ASTM E947-22

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Designation: E947 − 83 (Reapproved 2015) E947 − 22
Standard Specification for
Sampling Single-Phase Geothermal Liquid or Steam for
Purposes of Chemical Analysis
This standard is issued under the fixed designation E947; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers the basic requirements for equipment and the techniques to be used for the collection of
uncontaminated and representative samples from single-phase geothermal liquid or steam. Geopressured liquids are included. See
Fig. 1.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for
information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1192 Guide for Equipment for Sampling Water and Steam in Closed Conduits (Withdrawn 2003)
E1675 Practice for Sampling Two-Phase Geothermal Fluid for Purposes of Chemical Analysis
3. Application
3.1 This The equipment specification covers only that equipment which is commonly used for the sampling of single-phase
geothermal liquid or steam. It does not cover specialized equipment required for, and unique to, a specific test or method of
analysis. The specification covers items such as valves, fittings, tubing, cooling coils and condensers, pumps, degassers, sample
containers, and sample probes, and packaging materials, but excludes equipment used in specific testing and analysis.
3.2 This The sampling procedure applies to sampling of single-phase steam or liquid streams prior streams, including single-phase
steam or liquid streams separated from two-phase flow as described in Practice E1675to separation and to separated single-phase
This specification is under the jurisdiction of ASTM Committee E44 on Solar, Geothermal and Other Alternative Energy Sources and is the direct responsibility of
Subcommittee E44.15 on Geothermal Field Development, Utilization and Materials.
Current edition approved March 1, 2015Jan. 1, 2022. Published April 2015February 2022. Originally approved in 1983. Lasts previous edition approved in 20072015 as
E947-83(2007).E947-83(2015). DOI: 10.1520/E0947-83R15.10.1520/E0947-22.
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volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
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E947 − 22
steam or liquid streams., dry saturated steam, superheated steam, and pumped geothermal liquid. The sampling procedure is not
applicable to the collection of liquid droplets and entrained solids in steam (steam quality and purity), which must be collected by
isokinetic sampling utilizing different equipment and techniques. The single-phase steam sampling specification applies to
vapor-phase species in the steam only (noncondensable gases, HCl and boric acid). The single-phase liquid sampling specification
applies to fully dissolved species in the liquid only, including noncondensable gases if no gas bubbles are present (gas breakout).
3.3 For most geothermal and geopressured fluids tested by the procedures outlined in this specification, both liquid and gassteam
samples may be collected.
4. Sample Probes
4.1 SampleSampling probes shall be used to extract liquid or steam from the main part of the geothermal flow rather than using
a wall-accessing valve and pipe arrangement. This allows a representative sample to be collected of a homogeneous, single-phase
fluid. The probes are not designed for multi-phase sampling or sampling under isokinetic conditions (see Fig. 1). Consideration
should be given to the force generated by any specific combination of probe diameter and system pressure and to the limitations
and safety of sliding seals. A combination of probe tip bead and safety chain are recommended to restrict forcible ejection of the
probe from the line being sampled. In some cases, a permanently installed sampling probe is preferred.
4.1.1 The probe permits the sampling of various positions within the flow to determine whether stratified or annular two-phase
flow is present which would bias a single-point sample.
4.2 Sample probes shall be designed to extract representative samples from flowing systems. homogeneous single-phase fluid flow.
Special attention during construction of the probe shall be given to the stresses that the probe will later be subjected to during
insertion into, and operation in, a pressurized flowing system.
4.2.1 The sampling probe shaft should be constructed of UNS S30400, S31600, S30403, or S31603 tubing, or another suitable
material. Its outer diameter should be 9.5 mm (0.375 in.) to 12.7 mm (0.500 in.) with a wall thickness of at least 1.25 mm
(0.049 in.).
4.2.2 The probe shaft must be of sufficient length to reach the center of the pipeline.
4.3 The probe shall be equipped with a sliding seal mechanism that will allow the probe shaft to slide into and out of the flow
stream, while under pressure.
4.3.1 The temperature and pressure rating of the sliding seal shall be at least 1.5 times greater than that of the fluid or vapor to
be sampled.
4.4 The sampling probe (seeshaft Fig. 2) passes through the sliding seal and access valve in order that liquid or steam can be
sampled from the mainstream central stream of the flow line. Thereafter, the sample contacts only surfaces that the operator can
verify are noncontaminatingnon-contaminating and nonabsorbing. non-absorbing.
4.3.1 Moving the probe tip across the diameter of the pipe may allow the operator to determine the existence of stratification or
multiphase sampling problems.
4.3.2 Flow regulation is accomplished downstream of the cooling coils in order to avoid residual flashing into steam at the point
of pressure reduction. Flashing may cause scale deposition which would preclude the accurate determination of certain
constituents.
5. Sampling Lines
5.1 Safety—Sampling lines shall be as short as practical and of sufficient strength to prevent structural failure.
5.2 Construction—All sample lines shall be constructed to eliminate traps in which condensate, entrained particulates, or scale
precipitates might settle since they may be partially emptied with changes in flow conditions and may result in sample
contamination. Allow for thermal expansion.
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(1) Welded probe tip, 12.7 mm ( ⁄2 in.) diameter probe
(2) Sample holes, 6.4 mm ( ⁄4 in.) diameter, 4 each
(3) Welded bead safety stop
(4) Pipe nipple, 19.0 mm ( ⁄4 in.) NPT
(5) Probe tee, 19.0 mm ( ⁄4 in.) NPT
(6) Packing gland with PTFE or flexible graphite sliding seal element, 12.7 mm ( ⁄2 in.) bore size
(7) Probe cross, 6.4 mm ( ⁄4 in.) NPT
(8) Pressure port valve, 6.4 mm ( ⁄4 in.) NPT, PTFE seals
(9) Pressure gauge, vibration dampening, range 0 kPa to 2000 kPa (0 psig to 300 psig)
(10) Thermocouple, Type K, transition joint, 3.175 mm ( ⁄8 in.) sheath, length sufficient to reach tip of probe, signal cable
(11) Sample Port Valve, 6.4 mm ( ⁄4 in.) NPT, PTFE seals, #6 Male AN/JIC fitting
(12) Vent port valve, 6.4 mm ( ⁄4 in.) NPT, PTFE seals
Material specification: All metal components made from UNS S30400, S31600, S30403, or S31603. Alternative materials, such as N06625 may be appropriate when
sampling conditions are likely to cause stress corrosion cracking.
FIG. 21 SampleSingle-Phase Sampling Probe
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5. Valves, Fittings,Gauges, and GagesFittings
5.1 Valves which control access to the sampling point shall have straight throats (frequently designated as ball, plug, and gate
valves). Gate valves and ball valves shall be full-port style. This permits a probe to be inserted directly into the flow.
5.2 It is recommended that The sample probe shall be equipped with at least one full-port shut-off valve be placed on the
downstream end of the sample probe so that the sampling line may be isolated when desired.necessary.
5.3 Throttling For single-phase liquid sampling, the throttling devices such as valves, capillary tubes, or orifices, if used, shall be
placed at the sample outlet of the cooler or condenser. This practice will ensure cooling at the highest pressure and will minimize
the possibility of fluid flashing or scale forming in the cooling coil. A head column such as that recommended for normal water
and steam sampling (Specification D1192, for Equipment for Sampling Water and Steam) shall not be used because it provides
a mechanism for gas separation and escape prior to sample collection.
5.4 Equipment adequate to determine the pressure and temperature of the mainstremmainstream liquid or steam flow shallmay be
utilized.
5.4.1 Temperature measurements are made with a resistance temperature detector (RTD) or a Type-K thermocouple. 4-wire RTD
probes are preferred due to the large linear range and stable signal. Minimum accuracy of the meter should be at least 60.6 °C
(61 °F). Meters and temperature probes should be calibrated at the same intervals as the pressure transducers to ensure consistency
between the measurements of pressure and temperature. All meters and probes require permanent identification numbers so that
field data and calibration data can be traced to each specific instrument.
5.4.1.1 The temperature sensing element shall be housed in a sealed, ungrounded sheath of sufficient length to reach the inlet end
of the probe. The sheath shall be constructed from the same material as the probe, or other suitable inert material.
5.4.1.2 The sheath must be of small enough diameter so as not to occlude more than 20 % of the interior cross-sectional area of
the probe shaft.
5.4.2 Pressure measurements are made with a calibrated digital pressure transducer. A pressure-snubbing device is recommended
to minimize the pressure spikes and surges common in geothermal flow lines. Minimum accuracy of the gauge should be 61 %
of full-scale. The gauge should be calibrated at monthly intervals when in routine use and every six months for intermittent use.
All gauges require permanent identification numbers so that field data and calibration data can be traced to each specific instrument.
5.5 Sample ports on the probe often need to be replumbed, and fittings may need to be replaced. A selection of pipe fittings
including reducer bushings, pipe nipples, couplings, and elbows, plus those needed for sample equipment maintenance, is required
on site.
6. Sampling Lines
6.1 Sampling lines shall be as short as practical and of sufficient strength to prevent structural failure.
6.2 Standard sample lines are perfluoroalkoxy alkane (PFA) tubing with UNS S30400, S31600, S30403, or S31603 overbraid rated
to 1378 kPag and 243 °C (500 psig and 470 °F). Joint Industry Council/Army-Navy (JIC/AN) type fittings attach hoses to the
probe outlet and condenser/cooler inlet. Hoses are dedicated to either steam or liquid service to prevent cross-contamination.
6.2.1 The inner diameter of hose used for liquid sampling should not exceed 9.5 mm (0.375 in.).
6.2.2 The inner diameter of hose used for vapor sampling should not exceed 6.4 mm (0.250 in.).
6.2.3 When sampling pressure exceeds 1378 kPag, UNS S30400, S31600, S30403, or S31603 tubing should be used (6.4 mm to
9.5 mm (0.25-in. to 0.375-in.) outside diameter), although it is less convenient. Convoluted, flexible stainless steel hose is
specifically excluded due to potential entrapment and contamination problems caused by the internal convolutions. Alternative
materials such as N06625 may be appropriate when the fluid being sampled is likely to have high concentrations of halides.
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7. Sample Cooler
7.1 The tube through which the sample flows shall be continuous through the cooling location so there will be no possibility of
sample contamination or dilution from the cooling water. The internal diameter of the tube is suggested to be no larger than that
of the sample probe so that storage within the coil is low and the time lag of sample through the cooling phase will be a minimum.
7.2 When the temperature of the sample is above the boiling point of water, it may be advantageous, in order to conserve ice, to
advantageous to use a precooler containing water to lower the temperature of the sample before it enters the cooler. The
temperature of the sample can then be controlled by the flow rate and the temperature of the final cooling bath (frequently an ice
water bath).
7.3 The steam cooling coil has a regulating valve at the inlet. Regulating the flow at the condenser inlet maintains fluid velocity
on the condensate and prevents fluid holdup inside the condenser. The outside diameter of the steam cooling coil is typically
6.4 mm (0.250 in.). Outside diameters larger than 6.4 mm (0.250 in.) should not be used, as larger tubing sizes decrease fluid
velocities and increase residence times within the tubing. (See Fig. 2.)
(1) JIC fitting, 6.4 mm ( ⁄4 in.) NPT × S.A.E. 37° sample inlet
(2) Regulating valve, 6.4 mm ( ⁄4 in.) NPT
1 1
(3) Bulkhead fitting, 6.4 mm ( ⁄4 in.) NPT × 6.4 mm ( ⁄4 in.) Swagelok
(4) 6.1 m × 6.4 mm (20 ft × ⁄4 in.) O.D. tubing, 0.9 mm (0.035 in.) wall
1 1
(5) Bulkhead fitting, 6.4 mm ( ⁄4 in.) NPT × 6.4 mm ( ⁄4 in.) Swagelok
(6) 101.6 kPa × 206.8 kPa (30 in. Hg × 30 psi) vacuum ⁄pressure gauge
1 1 1
(7) Gauge tee, 6.4 mm ( ⁄4 in.) NPT and hose adapter, 6.4 mm ( ⁄4 in.) NPT × 6.4 mm ( ⁄4 in.) hose barb
3 3
(8) Plastic tubing, 9.5 mm ( ⁄8 in.) O.D., 4.8 mm ( ⁄16 in.) I.D. sample outlet
(9) 30 L to 76 L (8-gal to 20-gal) drum with perforated lid
Material specification: All metal components made from UNS S30400, S31600, S30403, or S31603. Alternative materials, such as N06625 may be appropriate when
sampling conditions are likely to cause stress corrosion cracking.
FIG. 32 Example Assembly (Particularly Suited for Steam Flows)Steam Sample Condenser
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7.3.1 The steam cooling coil is arranged as a downward spiral with the inlet at the top. This maintains the thermal gradient in the
cooling container, allowing the coolant at the surface to boil and radiate as much heat as possible, while preserving the cooler fluids
at the bottom of the vessel. The cooled sample fluid exits through a straight tube rising to the top of the cooler.
7.3.2 In cases where the noncondensable gas concentration in steam exceeds approximately 5 % by weight, the outlet of the steam
condenser coil should be at an elevation below the inlet with a continuous down-slope in the tubing from inlet to outlet. This allows
the small volume of condensate to drain freely out of the condenser and prevents hold-up within the coils. Smaller diameter coils
may be necessary if noncondensable gas concentrations exceed 5 % by weight. In these cases, tubing with an outer diameter of
3.2 mm (0.125 in.) will maintain flow velocities without excessive restriction of fluid flow.
7.3.3 It is necessary to ensure the cooling system for steam collection is free of leaks where atmospheric gases could enter the
system and contaminate the sample. Effective ways to check for leaks are to pressurize the system or subject it to vacuum and
monitor any change in pressure over a few minutes of time. If there is no change in pressure from the initial pressurization, then
the system is free of leaks and adequate for sampling.
7.4 The liquid cooling coil has a regulating valve at the outlet. Regulating the flow at the condenser outlet maintains pressure on
the liquid as it cools and prevents flashing of liquid inside the condenser which could result in gas break-out or chemical deposition,
or both. The outside diameter of the liquid cooling coil is typically 6.4 mm (0.250 in.). In cases where the liquid contains
substantial quantities of particulate matter, 9.5 mm (0.375 in.) outside diameter tubing coils may be used to minimize cooling coil
plugging problems. Outside diameters larger than 9.5 mm (0.375 in.) should not be use
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