---
kind: "section"
citation: "40 C.F.R. § 1065.925"
title: "40"
number: "1065.925"
heading: "PEMS preparation for field testing."
url: "https://uscodex.org/cfr/40/1065.925"
---

# §1065.925. PEMS preparation for field testing.


Take the following steps to prepare PEMS for field testing:

- (a) Verify that ambient conditions at the start of the test are within the limits specified in the standard-setting part. Continue to monitor these values to determine if ambient conditions exceed the limits during the test.
- (b) **Install a PEMS and any accessories needed to conduct a field test.**
- (c) Power the PEMS and allow pressures, temperatures, and flows to stabilize to their operating set points.
- (d) Bypass or purge any gaseous sampling PEMS instruments with ambient air until sampling begins to prevent system contamination from excessive cold-start emissions.
- (e) **Conduct calibrations and verifications.**
- (f) **Operate any PEMS dilution systems at their expected flow rates using a bypass.**
- (g) If you use a gravimetric balance to determine whether an engine meets an applicable PM standard, follow the procedures for PM sample preconditioning and tare weighing as described in [§ 1065.590](/cfr/40/1065.590.md). Operate the PM-sampling system at its expected flow rates using a bypass.
- (h) Verify the amount of contamination in the PEMS HC sampling system before the start of the field test as follows:
  - (1) **Select the HC analyzer range for measuring the maximum concentration expected at the HC standard.**
  - (2) **Zero the HC analyzers using a zero gas or ambient air introduced at the analyzer port.** When zeroing a FID, use the FID's burner air that would be used for in-use measurements (generally either ambient air or a portable source of burner air).
  - (3) **Span the HC analyzer using span gas introduced at the analyzer port.**
  - (4) **Overflow zero or ambient air at the HC probe inlet or into a tee near the probe outlet.**
  - (5) **Measure the HC concentration in the sampling system—**
    - (i) **For continuous sampling, record the mean HC concentration as overflow zero air flows.**
    - (ii) **For batch sampling, fill the sample medium and record its mean concentration.**
  - (6) Record this value as the initial HC concentration, xTHCinit, and use it to correct measured values as described in [§ 1065.660](/cfr/40/1065.660.md).
  - (7) If the initial HC concentration exceeds the greater of the following values, determine the source of the contamination and take corrective action, such as purging the system or replacing contaminated portions:
    - (i) 2% of the flow-weighted mean concentration expected at the standard or measured during testing.
    - (ii) 2 µmol/mol.
  - (8) If corrective action does not resolve the deficiency, you may use a contaminated HC system if it does not prevent you from demonstrating compliance with the applicable emission standards.

## Notes

### Amendments

[70 FR 40516, July 13, 2005, as amended at 73 FR 37345, June 30, 2008; 73 FR 59342, Oct. 8, 2008; 75 FR 68467, Nov. 8, 2010; 76 FR 57467, Sept. 15, 2011]

### Authority

Authority: 42 U.S.C. 7401-7671q.

### Source

Source: 70 FR 40516, July 13, 2005, unless otherwise noted.

### Amendments

[70 FR 40516, July 13, 2005, as amended at 73 FR 37345, June 30, 2008; 73 FR 59342, Oct. 8, 2008; 75 FR 68467, Nov. 8, 2010; 76 FR 57467, Sept. 15, 2011]