---
kind: "section"
citation: "43 C.F.R. § 3175.91"
title: "43"
number: "3175.91"
heading: "Installation and operation of mechanical recorders."
url: "https://uscodex.org/cfr/43/3175.91"
---

# §3175.91. Installation and operation of mechanical recorders.

- (a) **Gauge lines connecting the pressure taps to the mechanical recorder must—**
  - (1) Have a nominal diameter of not less than 3/8 inch, including ports and valves;
  - (2) Be sloped upwards from the pressure taps at a minimum pitch of 1 inch per foot of length with no visible sag;
  - (3) Be the same internal diameter along their entire length;
  - (4) Not include tees, except for the static-pressure line;
  - (5) Not be connected to more than one differential-pressure bellows and static-pressure element, or to any other device; and
  - (6) **Be no longer than 6 feet.**
- (b) The differential-pressure pen must record at a minimum reading of 10 percent of the differential-pressure-bellows range for the majority of the flowing period. This requirement does not apply to inverted charts.
- (c) The flowing temperature of the gas must be continuously recorded and used in the volume calculations under [§ 3175.94(a)(1)](/cfr/43/3175.94.md?p=a-1).
- (d) The following information must be maintained at the FMP in a legible condition, in compliance with [§ 3170.7(g)](/cfr/43/3170.7.md?p=g) of this part, and accessible to the AO at all times:
  - (1) Differential-pressure-bellows range;
  - (2) Static-pressure-element range;
  - (3) Temperature-element range;
  - (4) Relative density (specific gravity) of the gas;
  - (5) Static-pressure units of measure (psia or psig);
  - (6) Meter elevation;
  - (7) Meter-tube inside diameter;
  - (8) Primary device type;
  - (9) Orifice-bore or other primary-device dimensions necessary for device verification, Beta- or area-ratio determination, and gas-volume calculation;
  - (10) Make, model, and location of approved isolating flow conditioners, if used;
  - (11) Location of the downstream end of 19-tube-bundle flow straighteners, if used;
  - (12) Date of last primary-device inspection; and
  - (13) **Date of last meter verification.**
- (e) The differential pressure, static pressure, and flowing temperature elements must be operated between the lower- and upper-calibrated limits of the respective elements.

## Notes

### Source

Source: 81 FR 81609, Nov. 17, 2016, unless otherwise noted.

### Authority

Authority: 25 U.S.C. 396d and 2107; 30 U.S.C. 189, 306, 359, and 1751; and 43 U.S.C. 1732(b), 1733, and 1740.

### Source

Source: 81 FR 81421, Nov. 17, 2016, unless otherwise noted.