description

asymmetric piston seal for standard applications. design provides stable fit in the housing, ultimate sealing effect over a wide temperature range. avoids extensive drag pressure. back-to-back arrangement with guide ring in between or for double acting pistons or to separate different fluids.

 

 

 

 

  • asymmetric single acting piston lipseal, with the dynamic sealing lip beeing shorter and thinner than the static one in order to avoid drag pressure built up.
  • interference fit on the inside diameter.
  • various materials are available for different purposes.
  • snaps into simple grooves (see notes on installation).
  • best sealing effect across a wide temperature range.
  • sealing effect enhanced by high recovery rate.
  • for pressures up to 400 bar as a seal between pressurised spaces.
  • good sealing in the low pressure range.
  • excellent static and dynamic sealing.
  • suitable for long travel.
  • little inclination to“stick-slip”.
  • low break-awayload after prolonged periods of standstill.

 

application

not bolded symbols; please consult our technical for application limitations

 

category of profile

machined or molded/standard/trade product

 

single acting

the PS 01 seal is designed for use as a piston seal - either single or double acting where two seals are used ‘back to back’

 

area of application: hydraulics

reciprocating pistons in hydraulic cylinders. piston seal for applications with small extrusion gap and without special impact load. can also be used as a pivot seal at low loads.

 

note

  • this seal has the correct functioning dimensions only when mounted.in unmounted condition, the seal may appear too small.
  • the ratio between  nominal width and sealing height cs/H should not drop below a value of 1/1.25 (essentially according to ISO 5597housings for piston and rod seals).
  • for short strokes the pS03  type is preferred.

 

function

PS 01 profiles are lip seals designed to seal pressurised space against the atmosphere or -in case of back to back arrangement with inter- mediate guidering – to seal between two pressurised spaces, mainly for reciprocating movements. the design is based on application in standard hydraulic systems with conventional hydraulic oils. 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

material temperature max. surface speed max. pressure 1 hydrolysis dry running wear resistance
s-mart PU -30 °C ... +110  °C 0,5 m/s 400 bar (40 MPa) - + ++
s-mart HPU -20 °C ... +110  °C 0,5 m/s 400 bar (40 MPa) ++ + ++
s-mart SPU -20 °C ... +110  °C 0,7 m/s 400 bar (40 MPa) ++ ++ ++
s-mart LTPU -50 °C ... +110  °C 0,5 m/s 400 bar (40 MPa) - + ++
s-mart GPU -30 °C ... +110  °C 0,5 m/s 400 bar (40 MPa) ++ + ++

 

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.

++ ... particularly suitable                         o ... conditional suitable

+ ... suitable                                         - ... not suitable

for detailed information regarding chemical resistance please refer to our „list of resistance“. for increased chemical and thermal resistance rubber

materials are to be preferred, attention  should be paid to restrictions for pressure range and wear resistance. for higher gliding  speeds another system should be used (e.g. PTFE materials).

 

 

gap dimension

operating pressure cs = (ØD - Ød)/2 mm
4 5 7.5 10 12.5 15
safe extrusion gap (mm)
100 bar (10 MPa) 0.18 0.22 0.32 0.38 0.45 0.53
200 bar (20 MPa) 0.12 0.16 0.25 0.33 0.40 0.45
300 bar (30 MPa) 0.07 0.13 0.21 0.28 0.36 0.42
400 bar (40 MPa) 0.05 0.10 0.19 0.26 0.33 0.39

 

important note:

the above data are maximum value and can’t be used at the same time. e.g. the maximum operating speed depend on material type, pressure, tem- perature and gap value. temperature range also dependent on medium.

the table applies to an operating temperature  of 70 °C.

use larger cross sections to increase maximum allowed gap dimension. if the permissible extrusion gap cannot be achieved, K02-P is to be used.

 

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 h10
ØD H9


 

mode of installation

for inside diameters of 40mm and more, the seal can generally be slipped over the piston and snapped into closed grooves. due to occuring de- formation force at installation, assembly aid tools are to be used for large cross-sections. the material deformation should not exceed the value of 20%, otherwise the permanent deformation would be too large.

 

recommended mounting space:

plastic guiderings (wearbands) have to feature a adequate cutting gap (recommendation:  2-5% of D). if metalic guides are used, spiral grooves shall be provided. smaller values for Hmin will ease the installation (reduced elongation and mounting force) but the height of the retaining col- lar has to be sufficient to assure a stable fit in the housing ( larger than cs/2, smaller retaining collars will increase the danger of eversion of the profile in case of occuring drag pressure).

in order to avoid drag pressure built up in case of back-to-back arrangement, the distance between the seals should be as small as possible.

 

insertion chamfer:

in order to avoid damage to the piston  seal during installation, the piston and the housing 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
4 3.5 2
5 4 2.5
6 4.5 3
7.5 5 4
10 6 5
12.5 8.5 6.5
15 10 7.5
20 13 10

instead of a chamfer, the piston can also be designed with a radius. recommended size of the radius is equal to size of chamfer (R=c).

 

 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 ratio between nominal width and seal height cs/H should not drop below 1/1.25. therefore we recommend the following housing heights.

ØD [mm] Ød [mm] L [mm] cs = (ØD - Ød)/2 [mm]
5 ~ 24,9 ØD - 8 6 4
25 ~ 49,9 ØD - 10 7 5
50 ~ 74,9 ØD - 12 8 6
75 ~ 149,9 ØD - 16 10 7.5
150 ~ 299,9 ØD - 20 12 10
300 ~ 500 ØD - 24 18 12.5
500 ~ 750 ØD - 30 20 15
> 750 ØD - 40 26 20

 

fitted:

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.