D525_10 (12a)
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Bring the pressure
vessel and the gasoline
to be tested to a temperature
of 15 to 25 degrees Celsius.
Place the glass sample
container in the pressure vessel
and add 50 plus or minus 1
milliliter of test specimen.
Alternatively, transfer
50 plus or minus
1 milliliter of
the test specimen
into the glass sample
container first
before placing the glass sample
container into the pressure
vessel.
Cover the sample container.
Close the pressure vessel.
And using a quick release air
coupling, introduce oxygen
until a pressure of 690 to
705 kilopascals is attained.
Allow the gas in the bomb to
escape slowly in order to flush
out the air originally present.
Release the pressure at a slow
uniform rate through the needle
valve at a rate not to exceed
345 kilopascals per minute.
Introduce oxygen
again until a pressure
of 690 to 705
kilopascals is attained,
and observe for leaks,
ignoring an initial rapid drop
in pressure, generally not
over 40 kilopascals, which
may be observed because
of the solution of oxygen
in the sample.
When the rate of
pressure drop does not
exceed 7 kilopascals
in 10 minutes,
assume the absence of leaks
and proceed with the test
without repressuring.
Place the charged
pressure vessel
in the vigorously boiling water
bath or appropriate liquid bath
equipped with
mechanical stirring,
being careful to avoid
shaking, and record
the time of immersion
as the starting time.
Maintain the temperature of the
liquid bath between 98 and 102
degrees Celsius.
Observe the temperature to
the nearest 0.1 degree Celsius
at intervals during the test.
And record the
average temperature
to the near 0.1 degree Celsius
as the temperature of the test.
Make a continuous record of
the pressures in the pressure
vessel.
Or if an indicating
pressure gauge is used,
take pressure readings at
15-minute intervals or less.
If during the initial
30 minutes of the test
a leak develops, as indicated
by a steady drop in pressure
considerably in excess of 14
kilopascals in 15 minutes,
discard the test.
Continue the test until reaching
a point preceded by a pressure
drop of exactly 14
kilopascals in 15 minutes
and succeeded by a drop of not
less than 14 kilopascals in 15
minutes or until the induction
period exceeds the product
specification.
If no breakpoint is observed
at the termination of the test,
refer to section 12 of
the written standard
for reporting the result.
Warning-- if a boiling
water bath is used
and the test is made in a region
where the atmospheric pressure
is consistently below
normal, 101.3 kilopascals,
it is permissible to
add a liquid with higher
boiling point, such as
ethylene glycol, to the water
in order to maintain
the operating
temperature of the bath in the
neighborhood of 100 degrees
Celsius.
If a liquid other
than water is used,
be sure the liquid is compatible
with the seals in the pressure
vessel.
Record the number of
minutes from the time
the pressure vessel
is placed in the bath
until the break point
has been reached
as the observed induction period
at the temperature of the test.
Cool the pressure vessel to
approximately room temperature
within 30 minutes after removal
from the bath using ambient air
or water less than or
equal to 35 degrees
Celsius before releasing
the pressure slowly
from the pressure vessel through
the needle valve at a rate
not exceeding 345
kilopascal per minute.
Wash the pressure vessel
and sample container
in preparation
for the next test.