---
kind: "section"
citation: "40 C.F.R. § 63.1084"
title: "40"
number: "63.1084"
heading: "What heat exchange systems are exempt from the requirements of this subpart?"
url: "https://uscodex.org/cfr/40/63.1084"
---

# §63.1084. What heat exchange systems are exempt from the requirements of this subpart?


Except as specified in [paragraph (f)](#f) of this section, your heat exchange system is exempt from the requirements in §§ [63.1085](/cfr/40/63.1085.md) and [63.1086](/cfr/40/63.1086.md) if it meets any one of the criteria in [paragraphs (a) through (e)](#a..e) of this section.

- (a) Your heat exchange system operates with the minimum pressure on the cooling water side at least 35 kilopascals greater than the maximum pressure on the process side.
- (b) Your heat exchange system contains an intervening cooling fluid, containing less than 5 percent by weight of total HAP listed in Table 1 to this subpart, between the process and the cooling water. This intervening fluid must serve to isolate the cooling water from the process fluid and must not be sent through a cooling tower or discharged. For purposes of this section, discharge does not include emptying for maintenance purposes.
- (c) The once-through heat exchange system is subject to a National Pollution Discharge Elimination System (NPDES) permit with an allowable discharge limit of 1 part per million by volume (ppmv) or less above influent concentration, or 10 percent or less above influent concentration, whichever is greater.
- (d) Your once-through heat exchange system is subject to a NPDES permit that meets all of the conditions in [paragraphs (d)(1) through (4)](#d-1..d-4) of this section.
  - (1) The permit requires monitoring of a parameter or condition to detect a leak of process fluids to cooling water.
  - (2) **The permit specifies the normal range of the parameter or condition.**
  - (3) The permit requires monthly or more frequent monitoring for the parameters selected as leak indicators.
  - (4) The permit requires you to report and correct leaks to the cooling water when the parameter or condition exceeds the normal range.
- (e) Your recirculating or once-through heat exchange system cools process fluids that contain less than 5 percent by weight of total HAP listed in Table 1 to this subpart.
- (f) Beginning no later than the compliance dates specified in [§ 63.1081(a)](/cfr/40/63.1081.md?p=a), your heat exchange system is no longer exempt from the requirements in §§ [63.1085](/cfr/40/63.1085.md) and [63.1086](/cfr/40/63.1086.md) if it meets the criteria in paragraph [(c)](#c) or [(d)](#d) of this section; instead, your heat exchange system is exempt from the requirements in §§ [63.1085](/cfr/40/63.1085.md) and [63.1086](/cfr/40/63.1086.md) if it meets any one of the criteria in paragraph [(a)](#a), [(b)](#b), or [(e)](#e) of this section.

## Notes

### Amendments

[67 FR 46271, July 12, 2002, as amended at 85 FR 40419, July 6, 2020]

### Source

Source: 67 FR 46271, July 12, 2002, unless otherwise noted.

### Authority

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

### Source

Source: 57 FR 61992, Dec. 29, 1992, unless otherwise noted.

### Amendments

[67 FR 46271, July 12, 2002, as amended at 85 FR 40419, July 6, 2020]