A recommendation was made by the HSE Gas Safety Management Regulations Working Group in February 2000, that flow limiters should be installed in medium pressure services. This specification has been produced to meet the requirements of IGEM standards IGEM/TD/4, IGEM/PRS/28 and IGEM/PRS/29. The aim of this specification is to ensure that flow limiters installed not only conform to the HSE recommendations, but also meet the performance requirements specified herein, for reliable long-term operation within the prevailing conditions in the gas transporter medium pressure network.