Kaco Double cup seals are complete pistons for a pressure range up to 16 bar for sealing liquid and gaseous media. In this version, two cup seals are vulcanized to a metal washer which serves as a reinforcement for clamping onto the piston rod. One side of this washer has a rubber layer which, when installed, carries out sealing on the piston rod (fig. 44). The radial tension of the sealing lips is such that, even in the case of radial stressing of the piston rod and even if the guide clearance between the piston and cylinder is used to the full, a cylinder tolerance up to H 11 is still covered. With the sharp sealing edges, it is possible to seal off liquid media (e.g. hydropneumatic equipment, hydro-apportioning equipment).

When designing pneumatic cylinders or other pneumatic equipment we recommend, especially in the case of pure dry running, to provide for the TWIN LIP sealing pistons QTDF described on page 38.

Figure 45 shows a single-type complete piston from which the sealing lip not subjected to pressure is removed. Refer to the table on page 41for the installation dimensions of this version. As the rubber-covered side of the metal washer must always be in contact
with the rod shoulder for static sealing, make sure in the case of single-type double cup seals that the sealing lip is on the correct side of the cup seal in accordance with the desired working direction of the cylinder.