NASA Technical Reports Server (NTRS) 20070018809: International Space Station Atmosphere Control and Supply, Atmosphere Revitalization, and Water Recovery and Management Subsystem - Verification for Node 1

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International Space Station Atmosphere Control and Supply,
Atmosphere Revitalization, and Water Recovery and
Management Subsystem – Verification for Node 1
David E. Williams
NASA, Johnson Space Center
Copyright © 2007 SAE International
ABSTRACT

The International Space Station (ISS) Node 1 erative ECLS Water Processor Assembly (WPA) potable
Environmental Control and Life Support (ECLS) System water and 2) lines for routing waste water, i.e.
is comprised of five subsystems: Atmosphere Control condensate from the USOS condensing heat
and Supply (ACS), Atmosphere Revitalization (AR), Fire exchangers and waste water from the Extravehicular
Detection and Suppression (FDS), Temperature and Activity (EVA) space suits.
Humidity Control (THC), and Water Recovery and The Verification of the ISS hardware is accomplished
Management (WRM). This paper provides a summary using a building block process. Verification starts at the
of the nominal operation of the Node 1 ACS, AR, and Component Level and progresses until the Element
WRM design and detailed Element Verification Level Verification is complete. The primary objective of
methodologies utilized during the Qualification phase for the Qualification Verification program is to ensure that
Node 1. the subsystems meet the section three requirements in
the Prime Item Development Specifications (PIDS). The
INTRODUCTION PIDS dictates whether a section three requirement is
verified by test, analysis, inspection, and/or
Node 1 flew to ISS on Flight 2A. It was the first demonstration, as documented in section four of the
module of the United States On-Orbit Segment (USOS) PIDS.
that was launched to ISS. The Node 1 ISS ECLS design Node 1 is a Protoflight Test Article since no Element
featured limited ECLS capability. The main purpose of Qualification Test Article exists. Therefore, no additional
Node 1 was to provide internal storage by providing four ground testing or evaluations can be performed on Node
stowage rack locations within the module and to allow 1 after it has been installed into the Space Shuttle
docking of multiple modules and a truss segment to it. Payload Bay and launched to ISS. Node 1 is shown in
Of the five Node 1 ECLS subsystems this paper will Figure 1 during processing at Kennedy Space Center
only address the nominal operation of the ACS, AR, and (KSC) and in flight during the Flight 2A series of Flights
WRM subsystems. The nominal operation of the Node 1 (i.e., Flights 2A, 2A.1, 2A.2a, and 2A.2b).
ACS, AR, and WRM subsystems capabilities can be
subdivided into their sub-allocated functions. The Node SUBSYSTEM OVERVIEWS
1 ACS consists of: 1) a cabin pressure sensor for
monitoring total pressure in the Node 1 cabin, 2) lines for A general overview of the nominal operation of the
routing low-pressure oxygen and nitrogen, 3) Joint Node 1 ACS, AR, and WRM subsystem is provided
Airlock Depressurization Pump Assembly (DPA) outlet below.
line, 4) lines for routing high-pressure oxygen and
nitrogen, and 6) manual pressure equalization valves to ACS:
reduce the pressure differential across the hatch prior to
opening the hatch. The Node 1 AR consists of sample The Node 1 ACS hardware, as shown in Figure 2,
lines for routing air samples to the Major Constituent consists of a single cabin pressure sensor that can
Analyzer (MCA) in the U.S. Laboratory Module or in monitor the Node 1 cabin pressure between 0 to 104.8
Node 3. The Node 1 WRM consists of: 1) lines for kPa (0 to 15.2 psia), low-pressure oxygen and nitrogen
routing excess Space Shuttle Fuel Cell water or Regen- distribution lines, low-pressure oxygen and nitrogen
manual isolation provided by quick disconnects (QDs), a

1
Node 1 Sample Probe Node 1 Cabin Pressure Sensor

Node 1 Manual Pressure
Equalization Valve

PMA 1 and Node 1 at KSC Node 1, PMA 1, and PMA 2 during Flight 2A

Figure 1 - Node 1 during processing at KSC
and In Flight during the Flight 2A Series of Flights
2
Zenith Truss Cupola
Z P
PMA - 1
A N1Z N1P
Stowage 1 Stowage 3
O2
N2
N1N N1S
Stowage 2 Stowage 4
F
Lab
N S

Node 3 Airlock
Figure 2 – Node 1 Atmosphere Control and Supply Schematic

Joint Airlock DPA outlet line, high-pressure oxygen and flexible hose that runs from the Node 1 starboard
nitrogen distribution lines, and a single manual pressure bulkhead to the Node 1 IMV return ducting. This flexible
equalization valve (MPEV) in each of the six Node 1 hose was installed on-orbit by the ISS crew after the
hatches. delivery of the Joint Airlock.
The low-pressure oxygen line runs from the Node 1 The high-pressure oxygen and nitrogen lines run from
starboard hatch interface (the Joint Airlock interface) to the Node 1 nadir hatch interface and the Node 1 forward
the Node 1 forward interface (the United States [U.S.] interface to the Node 1 starboard hatch interface. The
Laboratory Module interface) and to the Node 1 nadir lines are made up of hard lines and flexible hoses. The
hatch interface (the Node 3 interface). The lines are high-pressure oxygen and nitrogen lines are part of the
made up of a combination of hard lines and flexible distribution for transferring excess Space Shuttle oxygen
hoses. The line supplies oxygen to users in Node 3, in and nitrogen gas from the Space Shuttle to the Joint
the U.S. Laboratory Module, and to elements Airlock for storage in the Joint Airlock oxygen and
downstream of the U.S. Laboratory Module. In case of a nitrogen tanks. There is no isolation capability for the
leak in the low-pressure oxygen line the distribution can high-pressure oxygen and nitrogen lines in Node 1. The
be isolated at the Node 1 starboard, nadir, and forward isolation capability for this subsystem is located in the
interfaces by disconnecting the male and female half of Space Shuttle oxygen and nitrogen distribution
the QD at the required interfaces. subsystem, in Pressurized Mating Adapter (PMA) 2/3,
The low-pressure nitrogen line runs from the Node 1 and in the Joint Airlock.
starboard hatch interface to the Node 1 forward interface The MPEVs are located in each of the Node 1
and to the Node 1 nadir hatch interface. The lines are hatches. They are designed for bi-directional flow and
made up of hard lines and flexible hoses. The line they are designed to be manually operated from both
supplies nitrogen to users in Node 3, in the U.S. sides of the hatch with no electrical or data system
Laboratory Module, and to elements downstream of the interfaces. On the Node 1 side of the hatch the MPEVs
U.S. Laboratory Module. In case of a leak in the low have a vacuum access jumper hose interface to allow
pressure nitrogen line the distribution can be isolated at depressurization of the vestibule, which is the small area
the Node 1 starboard, nadir, and forward interfaces by between the attached modules, depressurization of the
disconnecting the male and female half of the QD at the attached element, and to allow monitoring the
required interfaces. atmosphere on the other side of the hatch without
The Joint Airlock DPA outlet line provides an outlet for opening it.
the Joint Airlock air to the Node 1 cabin at the Node 1
starboard interface when the air being pumped out of the AR:
Joint Airlock by the DPA to support 70.3 kPa (10.2 psia)
operation in the Joint Airlock or when the Joint Airlock The MCA sample distribution lines in Node 1, as
Crewlock is being pumped down as part of the shown in Figure 3, consists of four electrical 3-way
preparation for the EVA crew members to exit the Joint valves, three manual isolation valves, a sample probe,
Airlock Crewlock to space vacuum. It consists of a hard lines, and flexible hoses. It allows the MCA in the
3
A5134 Deck A5135 Forward MV5135
A5133 AFT
A5132 Sel
MV5136 MV5133

Figure 3 – Node 1 Atmosphere Revitalization Schematic

U.S. Laboratory module or in Node 3 to sample and The Waste Water line runs from the Node 1 starboard
monitor the major constituents (partial pressure of interface to the Node 1 forward interface or to the Node
nitrogen [ppN2], partial pressure of oxygen [ppO2], 1 nadir interface, and it supports the transport of waste
partial pressure of carbon dioxide [ppCO2], partial water between the Node 1 forward interface to the Node
pressure of water vapor [ppH2O], partial pressure of 1 nadir interface, as shown in Figure 4. The lines are
hydrogen [ppH2], and the partial pressure of methane made up of hard lines, flexible hoses, and QDs. The
[ppCH4]) in Node 1, to transfer a cabin air sample from Waste Water lines transfer condensate and EVA suit
the Joint Airlock to the U.S. Laboratory module MCA, to waste water to the U.S. Laboratory Module condensate
transfer a cabin air sample from the Joint Airlock to the storage tank or to the Node 3 Regenerative ECLS WPA.
Node 3 MCA, to transfer a Node 3 or Mini-Pressurized In case of a leak in the Waste Water line the distribution
Logistic Module (MPLM) [the name for the MPLM was can be isolated at the Node 1 starboard, forward and
changed from Mini-Pressurized Logistic Module to Multi- nadir interfaces by disconnecting the male and female
Purpose Logistic Module later in the Program] cabin air half of the QD at the required interfaces.
samples to the U.S. Laboratory module MCA, and to
transfer a cabin air sample from the U.S. Laboratory ELEMENT LEVEL VERIFICATION PROGRAM
module and from modules forward of the U.S.
Laboratory to the Node 3 MCA. Node 1 ACS QUALIFICATION METHODOLOGY:

WRM: Cabin Pressure Monitoring:

The Node 1 WRM consists of the Fuel Cell Water Requirement Verification
distribution and the Waste Water distribution. Node 1 shall monitor The Node 1 monitor total pressure
The Fuel Cell Water line runs from the Node 1 forward cabin atmosphere requirement shall be verified by analysis.
interface to the Node 1 nadir hatch interface, as shown pressure in the range of 0 Analysis of the Node 1 end-to-end
to 15.2 psia, and provide pressure monitoring and reporting
in Figure 4. The lines are made up of hard lines, flexible
a proportional current scheme shall be performed to determine
hoses, and QDs. The Fuel Cell Water line transfers representing the pressure, measurement and reporting accuracy.
excess Space Shuttle Fuel Cell water to the scarred accurate to within +/- 0.35 Analysis determination of the accuracy of
location in the U.S. Laboratory Module for the Fuel Cell psia, at the PMA-1 the current at the Node 1/PMA-1
interface as specified in interface as representative of the
Water Storage Rack, to transfer stored excess Space
SSP 42122, paragraph pressure in the range from 0 to 15.2 psia.
Shuttle Fuel Cell water from the scarred Fuel Cell Water 3.2.1.5.4.1. Verification shall be considered
Storage Rack to Node 3 users, or to transfer potable successful when analysis shows the
water from the Regenerative ECLS WPA in Node 3 to current at the Node 1/PMA-1 interface
provides direct correlation to the internal
users in the U.S. Laboratory Module. In case of a leak
pressure as specified in SSP 42122,
in the Fuel Cell Water line the distribution can be paragraph 3.2.1.5.4.1, within +/- 0.35 psia
isolated at the Node 1 forward and nadir interfaces by of the actual pressure throughout
disconnecting the male and female half of the QD at the
required interfaces.
4
Figure 4 – Node 1 Water Recovery and Management Schematic

Requirement Verification Boeing – Huntington Beach also noted that the cabin
(cont’d) (cont’d) pressure sensor data from the equipment supplier
the entire range of 0 to 15.2 psia. Node 1 supported the required range of 0 – 104.8 kPa (0 – 15.2
end item testing shall monitor ambient psia).
pressure.

Results:
SSP 42122 From/To PMA-1

Interface Parameters and Node 1
The calculated sensor error for monitoring cabin
Node 1 ECLS Signals The Node 1 shall provide to and receive
pressure in Node 1 was +/- 2.28 kPa (0.33 psia) vs. the
from PMA-1 instrumentation signals for
the monitoring and control of the required level of +/- 2.41 kPa (0.35 psia). The analysis
following ECLSS equipment by the N1-1 results are very conservative since Boeing – Huntington
MDM: Atmosphere Revitalization valves, Beach used the specified cabin pressure sensor error,
Smoke Detector, Node 1 Air Mixing
the maximum transmission wire loss at the maximum
Valve, Cabin Fan, Node 1 Aft IMV Fan,
Node 1 Aft IMV Return and Supply current, and the specified MDM induced error. The
Valves, Node 1 Starboard Return and cabin pressure sensor went through a Qualification
Supply valves, Node 1 Port Supply valve, Program to show that the cabin pressure sensor
Node 1 Rheostat. The interface between
specified error of 1.65 kPa (0.24 psia) was very
the Node 1 ECLSS equipment and the
N1-1 MDM shall be in compliance with conservative.
SSP 30261:002. Based on the analysis results, the Node 1 cabin
pressure sensor met the range and accuracy
The Node 1 shall provide and receive
requirements.
from PMA-1 instrumentation signals for
the monitoring and control of the
following ECLSS equipment by the N1-2 Low-Pressure and High-Pressure Oxygen Distribution:
MDM: Cabin Pressure sensor, Smoke
Detector, Cupola Air Mixing Valve, Node
Requirement Verification
1 Port and Starboard IMV Fans, Node 1
Nadir IMV Return and Supply valves, Node 1 shall receive The Node 1 capability to distribute
Node 1 Forward Return and Supply recharge oxygen at either oxygen to the adjacent elements shall be
valves, Cupola Rheostat. The interface the USL or Node 3 verified by analysis. An analysis shall be
between the Node 1 ECLSS equipment interface and provide it to conducted to evaluate oxygen pressure
and the N1-2 MDM shall be in the Airlock interface as loss characteristics for all the distributed
compliance with SSP 30261:002. specified in SSP 41145, lines based upon pressure, temperature,
paragraph 3.2.1.3.9. and flow interface characteristics
Characteristics of specified in the appropriate ICDs

recharge oxygen received referenced requirements in SSP 41140,
Boeing – Huntington Beach analyzed the error for the from the USL and Node 3 SSP 41141, and SSP 41145.
cabin pressure sensor, the error from the wire run interfaces are as specified
between the cabin pressure sensor and the Multiplexer/ in SSP 41141, paragraph Analysis shall similarly be conducted for
3.2.1.2.13 and SSP recharge oxygen distribution lines during
Demultiplexer (MDM), and the error from the MDM.
41140, paragraph gas transfer to ISS based upon pressure,
3.2.1.2.12, respectively. temperature,

5
Maximum Pressure 200 psia (1379 kPa) N/A

Requirement Verification Boeing – Huntington Beach analyzed the pressure
(cont’d) (cont’d) loss of the Node 1 low-pressure oxygen distribution from
Node 1 shall receive and flow interface characteristics the Node 1 starboard interface to the Node 1 forward
oxygen at the Airlock specified in the appropriate ICDs. and also to the Node 1 nadir interface at the maximum
interface and provide it to specified flow rate, temperature, and the initial nominal
the USL and Node 3 The verification shall be considered
pressure, but not to both interfaces simultaneously.
interfaces as specified in successful when the analysis proves that
SSP 41141, paragraph interface conditions at each adjacent
3.2.1.2.3 and SSP 41140, element port are met as specified in Results:
paragraph 3.2.1.2.3, referenced ICDs.
respectively.
The calculated pressure loss for the low-pressure
Characteristics of oxygen
received at the Airlock oxygen distribution was 6.38 kPa differential (0.926 psid)
interface are as specified from the Node 1 starboard interface to the Node 1 nadir
in SSP 41145, paragraph interface and was 5.64 kPa differential (0.818 psid) from
3.2.1.3.3. Oxygen flow is
the Node 1 starboard interface to the Node 1 forward
required to both the USL
and the Node 3, but not interface. The analysis result for this subsystem is
both simultaneously. considered to be conservative since Boeing –
Huntington Beach used the flex hose pressure drop that
Node 1 shall provide for
was recommended by Boeing – Huntsville, which was
selective manual isolation
of oxygen flow at the shown to be conservative when compared to the results
Airlock, USL, and Node 3 from a flex hose development test. Boeing – Huntington
interfaces. This
Beach also used the QD specified pressure drop data in
requirement does not
the analysis. This data was shown to be conservative
apply to recharge oxygen
flow. since the specified pressure drop for the QD was higher
than the actual Qualification Program data.
The requirement references three ISS Interface Control Based on the analysis results, Node 1 met the
Documents (ICDs). The relevant requirements from pressure loss requirement for the low-pressure oxygen
those documents are as follows for low-pressure and distribution.
high-pressure oxygen:
High-Pressure Oxygen:
Low-Pressure Oxygen:
SSP 41140 From Node 3 to To Node 3 from
SSP 41140 From Node 3 to To Node 3 from Interface Node 1 Node 1
Interface Node 1 Node 1 Parameters
Parameters Temperature 25 to 113ºF (-3.9 to N/A
Temperature N/A 54 to 113ºF (12.2 to 45ºC)
45ºC) Flow Rate < 16 lbm/hr (7.3 N/A
Flow Rate N/A 0 - 0.2 lbm/min (0 - kg/hr)
0.09 kg/min) Nominal Pressure 750 - 1050 psia (5.2 - N/A
Nominal Pressure N/A 93 - 120 psia (641.2 - Range 7.2 MPa)
Range 827.4 kPa)
Maximum Pressure N/A 200 psia (1379 kPa) SSP 41141 From U.S. To U.S.
Interface Laboratory Laboratory
SSP 41141 From U.S. To U.S. Parameters Module to Module from
Interface Laboratory Laboratory Node 1 Node 1
Parameters Module to Module from Temperature 25 to 113ºF (-3.9 to N/A
Node 1 Node 1 45ºC)
Temperature N/A 54 to 113ºF (12.2 to Flow Rate < 16 lbm/hr (7.3 N/A
45ºC) kg/hr)
Flow Rate N/A 0 - 0.2 lbm/min (0 - Nominal Pressure 750 - 1050 psia (5.2 - N/A
0.09 kg/min) Range 7.2 MPa)
Nominal Pressure N/A 93 - 120 psia (641.2 -
Range 827.4 kPa) SSP 41145 From Joint To Joint Airlock
Maximum Pressure N/A 200 psia (1379 kPa) Interface Airlock to from Node 1
Parameters Node 1
SSP 41145 From Joint To Joint Airlock
Temperature N/A 25 to 113ºF (-3.9 to
Interface Airlock to from Node 1 45ºC)
Parameters Node 1 Flow Rate N/A < 16 lbm/hr (7.3
Temperature 47 to 113ºF (8.3 to N/A kg/hr)
45ºC) Nominal Pressure N/A 750 - 1050 psia (5.2 -
Flow Rate < 0.2 lbm/min (0.09 N/A Range 7.2 MPa)
kg/min)
Nominal Pressure 95 - 120 psia (655.0 - N/A
Range 827.4kPa)
6
Boeing – Huntington Beach analyzed the pressure requirement does not
loss of the Node 1 high-pressure oxygen distribution apply to recharge nitrogen
flow.
from the Node 1 forward or Node 1 nadir interface to the

Node 1 starboard interface at the maximum specified
The requirement references three ISS ICDs. The
flow rate, temperature, and nominal pressure.
relevant requirements from those documents are as

follows for low-pressure and high-pressure nitrogen:
Results:

Low-Pressure Nitrogen:
The calculated pressure loss for the high-pressure

oxygen distribution was 0.55 kPa differential (0.080 psid)
SSP 41140 From Node 3 to To Node 3 from
from the Node 1 nadir interface to the Node 1 starboard
Interface Node 1 Node 1
interface and was 0.53 kPa differential (0.077 psid) from
Parameters
the Node 1 forward interface to the Node 1 starboard
Temperature N/A 60 to 113ºF (15.6 to
interface. The analysis result for this subsystem is 45ºC)
considered to be conservative since Boeing – Flow Rate N/A 0 - 0.2 lbm/min (0 -
Huntington Beach used the flex hose pressure drop that 0.09 kg/min)
Nominal Pressure N/A 93 - 120 psia (641.2 -
was recommended by Boeing – Huntsville, which was
Range 827.4 kPa)
shown to be conservative when compared to the results Maximum Pressure N/A 200 psia (1379 kPa)
from a flex hose development test.
The requirement for this subsystem did not have any SSP 41141 From U.S. To U.S.
pressure loss pass/fail requirement but the value was Interface Laboratory Laboratory
very low and it was agreed based on that fact that the Parameters Module to Module from
analysis part of the verification was acceptable. Node 1 Node 1
Temperature N/A 60 to 113ºF (15.6 to
Low-Pressure and High-Pressure Nitrogen Distribution: 45ºC)
Flow Rate N/A 0 - 0.2 lbm/min (0 -

0.09 kg/min)
Requirement Verification Nominal Pressure N/A 93 - 120 psia (641.2 -
Node 1 shall provide The Node 1 capability to distribute Range 827.4 kPa)
recharge nitrogen, nitrogen to the adjacent elements shall Maximum Pressure N/A 200 psia (1379 kPa)
received at either the USL be verified by analysis. An analysis shall
or Node 3 interface, to the be conducted to evaluate nitrogen SSP 41145 From Joint To Joint Airlock
Airlock interface as pressure loss characteristics for all the
Interface Airlock to from Node 1
specified in SSP 41145, distributed lines based upon pressure,
Parameters Node 1
paragraph 3.2.1.3.10. temperature, and flow interface
Characteristics of characteristics specified in the Temperature 54 to 113ºF (12.2 to N/A
recharge nitrogen appropriate ICDs referenced 45ºC)
received from the USL requirements in SSP 41140, SSP 41141, Flow Rate 0 - 0.2 lbm/min (0 - N/A
and Node 3 interfaces are and SSP 41145. 0.09 kg/min)
as specified in SSP Nominal Pressure 95 - 120 psia (655.0 - N/A
41141, paragraph Analysis shall similarly be conducted for Range 827.4 kPa)
3.2.1.2.14 and SSP recharge nitrogen distribution lines during Maximum Pressure 200 psia (1379 kPa) N/A
41140, paragraph gas transfer to ISS based upon pressure,
3.2.1.2.13, respectively. temperature, and flow interface

characteristics specified in the
Boeing – Huntington Beach analyzed the pressure
Node 1 shall provide appropriate ICDs.
nitrogen, received at the loss of the Node 1 low-pressure nitrogen distribution
Airlock interface, to the The verification shall be considered from the Node 1 starboard interface to the Node 1
USL and Node 3 successful when the analysis proves that
forward and also to the Node 1 nadir interface at the
interfaces, as specified in interface conditions at each adjacent
SSP 41141, paragraph element port are met as specified in maximum specified flow rate, temperature, and the initial
3.2.1.2.4 and SSP 41140, referenced ICDs. nominal pressure, but not to both interfaces
paragraph 3.2.1.2.4, simultaneously.
respectively.

Characteristics of nitrogen
received at the Airlock Results:
interface are as specified
in SSP 41145, paragraph The calculated pressure loss for the low-pressure
3.2.1.3.4. Required
nitrogen distribution was 6.89 kPa differential (0.999
nitrogen flow is to both the
USL and Node 3 psid) from the Node 1 starboard interface to the Node 1
interfaces, but not both nadir interface and was 6.13 kPa differential (0.889 psid)
simultaneously. from the Node 1 starboard interface to the Node 1

forward interface. The analysis result for this subsystem
Node 1 shall provide for
selective manual shut off is considered to be conservative since Boeing –
of nitrogen flow at the Huntington Beach used the flex hose pressure drop that
Airlock, USL, and Node 3 was recommended by Boeing – Huntsville, which was
interfaces. This
shown to be conservative when compared to the results
7
from a flex hose development test. Boeing – Huntington
Beach also used the QD specified pressure drop data in
the analysis. This data was shown to be conservative

since the specified pressure drop for the QD was higher Pressure Equalization:
than the actual Qualification Program data.
Based on the analysis results, Node 1 met the Requirement Verification
pressure loss requirement for the low-pressure nitrogen Node 1 shall when The Node 1 equalize pressure
distribution. manually initiated by the requirement shall be verified by analysis.
crew internal to the Node The Node 1 drawings shall be analyzed

1, and when not to identify the devices that perform the
High-Pressure Nitrogen: exchanging atmosphere equalization function. Analysis of the
with the relevant adjacent identified devices shall be performed to
SSP 41140 From Node 3 to To Node 3 from module, provide for determine the method by which the
Interface Node 1 Node 1 equalization of differential equalization is activated. A dynamic gas
pressure across the flow analysis shall be performed to
Parameters
intermodule hatch determine the rate at which pressure
Temperature 25 to 113ºF (-3.9 to N/A between Node 1 at 14.9 equalization will occur across the device
45ºC) psia and an adjacent between the Node 1 at 14.9 psia and an
Flow Rate < 3 lbm/hr (1.4 kg/hr) N/A vestibule at vacuum to a adjacent vestibule at vacuum. The
Nominal Pressure < 3400 psia (23.4 N/A maximum differential of analysis shall determine the continuous
Range MPa) +/- 0.01 psi within 3 pressure differential, as a function of
minutes. time, at least until the differential
SSP 41141 From U.S. To U.S. becomes less than +/- 0.01 psi.
Interface Laboratory Laboratory Note: For purpose of this
requirement Node 1 is Verification shall be considered
Parameters Module to Module from
assumed to be isolated successful when (1) analysis of the Node
Node 1 Node 1 and the adjacent vestibule 1 drawings has identified the devices that
Temperature 25 to 113ºF (-3.9 to N/A is assumed to have a perform the equalization function; (2)
45ºC) volume of 52 cubic feet. analysis of the equalization initiation
Flow Rate < 3 lbm/hr (1.4 kg/hr) N/A methodology confirms it can be
Nominal Pressure < 3400 psia (23.4 N/A performed by an on-orbit crew inside the
Range MPa) Node 1, and (3) the gas flow analysis
shows that the differential pressure
SSP 41145 From Joint To Joint Airlock between the Node 1 and an adjacent
vestibule is reduced to 0.01 psi or less in
Interface Airlock to from Node 1
3 minutes or less.
Parameters Node 1
Temperature N/A 25 to 113ºF (-3.9 to
45ºC)
Boeing – Huntington Beach had performed an
Flow Rate N/A < 3 lbm/hr (1.4 kg/hr)
Nominal Pressure N/A < 3400 psia (23.4 analysis based on the old pressure equalization
Range MPa) requirement. The old version of the requirement
required Boeing – Huntington Beach to analyze the
equalization of pressure of Node 1 with the relevant
Boeing – Huntington Beach analyzed the pressure adjacent module from a differential pressure of +/- 4.8
loss of the Node 1 high-pressure nitrogen distribution kPa (0.7 psi) to +/- 0.07 kPa (0.01 psi) within 10 minutes.
from the Node 1 forward or Node 1 nadir interface to the For this analysis they analyzed two early ingress
Node 1 starboard interface at the maximum specified configurations and two Assembly Complete (AC)
flow rate, temperature, and nominal pressure. configurations. The two early ingress configurations
included equalization of Node 1 with PMA 2 or 3 and the
Results: Space Shuttle (89.4 cubic meter [3156 cubic feet]) and
Node 1 with PMA 1 and the Russian Segment (RS)
The calculated pressure loss for the high-pressure through Flight 4R (246.1 cubic meter [8689 cubic feet]).
nitrogen distribution was 0.02 kPa differential (0.003 While the two AC configurations that they analyzed were
psid) from the Node 1 nadir interface to the Node 1 the equalization of Node 1 with all of the AC modules
starboard interface and was 0.02 kPa differential (0.003 forward of Node 1 (481.4 cubic meter [16,997 cubic
psid) from the Node 1 forward interface to the Node 1 feet]) and all of the AC modules aft of Node 1 (516.6
starboard interface. The analysis result for this cubic meter [18,241 cubic feet]).
subsystem is considered to be conservative since Boeing – Houston decided to perform the analysis
Boeing – Huntington Beach used the flex hose pressure with and without the acoustic muffler attached to the
drop that was recommended by Boeing – Huntsville, MPEV and assumed the Node 1 with a volume of 51.4
which was shown to be conservative when compared to cubic meter (1814.4 cubic feet) and the vestibule on 1.3
the results from a flex hose development test. cubic meter (46.8 cubic feet) based on the new pressure
The requirement for this subsystem did not have any equalization requirement instead of having Boeing –
pressure loss pass/fail requirement but the value was Huntington Beach update their analysis.
very low and it was agreed based on that fact that the
analysis part of the verification was acceptable.
8
3.2.2.2.11. all others, by selective positioning of the
Characteristics of switching elements; (3) the switching

Results:
Requirement Verification
The calculated pressure equalization time for the old (cont’d) (cont’d)
requirement showed that for the early ingress atmosphere sample at the elements are remotely controllable by the
Airlock interface are discrete PMA-1, N1-MDM interfaces
configurations it would take 6.40 minutes to equalize
specified in SSP 41145, specified by SSP 42122, paragraph
Node 1 with PMA 2/3 and the Space Shuttle and 8.37 paragraph 3.2.1.3.8. 3.2.1.5.4.1; (4) the conduits and the
minutes to equalize Node 1 with PMA 1 and the 4R RS switching elements are sized to
configuration. For the AC configurations it would take When directed from the accommodate the range of pressures,
PMA-1 MDM control temperatures, and flows specified in SSP
9.15 minutes to equalize Node 1 with the elements
signals as specified by 41141, paragraph 3.2.1.2.11, SSP
forward of Node 1 and 9.22 minutes to equalize Node 1 SSP 42122, paragraph 41140, paragraph 3.2.1.2.10, and SSP
with elements aft of Node 1. 3.2.1.5.4.1, Node 1 shall 41145, paragraph 3.2.1.3.8, and (5) the
permit an atmosphere sample delivery system for Node 1
The Boeing – Houston analysis calculated that Node
sample obtained from the samples excludes particles larger than
1 would be equalized with the vestibule in 34 seconds
Airlock interface to be two microns.
without the muffler attached and 118 seconds with the drawn at the Node 3
muffler attached. Even though the vestibule volume interface as specified by
SSP 41140, paragraph
used in the analysis was smaller than the specified
3.2.1.2.10.
volume the results had so much margin the analysis was
Characteristics of
not redone with the correct vestibule volume. atmosphere sample at the
Based on the updated analysis results, Node 1 met its Airlock interface are
specified in SSP 41145,
pressure equalization requirement.
paragraph 3.2.1.3.8.

Node 1 AR QUALIFICATION METHODOLOGY: When directed from the
PMA-1 MDM control
signals as specified by
Requirement Verification
SSP 42122, paragraph
When directed from the Verification of the distribute atmosphere 3.2.1.5.4.1, Node 1 shall
PMA-1 Multiplexer/ samples requirement shall be performed permit an atmosphere
Demultiplexer (MDM) by analysis. Analysis of the Node 1 sample obtained from the
control signals as assembly drawings shall be performed to Node 3 interface to be
specified by SSP 42122, identify the conduits carrying atmosphere drawn at the USL
paragraph 3.2.1.5.4.1, samples from internal Node 1, the USL, interface as specified by
Node 1 shall permit a and Airlock interfaces to the Node 3 SSP 41141, paragraph
sample of its internal interface, and from internal Node 1, the 3.2.2.2.11.
atmosphere, containing Node 3, the MPLM, and the Airlock Characteristics of
particles no longer than 2 interfaces to the USL interface. The atmosphere sample at the
microns absolute, to be conduit geometry and installation shall be Node 3 interface are
drawn at the USL analyzed to confirm that they can specified in SSP 41140,
interface as specified by accommodate the pressures, paragraph 3.2.1.2.10.
SSP 41141, paragraph temperatures, and flow rates specified in
3.2.2.2.11. SSP 41141, paragraph 3.2.1.2.11, SSP When directed from the
41140, paragraph 3.2.1.2.10, and SSP PMA-1 MDM control
When directed from the 41145, paragraph 3.2.1.3.8. Analysis signals as specified by
PMA-1 MDM control shall also identify the remotely SSP 42122, paragraph
signals as specified by controllable switching elements in the 3.2.1.5.4.1, Node 1 shall
SSP 42122, paragraph conduits that allow the control of the permit an atmosphere
3.2.1.5.4.1, Node 1 shall sample flows between the interfaces, and sample obtained from the
permit a sample of its the variations in flow paths that are USL interface to be drawn
internal atmosphere, achievable by remote repositioning of the at the Node 3 interface as
containing particles no identified switching elements. Analysis of specified by SSP 41140,
longer than 2 microns the internal Node 1 atmosphere sampling paragraph 3.2.1.2.10.
absolute, to be drawn at flow shall be performed to determine the Characteristics of
the Node 3 interface as capability of the sample delivery system atmosphere sample at the
specified by SSP 41140, to exclude atmospheric particles larger USL interface are
paragraph 3.2.1.2.10. than two microns. specified in SSP 41141,
paragraph 3.2.1.2.11.
When directed from the Verification shall be considered
PMA-1 MDM control successful when the analysis shows that When directed from the
signals as specified by (1) there are sample atmosphere PMA-1 MDM control
SSP 42122, paragraph conduits paths from internal Node 1 to signals as specified by
3.2.1.5.4.1, Node 1 shall the USL, from internal Node 1 to the SSP 42122, paragraph
permit an atmosphere Node 3, from the Airlock to the USL, from 3.2.1.5.4.1, Node 1 shall
sample obtained from the the Airlock to the Node 3, from the USL permit an atmosphere
Airlock interface to be to the Node 3, from the Node 3 to the sample obtained from the
drawn at the USL USL, and from the MPLM to the USL; (2) MPLM interface to be
interface as specified by each of the paths specified in (1) can be drawn at the USL
SSP 41141, paragraph uniquely configured, to the exclusion of interface as specified by
9
SSP 41141, paragraph Probe to USL module
3.2.2.2.11. interface

SSP 41141 From U.S. To U.S.
Requirement Verification
Interface Laboratory Laboratory
(cont’d) (cont’d)
Parameters Module to Module from
Characteristics of
(cont’d) Node 1 Node 1
atmosphere sample at the
MPLM interface are (cont’d) (cont’d)
specified in SSP 42007, Pressure Loss from < 0.4 psid (2.8 kPa N/A
paragraph 3.2.1.3.5. Joint Airlock module differential)
interface to USL
module interface
Note: The Node 1 element requirement inadvertently did not reference
the “To Node 3 from Node 1” (SSP 41140, paragraph 3.2.1.2.15). Pressure Loss from < 0.25 psid (1.7 kPa N/A
Node 3 or MPLM differential)

module interface to
The requirement references five ISS ICDs. The relevant
USL module
requirements from those documents are as follows for interface
the Sample Delivery Subsystem (SDS) distribution:
SSP 41145 From Joint To Joint Airlock
SSP 42122 From/To PMA-1 Interface Airlock to from Node 1
Interface Parameters and Node 1 Parameters Node 1
Node 1 ECLS Signals The Node 1 shall provide to and receive Flow Rate 100 - 600 scc/min N/A
from PMA-1 instrumentation signals for
the monitoring and control of the SSP 42007 From MPLM to To MPLM from
following ECLSS equipment by the N1-1 Interface Node 1 Node 1
MDM: Atmosphere Revitalization valves,
Parameters
Smoke Detector, Node 1 Air Mixing
Flow Rate 100 - 400 scc/min N/A
Valve, Cabin Fan, Node 1 Aft IMV Fan,
Node 1 Aft IMV Return and Supply
Valves, Node 1 Starboard Return and Boeing – Huntington Beach analyzed the pressure
Supply valves, Node 1 Port Supply valve, loss of the Node 1 AR SDS distribution at 400 scc,
Node 1 Rheostat. The interface between
29.4ºC (85ºF), and at a pressure of 101.4 kPa (14.7
the Node 1 ECLSS equipment and the
N1-1 MDM shall be in compliance with psia) when transferring air samples to the U.S.
SSP 30261:002. Laboratory module or the Node 3 MCA.

The Node 1 shall provide and receive
Results:
from PMA-1 instrumentation signals for
the monitoring and control of the
following ECLSS equipment by the N1-2 The calculated pressure loss was determined to be
MDM: Cabin Pressure sensor, Smoke 1.8 kPa differential (0.26 psid) from the Node 1 sample
Detector, Cupola Air Mixing Valve, Node
probe to the U.S. Laboratory module interface, 2.3 kPa
1 Port and Starboard IMV Fans, Node 1
Nadir IMV Return and Supply valves, differential (0.34 psid) from the Joint Airlock interface to
Node 1 Forward Return and Supply the U.S. Laboratory module interface, 1.6 kPa
valves, Cupola Rheostat. The interface differential (0.23 psid) from the Node 3 or MPLM to the
between the Node 1 ECLSS equipment
U.S. Laboratory module interface, 2.6 kPa differential
and the N1-2 MDM shall be in
compliance with SSP 30261:002. (0.37 psid) from the Node 1 sample probe to the Node 3
module interface, and 3.1 kPa differential (0.45 psid)
SSP 41140 From Node 3 to To Node 3 from from the Joint Airlock interface to the Node 3 module
Interface Node 1 Node 1 interface. The analysis result for this subsystem is
Parameters satisfactory since Boeing – Huntington Beach used the
Flow Rate 100 - 400 scc/min 100 – 400 scc/min specified end of life pressure loss for the Node 1 sample
probe filter and the specified pressure loss for the
Note: The Node 1 Pressure Loss requirements for atmosphere
manual isolation valves in the analysis. The data used
samples going to Node 3 were inadvertently deleted when the Program
for the Node 1 sample probe filter and the manual
replaced the Habitation Module with Node 3 on Node 1 nadir. The
requirements were < 0.40 psid (2.8 KPa differential) from the Node 1 isolation valve is considered to be conservative since the
Sample Probe to Node 3 module interface, < 0.50 psid (3.4 KPa sample probe filter supplier and the manual isolation
differential) from Joint Airlock module interface to Node 3 module
valve supplier went through a Qualification Program to
interface, and < 0.25 psid (1.7 KPa differential).
show that the specified pressure drop data was higher

SSP 41141 From U.S. To U.S. when compared to the actual performance of the
Interface Laboratory Laboratory hardware. As for the flex hoses in the AR SDS
Parameters Module to Module from distribution Boeing – Huntington Beach used the Boeing
Node 1 Node 1 – Huntsville recommended pressure drop data, which
Flow Rate 100 - 400 scc/min N/A was shown to be conservative when compared to the
Pressure Loss from < 0.4 psid (2.8 kPa N/A results from a flex hose development test. The electrical
Node 1 Sample differential)
10