High pressures and corrosive conditions are a few of the challenges of these applications.
Flare Gas Applications
Rheotherm meters with insertion probes can be calibrated for up to a 2000:1 turndown ratio to provide low flow measurement under normal flaring conditions and high flow measurement during upset conditions. An FM approved model is available to meet hazardous location requirements.
Rheotherm advantage: wide rangeability, withstands harsh environment, hazardous location approvals
Click here for details on the Rheotherm flow meter used for this application
Chemical Injection Operations
Rheotherm flow instruments are used to 
meter various scale and corrosion inhibiting fluids in downhole and wellhead applications. The flow rates are quite low, often specified at just a couple gallons per day maximum, and required pressure ratings are typically up to 10,000 psi. Because of the fluids and environmental conditions, corrosion-resistant wetted materials, such as Super Duplex and Alloy C-276, have been used for these types of applications.
Rheotherm advantage: very low liquid flow rate capability, high pressure options, wetted material selections
Click here for details on the Rheotherm flow meter used for this application