FLOPAM FO 4358 SH Equivalent — Medium-Charge High-MW Cationic PAM

FLOPAM FO 4358 SH is the first column of the cationic structured polyacrylamide powder table on SNF Catalogue 2007 p.15. The grade sits at Medium charge and High molecular weight on SNF's own published scale. Of the six structured grades listed on that page, FO 4358 SH is the only one with a published bulk density of approximately 0.69; the remaining five all show 0.75. A volumetric feeder calibrated on a 0.75 powder will under-dose FO 4358 SH by approximately 8% on a mass basis. Before starting any trial, weigh the actual output per unit time from your feeder at the intended speed and compare it against your target active polymer dose, not just the scale reading.

The grade string FO 4358 SH should be read in full. FO 4350 is a cationic non-structured powder — it has a different grade number, carries no SH suffix, and is not classified as a structured polymer; using FO 4350 data as a reference for FO 4358 SH duty means starting from a different grade class. FO 4698 SH shares the Medium charge and High molecular weight position but is a distinct row: the viscosity curve shape at 2.5 g/L differs (350 vs 280 cps) and the bulk density differs (0.69 vs 0.75). A bare FO 4698 without a suffix sits at High charge and Standard molecular weight — a different position on both axes. The four-digit number and the suffix together are the grade identifier.

ChinaPAM screens for FO 4358 SH duty from C8001 or C8015 as the charge-aligned starting lane. Our published scale places C8001 and C8015 in the Medium charge, Medium molecular weight band. SNF's High molecular weight and our Medium band are different scales and do not convert directly; no equivalence is claimed on that dimension. The second lane, C8003 or C8035, has a higher molecular weight on our scale and is opened only when process evidence — typically floc survival data under centrifuge or belt press shear — points to a chain-length response. This is a two-lane screening programme, not a drop-in substitution.

The first failure mode is omitting or confusing the suffix. A buyer who requests "FO 4358 equivalent" without the SH suffix, or who uses FO 4350 data as a starting point, begins from the wrong grade class entirely: FO 4350 is a cationic non-structured powder with a different grade number, no SH suffix, and no structured-polymer designation — it is not a precursor or close variant of FO 4358 SH. A buyer who uses FO 4698 SH data as a proxy starts from the correct charge and MW position but with the wrong bulk density and a different viscosity curve shape at intermediate concentrations. Both paths invalidate the comparison against your incumbent before any dosing begins. Check the complete bag label and measure the incumbent 5 g/L solution viscosity as a baseline before placing any enquiry.

The second failure mode is using a 0.75 bulk-density calibration for a 0.69 powder. If your feeder was calibrated against a previous polymer with 0.75 bulk density and you dose FO 4358 SH on the same volumetric setting, you will under-dose by approximately 8% on a mass basis. The practical consequence is that apparent performance shortfall is caused by feeder setup, not polymer fit. Calibrate by weighing output per unit time at your intended feed rate, using the actual FO 4358 SH powder or a trial sample with similar bulk density. Record the calibration factor before committing to a production trial.