space saving, compact rod seal, fits standard O-Ring housings. advantage compared to O-Ring: integrated  active back-up rings for high pressure, design with interference fit on outside diameter maintains non-twisting in dynamic applications.

  • asymmetric double-acting rod compact seal. the preload is achieved by the inter- nal stress of the seal material.
  • interference fit on the outside diameter.
  • various materials are available for different purposes.
  • snaps into simple grooves (see notes on installation).
  • good sealing effect across a wide temperature range.
  • sealing effect enhanced by high recovery rate.
  • for pressures up to 700 bar as a seal between pressurised space and atmosphereor between pressurised spaces.
  • good sealing in the low pressure range.
  • excellent static sealing.
  • little inclination to“stick-slip”.
  • the housing grooves are same as housing grooves for O-rings(see “range ofprofile sizes”)
  • the activated back up rings reduce the risk of gap extrusion and prevent  twistingin dynamic applications.
  • space-saving design.


not bolded symbols; please consult our technical for application limitations

category of profile

machined only.

double acting

the RS 20 seal is designed for use as a rod seal.

area of application: hydraulics

  • static and dynamic seals in hydraulic and pneumatic systems.
  • use in systems with O-ringgrooves instead of O-rings in case of stability problems (twisting) or “pumping”.
  • for valve seals in offshore and aviation applications.


  • the design is based on standard O-ring dimensions according AS 568 A (american O-ring dimensions). in case of large deviations from standard groove dimensions the profile has to be checked .
  • a design in PU materials is not recommendable because of the large deformation force
  • recovery rate is lower compared  to standard lip seals.
  • high break-awayload after prolonged periods of standstill.


RS 20 profiles are compact seals designed to seal pressurised space against the atmosphere or between pressurised spaces mainly for re- ciprocating movements, but for slight rotations as well. the design is based on application  in standard hydraulic systems with conventional hydraulic oils, the use in pneumatic systems is furthermore  possible. the operating parameters are as defined in the sealing data sheet and material data. requirements deviating from these parameters can be met to a certain degree by changing the geometry in the software program.


operating parameters & material

sealing element back-up ring temperature max. surface speed max. pressure 1 hydrolysis dry running wear resistance
NBR  POM /  PA2 -30 °C … +100  °C 0,5 m/s 700 bar (70 MPa) O
HNBR  POM /  PA2 -25 °C … +100  °C 0,5 m/s 700 bar (70 MPa) + O +
FKM PEEK -20 °C … +200  °C 0,5 m/s 700 bar (70 MPa) O
FKM  PTFE  glass -25 °C … +200  °C 0,5 m/s 700 bar (70 MPa) O
 HNBR  PEEK -20 °C … +150  °C 0,5 m/s 700 bar (70 MPa) + O +
HNBR  PTFE  glass -25 °C … +150  °C 0,5 m/s 700 bar (70 MPa) + O +

the stated operation conditions represent general indications. it is recommended not to use all maximum  values simultaneously. surface speed limits apply only to the presence of adequate lubrication film.

1 pressure ratings are dependent on the size of the extrusion gap.

2 POM up to ø260 mm, PA above ø260 mm

++ … particularly suitable                         o … conditional suitable

+ … suitable                                         – … not suitable

for detailed information regarding chemical resistance please refer to our „list of resistance“. for increased wear resistance and higher pressure range

polyurethane materials are to be preferred, attention  should be paid to restrictions in chemical and thermal  resistance. for higher gliding speeds another sealing system should be used (e.g. PTFE materials).

note on special materials:

as the temperature limits are determined by POM, using special materials  for the back up ring can expand the temperature limits.

gap dimension

the size of the permissible gap on the side opposite the source of pressure depends mainly on the seal material and the design of the seal. if the permissible gap dimensions are exceeded, there will be extrusion wear on the side opposite the source of pressure which may make the seal unfit for usage.

the maximum value of the permissible extrusion gap is reached  when the piston or the piston rod touches one side of the cylindrical tube or the guide.

due to the small height of the back up rings and the resulting sensitivity to extrusion, the gap size is limited for all ranges of diameter, pressure and cross section  by the standard  hole/shaft basis fit f8/H8, influences  due to thermal  expansion  have to be considered.

surface quality

surface roughness

Rtmax (μm)

Ra (μm)

sliding surface ≤2,5 ≤0,1-0,5
bottom of groove ≤6,3 ≤1,6
groove face ≤15 ≤3

tolerance recommendation

seal housing tolerances
Ød f7
t 0.05
d R
≤ 40 max. 0,2
> 40 max. 0,4

mode of installation

for inside diameters of 25 mm or more, and dependant  on the radial cross section (cs), the seal can be snapped into the housing.

Ød type of installation
≤ 6•cs open mounting space required
> 6•cs …..≤ 10•cs snap mounting with tool
> 10•cs snap mounting by hand

at installation, pay attention that the radius on the backup elements fits to the corresponding radius on the sealing element (nonsymmetric backup elements).


recommended mounting space:

recommended guide tolerance D1:

d f8 [mm]

p ≤ 100 [bar]

100 < p ≤ 200 [bar]

p > 200 [bar]

≤ 100 H10 H8 H8
> 100 ≤ 200 H10 H8 H7
>200 H9 H8 H7

standard tolerance range for piston rods is f8. If a tolerance  range selection is possible f7 should be preferred.

insertion chamfer:

in order to avoid damage  to the rod seal during installation, the piston rod is to be chamfered  and rounded  as shown in the “recommended mounting space” drawing. the size of chamfer depends on the seal type and profile width.

cs (mm) c (mm)
α = 15⁰  … 20⁰ α = 20⁰  … 30⁰
(2) 2 1
(3) 3 1.5
4 3.5 2
5 4 2.5
6 4.5 3
7.5 5 4
10 6 5

seal & housing recommendations

please note that we are able to produce those profiles to your specific need or any non standard housing. for detail measurements, please see Jet seal pars catalog…

the recommendations  for mounting space heights and cross sections listed below are standard values for the corresponding  O-Ring without

(short), with one (medium) or with two (long) back-up rings.


cs [mm] corresponding O-ring [m] mounting space height [mm] diameter range [mm]
short medium long static dynamic
1.35 1.78 2.5 3.5 4.5 11 – 99.9
2.18 2.62 3.5 5 6.5 100 – 149.9 11 – 19.9
3 3.53 4.4 5.9 7.4 150 – 249.9 20 – 39.9
4.53 5.33 6.7 8.4 10.1 250 – 399.9 40 – 99.9
5.94 6.99 8.8 10.8 12.8 400 – 599.9 100 – 299.9
8.5 10 12.5 15 17.5 >600 300 – 600


don’t hesitate to contact our technical department for further information or for special requirements (temperature, speed etc.), so that suitable materi- als and/or designs can be recommended.