ASTM F78-97(2002)

Standard Test Method for Calibration of Helium Leak Detectors by Use of Secondary Standards (Withdrawn 2008)

SCOPE
1.1 This test method covers a procedure for calibrating a mass spectrometer-type helium leak detector with a series of commercially available calibrated leaks without need for recourse to a primary standard.
1.2 Leak detector parameters determined by this test method include:
1.2.1 Minimum detectable signal, drift noise (8.5, with recorder; 8.6, without recorder),
1.2.2 Response time,
1.2.3 Minimum detectable leak rate, and
1.2.4 Sensitivity.
1.3 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
WITHDRAWN RATIONALE
Formerly under the jurisdiction of Committee F01 on Electronics, this test method was withdrawn in June 2008 in accordance with section 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.

General Information

• Status: Withdrawn
• Publication Date: 09-Dec-2002
• Withdrawal Date: 29-Jul-2008
• ICS: 31.080.01 - Semiconductor devices in general
• Technical Committee: F01 - Electronics
• Drafting Committee: F01.03 - Metallic Materials, Wire Bonding, and Flip Chip

Relations

• Replaces: ASTM F78-97 - Standard Test Method for Calibration of Helium Leak Detectors by Use of Secondary Standards
• Effective Date: 10-Dec-2002

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:F 78–97 (Reapproved 2002)
Standard Test Method for
Calibration of Helium Leak Detectors by Use of Secondary
Standards
ThisstandardisissuedunderthefixeddesignationF78;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.3 standard leak rate—in leak detection, the rate of flow
of atmospheric air of dewpoint less than−25°C through a leak
1.1 This test method covers a procedure for calibrating a
under standard conditions specified as follows: (1) the inlet
mass spectrometer-type helium leak detector with a series of
pressure shall be 1 standard atmosphere 65% (1016 5 kPa),
commercially available calibrated leaks without need for
(2) the outlet pressure shall be less than 1 kPa (0.01 atm), and
recourse to a primary standard.
(3) the temperature shall be 23 6 3°C.
1.2 Leakdetectorparametersdeterminedbythistestmethod
3.2 Definitions of Terms Specific to This Standard:
include:
3.2.1 response time—of a leak detector, for the purposes of
1.2.1 Minimum detectable signal, drift noise (8.5, with
this test method, a measure of the speed of response of the
recorder; 8.6, without recorder),
detector to an incoming helium sample.
1.2.2 Response time,
3.2.1.1 Discussion—In this test method the cleanup time
1.2.3 Minimum detectable leak rate, and
and response time are assumed to be equal.
1.2.4 Sensitivity.
3.2.2 sensitivity—of a leak detector, for the purposes of this
1.3 This standard does not purport to address the safety
test method, the ratio of the change in the output signal to the
concerns, if any, associated with its use. It is the responsibility
applied helium leak rate.
of the user of this standard to establish appropriate safety and
3.3 Other terms used in this test method are defined in
health practices and determine the applicability of regulatory
Definitions E425.
limitations prior to use.
4. Summary of Test Method
2. Referenced Documents
4.1 Atleastthreecalibratedleaksaretestedonaheliumleak
2.1 ASTM Standards:
detector, and a correlation is obtained between the output
E1 Specification for ASTM Thermometers
indicationoftheleakdetectorandtheleakrateofthecalibrated
E425 Definitions of Terms Relating to Leak Testing
leaks. These readings are used to plot a calibration line from
3. Terminology which intermediate values, within specified limits, may be
read.
3.1 Definitions:
3.1.1 calibrated leak—in leak detection, a device that per-
5. Interferences
mits leakage through it at a specified rate, of a specific gas,
5.1 Certain materials, particularly organic compounds, will
under specific conditions, with the downstream side of the
entrap or hold helium tracer gas. Use of such materials in
deviceexposedtoapressuresufficientlylowtohavenegligible
connections between the calibrated leak and the leak should be
effect on the leak rate.
minimized to avoid erroneous results. (If the net output
3.1.2 minimum detectable signal—in leak detection, the
readings from any calibrated leak consistently lie outside the
smallest unambiguous output signal that can be derived from a
established limits, the leak should be returned to the supplier
given particular leak detector. Units are detector scale divi-
for a recalibration check.)
sions.
5.2 The background reading, B, should be at most one
3.1.2.1 Discussion—The minimum detectable signal is de-
quarter of the output reading, A. If the value of B approaches
terminedbythenoisepresentin,anddriftof,theoutputsignal.
thatofA,theaccuracyofthedeterminationofNwillsuffer(see
9.3.1).
This test method is under the jurisdiction of ASTM Committee F01 on
Electronics and is the direct responsibility of Subcommittee F01.03 on Metallic
6. Apparatus
Materials.
Current edition approved Dec. 10, 2002. Published May 2003. Originally
6.1 Calibrated Leaks—At least three commercial devices
approved in 1967. Last previous edition approved in 1997 as F78 – 97.
incorporating leaks, one having a leak rate of approximately
Annual Book of ASTM Standards, Vol 14.03.
−9 3 −1 −10 3 −1
3 10 atm·cm ·s (10 Pa·m ·s ), a second having a leak
Discontinued. See 1991 Annual Book of ASTM Standards, Vol 03.03.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 78–97 (2002)
−8 −7 3 −1 −9
value in the nominal range from 10 to 10 atm·cm ·s (10
−8 3 −1
to 10 Pa·m ·s ), and the third having a leak rate of
−6 3 −1 −7 3 −1
approximately 10 atm·cm ·s (10 Pa·m ·s ).
6.1.1 The calibrated leaks shall be obtained from at least
two independent suppliers.
6.1.2 The calibrated leaks shall have been calibrated with
helium gas at a pressure of approximately 1 standard atmo-
sphere 65% (101 6 5 kPa).
6.1.3 Thefollowinginformationshallbeprovidedwitheach
calibrated leak:
3 −1 3 −1
6.1.3.1 Calibrated leak rate, atm·cm ·s (or Pa·m ·s ),
FIG. 1 Schematic Diagram of Apparatus for the Calibration of the
Helium Mass Spectrometer Leak Detector
6.1.3.2 Date of calibration,
6.1.3.3 Temperature of calibration, °C,
3 −1 −1
6.1.3.4 Temperature coefficient, atm·cm ·s ·°C (or
7. Material
3 −1 −1
Pa·m ·s ·°C ), and
7.1 Helium Gas— for use with calibrated leaks not having
6.1.3.5 Ifareservoirisanintegralpartofthecalibratedleak,
an integral reservoir. The helium gas shall have a purity of at
the internal pressure in the reservoir, atm (or Pa) and an aging
least 99.9% and a supply pressure of nominally 1 atm (101
correction.
kPa).
NOTE 1—It is preferable that five, rather than three, calibrated leaks be
used for initial calibrations of helium leak detectors by this method. At
8. Procedure
least two leaks shall be obtained from each of two independent suppliers
8.1 Connecttheheliumleakdetectortobetestedtoasource
when more than three leaks are used.
ofelectricpowerconforminginvoltage,frequency,anddegree
NOTE 2—Although the data on which this specification has been based
of regulation to the manufacturer’s specifications.
were obtained largely from permeation-type leaks, the calibrated leaks
may be of various types such as capillary, pinched tubing, tapered plug, 8.2 Turnonthedetectorforthewarm-upperiodspecifiedby
etc. However, it is recommended that, with all types of leaks, the
the manufacturer.
manufacturer’s recommendations be followed to avoid erroneous test
8.3 Adjust the detector in accordance with the manufactur-
results.
er’s instructions for maximum sensitivity and for maximum
output for a given helium input.
6.2 Thermometer, accurate to 61°C or better in the range
8.4 Close the inlet valve of the detector.
from 18 to 28°C inclusive. A thermometer conforming to
8.5 If the electron-producing filament is not on, turn it on
Thermometer 63C as prescribed in Specification E1 is suit-
andadjustthedetectorzeropositioncontroltoobtainanoutput
able.
signal of at least 10% of the most sensitive scale.
6.3 Chart Recorder, for determining Minimum Detectable
8.6 If the detector has no recorder output or if a suitable
Leak, Method A; an instrument suitable for recording the
chart recorder is not available, continue with 8.8; otherwise,
output of the leak detector under test as a function of time.
continue with 8.7.
6.3.1 The chart recorder shall incorporate a gain control to
8.7 Minimum Detectable Signal, Test Method A, with Re-
permitthedeflectionoftherecorderstylustobeadjustedtofull
corder:
scalewhentheleakdetectormeterisreadingfullscalewiththe
8.7.1 Connect the detector output to the recorder.
leak detector at its most sensitive detection setting.
8.7.2 Record the detector output for 60 min or until the
6.3.2 The time constant of the chart recorder shall not be
output indication has reached full scale. Do not readjust any
greater than that of the leak-detector output meter.
controls during the recording period.
6.3.3 The chart recorder shall be capable of continuous
8.8 Minimum Detectable Signal, Test Method B, without
recording for at least 1 h.
Recorder:
6.4 Stopwatch, calibrated to read in tenths of a second to 60
8.8.1 Observe the detector meter and record its indications
min over an interval of at least 1 h.
as follows. Do not readjust the controls for the 60-min period
6.5 Leak Auxiliary Manifold—If not incorporated in the
of this test.
leak detector, evacuable means for connecting the calibrated
8.8.1.1 Record the pointer deflection, in scale divisions, at
leak to the leak detector, incorporating a roughing pump, leak
time T =0 min.
valve, and pump valve (see Fig. 1).
8.8.1.2 Record the minimum and maximum pointer deflec-
6.5.1 The roughing pump shall have sufficient pumping
tions occurring in the interval from time T =0to T =1 min.
capacity to evacuate the leak auxiliary manifold to an absolute
8.8.1.3 Record the minimum and maximum pointer deflec-
pressure of less than 50 millitorr (or 7 Pa).
tions occurring in the interval from time T =9to T =10 min;
6.5.2 The leak valve shall not act as a source of helium.
record the deflection occurring at T =10 min.
6.5.3 Valves and connections shall contain a minimum of
rubber or other polymeric surfaces that can serve as virtual
leaks.
Commercially available compressed helium of the specified minimum purity,
NOTE 3—It is preferable that the only exposed polymeric surfaces be
supplied in suitable cylinders with appropriate regulators, has been found suitable
those of O-rings. for this test method.
F 78–97 (2002)
8.8.1.4 In like manner, record the minimum, maximum, and 9.1.1 If spikes appear in the chart recorder trace, construct a
terminal deflections occurring during every tenth minute for smooth curve that represents the average values of the detector
the 60-min period, that is, from T =19to T =20 min, T =29 output.
to T =30 min, etc. 9.1.2 From the smoothed curve, determine the detector
output at the beginning and at the end of each minute, in chart
8.9 Minimum Detectable Leak Rate and Sensitivity:
scale divisions. Record these values.
8.9.1 Connect the apparatus as shown in Fig. 1, including
9.1.3 Calculate and record the change in output for each
one of the calibrated leaks.
1-min period. Compare each of these values to a reference
8.9.2 With the filament on, zero the deflector meter reading.
value of ⁄2% of the full-scale chart reading.
8.9.3 Open the leak valve and then the pump valve.
9.1.3.1 If the change in output per minute is always greater
8.9.4 If the calibrated leak has an integral reservoir, con-
than or equal to this reference value, identify by inspection the
tinue with 8.9.6; otherwise continue with 8.9.5.
largest of these changes and record this value, in chart scale
8.9.5 Connectasourceofheliumatapressureof1atm(101
divisions per minute, as the drift.
kPa) to the calibrated leak.
9.1.3.2 Ifthechangeinoutputperminuteisalwayslessthan
8.9.6 Evacuate the atmospheric air present in the connec-
this reference value, calculate the total change in the 60-min
tionsbetweentheleakandtheleakdetector(toprotecttheleak
observation period and divide this value by 60. Record the
detector).
quotient in chart scale divisions per minute as the drift.
NOTE 4—It may be desirable to turn off the filament of the mass
9.1.4 Examine the recorded output curve and determine if
spectrometer tube before continuing with 8.9.7.
spikes appear on both sides of the smoothed curve.
9.1.4.1 If they do, identify the two spikes, one on each side
8.9.7 Open the inlet valve slowly and maintain the leak
of the smoothed curve, that extend furthest from the curve.
detector pressure within the operational pressure range speci-
Measure the departures, in chart scale divisions, and add the
fied by the manufacturer.
two figures. Record this sum as the noise.
8.9.8 Close the pump valve.
9.1.4.2 If spikes appear on only one side of the smoothed
8.9.9 With the inlet valve fully open, observe the pressure
curve, record twice the largest departure from the curve, in
indicatoroftheleakdetector.Donotcontinueuntilthisreading
chart scale divisions, as the noise.
shows no observable change over 1 min.
9.1.5 Calculate and record the sum of the drift and noise.
8.9.10 Turnonthefilamentofthemass-spectrometertubeif
Comparethisvaluetoareferencevalueof2%ofthefull-scale
it is not on.
chart reading.
8.9.11 Adjust the range multiplier to bring the detector
9.1.5.1 If the sum of the drift and noise is greater than or
meterreadingonscale.Whenthemeterpointershowsasteady
equal to this reference value, record it, in chart scale divisions,
deflection, with no observable change over 1 min, record the
as the minimum detectable signal.
reading, A, in scale divisions. If required, adjust the gain
9.1.5.2 Ifthesumislessthanthisreferencevalue,recordthe
control, but do not readjust any controls thereafter for the
reference value as the minimum detectable signal.
duration of this test.
9.1.6 Convert the values for drift, noise, and minimum
8.9.12 Calculate and record a value equal to 37% of A.
detectablesignal,recordedinchartscaledivisions,intoequiva-
8.9.13 Using the thermometer, measure the ambient tem-
lent meter scale divisions as follows:
perature near the leak to the nearest 1°C. Record this value.
9.1.6.1 Determine and record the ratio of full-scale meter
8.9.14 Startthestopwatchandsimultaneouslyclosetheleak
divisions to the number of full-scale chart divisions.
valve as rapidly as possible.
9.1.6.2 Multiply by this ratio the values recorded in 9.1.3
8.9.15 Observe the detector meter continuously. Stop the
(drift), 9.1.4 (noise), and 9.1.5 (minimum detectable signal).
stopwatch when the reading has decreased to 37% of A (this
Record these values as the drift, noise, and minimum detect-
value was recorded in 8.9.12). Record the reading of the
able signal, respectively, expressed in meter scale divisions.
stopwatch to the nearest1sas T, the response time.
NOTE 6—For the purposes of this test method, it is acceptable to sum
NOTE 5—The actual value recorded is the cleanup time, which for the
drift and noise and to express the result in scale divisions, even though
purposes of this method is taken as the reponse time.
drift has units of scale divisions per unit time.
8.9.16 Continue to observe the detector meter. When the
9.2 Minimum Detectable Signal, Test Method B:
pointer shows a steady deflection, with no observable change
9.2.1 Calculate and record the change in output between the
over 1 min, record the reading in scale divisions as the
initialandfinalmeterreadingsforeachofthe10-minintervals,
background reading, B.
that is, between T =0 and T =10 min, T =10 and T =20
8.9.17 Close the inlet valve, vent the sample inlet line to
min, T =20 and T =30 min, etc.
atmosphere, and replace the calibrated le
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