Compression Capability
Rotary Vane Compressor
Rotary Vane compressors manage ratios up to 7:1 in compression applications.
Ro-Flo’s have a MAWP of 200 psig (13.6 barg).
Ro-Flo’s are capable of operating at deep vacuum levels
Screw Compressor
Flooded screws can manage pressure ratios up to 10:1 or greater.
Flooded Screws can reach discharge pressures up to 350 psig.
Flooded screw compressors typically cannot operate in vacuum
Oil
Rotary Vane Compressor
Rotary vanes require a small amount of oil which is continuously injected for lubrication purposes only.
Typically a rust & oxidation inhibiting mineral oil is sufficient for compressor option. Special applications (high H2S, H2, etc.) may require synthetic oil.
Screw Compressor
Flooded screws require a large amount of recirculating oil which lubricates and removes the heat of compression.
Typically a synthetic oil is used to ensure good operating life. This will need to be recycled/replenished on a regular basis.
Power
Rotary Vane Compressor
A significant portion of the power input into sliding vane compressors is imparted to the gas.
Sliding vane compressor power consumption is optimized during the manufacturing process by modifying the discharge port angle to best fit the application needs.
Screw Compressor
Flooded screws continuously pump oil through the compression chamber via an integral or external pump, which can increase power consumption
Flooded screw compressors use a variable Volume Ratio to optimize the pressure ratio
Cooling
Rotary Vane Compressor
Ro-Flo sliding vane compressors are water jacketed to provide thermal stabilization of the cylinder and remove heat from the bearings.
Screw Compressor
A large amount of heat is absorbed by the lubricating oil. This oil needs to be cooled before being recirculated.
Gas Composition Tolerance
Rotary Vane Compressor
Rotary Vane compressors can tolerate almost any gas, as well as varying compositions
Rotary Vane compressors can manage very low or very high molecular weights
Screw Compressor
The recirculated oil of a flooded screw can become contaminated from the process gas and condensation from the heating and cooling cycles
Flooded screw compressors cannot tolerate high molecular weight gases
Capacity Control
Rotary Vane Compressor
Sliding vane capacity control is most commonly implemented via a variable speed drive (VSD) or gas recycle loop.
Screw Compressor
Flooded screw compressors may have capacity control implemented via a slide valve (typically implemented with a fixed speed motor). Flooded screw compressors may also be controlled via a variable speed drive.
Field Service
Rotary Vane Compressor
Hand tools are needed for basic maintenance. A complete repair can be completed by properly trained machine shops.
Screw Compressor
Requires maintenance at a qualified repair facility. Often compressors are just replaced due to cost.