This is the forth post of city gas series. Check my previous post about how to calculate city gas flow rate, city gas network part 1, and understanding metering and regulating station. In this post, I want to share you about regulating sector.
Before being distributed to house, gas pressure and gas flow from tapping point will be monitored in metering and regulation station (MRS). After leaving MRS, gas will be distributed via distribution pipeline which is usually MDPE pipe.
In my project we use 63 mm pipe or 90 mm pipe for distribution pipeline.
Gas distribution is usually grouped. Each group covers several houses, which can be as low as 900 houses to 2000 houses. In each group, we installed regulating sector.
Basically the function of Regulating Sector is to reduce gas pressure so that it meets requirement at stoves. The gas pressure at stoves is about 20 – 30 mbarg. Gas pressure is reduced so that the pressure at the furthest house is about 20 mbarg.
Regulating Sector consists of:
1 – Inlet and outlet isolation valve
2 – Inlet and outlet pressure gauge
Range of pressure gauge at inlet and outlet may be different. It is because gas pressure before entering regulator is higher than gas pressure leaving regulator.
3 – Pressure regulator
It is used to reduce gas pressure to certain value.
4 – Slam shut valve
The function of slam shut valve is to totally and rapidly cut off gas pressure when outlet pressure exceeds or drops below the setting.