Aerospace materials & cleanliness handbook

Two objects, two evidence records

NASA JSC’s PRC-5001 Revision G describes hardware cleanliness in terms that can include particulate and nonvolatile residue criteria, with precision-cleaning verification beyond visual inspection. Its requirements have a defined program and process context; they are not a universal solvent specification.

The purchasing distinction is important: a chemical lot record describes the supplied material, while a hardware acceptance record addresses a component after the relevant process. Neither record should silently stand in for the other.

Ask for the method and the acceptance authority

Our proposed review captures the required property, method, units, limit and governing document revision in separate fields. If a request says only “low residue,” ask which object is being evaluated, how it is evaluated and who sets the limit.

A product’s advertised grade does not by itself demonstrate that a specific component meets a program cleanliness requirement. Request the exact chemical documents, then keep the component verification and process approval with the responsible engineering and quality team.

• Does the requirement apply to the liquid product, an extract or the hardware?
• Are particulate and residue requirements separately identified?
• Is the document revision the one required by the purchase order?
• What evidence must exist before the component can be released?

Requirement → evidence → decision boundary

An editorial checklist for your review—not a table of product specifications.

Cleanliness is part of a hazards assessment

NASA White Sands describes assessing oxygen-system cleanliness requirements and the risks associated with contamination. Its oxygen-service cleaning capability is not a generic cleaning recipe and does not establish that an off-the-shelf chemical is approved for every oxygen application.

Do not let a purity claim become a compatibility claim

White Sands also describes material and component compatibility assessment capabilities. For procurement, keep material identity, cleanliness evidence and compatibility approval as distinct records. Ask the responsible authority what evidence is required for the actual system.

Stop the substitution at the approval boundary

Our suggested purchase-order language identifies the approved material and document revision, the required lot evidence and the person authorized to accept a deviation. If those requirements are absent, mark the decision unresolved; a supplier’s general grade label cannot fill that gap.

This guide does not prescribe solvents, operating conditions, cleaning sequences or acceptance limits for oxygen hardware. Those decisions require qualified personnel and the governing process. Do not use a worksheet or a quote as permission to clean, test or operate an oxygen system.

• What exact system and requirement does the approval cover?
• Which organization owns compatibility and cleanliness acceptance?
• Does a proposed substitution require a new assessment?
• Which receiving discrepancy requires a hold instead of release?

Requirement → evidence → decision boundary

An editorial checklist for your review—not a table of product specifications.

A mission-specific case—not a universal limit

The 2017 OSIRIS-REx contamination-control paper’s abstract describes a mission-specific strategy, including witness materials used during assembly, testing and flight. It illustrates an evidence trail designed around the scientific purpose of that mission.

Only the abstract is reviewed here. We do not transfer its mission criteria into a general aerospace purchasing specification or present this older case as new research.

Treat preservation as a requirement

NASA JSC PRC-5001 addresses preventing recontamination during handling and interim packaging. That provides a useful foundation for asking what must remain protected between verification and use. Check the program’s actual requirements and current controlled documents.

Build a receiving evidence chain

Our proposed purchasing record connects the material lot, required verification, packaging configuration, receiving condition and release decision. Capture discrepancies without assuming that intact outer packaging proves every internal cleanliness requirement.

Specify who can assess a damaged seal, missing report or undocumented handling event. Keep the chemical supplier’s delivery evidence distinct from the program’s final hardware release record. The practical outcome is a clear handoff, not an unsupported promise of contamination-free performance.

• What must packaging preserve, and how is that requirement documented?
• Which evidence accompanies each lot or component?
• Who owns the decision after a preservation discrepancy?

Requirement → evidence → decision boundary

An editorial checklist for your review—not a table of product specifications.

Read what the process specification asks for

NASA JSC PRC-5001 Revision G, §5.12, states that “Isopropanol (IPA) must meet the requirements of TT-I-735A filtered to 10 microns or better prior to use.” It names a specification and a filtration state. It does not name a percentage. In the same paragraph, aqueous fluids “must utilize reagent grade water” meeting ASTM D1193 Type II except that silica content is not required, and where water is the verification fluid it must meet Grade A of JSC-SPEC-C-20D. Test fluids “shall be selected by the user and approved by the NASA procuring activity.”

That is the shape of a real cleanliness requirement, and a purchase request modelled on it looks nothing like “99.9% IPA.” It names the governing document and its revision, the specification the material must meet, the filtration or particulate condition required before use, and the authority that approves the fluid. A percentage on its own answers none of those. Confirm the current status and revision of any Federal Specification cited to you before writing it into an order; the designation on a decades-old drawing may no longer be active.

What the concentration figure actually changes

The difference between a 70 and a 99.9 figure is water, and water is a specification parameter with consequences you can reason about. It changes what is left behind when the solvent evaporates: nonvolatile residue is measured on the residue, and any dissolved or suspended matter carried in the diluent contributes to it. It changes evaporation behaviour and therefore drying and rinsing. It changes the handling classification of the delivered liquid: published closed-cup flash points aggregated for isopropanol give 12 °C (53 °F) for the substance and 75 °F open cup for a 91 percent solution, and 29 CFR 1910.106(a)(14)(iii) requires a mixture of compounds with different volatilities to be flash-tested in the form it is shipped.

It also changes what distillation can deliver. Isopropanol forms an azeotrope with water at 87.7 percent by weight, boiling at 80.37 °C at 760 mm Hg, so concentrations above that point are not reached by simple distillation and the higher figure implies a different production route and a tighter water specification. A container opened repeatedly in a humid room drifts back toward that composition, which is why the water content on the certificate and the water content at the bench are different numbers.

What the concentration figure does not do is make an antimicrobial claim. Efficacy statements for a specific concentration belong to registered products and their approved labelling, and this library makes none. Where a program requires an antimicrobial outcome, that requirement is answered from the governing document and the registered product’s label, not from a purity figure.

Separate the fluid record from the hardware record

PRC-5001 keeps cleanliness levels explicit and separable: Level 200 refers to size and count limits on particulate matter only, Level A refers to nonvolatile residue limits only — 1 mg per 0.1 m² — and Level 200A covers both. Verification is method-bound too: NVR determined in accordance with ASTM D2109-01, particulate determination in accordance with SAE-AS598, hydrocarbon content by total organic carbon per ASTM G144-01 where high-purity water is the final rinse. For HFE-7100 as a verification fluid, NVR “shall not be greater than 10 milligrams per one liter (mg/L)” determined by SSP 30573.

Our proposed record keeps three columns apart: what the delivered chemical is documented to be, what the cleaning process is approved to do, and what the component was verified to meet. The percentage on a drum sits only in the first column. Alliance sends a Certificate of Analysis when a customer asks, at no charge; name the analytes, methods and reporting limits you expect in the purchase order, and note which of your specification limits the certificate does not address at all.

• Which document and revision governs, and what does it name — a specification or a percentage?
• Is the requirement stated as assay, or as a maximum water content, and on which basis?
• What filtration or particulate condition must the fluid meet before use?
• Which cleanliness level applies to the hardware, and who approves the fluid for it?

Requirement → evidence → decision boundary

An editorial checklist for your review—not a table of product specifications.

The same property, from six sources, in one table

PubChem aggregates agency records for isopropanol. Its boiling-point entries read: 82.3 °C at 760 mm Hg from the Hazardous Substances Data Bank; 180.5 °F at 760 mmHg from CAMEO Chemicals citing NTP 1992; 83 °C from the ILO-WHO International Chemical Safety Card, with no pressure stated; 82.0–82.4 °C from the Joint FAO/WHO Expert Committee on Food Additives; 181 °F from OSHA and from NIOSH; and 82.3 °C at 760 mm Hg from the Department of Energy PAC database.

The density entries spread the same way and add a second trap: 0.785 at 68 °F, 0.78509 at 25 °C, 0.785 at 20 °C, 0.7809 at 25 °C — and, from the ICSC, “Relative density (water = 1): 0.79.” That last one is not a density. It is a dimensionless ratio, which is what a specific gravity is, and a ratio needs both temperatures to be meaningful. The same record supplies the reason it matters: a coefficient of expansion of 0.00107 per °C and a density correction of 0.00082 per °C. A hydrometer reading taken in a warm receiving bay and compared against a specification at 20 °C is not comparing like with like.

Even the reference value is a distribution

The NIST Chemistry WebBook gives isopropanol a normal boiling temperature of 355.5 ± 0.4 K, and states how that figure was produced: “Average of 102 out of 118 values.” Sixteen published values were excluded. The critical temperature is given as 509 ± 2 K from an average of 19 out of 20 values, and two separate fusion temperatures are listed, 185.75 K and 185.35 K, from different sources with an uncertainty assigned by NIST’s Thermodynamics Research Center.

This is what a well-curated property value looks like: a number, a unit, an uncertainty, a method label and a count. It is not a defect that the sources disagree; it is a defect to quote one of them stripped of all four. When a specification, a data sheet or a generated product page states a property as a bare number, the missing items are the ones that decide whether it can be compared against anything.

Write the property into a record that can be checked

NIST describes metrological traceability as a property of a measurement result: the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty, with a clearly defined property, a full description of the measurement system, a stated value with a documented uncertainty evaluation, and a complete specification of the reference at the time of comparison. Compiled literature values are not measurements of your lot, and a lot result is not a compiled literature value.

Our proposed field set for any numeric property is the same every time: the quantity and its units, the temperature and pressure or the reference-temperature pair, the concentration basis where the material is a mixture, the test method with its revision, the classification as typical, guaranteed or measured, and the document and revision it came from. Where an item is missing, record it as missing. Six fields is not bureaucracy; it is the difference between a value you can defend to a customer and a value you copied.

• Is this a specific gravity or a density, and at which two temperatures?
• At what pressure was a boiling point determined, and by which method?
• Is the figure typical, a guaranteed limit, or a measured lot result?
• Which document and revision does it come from, and when was that checked?

Requirement → evidence → decision boundary

An editorial checklist for your review—not a table of product specifications.

Every property comes back as a range

OSHA’s chemical sampling record for VM&P naphtha, CAS 8032-32-4, reports a boiling point of 203–320 °F, a molecular weight of 87–114 (approx), a flash point of 20–55 °F and a specific gravity of 0.73–0.76 at 60 °F. Four properties, four ranges. That is not imprecision. Varnish makers’ and painters’ naphtha is a petroleum distillation cut defined by where it boils, so its composition — and therefore every property that depends on composition — varies between producers and between batches.

The absence is as informative as the ranges. Queried on September 12, 2026, PubChem returned no compound record for CAS 8032-32-4 or for 64742-89-8; a compound database indexes molecules, and this material is not one. There is consequently no authoritative single value to look up, and any data sheet that presents one is presenting a typical value for one producer’s cut. The exposure picture is unsettled too: the OSHA record notes “TLV withdrawn in 2009 [VM&P naphtha 8032-32-4],” pointing instead to the reciprocal calculation method for refined hydrocarbon solvent vapour mixtures.

The row that looks right is a different substance

Table Z-1 of 29 CFR 1910.1000 contains an entry reading “Naphtha (Coal tar),” CAS 8030-30-6, at 100 ppm and 400 mg/m³. It is a different material with a different CAS number from VM&P naphtha, and OSHA’s own sampling record gives VM&P naphtha a PEL-TWA of 300 ppm (1350 mg/m³), alongside a NIOSH REL-TWA of 350 mg/m³ and a NIOSH ceiling of 1800 mg/m³ over 15 minutes. Reading the wrong row is a live risk precisely because the common names collide.

For comparison, the Table Z-1 entry for isopropyl alcohol is unambiguous — CAS 67-63-0, 400 ppm, 980 mg/m³ — because it names one molecule. Match on the CAS number, never on the word. And note that none of these figures is a property of a purchased product: an exposure limit is an obligation on an employer, met by an exposure assessment for the actual task, which no purchase document can supply.

• Which CAS number is on the material, and does it match the row being cited?
• What distillation range and flash point does this producer’s cut actually have?
• Who owns the exposure assessment for this task, and has it been done for this material?

Scope is what a solvent selection can honestly claim

For a cleanliness application, the boundary is sharp. PRC-5001 states that test fluids “shall be selected by the user and approved by the NASA procuring activity,” and records that at JSC the approved test fluids for precision cleaning are HFE-7100 and high-purity deionised water. A solvent being appropriate for a class of work in general has no bearing on whether it is approved for a particular process, and a supplier cannot make that determination.

Where a hydrocarbon cut is in scope, specify it as a cut: the distillation range with its method, the flash point of the material as supplied and its test method, the aromatic content if the process cares, the nonvolatile residue if it is a cleaning fluid, and the lot documentation for each. Under 29 CFR 1910.106(a)(19) a flash point sorts a liquid into one of four categories, and the ranges above straddle boundaries — which is a reason to classify the delivered material rather than the name on the order. This library provides no approval for any solvent in any application, and no Alliance product is recommended here for precision cleaning or for any other use.

Requirement → evidence → decision boundary

An editorial checklist for your review—not a table of product specifications.