ASTM D4194-23

Standard Test Methods for Operating Characteristics of Reverse Osmosis and Nanofiltration Devices

SIGNIFICANCE AND USE
5.1 Reverse osmosis and nanofiltration desalinating devices can be used to produce potable water from brackish supplies (
SCOPE
1.1 These test methods cover the determination of the operating characteristics of reverse osmosis devices using standard test conditions and are not necessarily applicable to natural waters. Three test methods are given, as follows:    
Sections  
Test Method A—Brackish Water Reverse Osmosis Devices  
8 – 14    
Test Method B—Nanofiltration Devices  
15 – 21    
Test Method B—Seawater Reverse Osmosis Devices  
22 – 28  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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.

General Information

• Status: Published
• Publication Date: 31-Dec-2022
• ICS: 71.040.50 - Physicochemical methods of analysis
• Technical Committee: D19 - Water
• Drafting Committee: D19.08 - Membranes and Ion Exchange Materials

Relations

• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM D6161-19 - Standard Terminology Used for Microfiltration, Ultrafiltration, Nanofiltration, and Reverse Osmosis Membrane Processes
• Effective Date: 01-Jul-2019
• Refers: ASTM D512-10 - Standard Test Methods for Chloride Ion In Water
• Effective Date: 15-Sep-2010
• Refers: ASTM D1129-10 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2010
• Refers: ASTM D6161-10 - Standard Terminology Used for Microfiltration, Ultrafiltration, Nanofiltration and Reverse Osmosis Membrane Processes (Withdrawn 2019)
• Effective Date: 01-Feb-2010
• Refers: ASTM D1129-06a - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D1129-06ae1 - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D1129-06 - Standard Terminology Relating to Water
• Effective Date: 15-Feb-2006
• Refers: ASTM D6161-05 - Standard Terminology Used for Microfiltration, Ultrafiltration, Nanofiltration and Reverse Osmosis Membrane Processes
• Effective Date: 01-Jun-2005
• Refers: ASTM D1125-95(2005) - Standard Test Methods for Electrical Conductivity and Resistivity of Water
• Effective Date: 01-Apr-2005
• Refers: ASTM D512-04 - Standard Test Methods for Chloride Ion In Water
• Effective Date: 01-Jul-2004
• Refers: ASTM D1129-04e1 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2004
• Refers: ASTM D1129-04 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2004
• Refers: ASTM D1129-03a - Standard Terminology Relating to Water
• Effective Date: 10-Aug-2003

Overview

ASTM D4194-23 - Standard Test Methods for Operating Characteristics of Reverse Osmosis and Nanofiltration Devices specifies laboratory test methods to determine the operating characteristics of reverse osmosis (RO) and nanofiltration (NF) devices. Developed by ASTM International, this standard enables consistent and reliable evaluation of membrane-based desalination technologies under controlled conditions. These tests are essential for comparing device performance and monitoring operational changes in both new and used equipment. The standard covers devices intended to treat brackish water, seawater, and for applications using nanofiltration.

Key Topics

• Test Methods for Different Membrane Devices:
  The standard provides three distinct procedures:

  • Brackish Water RO Devices
  • Nanofiltration Devices
  • Seawater RO Devices

• Operating Conditions:
  All procedures are performed under standard laboratory conditions, not in natural water environments, ensuring a controlled basis for comparison.

• Measurement of Performance:
  Testing determines key parameters, including:

  • Permeate (product water) flow rate
  • Salt rejection or salt passage
  • Conversion rate from feed to permeate
  • Pressure and temperature control throughout the process

• Precision and Repeatability:
  Guidance on data recording, calculation, and repeatability ensures results are valid for monitoring changes in device performance over time.

• Safety and Quality Practices:
  The standard emphasizes the importance of safe laboratory practices, proper equipment cleaning, and the use of reagent-grade chemicals.

Applications

• Desalination System Evaluation:
  Used to test performance of membranes intended for brackish water and seawater desalination. Results inform supplier and user about device quality and operational suitability.

• Potable Water Production:
  Performance data generated using these methods supports the selection and operation of systems designed to produce potable water from brackish or saline sources.

• Industrial Water Treatment:
  NF and RO membranes are widely used to improve industrial water quality by selectively removing salts and organic contaminants.

• Quality Assurance and Maintenance:
  Testing per ASTM D4194-23 allows tracking of device aging, fouling, or operational issues, informing maintenance or replacement decisions.

• Benchmarking and R&D:
  Device manufacturers and researchers use these standardized methods for benchmarking new materials or designs against industry norms.

Related Standards

• ASTM D1129 - Terminology Relating to Water: Provides relevant water treatment terms.
• ASTM D6161 - Terminology Used for Microfiltration, Ultrafiltration, Nanofiltration, and Reverse Osmosis Membrane Processes: Supplies membrane-specific definitions.
• ASTM D1193 - Specification for Reagent Water: Defines water purity for laboratory use.

Withdrawn standards:

• ASTM D512 (Chloride Ion in Water),
• ASTM D1125 (Electrical Conductivity and Resistivity of Water)

Summary

ASTM D4194-23 is an essential standard for testing the performance of reverse osmosis and nanofiltration devices under consistent laboratory conditions. By providing detailed methods for evaluating permeate flow, salt rejection, and operational reliability, it supports the advancement of membrane technologies for potable and industrial water applications. Users benefit from increased confidence in device selection, performance tracking, and ongoing maintenance, with procedures recognized internationally for quality and reliability.

Keywords: reverse osmosis, nanofiltration, operating characteristics, performance testing, membranes, desalination, brackish water, seawater, water treatment, ASTM D4194-23

Standards Content (Sample)

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.
Designation: D4194 − 23
Standard Test Methods for
Operating Characteristics of Reverse Osmosis and
Nanofiltration Devices
This standard is issued under the fixed designation D4194; 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 D1129 Terminology Relating to Water
D1193 Specification for Reagent Water
1.1 These test methods cover the determination of the
D6161 Terminology Used for Microfiltration, Ultrafiltration,
operating characteristics of reverse osmosis devices using
Nanofiltration, and Reverse Osmosis Membrane Processes
standard test conditions and are not necessarily applicable to
natural waters. Three test methods are given, as follows:
3. Terminology
Sections
3.1 Definitions:
Test Method A—Brackish Water Reverse Osmosis 8 – 14
3.1.1 For definitions of terms used in these test methods,
Devices
refer to Terminology D1129 and D6161.
Test Method B—Nanofiltration Devices 15 – 21
Test Method B—Seawater Reverse Osmosis Devices 22 – 28
3.1.2 brackish water, n—water that contains dissolved mat-
ter at an approximate concentration range from 1000 to
1.2 The values stated in SI units are to be regarded as
30 000 mg ⁄L.
standard. No other units of measurement are included in this
standard.
3.1.3 concentrate, n—stream exiting a crossflow membrane
device that has increased concentration of solutes and particles
1.3 This standard does not purport to address all of the
over the feed stream; portion of the feed steram that does not
safety concerns, if any, associated with its use. It is the
pass through the membrane; the stream in which dissolved
responsibility of the user of this standard to establish appro-
solids or particulates, or both, are concentrated in a membrane
priate safety, health, and environmental practices and deter-
separation process.
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
3.1.4 hollow-fiber (HF) membrane—self-supporting mem-
dance with internationally recognized principles on standard-
brane fibers that have a hollow bore like a cylinder; in reverse
ization established in the Decision on Principles for the
osmosis, the membrane is usually on the outside with the bore
Development of International Standards, Guides and Recom-
conveying the permeate; in ultra and micro filtration, the
mendations issued by the World Trade Organization Technical
membrane might be on the inside or outside of the fiber.
Barriers to Trade (TBT) Committee.
3.1.5 nanofiltration (NF), n—crossflow process with pore
sizes designed to remove selected salts and most organics
2. Referenced Documents
above about 300 molecular weight range, sometimes referred
2.1 ASTM Standards:
to as loose RO; a pressure-driven membrane separation process
D512 Test Methods for Chloride Ion In Water (Withdrawn
in which particles and dissolved molecules larger than about
2021)
2 nm are rejected.
D1125 Test Methods for Electrical Conductivity and Resis-
3 3.1.6 permeate, n—that portion of the feed which passes
tivity of Water (Withdrawn 2023)
through the membrane.
3.1.7 reverse osmosis (RO), n—separation process in which
These test methods are under the jurisdiction of ASTM Committee D19 on
one component of a solution is removed from another compo-
Water and are the direct responsibilities of Subcommittee D19.08 on Membranes
nent by flowing the feed stream under pressure across a
and Ion Exchange Materials.
Current edition approved Jan. 1, 2023. Published February 2023. Originally semipermeable membrane that causes selective movement of
approved in 1982. Last previous edition approved in 2014 as D4194 – 03 (2014).
solvent against its osmonic pressure difference; RO removes
DOI: 10.1520/D4194-23.
ions based on electrochemical forces, colloids, and organics
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
down to 150 molecular weight; may also be called hyperfil-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
tration.
the ASTM website.
3.1.8 sea water, n—water with approximate concentration of
The last approved version of this historical standard is referenced on www.ast-
m.org. total dissolved solids ranging from 30 000 to 60 000 mg ⁄L.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4194 − 23
3.1.9 spiral wound membrane, n—a flat sheet membrane from oil films on new metal piping, release agents on raw
with one or more feed channel spacers, and barrier layers, all plastic components, or from feed solutions previously used in
of which are rolled into a spiral configuration. the system. If materials are suspect, thoroughly clean or
degrease or both, before use. All pressurized components
3.1.10 tubular membrane, n—the element, similar to
whether stainless steel or plastic should be designed based on
hollow-fiber but with a bore diameter >5 mm (see hollow-
the manufacturer’s working pressure rating. Review manufac-
fiber); used mostly in MF and UF and sometimes wit RO and
turer’s rating for compliance with standard engineering prac-
NF when particulate loading is high.
tice.
4. Summary of Test Methods
7.2.2 The reverse osmosis testing apparatus, represented
schematically in Fig. 1 using a centrifugal pump, consists of a
4.1 These test methods consist of determining the desalinat-
feed holding tank equipped with a thermostated heat ex-
ing ability and permeate flow rate of reverse osmosis and
changer system to maintain the feed solution at the desired
nanofiltration devices. They are applicable to both new and
temperature, a booster pump, a high-pressure centrifugal
used reverse osmosis or nanofiltration devices.
pump, and a reverse osmosis device. Use a valve with a
5. Significance and Use minimum flow restriction (for example, ball valve or plug
valve) for the shut-off valve to prevent excessive pressure drop.
5.1 Reverse osmosis and nanofiltration desalinating devices
The filter can be either a strainer (100-mesh) or a 5-μm filter
can be used to produce potable water from brackish supplies
(based on supplier’s recommendation). Use a pressure control
(<10 000 mg/L) and seawater as well as to upgrade the quality
valve such as a ball valve for throttling the pump discharge. A
of industrial water. These test methods permit the measurement
flow control valve is needed to regulate the concentrate flow. A
of the performance of reverse osmosis devices using standard
manual throttling valve, such as a needle valve, is sufficient for
sets of conditions and are intended for short-term testing (<24
this application unless the flows are so low that plugging could
h). These test methods can be used to determine changes that
become a problem. In that case, use a long coil of high-pressure
may have occurred in the operating characteristics of reverse
media tubing to take the entire pressure drop through the
osmosis and nanofiltration devices but are not intended to be
tubing. Cut the tubing to length for the required flow.
used for plant design.
7.2.3 See Fig. 2 for a schematic piping diagram for a
6. Reagents positive displacement high-pressure pump test system. Valves
and arrangements are similar to the centrifugal system except
6.1 Purity of Reagents—Reagent grade chemicals shall be
for the high-pressure pump piping. The back-pressure regulator
used in all tests. Unless otherwise indicated, it is intended that
on the by-pass controls pressure on the pump discharge line.
all reagents shall conform to the specifications of the Commit-
Under no circumstances install throttling valves directly on a
tee on Analytical Reagents of the American Chemical Society,
positive displacement pump discharge line. An accumulator is
where such specifications are available. Other grades may be
required to minimize pressure pulsations (<1 % of value) if a
used, provided it is first ascertained that the reagent is of
reciprocating piston-type positive displacement pump is used
sufficiently high purity to permit its use without lessening the
to feed the reverse osmosis device.
accuracy of the determination.
7.2.4 Operate the apparatus by drawing the feed solution
6.2 Purity of Water—Unless otherwise indicated, references
from the tank and pumping it through the reverse osmosis
to water shall be understood to mean Type III reagent con-
device under pressure. Return both the concentrate stream and
forming to Specification D1193.
the permeate to the feed tank so that its volume and solute
concentration remain constant. Use the heat exchanger coils in
7. Apparatus
the feed tank to adjust the feed to specified operating tempera-
7.1 The apparatus for both methods is schematically de-
ture and thereafter use to remove the energy load generated by
scribed in Fig. 1 and Fig. 2. A conductivity meter can be used
the pump. Monitor the permeate temperature very near the
to determine the salt concentration in accordance with Test
reverse osmosis device (within 500 mm). Pressure gages
Methods D1125.
before and after the reverse osmosis device give the feed
7.2 Installation: pressure and the pressure drop across the device (ΔP; feed
7.2.1 Materials of construction shall be of high-quality pressure − concentrate pressure). Locate these gages as close
stainless steel (Type 316) or plastic for all wetted parts to as possible to the reverse osmosis device. Measure the con-
prevent contamination of the feed solution by corrosion prod- centrate and permeate flow rates with calibrated flowmeters
ucts. Do not use reactive piping material such as plain carbon from which the feed rate to the device may be determined.
steel, galvanized or cadmium-plated carbon steel, and cast iron Remove samples of these two streams through sampling valves
for piping. Take care to ensure that no contamination will occur for conductivity/concentration measurements. Sample the feed
using the feed sample valve. Direct the return flows in the feed
tank to provide adequate mixing.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington,
7.3 Systems—To protect the reverse osmosis device and the
DC. For suggestions on the testing of reagents not listed by the American Chemical
high-pressure pump from abnormal operating conditions, in-
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
stall limit controls in the system. An electric limit control is
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
copeial Convention, Inc. (USPC), Rockville, MD. used to shut down the high-pressure feed pump. The limit
D4194 − 23
P—pressure tap locations
T—temperature measurement location
L—low-pressure shutoff probe location
H—high-pressure shutoff probe location
HT—high-temperature shutoff probe location
FIG. 1 Centrifugal High-Pressure Pump System Piping Diagram
control circuit should have a manual reset relay in it so that 7.3.2 Low-Pressure Shut-Off—Set the cutoff point at a gage
when it shuts down it will not automatically restart. See Fig. 1 pressure of 103 kPa (15 psi) (shuts the system down when the
and Fig. 2 for the limit control locations. Their functions are as pump water supply is interrupted and thus protects the reverse
follows: osmosis pump).
7.3.1 High-Pressure Shut-Off—Set the cutoff point in accor- 7.3.3 High-Temperature Shut-Off—Set the maximum tem-
dance with the supplier’s recommendations (protects the re- perature at 30 °C (protects the reverse osmosis device against
verse osmosis device against excessive pressure). excessive temperature).
D4194 − 23
P—pressure tap locations
T—temperature measurement location
L—low-pressure shutoff probe location
H—high-pressure shutoff probe location
HT—high-temperature shutoff probe location
FIG. 2 Positive Displacement High-Pressure Pump System Piping Diagram
7.4 Instrumentation: 7.4.2 Temperature—See Fig. 1 and Fig. 2 for temperature-
7.4.1 Pressure—See Fig. 1 and Fig. 2 for pressure tap measurement locations. Calibrated dial thermometers with the
locations. Use a single gage equipped with a high-pressure probe immersed in the flowing water should provide good data.
“quick-connect” or Taylor plug gage fitting for measuring 7.4.3 Permeate Back-Pressure Considerations—It is per-
individual pressures and device pressure drop (ΔP). Individual missible to operate reverse osmosis devices with a back-
gages are also satisfactory but not as reliable as a “quick- pressure on the permeate. The maximum recommended back-
connect” test gage or a special ΔP gage. Use pressure snubbers pressure for these methods is 35 kPa (5 psi). This pressure is
to prevent pulsation damage to gages, and calibrate all pressure more than adequate for transferring the permeate back to the
gages. feed tank.
D4194 − 23
TEST METHOD A—BRACKISH WATER REVERSE 11.1.8 Once sustained operation is attained, energize the
OSMOSIS DEVICES low-pressure shut-off switch.
11.2 Data Recording:
8. Scope
11.2.1 One hour after start-up, measure and record on a data
8.1 This test method covers the determination of the oper-
sheet the inlet and outlet pressures of the filter and the feed,
ating characteristics of brackish water reverse osmosis devices
concentrate, and permeate pressures.
using standard test conditions and can be used for all types of
11.2.2 At the same time measure and record the permeate
devices (tubular, spiral wound, and hollow fiber).
and concentrate flows using the calibrated flowmeters or a
calibrated volume container and stopwatch.
9. Summary of Test Method
11.2.3 Also at the same time measure and record the
9.1 The test method provides for at least three different
permeate temperature and the conductivity of the feed,
concentrations of sodium chloride feed solution.
permeate, and concentrate, using a conductivity meter, or
determine the chloride content of the three streams in accor-
10. Reagents and Materials
dance with Test Methods D512.
10.1 Sodium Chloride Feed Solution (5.0 g/L)—Dissolve
11.2.4 Repeat the above measurements 2 to 3 h after start-up
enough sodium chloride (NaCl) in water to make a solution
and hourly thereafter until three successive permeate flow rates
containing in each litre 5.0 g of NaCl.
(corrected to 25 °C) and salt passages agree within 5 %
10.2 Sodium Chloride Feed Solution (1.5 g/L)—Dissolve
(relative). Industry manufacturers generally report perfor-
enough sodium chloride (NaCl) in water to make a solution
mance specifications based on a 20 to 30 min test.
containing in each litre 1.5 g of NaCl.
11.2.5 All data shall be obtained using the specified condi-
tions of temperature, pressure, and conversion. If any of these
10.3 Sodium Chloride Feed Solution (0.5 g/L)—Dissolve
parameters need adjusting, allow 1 h after making adjustments
enough sodium chloride (NaCl) in water to make a solution
before collecting data.
containing in each litre 0.5 g of NaCl.
11.3 Shutdown Procedure—Shut down by adjusting the
10.4 Sodium Chloride Feed Solutions, Optional—Other
by-pass valve or throttling valve to reduce the pressure,
concentrations of NaCl solutions (<10 g/L) can be used.
depressing the stop buttons on the high-pressure pump motor
11. Procedure
and the booster pump motor, and shutting off the feedsupply
valve (shutoff valve). When high concentrations (>5000 mg/L)
11.1 Start-Up and Operating Procedure:
are used, it is best to flush the reverse osmosis device with the
11.1.1 If the reverse osmosis device contains sanitizing or
feed solution to remove the high salt concentration in the
winterizing agents, or both, flush the device in accordance with
device. This can be done by opening the concentrate flow
the supplier’s recommendations.
control valve for approximately 10 min with at least 345 kPa
11.1.2 Make preliminary checks to make sure all fittings are
(50 psi) feed pressure. Allow the pressure to reach zero before
tight, all components are operational, and the feed solution is at
disconnecting the reverse osmosis device or carrying out
the proper concentration and temperature. Before energizing
maintenance on the piping system. Take care to ensure that the
the high-pressure pump, the low-pressure switch must be off
membranes are kept wet at all times and are properly sanitized
for start-up to complete the circuit past the low-pressure cutout.
or winterized, or both (based on supplier’s recommendations)
Energize the high-pressure pump momentarily to check proper
for long-term storage (more than 5 days).
rotation.
11.1.3 Open the feed supply valve, the concentrate flow
12. Calculation
control valve, the pump by-pass on the positive displacement
12.1 Calculate the feed flow rate as follows:
feed pump, or the centrifugal pump throttling valve. Start the
Q 5 Q 1Q
booster pump and then the high-pressure pump. f p c
11.1.4 Bring the feed pressure to a gage pressure that is in
where:
accordance with the specifications of membrane manufacturer
Q = feed flow rate,
f
for a given element model. It is possible that the by-pass valve
Q = permeate flow rate, and
p
or the throttling valve (depending on pump system) and the
Q = concentrate flow rate.
c
concentrate flow control valve may need to be adjusted
12.1.1 The permeate flow rate (Q ) should be corrected to
simultaneously. If necessary, another pressure agreed upon p
25°C using the supplier’s correction factor, or, if unavailable, a
between the user and the supplier may be used.
3 % per degree correction factor can be used.
11.1.5 Set concentrate flow in accordance with the suppli-
er’s recommendation by adjusting the concentrate flow control 12.2 Calculate the conversion as follows:
valve. But maintain conversion within 62 % of the supplier’s
Conversion, % 5 Q /Q × 100
~ !
p f
recommendation.
12.3 Calculate the salt passage as follows:
11.1.6 Recheck and adjust if necessary both the concentrate
Salt passage, % 5 ~K /K ! × 100 or ~1 2 ~~~K 1K !/2!/K ! × 100!
flow and feed pressure to give the selected values for flow and
p f f c f
pressure.
where:
11.1.7 Check and adjust the cooling system in the f
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4194 − 03 (Reapproved 2014) D4194 − 23
Standard Test Methods for
Operating Characteristics of Reverse Osmosis and
Nanofiltration Devices
This standard is issued under the fixed designation D4194; 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 These test methods cover the determination of the operating characteristics of reverse osmosis devices using standard test
conditions and are not necessarily applicable to natural waters. Three test methods are given, as follows:
Sections
Test Method A—Brackish Water Reverse Osmosis 8 – 13
Devices
Test Method A—Brackish Water Reverse Osmosis De- 8 – 14
vices
Test Method B—Nanofiltration Devices 14 – 19
Test Method B—Nanofiltration Devices 15 – 21
Test Method B—Seawater Reverse Osmosis Devices 20 – 25
Test Method B—Seawater Reverse Osmosis Devices 22 – 28
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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 and healthsafety, 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:
D512 Test Methods for Chloride Ion In Water (Withdrawn 2021)
D1125 Test Methods for Electrical Conductivity and Resistivity of Water (Withdrawn 2023)
D1129 Terminology Relating to Water
D1193 Specification for Reagent Water
D6161 Terminology Used for Microfiltration, Ultrafiltration, Nanofiltration, and Reverse Osmosis Membrane Processes
These test methods are under the jurisdiction of ASTM Committee D19 on Water and are the direct responsibilities of Subcommittee D19.08 on Membranes and Ion
Exchange Materials.
Current edition approved Jan. 1, 2014Jan. 1, 2023. Published February 2014February 2023. Originally approved in 1982. Last previous edition approved in 20082014 as
D4194 – 03 (2008).(2014). DOI: 10.1520/D4194-03R14.10.1520/D4194-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4194 − 23
3. Terminology
3.1 Definitions—For definitions of terms used in these test methods, refer to Terminology D1129 and D6161.
3.1 Definitions:
3.1.1 For definitions of terms used in these test methods, refer to Terminology D1129 and D6161.
3.1.2 brackish water, n—water that contains dissolved matter at an approximate concentration range from 1000 to 30 000 mg ⁄L.
3.1.3 concentrate, n—stream exiting a crossflow membrane device that has increased concentration of solutes and particles over
the feed stream; portion of the feed steram that does not pass through the membrane; the stream in which dissolved solids or
particulates, or both, are concentrated in a membrane separation process.
3.1.4 hollow-fiber (HF) membrane—self-supporting membrane fibers that have a hollow bore like a cylinder; in reverse osmosis,
the membrane is usually on the outside with the bore conveying the permeate; in ultra and micro filtration, the membrane might
be on the inside or outside of the fiber.
3.1.5 nanofiltration (NF), n—crossflow process with pore sizes designed to remove selected salts and most organics above about
300 molecular weight range, sometimes referred to as loose RO; a pressure-driven membrane separation process in which particles
and dissolved molecules larger than about 2 nm are rejected.
3.1.6 permeate, n—that portion of the feed which passes through the membrane.
3.1.7 reverse osmosis (RO), n—separation process in which one component of a solution is removed from another component by
flowing the feed stream under pressure across a semipermeable membrane that causes selective movement of solvent against its
osmonic pressure difference; RO removes ions based on electrochemical forces, colloids, and organics down to 150 molecular
weight; may also be called hyperfiltration.
3.1.8 sea water, n—water with approximate concentration of total dissolved solids ranging from 30 000 to 60 000 mg ⁄L.
3.1.9 spiral wound membrane, n—a flat sheet membrane with one or more feed channel spacers, and barrier layers, all of which
are rolled into a spiral configuration.
3.1.10 tubular membrane, n—the element, similar to hollow-fiber but with a bore diameter >5 mm (see hollow-fiber); used mostly
in MF and UF and sometimes wit RO and NF when particulate loading is high.
4. Summary of Test Methods
4.1 These test methods consist of determining the desalinating ability and permeate flow rate of reverse osmosis and nanofiltration
devices. They are applicable to both new and used reverse osmosis or nanofiltration devices.
5. Significance and Use
5.1 Reverse osmosis and nanofiltration desalinating devices can be used to produce potable water from brackish supplies (<10 000
mg/L) and seawater as well as to upgrade the quality of industrial water. These test methods permit the measurement of the
performance of reverse osmosis devices using standard sets of conditions and are intended for short-term testing (<24 h). These
test methods can be used to determine changes that may have occurred in the operating characteristics of reverse osmosis and
nanofiltration devices but are not intended to be used for plant design.
6. Reagents
6.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
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such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
6.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean Type III reagent conforming to
Specification D1193.
7. Apparatus
7.1 The apparatus for both methods is schematically described in Fig. 1 and Fig. 2. A conductivity meter can be used to determine
P—pressure tap locations
P—pressure tap locations
T—temperature measurement location
L—low-pressure shutoff probe location
H—high-pressure shutoff probe location
HT—high-temperature shutoff probe location
FIG. 1 Centrifugal High-Pressure Pump System Piping Diagram
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for
Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. PharmaceuticalPharmacopeial Convention, Inc.
(USPC), Rockville, MD.
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P—pressure tap locations
P—pressure tap locations
T—temperature measurement location
L—low-pressure shutoff probe location
H—high-pressure shutoff probe location
HT—high-temperature shutoff probe location
FIG. 2 Positive Displacement High-Pressure Pump System Piping Diagram
the salt concentration in accordance with Test Methods D1125.
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7.2 Installation:
7.2.1 Materials of construction shall be of high-quality stainless steel (Type 316) or plastic for all wetted parts to prevent
contamination of the feed solution by corrosion products. Do not use reactive piping material such as plain carbon steel, galvanized
or cadmium-plated carbon steel, and cast iron for piping. Take care to ensure that no contamination will occur from oil films on
new metal piping, release agents on raw plastic components, or from feed solutions previously used in the system. If materials are
suspect, thoroughly clean or degrease or both, before use. All pressurized components whether stainless steel or plastic should be
designed based on the manufacturer’s working pressure rating. Review manufacturer’s rating for compliance with standard
engineering practice.
7.2.2 The reverse osmosis testing apparatus, represented schematically in Fig. 1 using a centrifugal pump, consists of a feed
holding tank equipped with a thermostated heat ex-changer system to maintain the feed solution at the desired temperature, a
booster pump, a high-pressure centrifugal pump, and a reverse osmosis device. Use a valve with a minimum flow restriction (for
example, ball valve or plug valve) for the shut-off valve to prevent excessive pressure drop. The filter can be either a strainer
(100-mesh) or a 5-μm filter (based on supplier’s recommendation). Use a pressure control valve such as a ball valve for throttling
the pump discharge. A flow control valve is needed to regulate the concentrate flow. A manual throttling valve, such as a needle
valve, is sufficient for this application unless the flows are so low that plugging could become a problem. In that case, use a long
coil of high-pressure media tubing to take the entire pressure drop through the tubing. Cut the tubing to length for the required
flow.
7.2.3 See Fig. 2 for a schematic piping diagram for a positive displacement high-pressure pump test system.Valves system. Valves
and arrangements are similar to the centrifugal system except for the high-pressure pump piping. The back-pressure regulator on
the by-pass controls pressure on the pump discharge line. Under no circumstances install throttling valves directly on a positive
displacement pump discharge line. An accumulator is required to minimize pressure pulsations (<1 % of value) if a reciprocating
piston-type positive displacement pump is used to feed the reverse osmosis device.
7.2.4 Operate the apparatus by drawing the feed solution from the tank and pumping it through the reverse osmosis device under
pressure. Return both the concentrate stream and the permeate to the feed tank so that its volume and solute concentration remain
constant. Use the heat exchanger coils in the feed tank to adjust the feed to specified operating temperature and thereafter use to
remove the energy load generated by the pump. Monitor the permeate temperature very near the reverse osmosis device (within
500 mm). Pressure gages before and after the reverse osmosis device give the feed pressure and the pressure drop across the device
(ΔP; feed pressure − concentrate pressure). Locate these gages as close as possible to the reverse osmosis device. Measure the
concentrate and permeate flow rates with calibrated flowmeters from which the feed rate to the device may be determined. Remove
samples of these two streams through sampling valves for conductivity/concentration measurements. Sample the feed using the
feed sample valve. Direct the return flows in the feed tank to provide adequate mixing.
7.3 Systems—To protect the reverse osmosis device and the high-pressure pump from abnormal operating conditions, install limit
controls in the system. An electric limit control is used to shut down the high-pressure feed pump. The limit control circuit should
have a manual reset relay in it so that when it shuts down it will not automatically restart. See Fig. 1 and Fig. 2 for the limit control
locations. Their functions are as follows:
7.3.1 High-Pressure Shut-Off—Set the cutoff point in accordance with the supplier’s recommendations (protects the reverse
osmosis device against excessive pressure).
7.3.2 Low-Pressure Shut-Off—Set the cutoff point at a gage pressure of 103 kPa (15 psi) (shuts the system down when the pump
water supply is interrupted and thus protects the reverse osmosis pump).
7.3.3 High-Temperature Shut-Off—Set the maximum temperature at 30°C30 °C (protects the reverse osmosis device against
excessive temperature).
7.4 Instrumentation:
7.4.1 Pressure—See Fig. 1 and Fig. 2 for pressure tap locations. Use a single gage equipped with a high-pressure “quick-connect”
or Taylor plug gage fitting for measuring individual pressures and device pressure drop (ΔP). Individual gages are also satisfactory
but not as reliable as a “quick-connect” test gage or a special ΔP gage. Use pressure snubbers to prevent pulsation damage to gages,
and calibrate all pressure gages.
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7.4.2 Temperature—See Fig. 1 and Fig. 2 for temperature-measurement locations. Calibrated dial thermometers with the probe
immersed in the flowing water should provide good data.
7.4.3 Permeate Back-Pressure Considerations—It is permissible to operate reverse osmosis devices with a back-pressure on the
permeate. The maximum recommended back-pressure for these methods is 35 kPa (5 psi). This pressure is more than adequate for
transferring the permeate back to the feed tank.
TEST METHOD A—BRACKISH WATER REVERSE OSMOSIS DEVICES
8. Scope
8.1 This test method covers the determination of the operating characteristics of brackish water reverse osmosis devices using
standard test conditions and can be used for all types of devices (tubular, spiral wound, and hollow fiber).
8. Scope
8.1 This test method covers the determination of the operating characteristics of brackish water reverse osmosis devices using
standard test conditions and can be used for all types of devices (tubular, spiral wound, and hollow fiber).
9. Summary of Test Method
9.1 The test method provides for at least three different concentrations of sodium chloride feed solution.
10. Reagents and Materials
10.1 Sodium Chloride Feed Solution (5.0 g/L)—Dissolve enough sodium chloride (NaCl) in water to make a solution containing
in each litre 5.0 g of NaCl.
10.2 Sodium Chloride Feed Solution (1.5 g/L)—Dissolve enough sodium chloride (NaCl) in water to make a solution containing
in each litre 1.5 g of NaCl.
10.3 Sodium Chloride Feed Solution (0.5 g/L)—Dissolve enough sodium chloride (NaCl) in water to make a solution containing
in each litre 0.5 g of NaCl.
10.4 Sodium Chloride Feed Solutions, Optional—Other concentrations of NaCl solutions (<10 g/L) can be used.
11. Procedure
11.1 Start-Up and Operating Procedure:
11.1.1 If the reverse osmosis device contains sanitizing or winterizing agents, or both, flush the device in accordance with the
supplier’s recommendations.
11.1.2 Make preliminary checks to make sure all fittings are tight, all components are operational, and the feed solution is at the
proper concentration and temperature. Before energizing the high-pressure pump, the low-pressure switch must be off for start-up
to complete the circuit past the low-pressure cutout. Energize the high-pressure pump momentarily to check proper rotation.
11.1.3 Open the feed supply valve, the concentrate flow control valve, the pump by-pass on the positive displacement feed pump,
or the centrifugal pump throttling valve. Start the booster pump and then the high-pressure pump.
11.1.4 Bring the feed pressure to a gage pressure that is in accordance with the specifications of membrane manufacturer for a
given element model. It is possible that the by-pass valve or the throttling valve (depending on pump system) and the concentrate
flow control valve may need to be adjusted simultaneously. If necessary, another pressure agreed upon between the user and the
supplier may be used.
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11.1.5 Set concentrate flow in accordance with the supplier’s recommendation by adjusting the concentrate flow control valve. But
maintain conversion within 62 % of the supplier’s recommendation.
11.1.6 Recheck and adjust if necessary both the concentrate flow and feed pressure to give the selected values for flow and
pressure.
11.1.7 Check and adjust the cooling system in the feed solution to give a permeate temperature of 25 6 1°C.1 °C.
11.1.8 Once sustained operation is attained, energize the low-pressure shut-off switch.
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11.2 Data Recording:
11.2.1 One hour after start-up, measure and record on a data sheet the inlet and outlet pressures of the filter and the feed,
concentrate, and permeate pressures.
11.2.2 At the same time measure and record the permeate and concentrate flows using the calibrated flowmeters or a calibrated
volume container and stopwatch.
11.2.3 Also at the same time measure and record the permeate temperature and the conductivity of the feed, permeate, and
concentrate, using a conductivity meter, or determine the chloride content of the three streams in accordance with Test Methods
D512.
11.2.4 Repeat the above measurements 2 to 3 h after start-up and hourly thereafter until three successive permeate flow rates
(corrected to 25°C)25 °C) and salt passages agree within 5 % (relative). Industry manufacturers generally report performance
specifications based on a 20 to 30 min test.
11.2.5 All data shall be obtained using the specified conditions of temperature, pressure, and conversion. If any of these parameters
need adjusting, allow 1 h after making adjustments before collecting data.
11.3 Shutdown Procedure—Shut down by adjusting the by-pass valve or throttling valve to reduce the pressure, depressing the
stop buttons on the high-pressure pump motor and the booster pump motor, and shutting off the feedsupply valve (shutoff valve).
When high concentrations (>5000 mg/L) are used, it is best to flush the reverse osmosis device with the feed solution to remove
the high salt concentration in the device. This can be done by opening the concentrate flow control valve for approximately 10 min
with at least 345 kPa (50 psi) feed pressure. Allow the pressure to reach zero before disconnecting the reverse osmosis device or
carrying out maintenance on the piping system. Take care to ensure that the membranes are kept wet at all times and are properly
sanitized or winterized, or both (based on supplier’s recommendations) for long-term storage (more than 5 days).
12. Calculation
12.1 Calculate the feed flow rate as follows:
Q 5 Q 1Q
f p c
where:
Q = feed flow rate,
f
Q = permeate flow rate, and
p
Q = concentrate flow rate.
c
12.1.1 The permeate flow rate (Q ) should be corrected to 25°C using the supplier’s correction factor, or, i
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