Global warming is a major concern of today's world that mostly stems from greenhouse gases (GHG) emissions among which methane (CH₄) has the second highest potential to cause such a problem. Among various types of discharging CH₄ into atmosphere, fugitive emission from the natural gas (NG) supply chain has a significant contribution. In this study, methane emission from the pressure reduction station, distribution pipeline and end user regulating systems (EURSs) was experimentally investigated by a gas detector and a Hi-Flow sampler device. The research was conducted in Mashhad, the second metropolis of Iran; Iran plays a key role in NG reserves and consumptions. The results revealed that the fugitive methane emission from the EURSs is the main source of the GHG emission from the gas distribution network. This source was, then, investigated in detail through the being classified into six components including regulator, union fitting, coupling, locking valve, tee fitting, and elbow fitting. According to the obtained outcomes, the regulator is responsible for the highest emission factor (EF = 754 m³/year) along with the largest contribution (66.62%) in total fugitive methane emission of EURSs. Conversely, the elbow fitting demonstrates the lowest EF (= 134 m³/year) as well as the lowest contribution (0.39%). Additionally, the effect of EURSs lifespan on their EF was studied. The results indicate that the ratio of EF of EURSs with lifespans more than 20 years to mean EF is almost 1.4 while this value is approximately 0.8 for EURSs with lifespans less than 20 years. The results also show that the ratio of EF in different seasons to mean EF decreases as the temperature decreases (colder seasons). At the end, the findings of this research could give useful information about the methane emission from EURSs leading to designing and developing proper mitigation strategies.

全球变暖是当今世界的一个主要问题，其主要源于温室气体 (GHG) 排放，其中甲烷 (CH ₄ ) 具有引起此类问题的第二高潜力。_{CH 4}排入大气的各种类型中，无组织排放来自天然气（NG）供应链的贡献显着。在这项研究中，通过气体检测器和 Hi-Flow 采样器装置对减压站、分配管道和最终用户调节系统 (EURS) 的甲烷排放进行了实验研究。该研究在伊朗第二大城市马什哈德进行；伊朗在天然气储备和消费方面发挥着关键作用。结果表明，EURSs的逃逸甲烷排放是该气体温室气体排放的主要来源。分销渠道。然后，通过将其分为调节器、活接头、联轴器、锁止阀、三通接头和弯头接头等六个部件，对该来源进行了详细调查。根据所得结果，监管机构对 EURS 的总逃逸甲烷排放的排放因子最高（EF = 754 m ³ /年）和最大贡献（66.62%）负责。相反，弯头接头表现出最低的 EF (= 134 m ³/年）以及最低贡献（0.39％）。此外，还研究了 EURS 寿命对其 EF 的影响。结果表明，寿命超过 20 年的 EURS 的 EF 与平均 EF 的比值几乎为 1.4，而寿命小于 20 年的 EURS 的该值约为 0.8。结果还表明，不同季节的 EF 与平均 EF 的比率随着温度的降低（较冷的季节）而降低。最后，这项研究的结果可以提供有关 EURS 甲烷排放的有用信息，从而有助于设计和制定适当的缓解策略。