Novec 7100 Replacement: What NASA’s Testing Says About Your Options

Finding a Novec 7100 replacement stopped being a planning exercise once 2026 arrived. In December 2022, 3M announced it would exit PFAS manufacturing by the end of 2025, and Novec engineered fluids, widely used in aerospace precision cleaning, were part of that exit.

Since then, a long line of suppliers has stepped forward, each claiming to have the drop-in Novec 7100 replacement. What was missing was independent data. That changed this year. A NASA Engineering and Safety Center (NESC) assessment published its test results on HFE-7100 alternatives, and Kennedy Space Center named the solvents it plans to add to its surface cleanliness specification.

This guide covers what NASA found, why oxygen service raises the stakes, and what to ask before you trust any vendor's solvent switch with your hardware.

Key Takeaways

1. There is no universal Novec 7100 replacement. NASA's assessment and a KSC memorandum point to five candidate paths, and each carries trade-offs.
2. Molecularly equivalent HFE-7100 products keep processes nearly unchanged, but they are still PFAS.
3. Opteon SF33 and Amolea AS-300 cleaned best in NASA's lab testing. BestSolv Sierra was a solid third.
4. In oxygen service, autoignition temperature matters. SF33 and Sierra cleared NASA's preferred 204 °C line. AS-300 did not.
5. Solstice PF has a documented NASA oxygen-cleaning record dating to 2015, but its 19 °C boiling point makes it hard to drop into equipment built for HFE-7100.
6. KSC-C-123 has not been revised yet, so confirm what your contract specification allows before accepting a substitute.

Why Was HFE-7100 So Hard to Replace?

Because it did several jobs at once, and it did them in oxygen service. HFE-7100 was nonflammable, low in surface tension, quick to dry, and effective on the fluorinated greases and light hydrocarbons common on aerospace hardware. NASA facilities adopted it in the late 1990s and early 2000s as CFC-113 and HCFC-225 were phased out.

The bigger issue is where it sat in the process. NASA's 2026 HFE replacement assessment notes that HFE-7100 was frequently the only approved solvent for the final flush and cleanliness verification of oxygen system components at multiple NASA cleaning facilities. A true Novec 7100 replacement has to clean the part, serve as the fluid that nonvolatile residue (NVR) is measured in, and stay safe if a trace remains inside an oxygen line.

The market also turned out to be thinner than it looked. When NASA surveyed available products, many "new" solvents proved to be the same source chemical repackaged under different brand names.

Five Solvent Paths Identified for the Next KSC-C-123 Revision

In 2026, Kennedy Space Center's Engineering Directorate issued a memorandum (NASA-06545) to Precision Fabricating & Cleaning stating which solvents will be added to KSC-C-123, the KSC surface cleanliness specification for ground support equipment fluid systems, when it is revised. The list tracks the findings of the NESC assessment:

• Molecular equivalents of HFE-7100. NASA evaluated Inventec's Promosolv DR3. Equivalents from other makers need purity verification to confirm they match.
• Solstice PF / PF-HP (Honeywell, now Solstice Advanced Materials). Not retested this round. NASA relied on a 2015 evaluation that selected Solstice PF to replace HCFC-225 at Marshall and Stennis.
• Opteon SF33 (Chemours). Evaluated directly. Equivalents need purity verification.
• Amolea AS-300 (AGC). Evaluated directly, with oxygen-service caveats covered below.
• BestSolv Sierra (Best Technology). Evaluated directly. Equivalents need purity verification.

Here is how the options compare on the numbers NASA published:

Option	Boiling point	Cleaning (NASA lab)	Lowest measured oxygen AIT	Main caution
HFE-7100 / molecular equivalent	61 °C	Baseline	336 °C	Still PFAS; verify identity and purity
Solstice PF / PF-HP	19 °C	Selected by NASA in 2015	180 °C (impact threshold 7,500 psi)	High volatility; equipment changes
Opteon SF33	33 °C	Top tier	260 °C	High vapor pressure and evaporative loss
Amolea AS-300	54 °C	Top tier; best on silicone grease	151 °C	Less preferred for enriched oxygen; 4340 steel
BestSolv Sierra	56 °C	Third	243 °C	50 ppm recommended exposure limit; 4340 steel

Source: NASA NESC-RP-23-01850 (2026). AIT values are the lowest results measured in 2,000 psi oxygen under NASA test conditions. HFE-7100 and Solstice PF data come from earlier White Sands Test Facility testing cited in the report.

Read the table as a set of trade-offs, not a ranking. The strongest cleaner has the weakest oxygen profile, the option with NASA's 2015 oxygen-cleaning pedigree is the hardest to run in existing equipment, and the easiest Novec 7100 replacement to adopt carries the same regulatory exposure as the original.

Choosing a Novec 7100 Replacement Is About More Than Cleaning Power

Cleaning performance is where most comparisons stop, and it's only the first filter. In NASA's mixed-contaminant tests on real fittings and coupons, AS-300 and SF33 removed the most soil, AS-300 beat the HFE-7100 baseline, and Sierra finished slightly below it.

AS-300 was also the only candidate that handled silicone vacuum grease well. After that, four other factors decide whether a Novec 7100 replacement actually works in your process.

Materials Compatibility

4340 low-alloy steel was the clear weak point. In NASA's seven-day exposure tests, 4340 coupons corroded beyond the allowable limit with BestSolv Sierra, AS-300 and several other candidates, and AS-300 also produced isolated failures on 15-5PH stainless and Inconel 718. Coupon results don't prove every part made of those alloys will corrode, but NASA's advice is to review metals and soft-goods data against your actual materials before use.

Worker Exposure

BestSolv Sierra has no OSHA exposure limit, and its manufacturer recommends 50 ppm over an eight-hour shift, compared with the 750 ppm guideline cited for HFE-7100. The two figures come from different sources, but a gap that wide can mean new ventilation or respirators.

Equipment Fit

Boiling point and vapor pressure decide whether existing degreasers and flush stations still work. A Novec 7100 replacement that boils at 19 °C, as Solstice PF does, behaves very differently in a vapor degreaser designed around a 61 °C fluid, and SF33's vapor pressure at 25 °C is roughly three times that of HFE-7100. NASA found Solstice viable for small-to-medium throughput shops, but estimated about $200,000 for one standalone Solstice cleaning station of the configuration it priced and called conversion likely financially impractical for large, high-throughput facilities.

Regulatory Durability

Molecular equivalents buy time, not permanence. A UK Defence Science and Technology Laboratory assessment notes that exact HFE-7100 equivalents still fall under the PFAS definition and are a short-term fix while a proposed EU-wide PFAS restriction works through the process. Blends containing trans-1,2-dichloroethylene face a separate U.S. EPA risk evaluation, which is one reason NASA favored the tDCE-free candidates. If you pick a molecular equivalent as your Novec 7100 replacement today, plan for a second transition later.

How Does Oxygen Service Change Your Choice of Cleaning Solvent?

In oxygen service, any solvent left behind has to be treated as a potential fuel. Oxygen-enriched environments make materials far easier to ignite, and a residue that is harmless in air can become an ignition source. NASA's White Sands analysis of P-3 aircraft oxygen system fires points to ignition mechanisms like compression heating and particle impact.

Those fires weren't traced to cleaning solvent, but the same energy sources can ignite any contaminant left in a system. That's why CGA G-4.1 calls for oxygen-service cleaning of surfaces that contact gas or liquid above 23.5% oxygen. For that hardware, a Novec 7100 replacement has to pass a second test after cleaning performance: how it behaves in oxygen if any of it is left behind.

Autoignition Temperature: The 204 °C Line

NASA ranks an oxygen cleaning solvent partly by its autoignition temperature (AIT) in pressurized oxygen. Above 204 °C (400 °F) is acceptable for oxygen systems. Between 121 °C and 204 °C means use with caution, and below 121 °C is not recommended. AIT is one screening criterion, so clearing it doesn't qualify a solvent for every oxygen system. SF33 (260 °C) and Sierra (243 °C) cleared the line. AS-300, at 151 °C, did not, and the memo calls it a less preferred oxygen-compatible solvent overall, though acceptable for non-enriched hardware such as breathing air and compressed air systems.

Why One Test Never Settles It

Mechanical impact testing tells a different story. Solstice PF's AIT is below 204 °C, yet its impact threshold of 7,500 psi in earlier White Sands testing far exceeds the sub-500 psi results for SF33 and AS-300. The two tests measure different ignition mechanisms, so the results don't contradict each other. ASTM G127, the guide for selecting cleaning agents for oxygen-enriched systems, frames the decision around the contaminant, the materials, the operating conditions and, ultimately, testing on actual parts and processes.

Hydrocarbon Lockup and Verification

When a lower-AIT solvent is used, the safeguard is proving that it's gone. NASA's memo says AS-300 could serve oxygen hardware if a hydrocarbon lockup requirement is added. In a lockup, the cleaned component is purged with inert gas, sealed for a set time, and the trapped gas is sampled for residual vapor. For flammable solvents, Johnson Space Center's PRC-5001 cleaning specification requires a 24-hour lockup at a minimum of 15 °C with a limit of 18 ppm measured as methane. The March 2026 revision of that document also added Solstice PF as an approved verification fluid, with incoming NVR capped at 5 mg/L.

What Should You Ask Your Cleaning Vendor Before It Switches Solvents?

If your parts are cleaned outside, your vendor's solvent change is your risk too. A certificate of cleanliness may not name the solvent unless your contract requires it, so ask directly and require notice before any Novec 7100 replacement enters your process. Six questions cover most of it:

1. Which Novec 7100 replacement are you using, and is it one NASA evaluated?
2. If it's a molecular equivalent, how did you verify its identity and purity?
3. Does my contract specification allow the substitute, or do we need a written deviation?
4. For oxygen hardware, what is the solvent's AIT, and do you verify residual solvent by lockup or another method?
5. Do you test every incoming solvent lot for NVR before use?
6. Has the solvent been checked against the specific metals and elastomers in my parts?

On the third question, note that the current KSC-C-123 is still Revision J, dated 2009. Until the update is released, your purchase order and drawing notes govern which solvents are acceptable.

Your Outsourced Precision Cleaning Partner Through the Transition

Most companies have no reason to requalify their own cleaning lines around a new solvent. It takes compatibility data, verification methods, oxygen-safety controls, and in some cases six figures of new equipment.

At Precision Fabricating & Cleaning, the transition is already underway. PFC received NASA's memorandum directly and has moved primarily to Solstice, a solvent it was already using for other customers, which made scaling up straightforward. That fits NASA's own finding that Solstice works best for operations already set up to handle it. Where a process calls for HFE-7100's exact properties, PFC also uses molecular equivalents such as Promosolv.

PFC holds customer-approved processes for KSC-C-123 and a long list of other specifications, with precision cleaning and oxygen cleaning handled in-house on Florida's Space Coast. If you're unsure how the Novec 7100 replacement question affects your parts, talk to us about your specification and service medium.

Frequently Asked Questions

The Bottom Line

The search for a Novec 7100 replacement has moved from guesswork to data. NASA has named five workable paths, and none of them is universal. The right choice depends on your materials, your equipment, your specification and, above all, whether the hardware will see oxygen.

Pick a Novec 7100 replacement on cleaning power alone and you can trade a supply problem for a safety problem. Pick with the full picture and the transition becomes routine.