Wiper
MERKEL
DOUBLE WIPER PT1
Merkel Double Wiper PT1, consisting of a PTFE profile ring with VALUE TO THE CUSTOMER
one sealing and one wiping edge, plus two O-rings as pre-stressing
elements. y Enhanced functional reliability of the sealing system, due to
additional sealing edge
O-Ring y High operating reliability, due to sturdy profile ring made of PTFE
compound (can briefly withstand the full operating pressure)
y Very good wiping capability for dirt adhering, due to dimension-
PTFE Profile Ring ally stable wiping edge
y Excellent control and positioning characteristics due to
favorable frictional behavior (stick-slip-free)
Applications
Double wiper with integrated sealing function for improving over-
all sealing capabilities. The PT 1 is preferably used in conjunction
with our rod seals Merkel Omegat OMS-MR PR or U-Ring T20.
Material
PTFE Profile Ring
Material Designation Color
PTFE-glass-fibre -
PTFE GM201 light gray
MOS2 compound
PTFE-bronze compound PTFE B602 brown
O-Ring
Material Designation
Nitrile rubber NBR
Fluoro elastomer FKM
Other material combinations are available on request.
Wiper
TECHNICAL PROPERTIES
Operating Conditions Surface finish of the sliding surfaces
Material PTFE GM201/NBR PTFE B602/NBR PTFE B602/FKM Characteristic
Limit
Value
Hydraulic oils, HL, HLP –30 … +100 °C –30 … +100 °C –10 … +200 °C
Ra >0,05 µm <0,30 µm
HFA fluids + 5 … +60 °C – –
Rmax <2,5 µm
HFB fluids + 5 … +60 °C – –
Rpkx <0,5 µm
HFC fluids –30 … +60 °C – –
Rpk <0,5 µm
HFD fluids – – –10 … +200 °C
Rk >0,25 µm <0,7 µm
Water + 5 … +100 °C – –
Rvk >0,2 µm <0,65 µm
HETG (rape-seed oil) –30 … +80 °C –30 … +80 °C –10 … +80 °C
Rvkx >0,2 µm <2,0 µm
HEES (synth. ester) –30 … +80 °C –30 … +80 °C –10 … +100 °C
The limit values listed in the table do not
HEPG (glycol) –30 … +60 °C –30 … +60 °C –10 … +80 °C
currently apply for ceramic or semi-ceramic
Mineral greases –30 ... +100 °C –30 ... +100 °C –10 ... +200 °C counter surfaces. Please also consult our
Technical Manual.
Sliding speed 5 m/s 5 m/s 5 m/s
The figures given are maximum values and must not be applied simultaneously.
Surface Finish Tolerances
Peak-to-valley heights Ra Rmax Diameter D Tolerance
Sliding surface 0,05 … 0,3 µm ≤2,5 µm D H9
Groove base ≤1,6 µm ≤6,3 µm D1 H10
Groove sides ≤3,0 µm ≤15,0 µm
The tolerance for the diameter d is specified in connection with
Material content Mr > 50 % to max. 90 %, with cut depth c = Rz/2 and the gap dimension calculation for the primary seal. In typical hy-
reference line Cref = 0 % draulic applications up to a nominal dimension of 1.000 mm, the
tolerance fields f7 and f8 are usually chosen.
The long-time behavior of a sealing element and its dependabil-
ity against early failures are crucially influenced by the quality of Design Notes
the counter surface. A precise description and assessment of the We recommend a pressure-relief bore. In the case of upstream
surface is thus indispensable. seals with a good return capability, a pressure-relief feature is not
Based on recent findings, we recommend supplementing the necessary. Please also consult our Technical Manual.
above definition of surface finish for the sliding surface by the
characteristics detailed in the table below. With these new Installation & Assembly
characteristics derived from the material content, the hitherto Reliable seal function is dependent on correct installation. Please
merely general description of the material content is significantly also consult our Technical Manual.
improved, not least in regard to the abrasiveness of the surface.
Please also consult our Technical Manual.
Wiper
GLAND DESIGN
Installation Diagram
L1
H 2,5 L + 0,2
R1
45°
ØD 20°
Ø D1 rounded and burr-free
C
Ød
The information contained herein is believed to be reliable, but no representation, guarantees or warranties of any kind are made to its accuracy or
suitability for any purpose. The information presented herein is based on laboratory testing and does not necessarily indicate end product
performance. Full scale testing and end product performance are the responsibility of the user.
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