|Solid Removal Rating
||0.3 μm (99.99%)
||180 °F (82 °C)
150 °F (65 °C) with Water
|Clean & Saturated Pressure Drop
||Sized to your specification
Figure 1: Effect of Pressure Drop on Compressor Operating Costs5
5 Conditions: Delta P on inlet pressure
Inlet Pressure = 20 psia
Outlet Pressure = 200 psia
Gas compressed is methane
Costs based on $0.07/kwhr
Pall Corporation applies a patented oleophobic/hydrophobic chemical treatment on all of its SepraSol liquid/gas coalescers. This allows the coalescers to operate at a lower saturated pressure drop. As shown on Figure 1, a small difference in saturated pressure drop can result in significant savings in operating costs.
About Coalescer Efficiency Ratings
The measurement of the efficiency and the pressure drop of a coalescer should reflect operating conditions. Many manufacturers of coalescers measure efficiency using the dioctyl phthalate (DOP) test. The DOP test was not originally designed to measure the performance of a coalescer under operating conditions seen in the oil and gas industry. Rather, the DOP test is performed under the following conditions:
- Measures only capture efficiency and does not indicate how much liquid is at the filter outlet. It is the outlet concentration, which will indicate whether downstream equipment and processes are vulnerable to damage.
- Measures only the percent removal of DOP aerosols that are 0.3 μm compared to a range of sizes normally seen in oil and gas applications.
- Measures the removal of DOP, a liquid not typically found in oil and gas applications.
- Performed under a vacuum, not typical of operating conditions.
- Performed on a dry coalescing element; the effectiveness of a coalescer should be measured when a coalescer is completely saturated.
Pall has developed a test called the Liquid Aerosol Separation Efficiency (LASE) Test to specially measure the performance of a coalescer under operating conditions. The table below compares the LASE and DOP tests. For further details on the LASE test, see Pall literature GAS-4300b, "Recent Developments in Performance Ratings of Gas/Liquid Coalescers."
Pall LASE Test vs. Conventional DOP
||Measures ppmw of total downstream aerosol concentration
||Measures only the capture efficiency of 0.3 μm DOP aerosols
||Specifies performance based on total liquid removal
||Polydispersed 20 wt. compressor lube oil (size range 0.1-1.0 μm)
||Monodispersed dioctyl phthalate (size range at 0.3 μm only)
||Closely simulates actual process contamination
|Downstream Contaminant Measurement
||Full flow membrane sampling of all size contaminants
||Indirect light scattering of 0.3 μm contaminants
||Directly measures the amount of all liquid downstream
||Performed under positive pressure conditions
||Performed under vacuum
||More closely reflects actual process pressure conditions
||Performed on a saturated cartridge
||Performed on dry cartridge
||Reflects actual process cartridge service
|Pressure Drop Measurement
||Measures operating saturated cartridge pressure drop
||Measures dry cartridge pressure drop
||Provides a more realistic service pressure drop