43 CFR § 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.
(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;
(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.