................35
APPENDIX E. Adjustment profiles..............................................................37
APPENDIX F. Velocity of ultrasound for pure gases ..................................38

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The present manual covers the procedures for on-site mounting
and dismounting of "AFLOWT LV" ultrasonic Level gauges of LV-2xx
versions. In the course of work, also refer to "ULTRASONIC LEVEL
GAUGE AFLOWT LV. LV-2xx version. Operation manual, Part I and
Part II" document.
LIST OF ABBREVIATIONS
AS
- Acoustic system
BMD
- Digital measuring block
CB
- Communication block
PEP
- Piezoelectric converter
SPS
- Secondary power source
RTD
- Resistance temperature detector (temperature sensor)
LV
- Ultrasonic Level gauge.
NOTE. Words in the text marked in bold, for example, Setting,
correspond to the items displayed on the Device's screen.
CAUTION!
1. It is highly recommended to study Operation Manual before you start
work with the Level gauge.
2. You must not do the following, unless otherwise agreed by the
manufacturer:
- Perform any modifications to the recommended measurement and
mount procedures (Appendices B, C)
- Perform any modifications to PEP (Piezoelectric Converter) design
- Use cables of the types not specified in the present operational
documentation for making connections between BMD (Digital
Measuring Block) and PEP, and between RTDs (Resistance
temperature detectors) and BMD
- Install self-manufactured and modified acoustic systems (AS) excluding
fastening components.

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1. SAFETY INSTRUCTIONS
1.1. The Level gauge should be mounted (dismounted) by the qualified
technical staff:
- Certified for performing work of this type on the site where the Level
gauge is installed and authorized by the manufacturer
- Authorized to work with electrical installations up to 1000 V
- Familiar with all the instructions outlined for the Level gauge and
auxiliary equipment used for mounting and dismounting.
1.2 When working with the Level gauge, the dangerous factors are as
follows:
- AC voltage with RMS of up to 264 V, frequency 50 Hz (when the device
is powered from mains 220 V 50 Hz via Secondary Power Source)
- Other site-specific factors.
Prior to performing work, make sure that no dangerous AC/DC
voltage which may cause injury or death is applied to the tank (pipeline)
to be worked on. Use the appropriate measuring device for this
purpose.
In the course of mounting, start-up, commissioning and
dismounting works, it is strictly forbidden:
- To make connections to the Device, switch over modes and replace
electronic components, if the Level gauge is powered up
- To use electronic devices and electric tools unless their cases are
connected to the protective earthing trunk line. Also, you must not use
the defective devices and tools.
1.5. Prior to connection of the device to mains, it is necessary to connect
BMD grounding terminal and terminal of SPS (if applicable) to the
earthing trunk line.

5
2. PREPARATION FOR MOUNTING
2.1. To mount the Level gauge on site, the following areas should be
available:
- Free channel (tank, pipeline) section for mounting an acoustic system
(AS)
- Free space used to place structures providing protection of AS from
precipitation, wind, and solar/heat radiation
- Free area suitable for positioning BMD, SPS and CB (Communication
Block).
2.2. The Level gauge should be transported packed in the manufacturer’s
box.
After the Level gauge has been moved to the mounting location
from a cold environment into a warm one (with ambient temperature
above zero), it shall be left to stand in the manufacturer’s box for at
least 3 hours to make sure that no condensation remains inside.
When unpacking the Level gauge, check that the delivery package
contains all items specified in the Equipment Certificate.

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3. MOUNTING CONSIDERATIONS
3.1. Site requirements for mounting AS should be as follows:
- Tank (channel, pipeline) operation conditions exclude foreign items on
the surface of media interface within the area of measurements
- Liquid turbulence and pulsations are absent or minimal
- Foams on the surface of media interface are minimal
- There are no structural components on the way of acoustic beam from
PEP to the media interface
- Foreign items inside the AS sound guide are excluded
- Icing over PEP emitting surface and reference reflector surface as well
as built-up of ice caused by fumes inside the sound guide are
prevented.
3.2. AS can be mounted on a horizontal section of tank (channel, pipeline).
Mounting location is selected considering the minimal distance from
media interface to the AS base plane that must be no less than:
- 1400 mm –for acoustic systems of AS-40x-xx0 and AS-50x-xx0
versions
- 800 mm –for acoustic systems of AS-11x-xx3, AS-6xx-xx0, and AS-
7xx-xx0 versions.
3.3. AS must be mounted in vertical plane. Deflection of the sound guide axis
from the vertical axis must not exceed 3 degrees of arc.
It is recommended to mount acoustic systems of suspended type
AS-50x-xx0, and AS-7xx-xx0 in the areas where rocking by wind and
draft is excluded.
3.4. The on-site structure where AS is installed must be rigid enough to
prevent sound guide axis shift from the vertical and shift of the base
plane from the vertical.
Flanges on the ends of the acoustic system are fixed to the mount
adaptor via a rubber gasket included in the set of AS fittings.
3.5. When mounting (dismounting) and operating the Level gauge, protection
of PEP emitting surface from impacts must be provided.
3.6. The following conditions should be observed at the site of BMD
installation:
- Operation conditions are in accordance with the requirements of the
Operation Manual
- Free access to BMD and convenience in operation is provided
3.7. BMD must not be installed in areas where it can be exposed to water jets
or near sources of heat and electromagnetic radiation.
3.8. When mounting the two-channel Level gauge, the components originally
assigned to a particular measuring channel must be used: serial
numbers of the components specified in the Equipment Certificate and
marking of connection cables must relate to the measuring channel of a
particular number. The connection cables must not be changed in
length.
3.9. The following components may be sealed on completion of on-site
mounting procedure:
- Two fixing screws located on the front panel of BMD
- Cover of Communication Block case
- Cover of RTD (if applicable).

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4. MOUNTING THE LEVEL GAUGE
4.1. Types of acoustic systems
4.1.1. Simplistically designed AS-1xx-xx3 systems come without reference
reflectors and sound guides. AS-11x-xx3 systems is equipped with disc
mount ones (Fig.A.1). Mount disc both have holes for fixing an acoustic
system to the object under control.
4.1.2. A sound guide as part of AS-40x-xx0 (having reference reflectors)
systems is designed as a pipe run with a mount flange installed on the
upper end. There are holes in the flange used to fix the assembly to the
object under control (Fig.A.2). PEP is installed in the mount flange
center with the emitting surface facing inside the sound guide.
Reference reflector, a hollow fluoroplastic cylinder on a metal rod,
is fixed to the lower end of the sound guide by holders. Being installed
at the known distance from the PEP emitting surface, the reference
reflector provides reflection of ultrasonic waves from the reference
distance.
4.1.3. AS-50x-xx0 (with reference reflector) acoustic systems come with a
mount disc installed. The disc is without fixing holes, however, a ring
bolt mounted on it provides suspension of AS by snap hooks and a
cable (Fig.A.3).
Flexible suspension provides that the Level gauge is capable of
working in thin-walled tanks that are prone to distort in shape under the
effect of temperature.
4.1.4. A sound guide coming with AS-6xx-xx0 (with RTDs) acoustic systems
has a mount flange with fixing holes (Fig.A.4). PEP and RTD are both
installed on the flange. RTD's sensor is located inside the sound guide.
These sound guides come without reference reflectors.
4.1.5. A sound guide included in AS-7xx-xx0 (with RTDs) acoustic systems
has a mount flange without fixing holes, but it is equipped with a ring
bolt (Fig.A.5). These sound guides come without reference reflectors.
4.1.6. To seamlessly mount an AS on any tank regardless of the design, the
Level gauge can be supplied complete with optional mount adaptors of
corresponding type. Types of mount adaptors and adaptor pipes are
shown in Fig.A.6-A.9.
4.1.7. Selection of materials for the sound guide, mount adaptor, and seal
gaskets is determined by AS design.
4.2. Mounting acoustic systems
4.2.1. Depending on the design of an object under control and type of AS in
use, various types of mounting are available (Appendix B).
4.2.2. Various sets of fittings may be provided to mount BMD and AS on
various objects under control. Contents of the set of fittings and number
of particular items depend on the type of AS and mounting method.
4.2.3. Acoustic systems without sound guides are generally mounted on
existing tanks or open channel structures. AS-1xx-xx3 system is
installed on a mount disc (Fig.B.1).

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4.2.4. AS-40x-xx0 and AS-6xx-xx0 systems are mounted as shown in figures
B.2-B.4. Several mounting methods are available:
- Mounting AS on a frame installed on the object under control (Fig.B.2).
AS mount flange is fixed to the frame by bolts. Deflection of the
base plane of the mount flange from the horizontal plane is checked
with a builder's level in two mutually perpendicular directions. This will
ensure that the sound guide axis is positioned vertically.
- Mounting AS with use of mount adaptor (Fig.B.3, B.4).
A mount adaptor (Fig.A.6) is welded to the tank (pipe) wall or to a
frame constructed as desired and installed on the object under control,
after which the AS mount flange is fixed to the mount adaptor flange by
bolts.
- In the case when submerging of AS is possible, one (for AS-6xx-xx0
version) or two (for AS-40x-xx0 version) adaptor pipes are installed
(Fig.A.8). The adaptor pipes are fixed by bolts between the mount
adaptor flange and AS mount flange. Position of the sound guide axis is
checked with a builder's level.
To vent volatile gases in case these are present above the tank
(pipeline) and/or to optimize AS heat exchange, you may use perforated
adaptor pipes (Fig.A.9).
4.2.5. Acoustic systems of AS-50x-xx0 and AS-7xx-xx0 design versions are
installed with use of the "Flexible mount" method (Fig.B.5, B.6). Several
mounting techniques are available:
- AS is suspended from a structural component of the object under
control on a snap hook or a cable via a ring bolt (Fig.B.5).
- Mount adaptor is welded to a tank (pipeline) wall. A flange with a ring
bolt installed is fixed to the mount adaptor flange by bolts (Fig.A.7), and
the acoustic system is suspended on snap hooks or on a cable via the
ring bolt (Fig.B.6).
4.2.6. It is recommended to seal a recess on the mount flange at the PEP
cable output to prevent moisture accumulation.
4.3. Mounting the modules
BMD, Power Source and Communication block (CB) are installed
and fixed on the vertical plane considering their overall and mount
dimensions (see Fig.A.1, A.3, A.5, A.6, Appendix A of Part I of the
Operation manual). The modules are mounted on a pre-installed DIN
rail (mount rail 35/7.5). The Communication Block can be installed at a
certain distance from AS considering that the length of connection
cables terminated in PEP and RTD is 5 m.
It is not necessary that the room where the system is installed be
lighted considering that BMD has its own backlight.
4.4. Wiring the Level gauge
4.4.1. AS is connected to BMD considering that the components are assigned
to particular channels as outlined in section 3.8.
4.4.2. Communication and network cables are fixed on the wall wherever
possible. The network cable is laid separately at a distance of 0.3 m as

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a minimum from other cables. It is recommended not to coil the
excessive cables.
CAUTION! YOU MUST NOT change the length of BMD-CB and
CB-PEP cables.
To avoid mechanical damages, it is recommended to place all
cables in metal or plastic tubes, corrugated sleeves, and cable trays,
trunks, or conduits.
DO NOT lay BMD-PEP and BMD-RTD cables and signal cables for
external connections within proximity to power circuits, and, with
presence of high-level electromagnetic interference, DO NOT lay the
cables without putting them into properly grounded metal tubes or
sleeves. The metal tubes or sleeves shall only be grounded on one side
–on BMD side.
YOU MUST PREVENT tension of PEP and RTD cables connected
to CB. This may result in deflection of the sound guide from the vertical
axis.
4.4.4. Recommended cable types are given in Table.1.
Table 1
Circuit
Cable type
BMD –PEP *
UNITRONIC BUS IBS 3×2×0.22) –for AS-11х-хх3;
any cable 2×0.35 or 2×0.5 – for other types AS
BMD –RTD
any cable 4×0.2
Mains AC 220 V 50 Hz –SPS
any cable 3×0.5
SPS –BMD
any cable 2×0.5
* - Cable length is no more than 250 m
4.4.4. Prior to connection, cut isolation from the cable ends by 5 mm and
fabricate. The cables are directed via cable glands and attached to the
connectors according to the Wiring diagrams given in Appendix C. To
prevent ingress of moisture, the unused cable glands are covered by
plugs included in the set of fittings.
4.4.5. When mounting AS by the method shown in Fig. B.6, signal cables are
directed via cable glands on the mount flange and connected to CB.
4.4.6. The need for protective grounding is determined by power supply and
environment conditions under which the devise is operated.
The protective grounding and earthing device should correspond to
the rules on design of power electric installations.
Use a mechanically protected copper wire of no less than 2.5 mm2
cross-section or a copper wire without mechanical protection of no less
than 4 mm2cross section as a grounding wire connecting the Level
gauge with the grounding device.
Grounding terminal must not be connected to the lightning
protection system.
CAUTION! Prior to connecting the protective earthing trunk
line, you must make sure that the voltage is off.
4.4.7. The Level gauge has no standby mains switch, therefore, it is connected
to mains via an external switch.

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5. START-UP PROCEDURES
5.1. Initial configuration
5.1.1. Prior to work, it is necessary to check that the Level gauge's operation
settings specified in the Equipment Certificate or Check Form
correspond to the ones in the Device's internal memory as well as to
check its configuration settings.
The following settings shown in Fig.1 are determined during the
configuration procedure, after which they are entered in the Device's
Start-up List (Appendix D):
- B –base level, m
- Hmax –maximal level of liquid in the tank under control
- C0 –velocity of ultrasound in gas medium inside the tank under control
at 0°C (applicable only for systems AS-11x-xx3, AS-61x-xx0, AS-62x-
xx0, AS-71x-xx0, AS-72x-xx0), m/s
- Volume/Level characteristic of the tank under control (required for
calculation of volume and/or filled volume).
When configuring the Device, the following settings are also
checked and recalculated:
- Dmin, Dmax –threshold values of the distance measuring range, m
- Cmin, Cmax –threshold values of the range of actual ultrasound velocities
within the sound guide, m/s;
- Cmc –ultrasound velocity value entered for the manual correction mode
(if necessary), m/s.
5.1.2. In the course of start-up, the base level Bcan be determined by two
methods:
- Measuring the distance between the base (reference) plane, from which
the distance readings are taken, and the bottom of the tank or a
conventional plane which is taken as the reference for level
measurements
- Calculating the sum of measured distance Dmcr and liquid level Hmcr in
the tank under control: B = Dmcr + Hmcr (1)
The distance is determined as a range from the base plane to the
media interface. You may use the Level gauge readings to determine
the distance.
For all acoustic systems, the base plane is a plane going through
the outer surface of the mount flange, mount bar, or mount disc.
Values of distance, level and the measurement base can be
measured by a measuring crossbar, measuring needle, or laser ranger.
The recommended accuracy for distance, level, and base level
measurements is ± 1 mm.
5.1.3. The threshold values for distance measuring range Dmin and Dmax are
calculated as follows:
Dmin = B –1.2⋅Hmax (2)

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Dmax = 1.2⋅B (3)
The following conditions must be met:
B –Hmax ≥ 1.4 m –for AS-40x-xx0, AS-50x-xx0 acoustic systems
B –Hmax ≥ 0.8 m – for AS-1xx-xx3, AS-6xx-xx0, and AS-7xx-xx0
acoustic systems.
Dmin and Dmax calculation formulae contain 1.2 factor, which is
included to widen the range of signal search and prevent loss of signal
on powering up the Device after a standstill period (dead time). The loss
of signal may result from the situation, when characteristics of gas
medium have significantly changed during the standstill period, and no
ultrasound velocity correction has been performed.
Base plane
of readout
D
B
H
DR
Dmin
Dmax
Installation
flange AS
Media interface
B –measurement base level; Dmin, Dmax –minimal and maximal distances
respectively; H –level of liquid; DR –distance to the reference reflector.
Fig. 1. Configuration settings
5.2. Configuring the Level gauge installed on the object
under control
5.2.1. Configuration procedure is performed after determining all initial settings
and completing all mount procedures. The Level gauge is configured
from the keyboard, which is operated as described in "ULTRASONIC
LEVEL GAUGE AFLOWT LV. LV-2xx version. The operation manual,

12
Part II" document. Also, the Level gauge can be configured from a PC
with use of "Monitor AFLOWT LV-2xx" software.
5.2.2. The Level gauge is switched to SERVICE mode, and then powered on.
Setting/ Configuration menu is opened and the following
parameters are set for each channel:
- Calc. Mode –Algorithm of channels operation for two-channel versions
- Enable –Inclusion of measurements
- Auto C calc. –Turning on/off automatic ultrasound velocity correction
- Preset profile –Selecting the adjustment profile for an acoustic system
in use
- Indication settings –Selecting parameters to be displayed and
measurement units of volume (m3, L)
- Current profile –Viewing and correcting parameters of the preset
adjustment profile.
CAUTION! It is recommended to enable the standard profiles:
profile 1 for AS-40x-xx0 and AS-50x-xx0 acoustic systems, profile 2 -
for AS-1xx-xx3, AS-6xx-xx0 and AS-7xx-xx0 acoustic systems. Values
of the factory-installed parameters used in the standard profiles are
listed in Appendix E.
Note: The manufacturer corrects configuration settings in
exceptional cases under mandatory control of signal shapes.
5.2.3. Settings/ Object settings/ OBJ. SETTINGS chan. X menu is opened
and the following parameters are set for each channel:
- Dmin–Minimal distance
- Dmax –Maximal distance
- B –Measurement base
- Нmax –Maximal level (if necessary)
- Cman –Ultrasound velocity for the manual correction mode (when
automatic correction is disabled)
- HV-function –Volume/level characteristic of the tank under control (if
necessary).
Note: When entering Volume/Level characteristic data into the
Device, it is recommended to specify the values of level Н in ascending
order starting from the zero level. The maximum settable value of
volume Vis 999999.875 regardless of selected measurement units.
5.2.4. The Level gauge is connected to the service modules and external
devices. The parameters required to match the Level gauge's outputs
with the inputs of the devices are set in Settings / System settings /
Connection settings and Settings / Periphery settings menu.
Temperature measurement channels to be used are enabled, and
RTD sensor curve is set as specified in the Equipment Certificate (if
necessary) in Settings / Periphery settings / Temperature sensor /
Temp. channels / t channel Xmenu.
5.2.5. Current date and time are set if necessary in Settings / System
settings / Time settings menu.
5.2.6. Signal view (Settings / Object settings / Signal view) window is used
to set characteristics of a desired echo-signal per each channel. Then it

13
is necessary to check that the signals reflected from the media interface
and reference reflector (for AS with reference reflector) are displayed. If
the Device is configured correctly, the measured distance is equal to
the actual distance, and positions of the selection marker and the
desired echo-signal match on the display.
Note: The value of measured distance is displayed in the Signal
view window, presence of the desired echo-signal is detected by the
icon indicated in the lower left corner.
If the selection marker matches the image of a noise echo-signal,
the Level gauge should be reconfigured as described below.
In the menu Settings / Configuration / Current profile / Search
by: the operator selects one of the criteria by which the desired echo-
signal is detected among the following:
- max (A) - a signal with maximal amplitude within the specified
measuring range
- min (D) - a signal corresponding to the closest distance within the
specified measuring range
- max (D) - a signal corresponding to the longest distance within the
specified measuring range
- max (D∗A) - maximal value of the product of signal amplitude into the
square root of distance within the specified measuring range.
The manual alignment mode is selected from Signal view window.
When you press the button in Signal view window, the selection
marker starts blinking, and you can move it using buttons , . While
in the moving mode, the selection marker is positioned at the desired
signal. After pressing button , the tracing mode is activated, and the
marker stops blinking.
5.2.7. If necessary, you may configure the interval log and clear logged data.
Data is cleared from the Data logs menu, the same for event logs is
done from the Status logs menu.
5.2.8. The Level gauge is powered off and switched to OPERATION mode by
removing a jumper from the terminal used for modification of service
parameters. This service terminal is sealed. If necessary, two fixing
screws are sealed from the front panel side of BMD.
5.3. Special-purpose configuration
5.3.1. Special-purpose configuration is performed if required. Typically, this
configuration procedure is carried out on the sites where gas
composition differs considerably from the air composition or is
unknown.
5.3.2. Special-purpose configuration is performed for the Level gauges having
acoustic systems complete with RTDs (sensitive element): AS-11x-xx3,
AS-61x-xx0, AS-62x-xx0, AS-71x-xx0, or AS-72x-xx0. The procedure
follows the general configuration procedure and is made for the Device
being switched in SERVICE mode.

14
5.3.3. Prior to configuration, measurement base B (section 5.1.2) is
determined along with an actual value of liquid level in the tank Нact.
The measurements are performed with other measuring tools (e.g.,
measuring needle, measuring rod etc). At the same time, the actual
level value is measured by the Level gauge, and the following readings
are taken from the Device's display: distance D′, ultrasound velocity C′,
and gas medium temperature t′.
5.3.4. The actual value of ultrasound velocity in the gas medium near the tank
under control at 0°C is determined in the following order:
a) Actual value of distance Dact is derived from the formula:
Dact = B –Hact (4)
b) Actual value of time of receiving the desired echo-signal Tact is
determined according to the formula:
C′
dD)-D′ 2(
=Тact
, s (5)
where D′ - value of distance to liquid according to Level gauge's
readings, m
dD –zero offset as specified in the Equipment Certificate, m
C′ - ultrasound velocity according to Level gauge's readings, m/s
c) Actual value of ultrasound velocity Cact in the gas medium is derived from
the formula:
act
act
act TdD)-2(D
=С
, m/s (6)
d) Actual value of ultrasound velocity C0act at 0ºC is calculated by the
formula:
C0act = Cact –0.59⋅t′, (7)
where t′ - value of on-site temperature of gas medium according to
Level gauge's readings, °C
0.59 –correction factor, m/s⋅°C
5.3.5. In the menu Settings/ Object settings,the calculated value of C0act is
entered instead of C0 value used in the Level gauge.
In case of pure gas application, C0 correction can be made by
entering the ultrasound velocity value for the corresponding gas taken
from Table F.1, Appendix F.
5.3.6. The special-purpose configuration is finished by the procedure
described in section 5.2.8.

15
6. DISMOUNTING
To dismount the Level gauge before dispatching for regular
calibration or repair, it is necessary to:
- Turn power off the Device
- Unscrew 6 screws fixing the Measurement Subblock to the Mount
Module from the front panel side
- Disconnect signal cables connecting BMD with external devices from
the terminal blocks
- Screw 6 screws fixing the Measurement Subblock to the Mount Module
- Remove BMD
- Unscrew 4 screws on the cover of the Communication Block
- Disconnect all CB cables from the terminal blocks
- Remove AS together with the rigidly terminated cable.
When the Level gauge (BMD, AS) is dispatched for calibration or
repair, the acoustic systems should be cleaned off sediments, residue,
scale, etc.

16
APPENDIX A. Acoustic systems
. 6
*
2
1
3
2
170*
Æ 170 *
*
Æ 205
Base plane of
readout
3
* - reference dimension
1 –Mount rail; 2 –PEP; 3 –sensitive element RTD
Fig. A.1. AS-11x-xx3 acoustic system

17
* - reference dimension
1 –AS mount flange; 2 –PEP; 3 –sound guide; 4 –holder of reference
reflector; 5 –reference reflector
Fig. A.2. AS-40x-xx0 Acoustic system

18
* - reference dimension
1 –ring bolt; 2 –PEP; 3 –sound guide; 4 –holder of reference reflector;
5 –reference reflector
Fig. A.3. AS-50x-xx0 Acoustic system

19
* - reference dimension
1 –RTD; 2 –mount flange; 3 –PEP
Fig. A.4. 61x-xx0 Acoustic system

20
* - reference dimension
1 –ring bolt; 2 –RTD; 3 –PEP; 4 –sound guide; 5 –counterbalance
Fig. A.5. AS-71x-xx0 Acoustic system