Audit Neutral Density Filter Certification and Sales
Along with manufacturing our own neutral density filters, EMS offers industry-leading recertification of any competitor’s model.
Our filter certificatio
n service sets the industry standard for speed and cost. Contact us today for details.
Environmental Monitor Service manufactures quality, precision neutral density filters for the most popular opacity monitors. Used for EPA audits and service, our filters are NIST traceable, fully certified, and manufactured with high-quality optical substrate material. Each filter has a unique serial number and a scanned trace dated and signed. The filters are labeled with the value in both optical density and opacity.
| Nominal Density (O.D.) | % Opacity |
| 0.02 | 5 |
| 0.04 | 8.8 |
| 0.1 | 20.57 |
| 0.2 | 36.9 |
| 0.3 | 49.88 |
| 0.4 | 60.19 |
| 0.5 | 68.38 |
| 0.6 | 74.88 |
| 0.7 | 80.05 |
| 0.8 | 84.15 |
| 0.9 | 87.41 |
| 1.0 up | 90 up Special Order |
Contact us for pricing or more information
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