ASTM F324-75(1980)

An American National Standard
~~l~ Designation: F 324- 75 (Reapproved 1980)
Standard Test Method for
NONVOLATILE RESIDUE OF VOLATILE CLEANING
SOLVENTS USING THE SOLVENT PURITY METER
This Standard is issued u!lder the fixed designation F 324; the number immediately following the designation indicates the year
of ongmal adoptiOn or, m the case of reviSion, the year of last revision. A number in parentheses indicates the year of last
reapproval.
1. Scope The remaining air-suspension of solvent and
residue droplets is drawn to the input of the
1.1 This method covers the determination of
photometer. The meter of the unit is utilized to
nonvolatile residue of volatile cleaning solvents
provide a visual readout of the photometer
using a solvent purity meter.
measurement.
2. Applicable Document 4.1.3 Photometer-The photometer mea­
sures the concentration of the residual matter in
E 300, Recommended Practice for Sampling
2 the sample and provides a readout by means of
Industrial Chemicals
a meter with a linear scale. If the recorder of
3. Summary of Method the sampler-meter unit is being used, the read­
out is also furnished to the recorder. The
3.1 A method is described for measuring the
photometer provides readings with an accuracy
nonvolatile residue of cleaning solvents using a
of I ppm. The value of the meter reading is
is concen­
solvent purity meter. The residue
translated into terms of nonvolatile residue per
trated in aerosol form by evaporation of the
million parts, by volume, through use of a curve
more volatile solvents. The volume of the
established during calibration for the particular
concentrated aerosol is passed by a forward
solvent concerned.
light scattering photometer. Experimentally de­
vised curves relating photometer output to
5. Sampling
nonvolatile residue concentration are used to
5.1 Solvents to be analyzed for nonvolatiles
obtain parts per million of nonvolatile residue
should be sampled in accordance with Recom­
content of the cleaning solvents.
mended Practice E 300.
4. Apparatus
6. Preparation of Apparatus
4.1 The solvent purity meter consists of a
6.1 Preliminary Operation-With the sol­
sampler, JM-2000A photometer, and intercon­
vent purity meter connected to a 100-V a-c
necting hoses (Fig. I). Figures 2 and 3 illustrate
60-Hz, power source, adjust the teste; fo;
the sampler-and-meter unit and the photometer
proper operation.
individually.
6.1.1 Adjustment of NEBULIZER REGU­
4.1.1 Sample Source-Figure 3 provides a
LATOR valve for indication of 5 psi (34 kPa)
graphic representation of three different
on NEBULIZER PRESSURE gage assures
methods of sampling by the solvent purity
meter. Of the three methods, the pour sample
method offers least opportunity for concentra­
'This method is under the jurisdiction of ASTM Commit­
tion of the sample by the system. tee F-7 on Aerospace Industry Methods.
~urrent edition approved Jan. 24, 1975. Published March
4.1.2 Sampler and Meter Unit-This unit
reduces the sample to a fine spray and in­ Annu'!l Book of ASTM Standards, Parts 29 and 30.
'A sat.Isfactory source of this equipment is Jet Instru­
troduces the atomized sample into a drying
ments, Suite 1717, First National Bank Bldg, East Albuquer­
tube where most of the solvent is evaporated. que, N. M. 87108.
F324
proper air pressure for operation of the nebu­ position), out the bottom stem of the V 4 valve
lizer.
and into the nebulizer.
6.1.2 Adjustment of DRIER VOLUME 6.2.1.2 Open V l and V2 to allow excess fluid
valve for indication of 25 (approximately 3 psi to bleed off and return to the cleaning unit.
(21 kPa)) on DRIER VOLUME gage provides 6.2.1.3 Make adjustments to the VI and V4
correct volume of airflow to drying tube. valves to provide maximum flow of fluid from
6.1.3 A recorder (which is not part of the the cleaner while limiting the level of fluid in the
solvent purity meter, though sometimes housed nebulizer reservoir to a position approximately
therein) may be used as desired to provide a 25 mm ( /2 in.) below the lip of the atomizing
record of solvent purity meter indications.
tube. If the fluid is permitted to rise much
6.1.4 Adjustment of photometer METER higher than 25 mm below the lip of the
ZERO control for 0 indication on CONCEN­
atomizing tube, the unit will flood and the
TRATION meter "bucks out" the dark current liquid sample will pass ir.to the drying tube,
of the photomultiplier. nullifying test indications. If fluid falls much
6.1.5 Adjustment of two red controls of dual below the 25-mm level specified, too little
flowmeters allows proper flow of air into the sample may be available for atomization, and
once again, test results are nullified.
optical chamber, that is, approximately 26
litresjmin of sampling air and 3 litresjmin of 6.2.1.4 Return the unatomized portion of the
clean air. (Flowmeters are located in room-air­ sample to the cleaner, through open valve VI
intake filter line and in photometer air outlet
and the sample-return hose.
lines as indicated in Fig. 4.) Therefore, airflow 6.2.2 For Pour-Sample Analysis-Pour at
through the optical chamber consists of the least 25 em of sam pie to be tested into the
sample surrounded by a sheath of filtered room syringe. With VI and V2 closed, operate the
air. This sheath keeps out most of the sample syringe to pump approximately 20 em' of
air suspension from distributing through the
solvent into the nebulizer. Subsequent to test,
photomultiplier assembly, since it may contain open VI to permit the unatomized portion of
impurities which would deposit on component sample to drain out.
parts. 6.2.3 For Hand-Pump Sample Analysis
6.1.6 By swinging the photomultiplier as­ -Use the syringe pump of the solvent purity
sembly off-axis, the photomultiplier tube re­ to pump solvent to the SOL VENT IN
meter
ceives light directly from the lamp in the stem of the V4 valve (which is in the OPEN
light-source housing through a ground glass position) and through the check valve into the
lens. The luminosity represents a reference 100 syringe. With VI and V2 closed, pump approxi­
% light transmission to the photomultiplier mately 20 em' of solvent into the nebulizer.
tube. Adjustment of the meter gain control Subsequent to test, open V 1 to permit the
CONCENTRATION meter (Position I) for unatomized portion of sample to drain out.
full-scale deflection, corresponds to 100 % light
6.2.4 With the reservoir of the nebulizer
reception. The RECORDER SENSITIVITY filled to the proper level, feed compressed air
control is used to adjust the full-scale setting of (see AIR INPUT, Fig. 4) to the nebulizer and
the recorder so that the recorder tracks linearly to the drying tube of the sampler and recorder
with the CONCENTRATION meter. When unit. The nebulizer reduces the sample to a fine
the photomultiplier assembly is rotated to the spray and introduces it to the drying tube
on-axis position, the photomultiplier tube re­ where, if the sample is pure enough, it is
ceives negligible light and the CONCENTRA­ transformed by evaporation into an almost
TION meter indicates 0. completely gaseous state. Sample flow from the
6.2 Purity Test: drying tube is greater in volume than that which
6.2.1 For Continuous Monitoring of Recir­ the pump in the photometer can draw. Excess
sample spills out the gas overflow, keeping the
culating Systems:
6.2.1.1 Set the controls of the cleaning unit mixture at approximately ambient pressure for
(not part of the solvent purity meter) to pump accurate sampling rates.
the fluid sample through the SOL VENT IN 6.2.5 The sample moves into the highly
stem of the V4 valve (which is in the OPEN illuminated optical chamber, where light is
F324
excluded from the photomultiplier tube by a introduction of a new type of cleaning solvent
cone of darkness, as shown in Fig. 4. to be tested.
6.2.6 If the sample is extremely pure, the 7.3 Sequence-All calibration procedures
solvent will be in an almost pure gaseous state, must be performed in paragraph sequence.
with negligible refractive or reflecti~·e qualitit:s. 7.4 General Information:
Most contaminating residues are of relatively 7 .4.1 For calibration, introduce several sam­
low vapor pressure and a small percentage of ples consisting of various ratios of the applica­
such residues changes the vapor pressure of the ble clean solvent diluted with a known volume
mixture quite significantly. Such impurities in of nonvolatile contaminant into the solvent
the sample will retard vaporization in the purity meter. Plot readings that result from
drying tube. each of these samples on semi-log paper to
6.2. 7 Droplets, therefore, reach the optical obtain· a characteristic calibration curve. Then
chamber where light strikes them and reflects use the curve during test operations to convert
or refracts into the cone of darkness and passes any given photometer indication to impurities
the photomultiplier tube as indicated in that particular solvent.
on to in parts per million for
Fig. 4. Excitation of the photomultiplier tube Figure 5 is typical for trifluorotrichloroethane.
produces an electrical signal which is propor­ 7.4.2 For making the curve, take readings of
tional to the amount of light it receives. The dilutions of l, 2, 5, 10, 20, 40, 60, 80, and 100
rate at which small droplets in the atomized ppm by volume. The ideal contaminant would
sample are evaporated is inversely proportional be the one most likely to be confronted in the
to the amount of low-volatile material in the cleaning process. However, as contaminants
sample. are usually of similar volatility when compared
6.2.8 The signal from the photomultiplier
with the solvent, lightweight machine oil, liquid
tube is amplified and transmitted to'the CON­ solder flux, or similar material will provide
CENTRATION meter which provides a direct results that will form a good general curve.
indication relative to the purity of the sample. 7.4.3 To circumvent the need for measuring
If the recorder is being used, the recorder also extremely small amounts of contaminant sev­
indicates the degree of impurity. The value of eral times, make a master mix of 100 ppm and
the indication is translated into impurities in obtain the lesser ratios by diluting the clean
parts per million by volume, through use of a
solvent with the master mix. This technique
graph established during calibration of the minimizes hu'man error during measurement.
tester.
7.5 Calibration Procedures: ·
6.2.9 Calibration of the meter is accom­
7.5.1 Prepare the solvent purity meter in
plished by measuring known solutions of typi­ accordance with procedures in 8.1 through
cal contaminants of low volatility dissolved in 8.1.9. 7, except omit procedures in paragraph
the solvent of interest. From these known 8.1.8.11 or 8.1.9.7, depending on whether the
solutions, a calibration curve of residue content recorder is used or not.
in parts per million by volume versus the 7.5.2 Clean all glassware of calibration
indication of the CONCENTRATION meter equipment, using the solvent of the type con­
can be established. cerned.
7.5.3 Fill the. two !-litre flasks with clean
7. Calibration
solvent from the same source.
7.1 Calibration Interval-The tester must 7.5.4 Measure 500 ml of clean solvent from
have been calibrated at some time during the
either !-litre flask into a 500-ml graduate.
6-month period preceding use, for the particu­ Using a 50-microlitre syringe, add 50 mi­
lar solvent in question. crolitres of contaminant to the solvent in the
7.2 Invalidation-Calibration is invalidated 500-ml graduate. This provides a master mix of
by shipment, removal from use and subsequent 100 ppm.
storage, expiration of prescribed calibration 7.5.5 To facilitate handling, pour solvent oil
interval, replacement of glassware of sampler mixture from the. 500-ml graduate into a
and recorder, or by maintenance of the pho­ 250-ml beaker. For the same purpose, pour
tometer. Calibration is also required upon
clean solvent from either !-litre flask into the
F 324
remaining 250-ml beaker. and pour the approximately 25 em of the same
7 .5.6 Using the 10-m! graduate, measure 1 clean solvent into the syringe. Reinsert the
ml of the mixture into the 100-m! flask. Fill the
plunger to flush the solvent through the system
flask to the 100-ml mark with clean solvent. to clean tubing, valves, and other components.
This represents a dilution of I ppm (Table I). 7.5.16 Again extract the plunger from the
7.5.7 On the front panel of the sampler and
syringe and pour approximately 25 em of clean
meter unit, rotate the V4 valve to the OPEN solvent of the type being analyzed into the
valve position. syringe. Close the VI valve. Reinsert the
7.5.8 On the front panel of the sampler and plunger to pump approximately 20 cm of
meter unit, close the V2 valve and open the VI solvent into the nebulizer. If the solvent purity
valve.
meter has not been calibrated previously for the
7.5.9 Connect the 9.5-mm (3/s-in.) diameter solvent of interest, repeat procedures in 7.5.10
sample-return hose between the bottom stem of and 7.5.11 until consistently low indications of
the nebulizer (Fig. I) and the suitable drain the CONCENTRATION meter verify cleanli­
vessel or outlet. ness of the system. If a calibration curve for the
7 .5.10 Extract the plunger completely from solvent was established previously, check the
the syringe and pour approximately 25 em of indication of the CONCENTRATION meter
clean solvent of the type being analyzed into the against the curve to ensure cleanliness of the
syringe. Reinsert the plunger with sufficient system, repeating procedures in 7.5.10 and
force to flush the solvent through the system, to 7.5.11 as necessary.
clean tubing, valves, etc. of residue. 7.5.17 Open the VI valve, pump the remain­
7 .5.11 Again extract the plunger from the der of solvent from the system, and allow the
syringe and pour approximately 25 em of clean system to drain.
solvent of the type being analyzed into the 7.5.18 Using clean solvent, clean the 100-ml
syringe. Close the V 1 valve. Reinsert the flask.
plunger to pump approximately 20 cm of 7.5.19 Using the 10-ml graduate and the
solvent into the nebulizer. If the solvent purity 100-ml flask, prepare the next sample to be
meter has not been calibrated previously for the checked, following the sequence given in Table
solvent of interest, repeat procedures in 7. 5. I 0 I. After placing the mixture in the 100-ml flask,
and 7 .5.1 i until consistently low indications of fill the flask to the 100-ml mark. Repeat
the CONCENTRATION meter verify cleanli­
procedures in 7.5.12 through
...