Prater-Sterling is offering a new heavy-duty shaft seal design for their PAV Series Airlocks with a few significant differences from their standard seal design. New abrasion-resistant packing rings provide additional wear resistance against abrasive powders and a more form-fitting, positive seal around the shaft where smoother shaft finishes reduce cutting action on the packing rings. Additional packing rings are included for sealing against higher internal valve pressures. Tighter tolerances provide better support for the packing and throttle air leakage from within the valve. Lastly, the self-adjusting packing glands exclusively associated with Prater Airlocks are replaced with manually adjusted packing glands capable of additional pressure. Prater also offers the option of a new air purge kit with flow meters and oversized lines for proper flow to the lantern rings. In combination, the features mentioned above are an effective way of sealing the shaft when handling abrasive powders, or when the valve discharges to a positive pressure, pneumatic conveying line.