Testing & Validation Services | Jetsons Precision Cleaning

About the Standard

IEST-STD-CC1246E

IEST-STD-CC1246E (Institute of Environmental Sciences and Technology) is the industry benchmark for defining and verifying the cleanliness of surfaces, components, and assemblies. It establishes quantitative levels for both particulate contamination and non-volatile residue (NVR).

At Jetsons, we use this standard as our guiding framework for cleanliness inspection. We perform hands-on extraction, particle count evaluation, gravimetric analysis, and visual inspection to confirm your components comply with whatever IEST-1246E cleanliness level your specification demands.

Whether your requirement comes from a defense contract, aerospace OEM, medical device manufacturer, or semiconductor process spec, we translate your cleanliness requirement into a structured inspection workflow.

What IEST-1246E Defines

Particle size distribution limits by cleanliness level (25 through 1000)

Maximum allowable particle counts per size range across 9 size bins (5 to 1250 microns)

Non-volatile residue (NVR) levels from R1E-5 (10 ng) to R25 (25 mg)

Test methods: extraction flush, direct particle count, gravimetric analysis

Acceptance criteria for surfaces, tubing, fittings, and subassemblies

Formerly MIL-STD-1246, current revision is IEST-STD-CC1246E

How We Inspect

Inspection Methods

Multiple complementary inspection techniques provide thorough cleanliness confirmation. Each method targets a specific class of contamination.

Technician inspecting a part under microscope

Loading parts into the ultrasonic cleaning tank

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Particle Count

Extraction fluid flushed across the component surface and passed through a calibrated optical particle counter. Counts by size range compared to IEST-1246E level specified for your part across size bins from 5 to 1250 microns.

IEST-1246E Particulate

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Non-Volatile Residue (NVR)

Solvent-extracted rinse fluid evaporated and residual mass weighed on a precision analytical microbalance. NVR results (oils, greases, organic films) reported against IEST-1246E R-level limits for your cleanliness requirement.

IEST-1246E NVR

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Total Filterable Solids

Extraction rinse passed through a precision membrane filter. Captured solid mass weighed gravimetrically, providing a total particle burden result that complements optical particle count and confirms overall mass-based cleanliness.

Mass / Gravimetric

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UV Inspection

Ultraviolet light inspection reveals organic residues, oils, and fingerprint contamination fluorescing on critical surfaces without fluid contact. Ideal where wet extraction is not permitted, or as a supplemental visual check post-cleaning.

Non-Contact

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Dewpoint / Moisture Check

Digital dewpoint meter confirms no residual moisture remains after cleaning and drying. Critical for oxygen-service, aerospace, and medical components where trapped moisture causes corrosion or process contamination.

Dryness Verification

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Solvent / Cleaner Residue Check

Confirmation that no cleaning solvent or agent remains on or within the part after processing. Verified through photoionization detection or rinse conductivity checks to ensure the cleaning medium has not become the contaminant.

Residue Verification

IEST-1246E Reference Data

Cleanliness Level Tables

Use these tables to identify the applicable cleanliness level for your component and to understand what our inspection verifies against.

Maximum allowable particle counts per 0.1 m² of surface area per IEST-STD-CC1246E. Cells showing “—” are not applicable for that level.

Min (μm)	Max (μm)	Lvl 25	Lvl 50	Lvl 100	Lvl 200	Lvl 300	Lvl 400	Lvl 500	Lvl 750	Lvl 1000
5	15	19	141	1,519	n/a	n/a	n/a	n/a	n/a	n/a
15	25	2	17	186	2,949	n/a	n/a	n/a	n/a	n/a
25	50	1	6	67	1,069	6,433	n/a	n/a	n/a	n/a
50	100	0	1	9	154	926	3,583	10,716	n/a	n/a
100	250	0	0	1	15	92	359	1,073	8,704	n/a
250	500	0	0	0	0	2	8	25	205	983
500	750	0	0	0	0	0	0	1	7	33
750	1000	0	0	0	0	0	0	0	1	3
1000	1250	0	0	0	0	0	0	0	0	1

Maximum allowable NVR per 0.1 m² of surface area or per 0.1 L of fluid per IEST-STD-CC1246E.

R1E-5

Formerly AA5

10 ng

R2E-5

Formerly AA4.7

20 ng

R5E-5

Formerly AA4.3

50 ng

R1E-4

Formerly AA4

100 ng

R2E-4

Formerly AA3.7

200 ng

R5E-4

Formerly AA3.3

500 ng

R1E-3

Formerly AA3

1 μg

R2E-3

Formerly AA2.7

2 μg

R5E-3

Formerly AA2.3

5 μg

R1E-2

Formerly A/100

10 μg

R2E-2

Formerly A/50

20 μg

R5E-2

Formerly A/20

50 μg

R1E-1

Formerly A/10

100 μg

R2E-1

Formerly A/5

200 μg

R5E-1

Formerly A/2

500 μg

Formerly A

1 mg

Formerly B

2 mg

Formerly E

5 mg

R10

Formerly G

10 mg

R25

Formerly J

25 mg

Our Workflow

How an Inspection Works

Specification Review

We confirm the target IEST-1246E particulate level and NVR level from your drawing, purchase order, or inspection plan.

Controlled Extraction

Parts received and handled in our controlled environment. Extraction flush performed per the applicable method to collect the inspection sample.

Analysis

Samples analyzed for particle count by size range, NVR mass, TFS, moisture, and UV fluorescence depending on your requirements.

Results & Documentation

Results compared to IEST-1246E acceptance limits. Written inspection record with pass/fail determination provided for your quality records.

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