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European Space Agency Agence spatiale européenne

ESTEC

Keplerlaan 1, PO Box 299, 2200 AG Noordwijk zh, The Netherlands

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European Space Agency

Directorate of Technical and Quality Management

Statement of Work – Annex 1

Technical Requirements Specification

Latch Valve Development (for Space Propulsion Systems)

Reference: TEC-MPC/2009/804/MS

Issue: 1, Revision -

12.11.2009

Statement of Work - Annex 1 Issue: 1 Latch Valve Development Revision: - Date: 12.11.2009


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Table of Content 1 INTRODUCTION......................................................................................................................................... 4

1.1 SCOPE OF THE DOCUMENT ....................................................................................................................... 4 1.2 APPLICABLE AND REFERENCE DOCUMENTS ............................................................................................ 4

1.2.1 Applicable Documents (ADs) .......................................................................................................... 4 1.2.2 Reference Documents (RDs) ........................................................................................................... 6

1.3 ACRONYMS AND ABBREVIATIONS............................................................................................................ 7 2 END PRODUCT DEFINITION AND BREAKDOWN............................................................................. 9

2.1 CHARACTERISTICS ................................................................................................................................... 9 2.2 FUNCTION ................................................................................................................................................ 9

3 REQUIREMENTS........................................................................................................................................ 9 3.1 FUNCTIONAL AND PERFORMANCE REQUIREMENTS.................................................................................. 9

3.1.1 Operational Media and Compatibility ............................................................................................ 9 3.1.2 Temperatures................................................................................................................................. 10 3.1.3 Pressures....................................................................................................................................... 10 3.1.4 Pressure Cycles............................................................................................................................. 11 3.1.5 Maximum Steady State Flow ......................................................................................................... 11 3.1.6 Surge Flow .................................................................................................................................... 12 3.1.7 Leakage Limits .............................................................................................................................. 13 3.1.8 Electrical Requirements ................................................................................................................ 13 3.1.9 Position Indicator.......................................................................................................................... 14 3.1.10 Response Time............................................................................................................................... 15

3.2 INTERFACE REQUIREMENTS ................................................................................................................... 15 3.2.1 Mounting ....................................................................................................................................... 15 3.2.2 Tubing ........................................................................................................................................... 15 3.2.3 Thermal Interface.......................................................................................................................... 16 3.2.4 Electrical Interface........................................................................................................................ 16

3.3 ENVIRONMENTAL REQUIREMENTS......................................................................................................... 21 3.3.1 Natural Environments ................................................................................................................... 21 3.3.2 System Generated Environments................................................................................................... 22 3.3.3 Self Induced Environments............................................................................................................ 25

3.4 PHYSICAL & RESOURCE REQUIREMENTS............................................................................................... 26 3.4.1 Mass .............................................................................................................................................. 26 3.4.2 Eigen frequency............................................................................................................................. 26 3.4.3 Envelope Dimensions and Characteristics.................................................................................... 26 3.4.4 Flow Path...................................................................................................................................... 26 3.4.5 Valve Stability ............................................................................................................................... 27

3.5 OPERATIONAL REQUIREMENTS.............................................................................................................. 27 3.5.1 Storage Life ................................................................................................................................... 27 3.5.2 Operational Life ............................................................................................................................ 27 3.5.3 Cycle Life ...................................................................................................................................... 27

3.6 HUMAN FACTORS REQUIREMENTS......................................................................................................... 28 3.7 PRODUCT ASSURANCE REQUIREMENTS ................................................................................................. 28

3.7.1 Feared Events (For Flight Units).................................................................................................. 28 3.7.2 Failure Tolerance.......................................................................................................................... 29 3.7.3 Failure Propagation and Redundancy Policy ............................................................................... 29 3.7.4 Availability .................................................................................................................................... 29 3.7.5 Reliability ...................................................................................................................................... 29



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3.7.6 Maintainability.............................................................................................................................. 29 3.7.7 Safety............................................................................................................................................. 29

3.8 CONFIGURATION AND IMPLEMENTATION REQUIREMENTS - N/A .......................................................... 30 3.9 DESIGN REQUIREMENTS ........................................................................................................................ 30

3.9.1 General Design ............................................................................................................................. 30 3.9.2 Electrical Design........................................................................................................................... 30 3.9.3 Structural Design and Fracture Control....................................................................................... 32 3.9.4 Parts, Materials and Processes..................................................................................................... 33

3.10 VERIFICATION & TESTING REQUIREMENTS ........................................................................................... 37 3.10.1 Development Tests ........................................................................................................................ 38 3.10.2 Acceptance Tests ........................................................................................................................... 41 3.10.3 Qualification Tests ........................................................................................................................ 42



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1 Introduction

1.1 Scope of the Document

This specification describes the technical requirements for an end item space propulsion latch valve(s). Both of the following options are covered in this specification:

Option A. Design of a single valve that meets the needs of both high flow and low flow valves. Here the low flow valve would be comprised of 2 valves, one for MON and one for MMH; however, the 2 valves combined must meet the interface and physical requirements of a single low flow valve (e.g. electrical interface, envelope, mass, etc.).

Option B. Design of two valves, one high flow and one low flow. Here the low flow valve would be a single valve with separate fluid bodies for MON and MMH, as with the present ATV low flow valve.

Henceforth in this document, the valve shall be referred to in singular terms (i.e. “valve” instead of “valve(s)”) to refer to either of the options (A. or B.) above. Where requirements are applicable to both high flow and low flow valves, only one set of requirements will be specified. Where necessary, separate requirements will be specified for the high flow and low flow valves to allow for option B. For option A. in this case, the valve shall meet both sets of requirements.

The requirements of this document are applicable during the development of this latch valve.

In addition to the specified requirement levels, certain sections also indicate targets. Achieving these targets will reduce existing ATV risks and allow greater capability for future programmes. The valve developer should strive to meet these targets to the extent feasible.

The document will be part of the contract and shall serve as an applicable document throughout the execution of the contract work.

1.2 Applicable and Reference Documents

1.2.1 Applicable Documents (ADs)

The following documents are applicable to and form a part of this specification: AD1 TEC-

MPC/2009/788/MS LV Interface and Envelope Dimensions http://emits.esa.int/emits-doc/ESTEC/AO6337_AD1_TEC_MPC_2009_788_MS_LV_Interface_and_Envelope_Dimensions.pdf

http://emits.esa.int/emits-doc/ESTEC/AO6337_AD1_TEC_MPC_2009_788_MS_LV_Interface_and_Envelope_Dimensions.pdf





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AD2 ATV-AS-SSS-3200 5A

Specification of the Equipment Qualification & Acceptance Environmental Tests http://emits.esa.int/emits-doc/ESTEC/AO6337_AD2_ATV_AS_SSS_3200_5A.pdf


EMC Specifications and Design Requirements for Power Quality http://emits.esa.int/emits-doc/ESTEC/AO6337_AD3_ATV_AS_SSS_3300_6A.pdf


Structure Design, Sizing and Test Specifications http://emits.esa.int/emits-doc/ESTEC/AO6337_AD4_ATV_AS_SSS_1100_6A.pdf

AD5 IS0 14951-5-1999(E)

Space systems - Fluid Characteristics - Part 5: Nitrogen Tetroxide propellant

AD6 IS0 14951-5-1999(E)

Space systems — Fluid characteristics — Part 6: Monomethylhydrazine propellant

AD7 IS0 14951-4-1999(E)

Space systems - Fluid characteristics - Part 4: Helium

AD8 TT-I-735 A Alcohol, Isopropyl, Grade A AD9 IS0 14951-9-

1999(E) Space systems - Fluid characteristics - Part 9: Argon

AD10 IS0 14951-3-1999(E) Space systems - Fluid characteristics - Part 3: Nitrogen

AD11 IS0 14951-10-

1999(E) Space systems - Fluid characteristics - Part 10: Water

AD12 ECSS-Q-ST-70-36C

Material Selection for Controlling Stress Corrosion Cracking


Determination of Susceptibility of Metals to Stress Corrosion Cracking

AD14 ECSS-Q-70-71A Data for Selection of Space Materials and Processes AD15 ECSS-Q-ST-30-

11C Derating - EEE Components

AD16 ECSS-Q-ST-60C EEE Components AD17 ECSS-E-ST-10-

04C Space Environment

AD18 MIL-STD-22 (or DIN 65118)

Weld Joint Design

AD19 MIL-W-8611 Process for Metal Arc and Gas Welding, Steels and Corrosion and Heat Resistant Alloys

AD20 (TBD) AD21 SAE-AMS-STD-

1595 (or DIN 29591)

Qualification of Aircraft, Missile & Aerospace Fusion Welders

AD22 MIL-STD-1890 Class I

Inspection of Welded Joint

http://emits.esa.int/emits-doc/ESTEC/AO6337_AD2_ATV_AS_SSS_3200_5A.pdf








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(or DIN 29595) AD23 MIL-STD-453

Class I (or DIN 54111)

Radiographic Inspection

AD24 NAS-1514 Class I (or DIN 29595)

Radiographic Standard for Classification of Fusion Weld Discontinuities


Manual soldering of high-reliability electrical connections


Cleanliness and Contamination Control

AD27 ECSS-E-ST-35-06C

Cleanliness Requirements for Spacecraft Propulsion Hardware

AD28 ECSS –E-ST-33-01C

Space Engineering - Mechanisms

AD29 MIL-STD-889 Dissimilar Metals AD30 FED-STD-209 Federal Standard Clean Room and Work Station Requirements,

Controlled Environment AD31 ECSS-E-ST-35-

10C Compatibility testing for liquid propulsion systems

1.2.2 Reference Documents (RDs)

The following documents can be consulted by the Contractor as they contain relevant information: RD1 TEC-MPC/2009/787/MS ATV Latch Valve Issues Summary

http://emits.esa.int/emits-doc/ESTEC/AO6337_RD1.pdf

RD2 ECSS-E-ST-35C Space Engineering - Propulsion General Requirements RD3 ECSS-E-ST-35-01C Space Engineering – Liquid and Electric Propulsion

for Spacecraft RD4 TOS-MMM/2002/341 European Space Technology Harmonisation -

Technical Dossier on Mapping Mechanisms and Motors http://emits.esa.int/emits-doc/ESTEC/AO6337_RD4.pdf

RD5 TEC-MMM 2008 /129 European Space Technology Harmonisation - Technical Dossier Position sensors http://emits.esa.int/emits-doc/ESTEC/AO6337_RD5.pdf

RD6 ECSS-E-ST-20C Electrical and Electronic









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RD7 ECSS-E-ST-20-07C E&M Compatibility RD8 ECSS-E-ST-30-01A Worst Circuit Performance Analysis RD9 ECSS-E-ST-30-02C FMECA RD10 ECSS-E-ST-30-09C Availability Analysis RD11 MIL-STD-1576 Electroexplosive Subsystem Safety Requirements and

Test Methods for Space Systems RD12 MIL-HDBK-5 Metallic Materials and Elements for Aerospace

Vehicle Structures RD13 NBS HDBK H28 Threads RD14 ISO-6358 Components Using Compressible Fluids –

Determination of Flow Rate Characteristics RD15 ECSS-Q-ST-70-02C Thermal Vacuum Outgassing Test for the Screening of

Space Materials RD16 ECSS-Q-ST-70-06C Particle and UV Radiation Testing of Space Materials RD17 ECSS-Q-ST-70-29C Determination of offgassing products from materials

and assembled articles to be used in a manned space vehicle crew compartment

RD18 NASA-STD-6001 Flammability, Odour, Off gassing, and Compatibility Requirements and Test Procedures for Materials in Environments that support Combustion

1.3 Acronyms and abbreviations

ATV Automated Transfer Vehicle

CAM Collision Avoidance Manoeuvre

DM Development Model

EMC Electromagnetic Compatibility

gHe Gaseous Helium

gN2 Gaseous Nitrogen

IPA Isopropyl Alcohol

LV Latch Valve

MDP Maximum Design Pressure

MMH Monomethyl Hydrazine

MON Mixed Oxides of Nitrogen

NVR Non-volatile Residue



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PDE Propulsion Drive Electronics

PSD Power Spectral Density

PRSS Propulsion and Reboost Sub-system

QM Qualification Model

SOW Statement of Work

TBC To be confirmed

TBD To be determined



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2 End Product Definition and Breakdown

2.1 Characteristics

The valve shall have the following characteristics:

• Utilised in low pressure segment of space propulsion sub-systems (spacecraft or space transportation vehicle).

• Electrically powered/commanded by spacecraft valve driver (PDE)

• Bistable – no electric power shall be required to maintain open or closed position

• Back pressure relief (back relief ) capability

• Electrical failure tolerance for power/command circuit

• Position indicator (open/closed status indication)

2.2 Function

The valve shall have the following key functions in the propulsion sub-system:

• Isolate propellant or pressurant segments of the propulsion system

• Allow flow of propellant or pressurant

• Allow back pressure relief (outlet to inlet)

3 Requirements

3.1 Functional and Performance Requirements

3.1.1 Operational Media and Compatibility

The valve shall be compatible with the following media. This media will be used for operation and testing of the valve.

• MMH (per AD6)

• MON (per AD5)

• Helium (per AD7)



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• Deionised Water (per AD11)

• Argon (per AD9)

• Nitrogen (per AD10)

• IPA (per AD8)

3.1.2 Temperatures

The valve shall meet performance requirements with the medium in the range of temperatures shown in Table 3.1.2-1 below. “Operational” means opening and closing of the valve. For the “Non-operational” temperatures, the valve shall meet performance requirements after having been exposed to the media at these temperatures and then returned to the “operational” temperatures.

Table 3.1.2-1

Non-operational Operational

Expected* -20°C to +45°C +5°C to +45°C

Acceptance -25°C to +50°C 0°C to +50°C

Qualification -30°C to +55°C -5°C to +55°C

*Here, “expected” refers to the maximum expected range during transport, storage or flight.

3.1.3 Pressures

Unless otherwise specified, all pressures referred to in this specification are absolute pressures. Throughout this specification the term “transient”, when applied to pressures, shall mean total pressure (i.e. static + dynamic pressure).

The valve shall meet the performance requirements while operating with the internal pressure values shown in the table below. The valve shall not experience any unintended plastic deformation when exposed to pressures up to and including proof pressure.

Table 3.1.3-1

Valve Position Requirement Level Target level

MDP* Closed 35 bar 50 bar

MDP* Open 50 bar

Minimum pressure Open or closed 1 mbar

Back relief (outlet to inlet) Closed 2 bar ≤ back relief < 5 bar (TBC)



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Proof (5 minutes – no plastic deformation)

Open and closed 1.5 x MDP

Burst (5 seconds (TBC) – no rupture)

Open and closed 2.5 x MDP

*MDP (Maximum Design Pressure) is the maximum expected pressure, including transients, during transport, storage or flight. Maximum expected steady state pressure for this valve is 25 bar (open or closed).

For the low flow latch valve option B only: The valve shall operate at worst case unsymmetrical pressure in the parallel flow paths (MON & MMH). For Qualification, the valve shall be switched 320 times with unsymmetrical pressure conditions.

3.1.4 Pressure Cycles

The valve shall withstand the following transient pressure peaks while in the open position without incurring degradation of performance or an interruption of flow: 22000 @ 25 bar, 270000 @ 10 bar and 850000 @ 7 bar (TBC). Here, the pressures listed are transient pressure peaks. These are on top of a 25 bar steady state value that shall be applied during the testing. Rise rates and durations for these peaks are TBD.

3.1.5 Maximum Steady State Flow

The maximum steady state flow requirements shall be applicable for all expected operational temperatures specified herein. With pressure at 25 bar, the valve shall operate at the flow rates specified in Tables 3.1.5-1 and 3.1.5-2 below. The noted pressure drop requirements shall be met.

Table 3.1.5-1 - High Flow Valve Flow Rates Medium Requirement

Flow Rate (g/s)

Pressure Drop (bar)

Target Flow Rate (g/s)

Pressure Drop (bar)

MMH 390 ≤ 0.5 432 ** MON 640 ≤ 0.5 744 **

**No specific pressure drop requirement at these higher flow rates



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Table 3.1.5-2 - Low Flow Valve Flow Rates Medium Requirement

Flow Rate (g/s)

Pressure Drop (bar)

Target Flow Rate (g/s)

Pressure Drop (bar)

MMH 72 ≤ 0.4 108 ** MON 118 ≤ 0.4 186 **

**No specific pressure drop requirement at these higher flow rates The stability of the flow (pressure fluctuation, roughness) downstream of the unit shall be < 5 % of the inlet pressure. The pressure drop deviation from unit to unit shall not vary by more than ±50 mbar at the maximum required mass flow rate. Target: The high flow valve shall be able to be closed during a flow rate of 190 g/s MON and 110 g/s MMH without loss of tightness or performance degradation. Target: The low flow valve shall be able to be closed during a flow rate of 70 g/s MON and 40 g/s MMH without loss of tightness or performance degradation.

3.1.6 Surge Flow

The surge flow requirements are applicable for all expected operational temperatures specified herein. The high flow valve in open position shall withstand a mass flow of 1.0 kg/s of MON for 2 seconds without: • Damage • Degradation to performance or • Interruption of flow (e.g. valve closing)

The low flow valve shall withstand a mass flow of 600 g/s of MON for > 5 seconds, without: • Damage • Degradation to performance or • Interruption of flow (e.g. valve closing)



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3.1.7 Leakage Limits

Internal : At any combination of pressure and temperature within the operational range specified herein, the internal leakage from inlet to outlet shall not exceed 1x10^-4 scc/s gHe. Internal leakage requirements during vibration and shock are defined in section 3.3.2.

External: At any combination of pressure from 0-35 bar and temperature within the operational range specified herein, the external leakage shall not exceed 1x10^-6 scc/s gHe. This requirement shall also apply during and after vibration and shock loads as defined herein.

3.1.8 Electrical Requirements

Electrical power and voltage requirements and associated measurements to verify these requirements apply at the input to the valve, excluding the valves external 3m leads.

3.1.8.1 Pulse Duration

The pulse duration for opening or closing the valve will be 100 - 130 ms.

The valve shall withstand a maximum pulse length of 60 seconds (e.g. PDE failure case) with voltage and temperature in the operational range without degradation of functional performance .

3.1.8.2 Electrical Power Consumption

The power consumption shall not exceed the following levels when opening or closing:

At 27 VDC and 21°C environment temperature, the opening or closing power consumption shall be ≤ 50 W.

For design options where the low flow bipropellant valve is split into 2 single valves (option A), the power consumption must be applicable to the pair of valves as if it were still a single valve. (TBC)

3.1.8.3 Supply Voltage

The valve shall operate nominally with a supply voltage in the range of 22 to 36 VDC. The valve shall be able to handle an over-voltage of 54 V (e.g. in case of a PDE failure) without degradation of performance. The valve’s actual over-voltage limit and duration (i.e. valve’s margin on 54V requirement) shall be determined through testing.



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3.1.8.4 Opening/Closing Voltage

At all combinations of delta pressure across the valve ranging from 0 to 25 bar and temperature ranging from +5°C to +45°C, the opening voltage shall be ≤ 20 VDC; however, the valve shall not inadvertently open due to stray voltage ≤ 7 VDC (TBC) under these conditions.

At all combinations of pressure ranging from 0 to 25 bar and temperatures ranging from +5°C to +45°C, the closing voltage shall be ≤ 20 VDC; however, the valve shall not inadvertently close due to stray voltage ≤ 7 VDC (TBC) under these conditions.

3.1.8.5 Dielectric Strength

There shall be no evidence of damage, arcing or breakdown when 250 VAC are applied for 60 seconds. Leakage current shall not exceed 0.5mA when a voltage of 500 VAC at 60Hz is applied across the equipment.

3.1.8.6 Insulation Resistance The insulation resistance between any terminal and case and between the leads of the opening/closing coils shall be > 100 MOhm at 500 VDC for 60 seconds.

The isolation resistance between the coils shall be > 2 MOhm at 50 VDC for 60 seconds.

3.1.8.7 Inductance

The inductance of each of the valves power/command circuits at 1 kHz shall be less than 0.35 H.

3.1.8.8 Polarity Reversal

The PDE has a pole reverse relay which allows each coil’s command and return pair to operate in forward or reverse direction. The latch valve design shall allow for opening and closing using this polarity reversal on each command and return pair. See Figure 3.2.4.1-1 .

3.1.9 Position Indicator

The valve shall have an electrical circuit that includes position indicator(s) showing the open and closed status of the valve. Interface requirements for this circuit are described in section 3.2.4.1 of this document.



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3.1.10 Response Time

The valve opening response time (i.e. application of the electrical signal to fully open) shall be ≤ 50 ms. The valve closing response time (i.e. application of the electrical signal to fully closed) shall be ≤ 50 ms.

These requirements shall apply at any combination of expected operational voltage, temperature and pressure specified herein.

This requirement shall be met with IPA and GN2

For Qualification and Flight Units: This requirement shall be met with MON3 and MMH. Note: This fast acting requirement is mandatory for current valve applications; however, there are potential advantages if the contractor’s design would also allow options for a slow acting valve for future applications.

3.2 Interface Requirements

Note: If option A (as defined in section 1.1) is selected, the low flow valve would be comprised of 2 valves, one for MON and one for MMH. In this case these two valves combined must meet the interface requirements for the low flow valve as noted below.

3.2.1 Mounting

The latch valve mounting interface shall comply with AD1. The valve will be attached to the structure by M5 screws. The screws shall be installed from the latch valve side of the interface (i.e. screw head on valve side). The valve design must allow for access from above for screw installation.

3.2.2 Tubing

The connection of the unit to the tubing system shall be weldable tubes of titanium alloy as shown in AD1. The tubing dimensions and characteristics shall be as follows:

• High flow valve: 3/4” diameter with 0.039” wall thickness

• Low flow valve: 3/8” diameter with 0.019” wall thickness

• The free accessible tube length shall be 30 mm minimum.



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• The centreline of the inlet and outlet tubing must lie on the same axis.

• The position of the tubing centreline shall be as defined in AD1.

The valves interface tubing shall withstand the loads in Table 3.2.2-1 below.

Table 3.2.2-1

Tube size Mres (Nmm) Fres(lat) (N) Fax (N) T (Nmm)

3/8” 12000 200 1550 3650

3/4” 48000 650 2600 21500

3.2.3 Thermal Interface

The contractor shall define a thermal reference point for temperature measurements as applied during thermal tests.

3.2.4 Electrical Interface

The interface characteristics in section 3.2.4.1 below do not consider the harness between the PDE and the latch valve leads. Harness and latch valve lead characteristics are described in section 3.2.4.2 below. PDE, harness and valve lead characteristics must be considered when assessing the parameters (e.g. harness + lead impedance and the effects on available voltage, etc.).

3.2.4.1 Propulsion Drive Electronics Interface

The valve shall interface with the PDE (command signals and position indicator signals) in accordance with the following requirements.

On the ATV, the Propulsion Drive Electronics includes two types of drivers, a nominal driver and a CAM (Collision Avoidance Manoeuvre) driver. The nominal driver is used for all nominal operations. Its characteristics are shown in Table 3.2.4.1-1 and Figure 3.2.4.1-1 below. The CAM driver is used in a degraded case when a key propulsion system failure has occurred. Its characteristics are shown in Table 3.2.4.1-2 and Figure 3.2.4.1-2 below. All existing latch valves have at least one coil attached to a nominal driver. A portion of the high flow and low flow latch valves have the second (redundant) coil attached to the CAM driver. The latch valve shall be capable of interfacing with either type of driver.



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Nominal Driver

Table 3.2.4.1-1 - PDE Nominal Driver Output Parameters

Figure 3.2.4.1-1 - Simplified Equivalent PDE Nominal Driver Electric Circuit All latch valves will be operated from the nominal driver with pole reversal polarity of the activation voltage. For the ‘Valve Open’ pulse the polarity of LVx_OUT is positive with



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respect to LVx_RTN. Consequently the ‘Valve Close’ pulse is negative with respect to LVx_RTN. This polarity reversal is not applicable for the CAM driver.

CAM Driver

Table 3.2.4.1-2 - PDE CAM Driver Output Parameters



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Figure 3.2.4.1-2 - Simplified Equivalent PDE CAM Driver Electric Circuit

Position Indicator

The PDE position indicator circuit characteristics are noted in Table 3.2.4.1-3 below.

Table 3.2.4.1-3 Position Indicator Input Parameters



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The PDE Position Indicator Circuit interface is shown in Figures 3.2.4.1-3 and -4 below. The latch valve must meet the requirements herein with the position indicator(s) connected to this interface.

Figure 3.2.4.1-3 - PDE Position Indicator Circuit (signal status definitions)

Figure 3.2.4.1-4 - PDE Position Indicator Circuit (signal processing detail)



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3.2.4.2 Harness – Latch Valve Lead Interface

The ATV has 46 latch valves. The harness length from PDE to LV leads varies from valve to valve. The worst case harness impedance (longest harness, high temperature) is 1.5 ohms.

The valve shall have 3m long flying leads (command and position indicator interface cables) and shall meet the requirements in Table 3.2.4.2-1 below. Reference section 3.9.2 Electrical Design for additional wiring requirements.

Table 3.2.4.2-1 Cable T/S AWG

Power in / out (command) TTP 22

2 twisted pair (1 pair for primary circuit and 1 pair for redundant

circuit) Signal in / out (position indicator) TS3C 22 (TBC) 1 twisted shielded 3 conductor

cable

3.2.4.3 Low Flow Latch Valve Specific Interface Requirements

For the low flow valves, the two bodies (1 MON and 1 MMH) are to be activated at the same time. This is applicable regardless of the choice of a single low flow valve (option B) or two separate valves (option A).

3.3 Environmental Requirements

3.3.1 Natural Environments

3.3.1.1 Temperature

The valve shall meet performance requirements when exposed to natural environments with sustained temperature ranges as shown in Table 3.3.1.1-1 below. “Operational” means opening and closing of the valve. For the “Non-operational” temperatures, the valve shall meet performance requirements after having been exposed to these temperatures, then returned to the “operational” temperatures.

Table 3.3.1.1-1

Non-operational Operational

Expected* -20°C to +45°C +5°C to +45°C

Acceptance -25°C to +50°C 0°C to +50°C

Qualification -30°C to +55°C -5°C to +55°C



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* “Expected” refers to the maximum expected range during transport, storage or flight.

3.3.1.2 Pressure The valve shall operate as specified herein when exposed to an ambient pressure at sea level (1100 mbar) and to space conditions (1x10-10Torr).

3.3.1.3 Humidity

The valve shall operate as specified after exposure to an environment having a relative humidity up to 100 %, including condensation, at ambient temperature levels.

3.3.1.4 Space Environment

The valve shall meet the requirements herein during exposure to the space environment defined in AD17. (TBC)

3.3.2 System Generated Environments

The valve shall meet the design and performance requirements specified herein during and after exposure to the environments specified hereafter. This exposure shall not result in valve degradation. AD2 is applicable for these requirements and the associated testing. The unit shall actuate during the environment levels given below and the unit shall not change position (open/close) during the environments specified hereafter without being commanded.

3.3.2.1 Resonance Search

The valve shall be subjected to a resonance search test in the open and closed positions at ambient pressure and temperature with the excitation frequencies and levels shown in Table 3.3.2.1-1. In the frame of random vibration testing, the resonance search will be executed with IPA in the valve.

Table 3.3.2.1-1 Frequency Peak Amplitude per

Acceleration* Sweep Rate

5 - 13 Hz 13 - 50 Hz

50 - 2000 Hz

+/- 3 mm +/- 2 g

+/- 2.5 g

2 oct/min corresponding to

T = 4 min

*These levels may be reduced, if necessary, as long as a clear eigen frequency response can be detected.



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This test under the same ambient conditions shall be performed before and after the random vibration and sinusoidal vibration test for each axis. - The test fixture shall be subjected to a low level sweep to identify the natural frequency - The test article shall be mounted in the flight configuration and orientation on a rigid test fixture.

The lowest eigen frequency value of the valve shall be ≥ 150 Hz. Variance in eigen frequency before vs. after vibration testing shall be evaluated to ensure no degradation to the valve has occurred.

3.3.2.2 Sinusoidal Vibration (For Qualification Units)

Spectrum 1

The valve shall be vibrated in the open (TBC) and closed position to the levels specified in Table 3.3.2.2-1 below, while pressurized to delta P = 5 bar (TBC) inlet to outlet. The position indication and leakage shall be monitored during mechanical verification. Internal leakage shall not exceed 1x10^-3 scc/s gHe (TBC) in the closed position. The valve position (open/closed) shall not change unless commanded as such.


Acceleration Sweep Rate

5 - 16 Hz 16 - 60 Hz 60 - 70 Hz

+/- 10 mm +/- 10 g

+/- 22.5 g

1/3 oct/min corresponding to

T = 11.4 min 70 - 200 Hz

200 - 2000 Hz +/- 22.5 g +/- 10 g

2 oct/min T = 2.4 min

Spectrum 2

The vibration levels shown in Table 3.3.2.2-2 shall be applied 26 times for each of the three mutually perpendicular axes which corresponds to 4 hours per axis, while the valve is in the position recommended by the manufacturer.


Acceleration Sweep Rate

0.5 - 5 Hz 5 - 300 Hz

+/- 10 mm +/- 1 g

1 oct/min corresponding to

T = 9 min



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3.3.2.3 Random Vibration

The valve shall withstand the random vibration loads specified in Tables 3.3.2.3-1 and -2 below in each of the 3 mutually perpendicular axes, while pressurized to delta P = 5 bar (TBC) inlet to outlet in the closed position.

The valve shall be actuated under vibration loads.

The position indication and internal leakage shall be monitored during mechanical verification. Internal leakage shall not exceed 1x10^-3 scc/s gHe (TBC) in the closed position. The valve position (open/closed) shall not change unless commanded as such.

Table 3.3.2.3-1 - For Qualification - Duration 4 minutes each axis

Frequency PSD Level 20 - 60 Hz +3 dB/oct 60 - 1000 Hz 0.273 g²/Hz

1000 - 2000 Hz -6 dB/oct

Overall 20 geff

Table 3.3.2.3-2 - For Acceptance – Duration 2 minutes each axis

Frequency PSD Level

20 - 2000 Hz 0.0727 g²/Hz

12 geff

3.3.2.4 Pyrotechnic Shock (For Qualification Units)

The unit shall withstand the pyrotechnic shock spectrum specified in Table 3.3.2.4-1 and Figure 3.3.2.4-1 below in both open and closed positions and shall meet the requirements of this specification after the shock.

The unit shall not move from the selected position (open/close) due to the shock. Leakage shall be checked during shock testing. Internal leakage shall not exceed 1x10^-3 scc/s gHe (TBC) in the closed position.

Table 3.3.2.4-1

Frequency (Hz)

Level (g)

400 420

950 980

10000 980



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Figure 3.3.2.4-1

3.3.2.5 EMC

Power Circuits (TBD)

Arc Discharge Susceptibility

No malfunction, degradation of performance or deviation from specified parameters beyond tolerances given by the corresponding specification shall occur when equipment and interface lines are exposed to repetitive electrostatic arc discharges of at least 5.6 mJ energy

3.3.3 Self Induced Environments

3.3.3.1 Conducted and Radiated Emissions

(TBD)

3.3.3.2 Thermal

The unit temperature shall not exceed 60 deg C when a maximum pulse length of 60 seconds is applied



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3.4 Physical & Resource Requirements

Note: If option A (as defined in section 1.1) is selected, the low flow valve would be comprised of 2 valves, one for MON and one for MMH. In this case these two valves combined must meet the mass and envelope requirements for the low flow valve as noted below.

3.4.1 Mass

The mass of the high flow valve shall be < 1.47 kg. The mass of the low flow valve shall be ≤ 2.1 kg. These masses shall include 3m cable. Mass shall be minimised to the greatest extent feasible. The contractor shall provide moments of inertia and centre of mass position.

3.4.2 Eigen frequency

The lowest eigen frequency of the valve shall be ≥ 150 Hz

3.4.3 Envelope Dimensions and Characteristics

Valve dimensions and characteristics shall comply with AD1. If option A is chosen, two low flow valves will have to be mounted using a total of only 4 mounting fasteners. For this option, a single mounting interface (e.g. pedestal) may be used to attach both valves to the structure. Design of the necessary mounting interface (e.g. pedestal) for the high flow and low flow valves shall be part of this valve development.

3.4.4 Flow Path

The flow path shall be designed to avoid accumulation of particles. Blind cavities in the flow path that could act as a particle trap shall be avoided. The flow path design shall permit easy removal of any particles with standard cleaning processes (e.g. purging with liquid or gas). Surface area in contact with operational media shall be minimised.



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3.4.5 Valve Stability

The valve shall meet the requirements herein when operated in any attitude or zero-gravity.

The valve shall not change its selected position (open or closed) during surge pressure, surge flow or during the environmental loads specified herein.

3.5 Operational Requirements

3.5.1 Storage Life

The valve shall meet all performance requirements after having been suitably packed and stored for 5 years. After this storage period and integration into the propulsion system, the valve shall meet all performance requirements after 14 months of propulsion system storage.

3.5.2 Operational Life

After storage and integration activity, the valve shall meet all performance requirements after being in contact with the operating media and under the specified natural environment for a minimum period of 12 months.

3.5.3 Cycle Life

The valve shall be capable of meeting the functional requirements after being subjected to: • 900 (TBC) wet activation cycles and 360 (TBC) dry activation cycles.

One activation cycle shall consist of actuation to the open position followed by actuation to the closed position. The pause duration (no current) between opening and closing and between closing and opening should be > 1 s (TBC). The position indications shall be monitored during the cycle test. The cycles shall be verified at maximum operating inlet pressure using deionised water as the test medium.

• 30000 back relief cycles (including TBD dry cycles).



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3.6 Human Factors Requirements

The valve design shall allow ease of handling and installation. The valve design shall avoid characteristics that may cause injury/health hazards to personnel during handling or installation, including the following: • Sharp edges • Personnel exposure to toxic substances or materials • Corrosive substances The operating media are predefined in this specification and are thus excepted from this requirement.

3.7 Product Assurance Requirements

3.7.1 Feared Events (For Flight Units)

The valve shall be designed to preclude the following feared events. Events with Catastrophic Consequences

• Burst of unit

• External leakage of Propellants beyond specified limits

• Leakage between MON and MMH paths of low flow valve

• Valve fails to open • Valve fails to close (or fails to close in sufficient time)

Events with Critical Consequences • External leakage of Helium beyond specified limits • Uncommanded position change

Events with Major Consequences • Internal leakage (valve seat) beyond specification limits • Insufficient opening (pressure drop too high) • Valve fails to close • False position indication • Loss of back relief valve function



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3.7.2 Failure Tolerance

The valve shall have a failure tolerant power/command electrical circuit (i.e. primary and redundant circuits). After failure of the primary circuit, the redundant circuit shall be able to open or close the valve in accordance with the requirements of this specification.

3.7.3 Failure Propagation and Redundancy Policy

The valves shall be designed such that failure of one of the circuits (i.e. primary power, redundant power or position indicator circuits) shall not propagate failure to the others. The redundant sections of the valve shall be able to be tested individually.

3.7.4 Availability

After final installation into the propulsion system, the valve shall not require any further preparation prior to operation.

3.7.5 Reliability

The valve shall fulfil its main functions during its life duration under the specified environmental conditions with a probability of success:

R ≥ 0.99999 at a confidence level of 60 %

3.7.6 Maintainability

The unit shall not require any maintenance effort during its life duration.

3.7.7 Safety

The valve design shall minimise hazards originating from assembly, handling, testing, integration and operation. Hazardous procedures and hardware items of the unit shall be marked.



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3.8 Configuration and Implementation Requirements - N/A

3.9 Design Requirements

3.9.1 General Design

3.9.1.1 Past Valve Anomalies

The valve shall be designed to preclude anomalies described in RD1.

3.9.1.2 Plastic Deformation

The valve and its components shall not undergo plastic or other non-recoverable deformation when subjected to the operational and test conditions defined in this specification, unless the this non-recoverable deformation and its location has been specifically identified as an intended part of the approved design.

3.9.1.3 Crack Formation

Static and cyclic loading as defined herein shall not induce cracks in the valve or its components.

Valve design and processing shall preclude the introduction of contaminants that can degrade material properties and increase the likelihood of cracking or functional failure (e.g. embrittlement due to hydride formation).

3.9.1.4 Operational Margin

The valve’s functional dimensioning and operational margin shall be in accordance with section 4.7.5.3 of AD28.

3.9.2 Electrical Design

3.9.2.1 Grounding

All the wired interfaces shall use wired returns. They shall be electrically isolated from the valve housing.



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Signal circuits interfacing between equipment shall follow the distributed single point grounding system. Where single-ended signal sources are used (i.e. signal return and ground reference are interconnected), the signal destination shall isolate the signal lines from chassis ground (differential amplifier, opto-coupler, solid state relay, transformer). Vice versa, where the signal source is completely isolated (e.g. contact closure) the destination shall not be isolating but can be single-ended.

Isolation according to Figure 3.9.2.1-1 shall be maintained for the nominal operating frequency of the signal interface.

Figure 3.9.2.1-1 - Signal Interface Isolation

3.9.2.2 Shield Termination/Connector Shells

All cable shall be grounded at least at both ends (signal source and destination).

3.9.2.3 Bonding Equipment shall be designed to achieve a bonding resistance of equal or less than 2.5 mΩ per bonding junction between:



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• different parts of the equipment chassis, • connector receptacles and equipment chassis/connector brackets, • equipment chassis and bonding strap (if used) • bonding strap (if used) and structure

Te valve mounting surfaces shall be unpainted. Any protective coating shall produce a conductive surface suitable for electric bonding. Additionally the valve shall have an attachment point for bonding between valve and structure preferably a component mounting flange. The valve shall be designed to achieve a resistance to the bonding point of: R < 2.5 mΩ

3.9.2.4 Cable Shielding

The unshielded length of the twisted conductors at the shield termination shall not exceed a length of 2.5 cm.

Cable shielding shall not be used as intentional current-carrying conductor, except coaxial cables in radio frequency circuit interfaces.

3.9.3 Structural Design and Fracture Control

The contractor shall comply with requirements of AD4; however, the last paragraph of AD4, Appendix 3, section 4.8 shall be replaced by:

“For lines fittings and components, safe life analysis may be omitted if the item is proof tested to a level of 1.5 or more times the design limit load, including MDP and vehicle accelerations. NOTE: Where the proof factor of 1.5 on limit load/stress cannot be achieved, e.g. due to bending of tube ends, additional NDI (esp. of welds, e.g. high sensitivity eddy current inspection) shall be considered.”

The following additional requirements shall also be met:

All flight hardware structure shall be designed to preclude failure resulting from cumulative damage due to cyclic loading and sustained stress experience during its service life

The dimensioning lifetime shall be four times the service lifetime. For fatigue analysis, the alternating and mean stress / strain shall include the effects of stress concentration factors when applicable. The limit stress / strain shall be multiplied by a minimum factor of 1.15 on typical properties or 1.0 on lower bound properties prior to entering the stress versus cycle life (S/N) design curve to determine the low cycle / high cycle life. NOTE: this requirement applies to analytical verification. When fatigue verification is performed by test on representative hardware (e.g. QM), the factor on stress does not need to be applied.



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3.9.4 Parts, Materials and Processes

The selection of materials, parts and processes shall consider the required quality level of the final product and shall be defined in a declared materials, parts and processes list approved by ESA.

All materials and protective finishes shall be resistant to the operational media, test media and their vapours and shall provide the required long-term compatibility with these.

3.9.4.1 EEE Parts

The selection, control and usage of EEE parts shall be in accordance with AD16. The derating of EEE parts shall be in accordance with AD15.

3.9.4.2 Materials

The materials used in the design and fabrication of the unit shall be selected in accordance with the AD14.

3.9.4.3 Lubricants

No lubrication oils or greases shall be used on this valve.

3.9.4.4 Processes Processes to be used in the manufacturing shall be selected according to the following criteria: successful usage history future availability process covered by qualified specifications availability of trained personnel and of approved and audited facilities

All processes shall be indicated in the appropriate processes list and will be controlled via these lists.

3.9.4.5 Welding

The welding technique shall be such to achieve a maximum joint efficiency with a minimum of heat input. The joint shall be in conformance with AD18. All welding shall be in



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conformance with accepted welding practices to avoid interstitial contamination, metal vapour condensation and temper colours. All welds shall be performed in accordance with the following processes: GTAW (Tungsten Inert Gas) per AD19 PAW (Plasma Arc Welding) EBW (Electron Beam Welding) LBW (Laser Beam Welding)

Inert shielding gas must be either reactor grade helium or vaporized liquid argon (per AD20). All operators performing fusion welding shall be certified per AD21 or national equivalent standard.

Weld qualification shall show that particular parameter settings of a specific weld machine will repeatedly produce an acceptable weld (including weld repairs). Qualification shall be completed prior to welding the first production assembly of a new design. The weld qualification report shall be approved by ESA.

Prior to any welding, the following steps shall be taken to ensure conformity to the requirements of this specification: • At the optimum setting determined during weld qualification, weld samples shall be made. • The sample shall pass the visual inspection. • The required weld penetration shall be verified either by visual inspection or by micro

section. All welds shall be inspected: • Visually per AD22 • X-ray per AD23 All welds shall meet the requirements of AD24. Welds may be dressed to leave 0.03 mm minimum to 0.3 mm maximum reinforcement. The surface exposed to the flow stream shall have a surface finish of 1.6 m RMS. Materials selected for the tubing interfacing with the propulsion system shall be compatible with and weldable to propulsion system tubing.

3.9.4.6 Soldering

Soldering shall be performed in accordance with AD25.



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3.9.4.7 Protective Coating

Where materials used in the construction of the unit are subjected to deterioration if exposed to climatic and environmental conditions likely to occur during service usage, they shall be protected against such deterioration in a manner that will in no way prevent compliance with the performance requirements of this specification. The use of any protective coating that will crack, chip or scale with age or under extreme climatic and environmental conditions shall be avoided. Any protective coating used shall not contaminate or affect the performance of the process or test fluids.

3.9.4.8 Moisture and Fungus Resistance

Only materials which will resist degradation from moisture and fungi shall be used.

3.9.4.9 Corrosion

All surfaces normally in contact with the atmosphere during the life of the valve have to resist the environment specified herein without any deterioration. Surfaces of materials which are not inherently resistant to the stated requirements shall be suitably protected.

Materials susceptible to stress corrosion cracking shall be avoided. Materials with high resistance to stress corrosion cracking shall be selected in accordance with AD12 and AD13.

Selected materials which are not inherently resistant to corrosion shall be suitably protected against the anticipated corrosion environment. Dissimilar metals, as defined in AD29 shall not be used in intimate contact without suitable protection against galvanic corrosion. Where the use of dissimilar metals in contact cannot be avoided, adequate insulation between the metals or approved plating on one of the surfaces shall be used.

3.9.4.10 Compatibility

All parts and materials in contact with the operating and test media shall be compatible and resistant, without degradation or reaction and without corrosion or surface damage of an amount which could affect the performance parameters to be achieved for the operating durations specified herein.

The valve shall be designed to withstand external exposure to propellant vapours for a period of two hours and liquid splash for one minute with provisions to purge or wash away any residual propellant or the propellant fumes within one hour after exposure. The external surface of the unit shall also be designed to be cleaned with IPA.



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3.9.4.11 Contamination Resistance

Contamination by the operational and test media specified herein shall not result in any corrosion or damage to painted surfaces or cause deterioration of materials or components which could influence the reliability or performance of the unit. Where contamination is likely to cause corrosion, a suitable corrosion resistance treatment shall be applied to the material.

The valve shall not show any performance degradation when exposed to a pollution within the levels specified in sections 3.9.4.13 and 3.9.4.14 below.

3.9.4.12 Inlet Filter

The valve shall include an inlet filter to protect against degradation from contaminants originating upstream in the propulsion system. The filter shall be sized to ensure compliance with cleanliness requirements and valve pressure drop requirements.

3.9.4.13 Cleanliness

Valve cleanliness requirements shall be met in accordance with AD26, AD27 and section 3.9.4.14 below.

The cleanliness conditions and environmental control at the supplier’s facility shall be in accordance with AD30 class 100,000. For qualification and flight units, the contractor shall implement provisions to ensure: • Correct cleanliness levels for manufacturing, assembly, integration and test areas • Valve, valve component and test equipment protection from contamination by proper

preservation, packaging and storage.

3.9.4.14 Cleanliness Levels

After cleaning the valve, then flushing with 100 ml of IPA and collecting all particles, the particle count shall be in accordance with Table 3.9.4.14-1 below.

Table 3.9.4.14-1 Particle Size (micron) Max. Permissible Counts per Sample

> 100 none 51 - 100 1 (non-metallic) 26 - 50 5 11 - 25 20 6 - 10 140

less than 6 no silting NVR less than 1 mg/100 ml liquid



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Drying shall be performed within one hour after flushing or cleanliness verification to remove all traces of test liquid. The dryness shall be: ≤ 10 ppm of IPA ≤ -40 deg C dew point of GN2

This level shall be achieved via a qualified drying process. The use of water as a test or cleaning medium should be minimised. Instant drying after each application is recommended.

3.9.4.15 Interchangeability

All valves of the same part number must be completely interchangeable without recalibration and adjustment. All means shall be considered to avoid maintenance faults due to human error, such as misconnecting of lines, electrical connector or incorrect interchange of components or the unit itself. Where, due to human errors incorrect interchange of components affecting operation, safety or reliability may be possible, the parts shall be made physically non-interchangeable and non-reversible by design.

3.9.4.16 Identification Each valve shall be permanently marked with the following data: • Customer furnished identification number • Manufacturers trade name and trade mark • Manufacturers part ID number including index • Manufacturers serial lot number • Flow arrow • Date of manufacture

3.9.4.17 Workmanship

The workmanship shall be in accordance with manufacturing and process standards and procedures that are documented, controlled and approved.

3.10 Verification & Testing Requirements

Full valve qualification will be required in a later phase of the valve development. Verification of compliance with each of the requirements in the valve specification will be



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required for valve qualification. This will be accomplished by testing, analysis, inspection or clear demonstration of similarity to an acceptably qualified component.

Acceptance testing will be required for all qualification and flight hardware.

The contractor shall consider these future qualification and acceptance requirements in the design and development activity described in this SOW.

For the development activity described in this SOW, verification of the requirements in this Technical Requirements Specification shall be demonstrated as follows: • Development tests (as defined below). • Similarity of valve components to other components previously qualified (if applicable). • Analysis of design – For verification of requirements not covered by development tests or

similarity, the contractor shall utilise analysis to show that the design meets the requirements; or for cases where the design does not yet meet the requirements, the contractor must clearly show in detail how the design will be refined to ensure requirements compliance at the time of qualification.

Gases and liquids used for testing shall be in accordance with the relevant applicable document as specified in section 3.1.1. The verification applicable to this SOW shall also demonstrate that the design prevents the anomalies as defined in RD1.

3.10.1 Development Tests

As part of the preliminary design and development tasks defined in the SOW, the following tests are to be performed on the development model in accordance with a test plan generated by the contractor and approved by ESA. The contractor may opt to perform additional testing at component or valve level as a development aid or for requirements verification. This additional testing shall be identified in the development plan. If the additional testing is to be used for verification then it shall also be included in a test plan to be approved by ESA.

Test equipment used shall be suitable for the intended purpose. The measurement approach shall be included in the test plan and must be approved by ESA. Measurement capability shall be sufficient to meet verification and performance demonstration needs. Test equipment shall include a valve driver that can interface with the valve and provide the range of inputs needed for the testing. The driver characteristics shall be representative of the Propulsion Drive Electronics as specified in section 3.2.4.1.



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3.10.1.1 Compatibility Testing

Compatibility testing shall be performed in accordance with AD31 to demonstrate compliance with section 3.9.4.10 herein. Where former testing has been performed with the relevant materials, the results of this testing may be used providing the testing was performed in accordance with AD31.

3.10.1.2 Leak Testing

Leak testing shall be performed to verify compliance with external and internal leakage requirements of section 3.1.7 with the valve in open and closed positions.

3.10.1.3 Characterisation of Functional/Electrical Behaviour

The following functional/electrical tests shall be performed to verify compliance with the requirements of this specification:

a. Opening and closing voltage – to be performed at nominal and worst case conditions (temperature and pressure).

b. Response time (opening and closing time) – to be recorded during each of the opening and closing voltage tests.

c. Electric power consumption – to be performed at all combinations of maximum and minimum voltage and temperature at: 1) actuator level, 2) valve level in vacuum and 3) valve level with representative fluid at worst case pressure.

d. The valve shall be tested to determine the maximum over-voltage level and duration without degradation (i.e. determine margin on the 54V requirement).

e. Coil resistance – for each operational circuit at maximum, nominal and minimum temperatures.

f. Maximum pulse length – 60 second pulse.

g. Functional/Operating margin as defined in section 3.9.1.4.

h. Position indicator functioning.

i. Dielectric strength, insulation resistance. These tests may be performed at actuator level.

j. Bonding.

3.10.1.4 Activation Cycle Testing

The valve shall be subjected to 900 (TBC) wet activation cycles and 360 (TBC) dry activation cycles in accordance with section 3.5.3.



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The valve shall be subjected to 30000 (TBC) back relief cycles in accordance with section 3.5.3.

3.10.1.5 Pressure Cycle Testing

Pressure cycle testing shall be performed. Quantity and characteristics of pressure cycles to be performed are TBD. Operating media for these tests is TBD.

3.10.1.6 Static and Dynamic Pressure Tests

The valve shall be subjected to static proof pressure tests at levels defined in section 3.1.3 herein.

Testing shall be performed to characterise pressure dynamics (associated with valve activation under nominal and worst case conditions) at: 1) valve seal, 2) valve inlet and 3)valve outlet. The intent of this testing is to show pressure peaks that the valve can generate and the valve’s ability to withstand these pressure peaks. Operating media for these tests is TBD.

3.10.1.7 Flow and Pressure Drop

Testing shall be performed to demonstrate nominal and maximum flow capabilities (both high flow and low flow valve requirements). This testing shall show compliance with the pressure drop requirements defined herein. Back pressure relief performance testing shall also be included. Operating media for these tests shall be representative of the propellants to be used.

3.10.1.8 Environmental Tests

Vibration and shock testing shall be performed. Operating media to be used during this testing is TBD. Leakage shall be monitored during this testing and shall meet the leakage requirements as specified in section 3.1.7 (external) and 3.3.2 (internal).

3.10.1.9 Temperature tests

Testing shall include valve exposure to upper, lower and nominal operational temperatures defined herein. This shall be applicable for valve body, actuator and position indicator. Integration of this testing with other tests noted above is to be agreed by ESA.

3.10.1.10 Thermal Vacuum Testing (TBD)



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3.10.1.11 Cleanliness

Cleanliness tests shall be defined and performed in accordance with AD27 and to the levels specified in sections 3.9.4.13 and 3.9.4.14 herein.

3.10.1.12 Reference Testing

The contractor shall define and perform reference tests sufficient to demonstrate that valve performance has not degraded after the testing noted above. Among these tests, non-destructive testing to verify absence of non-recoverable deformation shall be included.

3.10.2 Acceptance Tests

Table 3.10.2-1 below lists the sequence of acceptance tests currently foreseen. This list and the test descriptions will be refined for use in later phases of the valve development.

Table 3.10.2-1 - Acceptance Tests Initial Inspection and Examination Proof Pressure (valve open and closed) External Leakage Reference (Function) Tests at Ambient Temperature - Internal leakage - Insulation - Dielectric strength - Opening / closing voltage - Coil resistance - Response time - Contact resistance Vibration Tests

- Random vibration including resonance search Reference (Function) Tests at Ambient Temperature - External leakage - Internal leakage - Insulation - Dielectric strength - opening / closing voltage - coil resistance - response time - contact resistance Thermal Reference (Function) Tests - Internal leakage



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- External leakage - Insulation - Dielectric strength - Coil resistance - Opening / closing voltage - Response time - Contact resistance Flow Characteristics and Pressure Drop - Nominal flow with pressure drop and pressure fluctuation recorded - Maximum steady state flow with pressure drop and pressure fluctuation recorded - Surge flow - Back pressure relief Cleanliness Verification Final Examination

3.10.3 Qualification Tests

Qualification tests shall be performed on TBD number of qualification valves. Table 3.10.3-1 below lists the sequence of qualification tests currently foreseen. This list and the test descriptions will be refined for use in later phases of the valve development.

Table 3.10.3-1 - Qualification Tests Acceptance Test (perform proof pressure test ten times in open and closed positions) Vibration Tests - Resonance search - Sinusoidal vibration - Random vibration - Transport vibration - Pyrotechnic shock Reference (Function) Tests at Ambient Temperature - Internal leakage - Opening / closing voltage - Coil resistance - Response time - Contact resistance - Flow characteristics and pressure drop

- Nominal flow with pressure drop and pressure fluctuation recorded - Maximum steady state flow with pressure drop and pressure fluctuation recorded - Surge flow - Back pressure relief

- Unsymmetrical pressure test (for low flow LV option B only)



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Thermal Vacuum Reference (Function) Test (hot, cold, thermal shock, damp heat) - Internal leakage - External leakage - Opening / closing voltage - Response time - Coil resistance - Contact resistance - Insulation - Dielectric strength Reference (Function) Tests at Ambient Temperature - Internal leakage - Insulation - Dielectric strength - Flow characteristics and pressure drop


- opening / closing voltage - coil resistance - response time - contact resistance Life Cycle Test - Activation cycle and pressure cycle testing (including back pressure relief cycles) Maximum pulse length – 60 second pulse Reference (Function) Tests at Ambient Temperature - External leakage - Internal leakage - Insulation - Dielectric strength - Flow characteristics and pressure drop


- opening / closing voltage - coil resistance - response time - contact resistance Cleanliness Verification EMC Tests Radiation Tests (TBC) Burst Pressure Test Final Inspection



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