Specifi Gravity Skimmer (Spg) - QED SOS Operator's Manual

Skimmer Manual
B. Specific Gravity Skimmer (SPG)
The SPG uses the difference in density to distinguish between water and
product. The floating intake has a specific gravity of about 0.94. So, it
floats in water, but sinks in most products. Because the product intake is
on the top of the float, it recovers only product.
By design, the SPG does not usually remove all of the product on the
surface of the water. It typically leaves about 1.5 to 2 inches of product
in the well at all times. The amount of fuel or oil le in the well depends
mainly on the specific gravity of the product. This residual product can
enhance the influx of additional product into the well.
As the specific gravity of the product increases or approaches the specific
gravity of the skimmer float, more product is le in the well. The skimmer
has variable inlet holes on the side of the float that allow the user to adjust
the intake level of the skimmer. This is usually done when the specific
gravity of the product is greater than 0.85 or when there is an emulsion.
The SPG will perform be er that the SOS when the product is emulsifed,
viscous, or dirty.
The SPG is available in two diameters to fit 2-inch and 4-inch wells.
The SPG usually requires 1.5 to 2 inches of fuel in the well to begin
recovering. If it is submerged by a high-water condition in the well, and is
not controlled by the HWSO system, water will pass to any of the product
pumps.
Revision 1 - December 2007
Chapter 3: Equipment
Page 15