HPRS MA21 - U-rings

Type/Ref.: Piston/Rod seal
Pressure (bar): 16/160
Temperature (°C): –30 to + 100
Running speed (m/s): 0.5

Piston and piston rod seal with symmetrical sealing lips which are cut at an angle of less than 45°.

Standard material


Area of application

Hydraulics and pneumatics
reciprocating movements


The HPRS MA21 is a single function piston seal in the form of a U-ring which can be used as a piston and piston rod seal due to its symmetrical sealing lips. Its sealing function is very effective due to the sealing lips being provided with radial self energising which is activated by the system pressure.


Hydraulic oils acc. DIN 51524/51525,
lubricating oils, mineral oil based
lubricating fats, non-flammable
hydraulic fluids HFA, HFB, HFC acc.
VDMA 24317.

Operational application limits

Pressure (MPa/bar): 16/160
Temperature (°C): –30 to + 100
Running speed (m/s): = 0.5


The HPRS MA21, with an inner diameter of 25 mm and a thinner profile can always be installed in cut housing. With an inner diameter of less than 25 mm, we recommend axially accessible housing. To push the piston body and seal into the cylinder pipe or over the piston rod without damaging it, a lead-in chamfer C acc. to the following table is required:

Profile width (mm) Lead-in chamfer C (mm)
4 2
5 2.5
7.5 4
10 5
12.5 6.5
15 7.5
20 10
25 10

If the housing is provided with a metallic fitting on the side opposite the pressure, the service life of the seal is lengthened. Within the operating parameters given above, depending on the pressure, a metallic wedge can be fitted between the cylinder pipe and piston acc. to the following table:

Pressure (MPa) Radial wedge G (mm)
5 0.2
10 0.15
16 0.1

The piston diameter d1 should generally be by factor 0.65 of the profile smaller than the DN diameter provided.

Please also follow the general installation instructions.


In addition, we are able to supply other dimensions required. For operating conditions other than the standard applications, further elastomers are available.