StacksVerified U.S. regulatory reference

43 CFR §3175.91

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
  1. (a)Gauge lines connecting the pressure taps to the mechanical recorder must:
    1. (1)Have a nominal diameter of not less than 3/8 inch, including ports and valves;
    2. (2)Be sloped upwards from the pressure taps at a minimum pitch of 1 inch per foot of length with no visible sag;
    3. (3)Be the same internal diameter along their entire length;
    4. (4)Not include tees, except for the static-pressure line;
    5. (5)Not be connected to more than one differential-pressure bellows and static-pressure element, or to any other device; and
    6. (6)Be no longer than 6 feet.
  2. (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.
  3. (c)The flowing temperature of the gas must be continuously recorded and used in the volume calculations under § 3175.94(a)(1).
  4. (d)The following information must be maintained at the FMP in a legible condition, in compliance with § 3170.7(g) of this part, and accessible to the AO at all times:
    1. (1)Differential-pressure-bellows range;
    2. (2)Static-pressure-element range;
    3. (3)Temperature-element range;
    4. (4)Relative density (specific gravity) of the gas;
    5. (5)Static-pressure units of measure (psia or psig);
    6. (6)Meter elevation;
    7. (7)Meter-tube inside diameter;
    8. (8)Primary device type;
    9. (9)Orifice-bore or other primary-device dimensions necessary for device verification, Beta- or area-ratio determination, and gas-volume calculation;
    10. (10)Make, model, and location of approved isolating flow conditioners, if used;
    11. (11)Location of the downstream end of 19-tube-bundle flow straighteners, if used;
    12. (12)Date of last primary-device inspection; and
    13. (13)Date of last meter verification.
  5. (e)The differential pressure, static pressure, and flowing temperature elements must be operated between the lower- and upper-calibrated limits of the respective elements.