Solenoid Valves and Ball Valves: Seats, Oxygen Compatibility, Cryogenic Service and Leak Testing
Solenoid valves open and close a flow path electrically, and ball valves do it with a quarter turn of a ported ball, by hand or with an actuator. For ground and test stand use, seat material, oxygen compatibility under ASTM G88, G94 and G63, cleanliness under ASTM G93 and a stated helium leak rate govern the purchase.
Updated
Valve types and where they are used
Most solenoid and ball valves bought through aerospace programs go into ground systems: test stands, propellant and pressurant panels, servicing carts and facility gas lines. Flight valves are usually program designed, qualified components bought by drawing from a qualified source, so the buying rules differ.
| Valve | How it works | Typical use |
|---|---|---|
| Direct acting solenoid valve | The coil lifts the plunger off the seat directly | Small orifices, low flow pilot, sampling and purge lines |
| Pilot operated solenoid valve | The coil opens a small pilot, and line pressure moves the main seat | Larger flows where a minimum pressure differential is available |
| Manual ball valve | Quarter turn of a ported ball between two seats | Isolation, vent and drain points on panels and stands |
| Actuated ball valve | Pneumatic or electric actuator turns the ball, often with position switches | Remote isolation, sequenced operations, fail safe shutoff on test stands |
| Cryogenic ball valve | Extended bonnet keeps stem packing away from the cold fluid | Liquid nitrogen, liquid oxygen and other cryogenic lines |
Two questions decide the type before anything else: does the valve have to fail open or fail closed when power or control air is lost, and does it need to show its position to the control system. Write both on the request.
Ground support and test stand valves versus flight valves
Ground and flight valves are bought under different rules. Ground valves are usually commercial or industrial products selected for the duty and installed under the governing pressure system code, while flight valves are qualified to a program specification and bought by part number from a qualified source.
- Ground systems at NASA sites. NASA-STD-8719.17 Revision D governs ground-based pressure vessels and pressurized systems and points new process piping to ASME B31.3. Valves are components of that piping, so the valve's pressure and temperature rating, materials and documentation have to support the system certification.
- Commercial sites. ASME B31.3 or the owner's own pressure system rules usually apply directly. Our tube and fluid systems guide covers the B31.3 test and documentation side.
- Flight hardware. Buy to the drawing and the qualification record. A commercial valve with matching ports and ratings is not a substitute for a qualified flight valve, even on a test article, unless engineering approves it in writing.
For solenoid valves on ground systems, also state the coil voltage, duty cycle, electrical connector or lead type, enclosure rating and any hazardous location classification at the site. A coil rated for intermittent duty will overheat if it is held energized on a long test.
Have a part like this?Send it in under a minute. A person replies within 1 business day.The specifications and guides buyers should cite
There is no single procurement specification for commercial solenoid and ball valves, so the purchase is defined by the guides and codes the system follows. The ASTM oxygen guides are written as guides, not specifications: they tell the designer how to evaluate risk rather than giving a pass or fail.
| Document | What it covers | Status as verified |
|---|---|---|
| ASTM G88 | Standard guide for designing systems for oxygen service, focused on what leads to ignition and fire; can be used to audit existing systems | ASTM store lists G88-21 |
| ASTM G94 | Standard guide for evaluating metals for oxygen service | ASTM lists G94-22 |
| ASTM G63 | Standard guide for evaluating nonmetallic materials for oxygen service, limited to nonmetals after G94 was created for metals | G63-15, reaffirmed 2023 |
| ASTM G93/G93M | Cleanliness levels and cleaning methods for materials and equipment used in oxygen-enriched environments | ASTM lists G93/G93M-25 |
| ASTM E499/E499M | Leak testing with a mass spectrometer leak detector in detector probe mode, for leaks of about 1 x 10^-8 std cm3/s and larger | Current listing reapproved 2025; confirm the current revision on ASTM |
| NASA-STD-8719.17 Revision D | Ground-based pressure vessels and pressurized systems at NASA sites | Approved 26 April 2022 |
| ASME B31.3 | Process piping, including the components installed in it | Confirm the edition your site invokes |
ASTM notes that G88 is meant to be used with G63 and G94 for a full fire hazard review of an oxygen system. A buyer's job is to require the valve maker's oxygen service data and cleaning level so the system designer can complete that review.
Seats and seals: PTFE, PCTFE, Vespel and others
The seat material sets the valve's temperature range, its tolerance of particles, and much of its oxygen risk. ASC Engineered Solutions' published bulletin on ball valve seat and seal materials (EB-2002, revision B, September 2025) is a clear example of how makers describe the choices.
| Seat material | What the maker states | Buying notes |
|---|---|---|
| Virgin PTFE | Excellent chemical resistance, low friction; temperature range is load dependent and read from the valve's pressure and temperature curves | Common default; cold flow under load at temperature |
| Reinforced PTFE | Filler improves strength, stability and wear, allowing higher pressure and wider temperature ratings than unfilled PTFE | Ask what the filler is when the valve is for oxygen |
| PCTFE | Non-flammability, chemical resistance and near zero moisture absorption, which suits cryogenic service | Frequent choice for cryogenic and oxygen seats |
| Vespel SP-21 polyimide | 15 percent graphite filled; continuous operating range from cryogenic temperatures to 550°F (288°C); special order | Long lead item at some makers |
| PEEK | Water and steam up to 600°F (316°C); not suitable for sulfuric acid | Hot service rather than cold |
| Acetal (Delrin) | Rigid, low wear, not a high temperature material; the bulletin says not to use it in oxygen service | Reject for any oxygen line |
Always read the specific valve's pressure and temperature curve rather than a generic material range; the same seat rates differently in different body sizes and pressure classes. Stem and body seals need the same review, since an elastomer stem seal can be the limiting part in cold or oxygen service.
Oxygen compatibility
Oxygen compatibility is a property of the valve in its system, not of a material alone. ASTM G88 frames the review around ignition mechanisms, and G94 and G63 cover the metals and nonmetals that are present. Fast opening valves deserve particular attention, because rapid pressurization of a dead ended volume downstream heats the gas and can ignite soft seats and contamination.
- Ask the valve maker for the materials of every wetted part, including seats, seals, lubricants and thread sealants.
- Ask whether the valve is offered in an oxygen cleaned and tested configuration, and to what cleaning specification and level.
- For ball valves in oxygen, ask how the valve is to be operated; quarter turn valves open quickly, and many system designs restrict where they are used on high pressure oxygen.
- Require that no substitutions of seat, seal or lubricant be made without approval.
Cleaning sequence and certificates are covered on our precision oxygen cleaning page and the cleaning reference.
Cryogenic service
Cryogenic valves need materials that stay tough when cold, seats that seal after shrinking, and a stem seal kept warm enough to work. Plastic seats get harder and can crack at cryogenic temperature, so makers pair PCTFE or polyimide seats with metal seat rings or springs to keep load on them.
- Extended bonnet. A longer bonnet keeps the stem packing away from the cold fluid so it does not freeze or leak. State the service temperature so the maker can size the extension.
- Body cavity relief. Liquid trapped in the ball cavity of a closed valve can warm and build pressure. Many cryogenic ball valves vent the cavity to one side, which makes the valve directional; the installed flow direction must match the marking.
- Testing cold. Ask whether seat leakage was tested at cryogenic temperature or only at room temperature with gas.
- Solenoid valves. Confirm the coil and plunger materials are rated for the cold, and that the valve opens against the pressure differential at temperature.
Leak rate specifications and helium testing
Write the allowable leak rate as a number, a unit, a test gas, a pressure and a method, separately for seat leakage and for external leakage. "Bubble tight" or "zero leakage" cannot be verified at receiving.
- Seat leakage. Flow past the closed seat, usually measured with gas at a stated upstream pressure.
- External leakage. Leakage through the body joints and stem seal to atmosphere. Helium mass spectrometer testing finds small external leaks; ASTM E499 describes the detector probe method for leaks of about 1 x 10^-8 std cm3/s and larger, with one method to locate leaks and one to accumulate for a rate.
- Conditions. Give the pressure, the temperature, and whether the test is done before or after cleaning.
For systems that will be leak tested as a whole after installation, ask the valve maker for its factory leak data so a failed system test can be traced quickly.
How the part number is built
Commercial solenoid and ball valve part numbers are maker specific configuration codes for body material, size, end connection, seat, seal, actuator and options. We did not find a coding scheme we could verify that applies across makers, so we do not decode one here.
Read the configuration from the maker's current catalog page for that series, confirm every option against your requirement, and copy the full code onto the PO. A single character can change the seat material or the cleaning option, and an abbreviated number invites a substitute.
Documentation to ask for
- Certificate of conformance tying the serial or lot to your PO; see our C of C guide
- Material certs for pressure containing parts, traceable to heat
- Pressure and temperature rating for the exact configuration
- Seat and external leak test records with method, gas, pressure and result
- Cleaning certificate with specification, level and verification data for oxygen or propellant service
- Coil data for solenoid valves: voltage, power, duty cycle and enclosure
- Actuator data, position switch data and fail position for actuated valves
- Installation and maintenance instructions, including flow direction
Ordering checklist for solenoid and ball valves
- Full maker part number or configuration code, or the drawing for flight valves
- Fluid, pressure, temperature range, and fail position
- Body, seat and seal materials and any lubricant, with no substitution without approval
- End connections matched to your fittings; see our fluid fittings page
- Allowable seat and external leak rates with method
- Cleaning specification, level and packaging
- DFARS specialty metals clause where the contract carries it; see our specialty metals page
- Governing code and site requirements, such as NASA-STD-8719.17 or ASME B31.3
- Elastomer cure dates and shelf life for soft sealed valves
Counterfeit and quality risks, and how to receive valves
The common problems are valves with substituted seats or seals, refurbished valves sold as new, and valves sold as oxygen cleaned that were never cleaned to a stated level. The inside of a valve is where the risk sits, so records matter more than appearance.
- Buy from the maker or its authorized and franchised distributors.
- Check marking, configuration code and flow direction arrow against the order.
- Do not open the bag of an oxygen cleaned valve at receiving; inspect the label, seal and certificate, and reclean if the bag is damaged.
- Function check solenoid valves at the rated voltage and actuated valves through full travel before installation.
See our counterfeit parts avoidance process and receiving inspection guide.
How we source solenoid and ball valves
We do not hold inventory or publish prices, and we are not an authorized distributor for any valve maker. We source valves from the manufacturer or through authorized and franchised distributors, flow down the configuration, cleaning, leak test and documentation requirements, and check the paperwork before shipment.
Valves for a panel or test stand can go on one purchase order with the relief and check valves, filters, quick disconnects, hose and the fabricated frame, so the whole ground support equipment build is tracked as one job. Discontinued valves are searched under our obsolete parts controls. See the full fluid components family.
Request solenoid or ball valves
Use the fluid systems quote form and include the maker part numbers or drawing, fluid, pressure, temperature, fail position, seat material, leak rate and cleaning level. A person replies within one business day, and rush requests are prioritized. Proprietary panel drawings can be shared under our confidentiality process.
Send the job. A person replies within 1 business day.
Part, quantity and date are enough to start. Drawings and the mutual NDA follow by reply, and controlled programs never send technical data through this site.
We have it.
Reference . A person replies within 1 business day. Watch for our email from [email protected].
Questions
Which seat material is best for a liquid oxygen ball valve?
There is no single answer; the system designer decides using ASTM G88 with G63 for nonmetals. PCTFE is a common choice because makers cite its non-flammability and suitability for cryogenic service, and polyimide such as Vespel SP-21 is rated by one maker from cryogenic temperature to 550°F. Acetal should not be used in oxygen. Require the valve maker's oxygen service data for the exact configuration.
Why do cryogenic ball valves have an extended bonnet?
The extension moves the stem packing away from the cold fluid so it stays warm enough to seal and operate. Without it, the packing can freeze, leak or seize the stem. Give the maker your service temperature so the extension length suits it, and check whether the valve vents its body cavity to one side, which makes the installed flow direction matter.
How should I specify valve leak rate?
Give separate numbers for seat leakage and external leakage, each with units, test gas, test pressure, temperature and method. For external leakage on gas systems, helium mass spectrometer testing is common; ASTM E499 covers the detector probe method for leaks of about 1 x 10^-8 std cm3/s and larger. Avoid terms like bubble tight or zero leakage, which cannot be verified at receiving.
Can I use an industrial solenoid valve on a test stand?
Often yes for ground systems, if it is rated for the fluid, pressure, temperature and duty cycle and the governing code for the site accepts it. At NASA sites, ground systems fall under NASA-STD-8719.17, which points process piping to ASME B31.3. Check coil duty cycle, enclosure and hazardous location rating. Flight hardware is different: use only valves qualified to the drawing.
Do ASTM G88, G94 and G63 certify a valve for oxygen?
No. They are guides. G88 covers designing systems for oxygen service, G94 evaluating metals and G63 evaluating nonmetals, and ASTM describes using them together for a fire hazard review. They help an engineer decide whether a valve is acceptable in a specific system. Cleanliness is a separate requirement, covered by ASTM G93 or your program's cleaning specification.
Related
Sources
- ASTM G88: Standard Guide for Designing Systems for Oxygen Service
- ASTM G94: Standard Guide for Evaluating Metals for Oxygen Service
- ASTM G63: Standard Guide for Evaluating Nonmetallic Materials for Oxygen Service
- ASTM G93/G93M: Cleanliness Levels and Cleaning Methods for Oxygen-Enriched Environments
- ASTM E499/E499M: Mass Spectrometer Leak Detector in the Detector Probe Mode
- ASC Engineered Solutions EB-2002 Rev B: Ball Valve Seat and Seal Materials
- NASA-STD-8719.17 Revision D, Ground-Based Pressure Vessels and Pressurized Systems
- ASTM oxygen-enriched atmospheres standards listing
Ready to
source it?
A person replies within 1 business day. NDA first.
Request a quote