Walle produce all series of hydraulic seals,according to category by purpose,including rotary seals, all kinds of O ring(FKM O ring), step seal, glyd ring, oil seal and various of combination seals, gasket, spring energised seals, food machinery seals and so on.

1. © Merkel Freudenberg Fluidtechnic GmbH | Seals for Fluid Power Catalog 2007
Hydraulics | Rod Seals | Merkel U-Ring NI 300
Merkel U-Ring NI 300
Sealing edge
Asymmetrical sealing lips
PUR profile ring
Fig. 1 Merkel U-Ring NI 300
Product description
Merkel U-ring with asymmetrical profile,
inner lip set back, additional support
edge and sealing edge as well as press
fit at the outside diameter.
Product advantages
Single-acting rod seal for standardised
housings, amongst others, according to
ISO 5597
Very good static and dynamic
tightness
Additional sealing edge, prevents
ingress of dirt to a large degree
Recommended for use in combination
with single-acting wipers.
Application
Earth moving equipment, support cylin-
ders, cranes, presses.
Material
Material Code Hardness
Polyurethane 94 AU 925 94 Shore A
Operating conditions
Material 94 AU 925
Temperature range in °C
Hydraulic oils HL, HLP –30 … +110
HFA fluids +5 … +50
HFB fluids +5 … +50
HFC fluids –30 … +40
HFD fluids –
Water +5 … +40
HETG (rapeseed oil) –30 … +60
HEES (synthetic ester) –30 … +60
HEPG (glycol) –30 … +40
Mineral greases –30 … +110
Pressure p in MPa 40
Running speed v in m/s 0,5
Surface quality
Surface roughness Ra Rmax
Sliding surface 0,05 … 0,3 µm ≤2,5 µm
Groove base ≤1,6 µm ≤6,3 µm
Groove flanks ≤3,0 µm ≤15,0 µm
Percentage contact area Mr >50% to max. 90% at cutting depth c = Rz/2 and reference line C ref = 0%.
Merkel U-Ring NI 300

2. © Merkel Freudenberg Fluidtechnic GmbH | Seals for Fluid Power Catalog 2007
Hydraulics | Rod Seals | Merkel U-Ring NI 300
Design notes
Please observe our general design notes in → Technical Manual.
Gap dimension
The decisive factor for the function of the seal is the largest gap dimension occurring
during operation on the non-pressurised side of the seal. → Technical Manual.
Profile Max. permissible gap dimension
16 MPa 26 MPa 32 MPa 40 MPa
4,0 … 5,0 0,50 0,40 0,35 0,30
>5,0 … 7,5 0,55 0,45 0,40 0,35
>7,5 … 12,5 0,66 0,50 0,45 0,40
>12,5 0,60 0,55 0,50 0,45
Tolerance recommendation and dimension d2
The admissible gap width, tolerances, guide play and deflection of the guide under
load are to be taken into account when designing D2. → Technical Manual.
Nominal Ø d d D
4 … 260 f8 H11
Fitting & installation
Careful fitting is a prerequisite for the correct function of the seal.
→ Technical Manual.

3. © Merkel Freudenberg Fluidtechnic GmbH | Seals for Fluid Power Catalog 2007
Hydraulics | Rod Seals | Merkel U-Ring NI 300
Article list
dØ
H
DØ
D2
Ø
L 0,2+
R1
0,4
C
20°
Rounded and free of burrs R
2
<0,2
Rounded and free of burrs
d D H L Profile C Fitting Housing Material Article No.
10 20 8 9 5 4 94 AU P00925 21258 BB
12 20 5,5 6,3 4 3,5 ISO 94 AU P00925 337339 BB
12 20 8 9 4 3,5 94 AU P00925 68421 BB
12 22 7 8 5 4 ISO 94 AU P00925 337340 DD
12 22 8 9 5 4 94 AU P00925 21261 BB
14 22 5,5 6,3 4 3,5 ISO 94 AU P00925 435813 DD
14 24 8 9 5 4 94 AU P00925 21263 BB
15 25 8 9 5 4 94 AU P00925 21265 BB
16 24 5,5 6,3 4 4 ISO 94 AU P00925 337342 BB
16 26 8 9 5 4,5 94 AU P00925 18733 BB
18 26 5,5 6,3 4 4 ISO 94 AU P00925 364610 BB
18 26 8 9 4 4 94 AU P00925 81789 DD
18 28 8 9 5 4,5 94 AU P00925 21266 BB
20 28 5,5 6,3 4 4 ISO 94 AU P00925 337344 BB
20 30 8 9 5 4,5 94 AU P00925 18735 BB
20 30 10 11 5 4,5 94 AU P00925 21269 BB
20 35 10 11 7,5 5,5 94 AU P00925 401667 DD
22 30 5,5 6,3 4 4 ISO 94 AU P00925 429357 DD
22 32 7 8 5 4,5 ISO 94 AU P00925 381991 DD
22 32 8 9 5 4,5 94 AU P00925 21271 BB
22 32 10 11 5 4,5 94 AU P00925 21272 BB
22 35 10 11 6,5 5,5 94 AU P00925 401668 DD
23 35 10 11 6 5 94 AU P00925 336462 DD
25 33 5,5 6,3 4 4 W ISO 94 AU P00925 337346 BB
25 35 8 9 5 4,5 94 AU P00925 21274 BB
25 35 10 11 5 4,5 94 AU P00925 21275 BB
25 40 10 11 7,5 5,5 94 AU P00925 18741 BB
25 45 12 13 10 6 94 AU P00925 401770 DD
26 36 10 11 5 4,5 94 AU P00925 370114 BB
28 36 8 9 4 4 W 94 AU P00925 5148 BB
28 38 7 8 5 4,5 94 AU P00925 319964 DD
28 38 8 9 5 4,5 94 AU P00925 21280 BB
28 38 10 11 5 4,5 94 AU P00925 21282 BB
28 43 10 11 7,5 5,5 94 AU P00925 21285 DD
30 38 6 7 4 4 W 94 AU P00925 429363 DD
BB Available from stockAvailable from stock DD On request: Tool is available, delivery at short noticeOn request: Tool is available, delivery at short notice
Fitting: H = by hand; W = with fitting tool; blank = axially accessible housingFitting: H = by hand; W = with fitting tool; blank = axially accessible housing

4. © Merkel Freudenberg Fluidtechnic GmbH | Seals for Fluid Power Catalog 2007
Hydraulics | Rod Seals | Merkel U-Ring NI 300
d D H L Profile C Fitting Housing Material Article No.
30 40 10 11 5 4,5 W 94 AU P00925 21286 BB
30 45 10 11 7,5 5,5 94 AU P00925 21305 BB
30 50 12 13 10 6 94 AU P00925 401781 DD
32 40 5,5 6,3 4 4 W 94 AU P00925 406663 DD
32 40 6,5 7,5 4 4 W 94 AU P00925 315748 BB
32 40 8 9 4 4 W 94 AU P00925 429370 BB
32 42 10 11 5 4,5 W 94 AU P00925 21306 BB
32 45 10 11 6,5 5,5 94 AU P00925 401826 BB
32 47 10 11 7,5 5,5 94 AU P00925 21307 BB
35 43 6 7 4 4 W 94 AU P00925 429378 DD
35 45 10 11 5 4,5 W 94 AU P00925 18756 BB
35 50 10 11 7,5 5,5 94 AU P00925 18759 BB
36 44 6 7 4 4 W 94 AU P00925 429359 DD
36 46 7 8 5 4,5 W ISO 94 AU P00925 319965 BB
36 46 10 11 5 4,5 W 94 AU P00925 21315 BB
36 51 10 11 7,5 5,5 94 AU P00925 21317 BB
36 56 12 13 10 6 94 AU P00925 21324 BB
37 47 8 9 5 4,5 W 94 AU P00925 368268 BB
37 47 10 11 5 4,5 W 94 AU P00925 375755 BB
38 55 10 11 8,5 6 94 AU P00925 401832 DD
40 48 8 9 4 4 H 94 AU P00925 429264 DD
40 50 7 8 5 4,5 H ISO 94 AU P00925 319563 BB
40 50 10 11 5 4,5 H 94 AU P00925 18760 BB
40 55 10 11 7,5 5,5 94 AU P00925 21326 BB
40 55 11,5 12,5 7,5 5,5 ISO 94 AU P00925 337351 DD
40 60 12 13 10 6 94 AU P00925 21338 BB
42 52 10 11 5 4,5 H 94 AU P00925 116182 BB
43 53 10 11 5 4,5 H 94 AU P00925 413930 DD
45 55 7 8 5 4,5 H ISO 94 AU P00925 429849 BB
45 55 10 11 5 4,5 H 94 AU P00925 18763 BB
45 60 10 11 7,5 5,5 94 AU P00925 18764 BB
45 60 11,5 12,5 7,5 5,5 ISO 94 AU P00925 381990 DD
45 65 12 13 10 6 94 AU P00925 21339 DD
46 56 10 11 5 4,5 H 94 AU P00925 413959 DD
50 58 8 9 4 4 H 94 AU P00925 429254 DD
50 59 8 9 4,5 4,5 H 94 AU P00925 420826 BB
50 60 10 11 5 4,5 H 94 AU P00925 18765 BB
50 65 10 11 7,5 5,5 W 94 AU P00925 21344 BB
50 65 11,5 12,5 7,5 5,5 W 94 AU P00925 457406 DD
50 70 12 13 10 6 94 AU P00925 21349 BB
52 62 10 11 5 4,5 H 94 AU P00925 112670 BB
55 63 8 9 4 4 H 94 AU P00925 523147 DD
55 65 8 9 5 4,5 H 94 AU P00925 384050 DD
55 65 10 11 5 4,5 H 94 AU P00925 21357 BB
55 65 12 13 5 4,5 H 94 AU P00925 21361 BB
55 70 10 11 7,5 5,5 W 94 AU P00925 18766 BB
55 70 12 13 7,5 5,5 W 94 AU P00925 21364 BB
55 75 12 13 10 6 94 AU P00925 21365 DD
56 66 10 11 5 4,5 H 94 AU P00925 21368 BB
BB Available from stockAvailable from stock DD On request: Tool is available, delivery at short noticeOn request: Tool is available, delivery at short notice
Fitting: H = by hand; W = with fitting tool; blank = axially accessible housingFitting: H = by hand; W = with fitting tool; blank = axially accessible housing

5. © Merkel Freudenberg Fluidtechnic GmbH | Seals for Fluid Power Catalog 2007
d D H L Profile C Fitting Housing Material Article No.
56 71 10 11 7,5 5,5 W 94 AU P00925 21374 BB
56 76 12 13 10 6 94 AU P00925 21379 DD
58 68 10 11 5 4,5 H 94 AU P00925 472965 DD
60 70 10 11 5 4,5 H 94 AU P00925 18771 BB
60 70 12 13 5 4,5 H 94 AU P00925 21386 BB
60 75 10 11 7,5 5,5 W 94 AU P00925 21391 BB
60 75 11,5 12,5 7,5 5,5 W 94 AU P00925 531745 DD
60 75 12 13 7,5 5,5 W 94 AU P00925 21395 BB
60 80 12 13 10 6 94 AU P00925 18772 BB
63 73 12 13 5 4,5 H 94 AU P00925 21396 BB
63 78 10 11 7,5 5,5 W 94 AU P00925 21406 BB
63 83 12 13 10 6 94 AU P00925 21407 BB
65 75 12 13 5 4,5 H 94 AU P00925 21420 BB
65 80 12 13 7,5 5,5 W 94 AU P00925 21429 BB
65 85 12 13 10 6 94 AU P00925 18773 BB
68 78 12 13 5 4,5 H 94 AU P00925 380798 DD
70 80 12 13 5 4,5 H 94 AU P00925 21430 BB
70 85 10 11 7,5 5,5 W 94 AU P00925 18776 BB
70 85 11,5 12,5 7,5 5,5 W ISO 94 AU P00925 319968 DD
70 85 12 13 7,5 5,5 W 94 AU P00925 21438 BB
70 90 12 13 10 6 94 AU P00925 18777 BB
75 85 12 13 5 4,5 H 94 AU P00925 21440 BB
75 90 10 11 7,5 5,5 W 94 AU P00925 21446 BB
75 90 12 13 7,5 5,5 W 94 AU P00925 18779 BB
77 87 12 13 5 4,5 H 94 AU P00925 369026 DD
80 90 10 11 5 4,5 H 94 AU P00925 127310 DD
80 90 12 13 5 4,5 H 94 AU P00925 21447 BB
80 95 10 11 7,5 5,5 H 94 AU P00925 21454 BB
80 95 12 13 7,5 5,5 H 94 AU P00925 21455 BB
80 100 12 13 10 6 W 94 AU P00925 18781 BB
80 100 15 16 10 6 W ISO 94 AU P00925 337358 DD
85 95 12 13 5 4,5 H 94 AU P00925 432307 DD
85 100 12 13 7,5 5,5 H 94 AU P00925 21466 BB
85 105 12 13 10 6 W 94 AU P00925 21472 DD
90 100 12 13 5 4,5 H 94 AU P00925 29310 DD
90 105 11,5 12,5 7,5 5,5 H ISO 94 AU P00925 344874 DD
BB Available from stockAvailable from stock DD On request: Tool is available, delivery at short noticeOn request: Tool is available, delivery at short notice
Fitting: H = by hand; W = with fitting tool; blank = axially accessible housingFitting: H = by hand; W = with fitting tool; blank = axially accessible housing
Hydraulics | Rod Seals | Merkel U-Ring NI 300
dØ
H
DØ
D2
Ø
L 0,2+
R1
0,4
C
20°
Rounded and free of burrs R
2
<0,2
Rounded and free of burrs

6. © Merkel Freudenberg Fluidtechnic GmbH | Seals for Fluid Power Catalog 2007
Hydraulics | Rod Seals | Merkel U-Ring NI 300
d D H L Profile C Fitting Housing Material Article No.
90 105 12 13 7,5 5,5 H 94 AU P00925 21474 BB
90 110 12 13 10 6 W 94 AU P00925 18786 BB
95 110 12 13 7,5 5,5 H 94 AU P00925 335953 DD
95 115 12 13 10 6 W 94 AU P00925 324248 BB
100 115 12 13 7,5 5,5 H 94 AU P00925 21482 BB
100 120 12 13 10 6 W 94 AU P00925 18789 BB
100 120 15 16 10 6 W ISO 94 AU P00925 21483 BB
100 125 15 16 12,5 6,5 W 94 AU P00925 401873 DD
110 125 15 16 7,5 5,5 H 94 AU P00925 30970 BB
110 130 12 13 10 6 W 94 AU P00925 21849 BB
110 130 15 16 10 6 W ISO 94 AU P00925 21486 BB
110 135 15 16 12,5 6,5 W 94 AU P00925 401889 DD
115 140 15 16 12,5 6,5 W 94 AU P00925 407165 DD
120 135 15 16 7,5 5,5 H 94 AU P00925 21493 BB
120 140 12 13 10 6 W 94 AU P00925 21497 BB
120 140 15 16 10 6 W 94 AU P00925 21500 BB
125 145 12 13 10 6 H 94 AU P00925 21852 BB
125 145 15 16 10 6 H ISO 94 AU P00925 21501 BB
125 150 15 16 12,5 6,5 W 94 AU P00925 401892 DD
125 155 18 19 15 7,5 W 94 AU P00925 21505 DD
130 150 12 13 10 6 H 94 AU P00925 21511 BB
130 150 15 16 10 6 H 94 AU P00925 21514 BB
140 160 12 13 10 6 H 94 AU P00925 21516 BB
140 160 15 16 10 6 H ISO 94 AU P00925 21518 BB
140 165 15 16 12,5 6,5 W 94 AU P00925 401895 DD
140 170 18 19 15 7,5 W 94 AU P00925 21520 DD
150 170 15 16 10 6 H 94 AU P00925 18792 BB
150 180 18 19 15 7,5 W 94 AU P00925 21522 DD
160 180 15 16 10 6 H 94 AU P00925 21538 BB
160 185 15 16 12,5 6,5 H ISO 94 AU P00925 401896 BB
170 190 15 16 10 6 H 94 AU P00925 21561 BB
180 200 15 16 10 6 H 94 AU P00925 18793 BB
180 205 15 16 12,5 6,5 H ISO 94 AU P00925 401907 DD
180 210 18 19 15 7,5 W 94 AU P00925 21569 DD
BB Available from stockAvailable from stock DD On request: Tool is available, delivery at short noticeOn request: Tool is available, delivery at short notice
Fitting: H = by hand; W = with fitting tool; blank = axially accessible housingFitting: H = by hand; W = with fitting tool; blank = axially accessible housing

7. © Merkel Freudenberg Fluidtechnic GmbH | Seals for Fluid Power Catalog 2007
Merkel Freudenberg
Fluidtechnic GmbH
Industriestr. 64
D-21107 Hamburg
Tel.: +49(0)40/75 30 6-0
Fax: +49(0)40/75 30 6-440
E-mail: merkel@freudenberg.de
www.merkel-freudenberg.de
The catalog details are based on the
experience of many years of research
in the development and production of
seals in the Freudenberg Group and
correspond to our current level of know-
how.
The sealing action of many catalog
products is, however, not only created
by the component itself. In many
cases – depending on the specific
application – it depends significantly on
the other parameters, such as installa-
tion point, counter surface, pressure,
operating temperature, media to be
sealed, lubrication, effects of vibration
and any ingress of dirt from outside.
These and other unknown factors in
practical use may noticeably influence
the functioning of the seals. Against this
background generalised statements
on the function of the catalog products
are not possible. Details in this catalog
merely represent general and non-bin-
ding reference values which make no
claim to be valid for every application.
We therefore recommend you to always
discuss specific applications with our
consultancy service. In the event of very
high and special loads, for example due
to aggressive media, the seal should be
selected in co-operation with us; trials to
check the functional reliability are often
indispensable.