Instrument Line Symbols Drawing

These symbols represent the following:

• Instrument and device connections at process measurement points
• Connections to instrument power supplies
• Signals between measurement and control instruments and functions

Lines shall be

• Fine in relation to process equipment and piping lines
• As short as possible and consistent with clarity

Gas metering station

Before ordering gas meter station there we have to specify some of the data required in the engineering process. tkenik process data are as follows:

Line Size (inch)

Operating Temperature : Max. , Min., Normal (deg F)

Operating Pressure (upstream) : Max. , Min., Normal (Psig) see pressure on gas source.

Operating Pressure (downstream) : Max. , Min., Normal (Psig) see pressure on gas to customer/User

Flowrate: Max. , Min., Normal (MMSCFD)

Molecular Wight of Gas : 16.4 (ussualy) 

Cp/Cv Ratio

Compressibility Factor: 0.997 (ussualy) 

Viscosity , µ at op.condition (CP) : 0.0129 (ussualy)

Specific Gravity of gas (SG) : 0.66 

Piping Class

Instrument type: orifice plate, etc 

A data processing techniques should be also equipped with a PID drawing as follows:

Pressure Relief Devices for CNG (NFPA52 - 4.5)

4.5 Pressure vessels complying with 4.4.5 or cylinders used for stationary storage without temperature compensation of the storage pressure shall be protected with one or more spring-loaded pressure relief valves in accordance with the ASME Boiler and Pressure Vessel Code.