Measurement Units
Emerson ROC field devices can be configured to display values in defined sets of imperial/US or metric measurement units. Once you have defined a unit set, the field device tells CygNet what unit set it is running and CygNet displays the appropriate fields on remote device editor dialog boxes. For Emerson ROC devices, most units are viewed in the AGA Gas/Flow Parms data group.
Measurement Units List
The following table categorizes units into Imperial/US and Metric unit sets.
| Item Name | Imperial/US Unit Set | Metric Unit Set |
|---|---|---|
| Alarm Deadband | MCFD (thousand cubic feet per day) | Km3D (thousand cubic meters per day) |
| Atmospheric Pressure | psi (pound-force per square inch ) | KPa (kilopascal) |
| Base Pressure | psi (pound-force per square inch ) | KPa (kilopascal) |
| Base Temperature | F (degree Fahrenheit) | C (degree Celsius) |
| Differential Pressure | inH2O (inch of water) | KPa (kilopascal) |
| Elevation | ft (foot) | m (meter) |
| Energy‡ | MMBTU (million British thermal units) | GJ (gigajoule) |
| Flow | MCFD (thousand cubic feet per day) | Km3D (thousand cubic meters per day) |
| Flow Time | mins | |
| Grav. Acc. Correction | ft/s2 (feet per second squared) | m/s2 (meter per second squared) |
| Heating Value Mass* | BTU/Lb (British thermal unit per pound) | MJ/kg (megajoule per kilogram) |
| Heating Value Volume* | BTU/CF (BTU per cubic foot) | MJ/m3 (megajoule per cubic meter) |
| High Alarm | MCFD (thousand cubic feet per day) | Km3D (thousand cubic meters per day) |
| High Differential Pressure Setpoint | inH2O (inch of water) | KPa (kilopascal) |
| K-Factor | Pulses/Cf | Pulses/M3 |
| Latitude | Deg (degree) | Deg (degree) |
| Local Grav Accel | ft/s2 (feet per second squared) | m/s2 (meter per second squared) |
| Low Alarm | MCFD (thousand cubic feet per day) | Km3/D (thousand cubic meters per day) |
| Low Differential Pressure Setpoint | inH2O g (inch of water gauge) | KPa (kilopascal) |
| Low Flow Cutoff | inH2O (inch of water) | KPa (kilopascal) |
| Mass | lb (pound) | kg (kilogram) |
| Orifice Diameter | in (inch) | mm (millimeter) |
| Orifice Temperature | F (degree Fahrenheit) | C (degree Celsius) |
| Pipe Diameter | in (inch) | mm (millimeter) |
| Pipe Ref Temp | F (degree Fahrenheit) | C (degree Celsius) |
| Static (Line) Pressure | psi (pound-force per square inch ) | KPa (kilopascal) |
| Temperature‡ | F (degree Fahrenheit) | C (degree Celsius) |
| Volume‡ | MCF (thousand cubic feet) | Km3 (thousand cubic meters) |
| Viscosity** | Lbm/Ft-Sec (pound mass per foot second) | cp (centipoise) |
*For Emerson ROC remote devices, Heating Value displays in Mass or Volume depending on your setting on the Gas Analysis dialog box under Heating Basic/Units.
**For Emerson ROC remote devices except the FloBoss 103, users can control the type of viscosity units used. Viscosity values in the range 0.005 to 0.5 are displayed as metric (i.e., cp) by default and no conversion occurs. If a viscosity value is outside of this range, the units are set to imperial or metric, depending on how the device is configured, and no conversion occurs. If you want to pass through units for this value range, set the "FMS Configuration" (FmsConfig) data group attribute PassVisc to "true". If you do not want to pass through units for this value range and instead want them to be set by CygNet (the default behavior), set the attribute value PassVisc to "false" or remove PassVisc. For FloBoss 103 devices, viscosity units are always cp.
‡Includes various types of energy, temperature, and volume.
