---
kind: "section"
citation: "40 C.F.R. § 60.4405"
title: "40"
number: "60.4405"
heading: "How do I perform the initial performance test if I have chosen to install a NO X -diluent CEMS?"
url: "https://uscodex.org/cfr/40/60.4405"
---

# §60.4405. How do I perform the initial performance test if I have chosen to install a NO X -diluent CEMS?


If you elect to install and certify a NOX-diluent CEMS under [§ 60.4345](/cfr/40/60.4345.md), then the initial performance test required under [§ 60.8](/cfr/40/60.8.md) may be performed in the following alternative manner:

- (a) Perform a minimum of nine RATA reference method runs, with a minimum time per run of 21 minutes, at a single load level, within plus or minus 25 percent of 100 percent of peak load, while the source is combusting the fuel that is a normal primary fuel for that source. The ambient temperature must be greater than 0 °F during the RATA runs.
- (b) For each RATA run, concurrently measure the heat input to the unit using a fuel flow meter (or flow meters) and measure the electrical and thermal output from the unit.
- (c) Use the test data both to demonstrate compliance with the applicable NOX emission limit under [§ 60.4320](/cfr/40/60.4320.md) and to provide the required reference method data for the RATA of the CEMS described under [§ 60.4335](/cfr/40/60.4335.md).
- (d) Compliance with the applicable emission limit in [§ 60.4320](/cfr/40/60.4320.md) is achieved if the arithmetic average of all of the NOX emission rates for the RATA runs, expressed in units of ppm or lb/MWh, does not exceed the emission limit.

## Notes

### Amendments

[71 FR 38497, July 6, 2006, as amended at 91 FR 1983, Jan. 15, 2026]

### Source

Source: 71 FR 38497, July 6, 2006, unless otherwise noted.

### Authority

Authority: 42 U.S.C. 7401 et seq.

### Source

Source: 36 FR 24877, Dec. 23, 1971, unless otherwise noted.

### Amendments

[71 FR 38497, July 6, 2006, as amended at 91 FR 1983, Jan. 15, 2026]