| RTD Serial number:
___________
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Adult Reference Test Device - Buoyancy Tracking and Verification
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To achieve repeatability in human subject
testing, the overall buoyancy and distribution of buoyancy between
the front and back of the RTD must be maintained within a tight tolerance
as specified in Table 1.
Table 1 SOLAS adult RTD buoyancy
and tolerance
| Limit / Units
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Front
buoyancy1
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Back buoyancy
|
Total buoyancy
|
Buoyancy
distribution2
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| Design / N
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103
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46
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149
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69% in front
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| Maximum / N
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107
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48
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155
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70.5% in front
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| Minimum / N
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100
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45
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145
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67.5% in front
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| Note
1: Values at or corrected to standard temperature and pressure.
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| Note 2: Buoyancy distribution is
calculated by dividing the front buoyancy by the total buoyancy.
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The buoyancy of a new RTD may exceed the allowable tolerance
range until the normal shrinkage or compression of the foam inserts
stabilizes. Until the buoyancies of the foam inserts have stabilized,
buoyancy and distribution should be checked at regular intervals (perhaps
weekly), and then at least monthly thereafter or whenever used for
testing, whichever is longer (frequent use may require more frequent
checks). Only RTDs with buoyancies within tolerance should be used
for certification testing. A data sheet to document the buoyancy and
buoyancy distribution of the RTD is attached.
Adjustment of buoyancy: At the time of manufacture
the left-to-right distribution of buoyancy in the front inserts was
adjusted to be within 1.3 N of each other. To achieve this tolerance,
thin layers of foam ("make-up" inserts) may have been inserted between
the front and inside front foam inserts. The test house may need to
increase the size of these make-up inserts from time to time to keep
these parameters within tolerance, or may need to add buoyancy to
the back or collar inserts (or trim buoyancy, if the back insert has
not shrunk as anticipated). Figure 2 provides guidance for sizing
of make-up inserts to adjust buoyancy. After a full sheet of 6.5 mm
thick foam is required in any one of the four major areas, an inside
front or back insert probably needs to be replaced. If the front buoyancy
is under the minimum value, measure the buoyancy of the right and
left sides so that the proper distribution of buoyancy (no more than
a 1.3 N difference) between the right and left front panels can be
maintained.
Table 2 SOLAS adult RTD insert
design buoyancies
|
|
Combined left front
and inside front1
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Combined right front
and inside front1
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Back
|
Collar
|
| Design (N)
|
34 + 17.5 =
51.5
|
34 + 17.5 =
51.5
|
18
|
28
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| S/N ____ Date:
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Note 1: Plus make-up inserts, if used.
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RTD Buoyancy Data Sheet
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| RTD
Serial number/identification: _________________
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| Date
|
Left front
buoyancy
(N)
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Right front
buoyancy
(N)
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Total front
buoyancy
(N)
|
Total back
buoyancy
(N)
|
Total
buoyancy
(N)
|
Buoyancy
distribution
(% in front)
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Remarks
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(1)
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(2)
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Note (1): Left and right front buoyancy need not be
checked if distribution is within tolerance.
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| Note (2): If the
temperature and pressure at the time of measurement is not at standard
conditions, these values should be corrected to standard temperature and
pressure.
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Figure 1 Audit RTD foam insert nomenclature
Figure 2 Audit RTD "make-up" foam insert sizes