Section 3175.112 - Sampling probe and tubing(a) All gas samples must be taken from a sample probe that complies with the requirements of paragraphs (b) and (c) of this section.(b)Location of sample probe.(1) The sample probe must be located in the meter tube in accordance with API 14.1, Subsection 6.4.2 (incorporated by reference, see § 3175.30 ), and must be the first obstruction downstream of the primary device.(2) The sample probe must be exposed to the same ambient temperature as the primary device. The operator may accomplish this by physically locating the sample probe in the same ambient temperature conditions as the primary device (such as in a heated meter house) or by installing insulation and/or heat tracing along the entire meter run. If the operator chooses to use insulation to comply with this requirement, the AO may prescribe the quality of the insulation based on site specific factors such as ambient temperature, flowing temperature of the gas, composition of the gas, and location of the sample probe in relation to the orifice plate (i.e., inside or outside of a meter house).(c)Sample probe design and type.(1) Sample probes must be constructed from stainless steel.(2) If a regulating type of sample probe is used, the pressure-regulating mechanism must be inside the pipe or maintained at a temperature of at least 30 °F above the hydrocarbon dew point of the gas.(3) The sample probe length must be the shorter of:(i) The length necessary to place the collection end of the probe in the center one third of the pipe cross-section; or(ii) The recommended length of the probe in Table 1 in API 14.1, Subsection 6.4 (incorporated by reference, see § 3175.30 ).(4) The use of membranes, screens, or filters at any point in the sample probe is prohibited.(d) Sample tubing connecting the sample probe to the sample container or analyzer must be constructed of stainless steel or nylon 11.