Selecting the Correct Wedge

The choice of wedge is determined by the column packing, solvents, flow rate and other operational parameters. Packing visibility and materials of construction can also have an effect.

Standard Wedge Columns.

Standard wedge columns are constructed of acrylic, with Stainless steel frits and EPDM gaskets (Table 1). These columns are designed for applications with temperatures from 4-40^oC.

Table 1. Construction materials for Sepragen Wedge Columns.
Column Part	Material
Column body and end plates	Acrylic
frits	10 Micron nominal (stainless steel 316L)
Gaskets	EPDM rubber
Fasteners	Stainless Steel
Fittings	Polypropylene
Tubing	PVC

Custom Stainless Steel and HDPE Columns

Custom-made Stainless steel and HDPE Wedge columns with all stainless steel or HDPE construction are also available.

Working Pressure and Pressure Gauges

Wedge columns are rated for 25 psi, although most applications will run at significantly lower pressure.

A pressure gauge with a gauge guard (to prevent the incursion of fluids into the gauge machinery) is required for proper packing of the Wedge column. It is also recommended for safe operation of the column. Operating the column at pressures in excess of the rated pressure is dangerous and may result in column failure.

Pumps and pumping capacity.

Due to the high flow rate capabilities of Wedge columns, a properly chosen pump is critical in deriving the most benefit from your column. Further, for maximum efficiency, columns have to be packed properly for optimal performance. Table 3 indicates the general range of pumps needed for a particular column size. If you need to be more precise, please calculate the flow rate for your application and media as described in chapter 2.

Table 3. Pump capacity needed to pack column
Column Size	Pumping Capacity
50 ml 100 ml 250 ml 500 ml 1000 ml	150 mls/min. 300 mls/min. 750 mls/min. 1500 mls/min. 3000 mls/min.

Pumping capacities for running the column may be different than in the above table depending on the maximum flow rate in your chromatographic procedure. It is not advisable to operate these pumps at the bottom or top 15% of their flow rate range.