1
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Return line and
Suction Boost Filter RKM
up to 850 l/min, up to 10 bar
1. TECHNICAL
SPECIFICATIONS
1.1 FILTER HOUSING
Construction
The lter housings are designed
in accordance with international
regulations. They consist of a lter head,
lter bowl and a screw-on or bolt-on
cover plate.
Standard equipment:
with bypass valve
with back-pressure valve
without anti-cavitation valve
Application
RKM return line & suction boost lters
are ideally suited for use in equipment
with two or more circuits. In particular
this lter is the "rst choice" for mobile
machinery using hydrostatic drives (e.g.
wheel loaders, fork-lift trucks, harvesting
machines), if the return ow is greater than
the ow required on the suction side under
operating conditions.
Function
The return ow of the operating hydraulics
is supplied to the lter via one or several
inlets "A" and is cleaned by the lter
element (full ow return line ltration). A
pressure of 0.5 bar (standard) is applied
inside the element by the back-pressure
valve "V1".
This ensures that the ltered return
line ow is available to the hydrostatic
feed pumps connected in "B" ports (full
ow suction boost ltration). The risk of
cavitation is signicantly reduced. The
excess ow is drained to the tank via port
"T". A bypass valve "V2" (standard = 2.5
bar) is tted to relieve excessive back-
pressures in the element (important on
cold starts when viscosity is high). This
valve arrangement ensures that only nely
ltered oil is available to the suction port
during operation (exception: RKM 350).
With optional valve "V3", oil can be drawn
from the tank for short periods, e.g. initial
lling, venting after changing element.
1.2 FILTER ELEMENTS
The lter elements used in RKM lters
are notable for low back-pressures,
especially at high viscosities (e.g. cold
starts).
1.9 COMPATIBILITY WITH
HYDRAULIC FLUIDS ISO 2943
Hydraulic oils H to HLPD DIN 51524
Lubrication oils DIN 51517, API,
ACEA, DIN 51515, ISO 6743
Compressor oils DIN 51506
Biodegradable operating uids
VDMA 24568 HETG, HEES, HEPG
Fire-resistant uids HFA, HFB, HFC
und HFD
Operating uids with high water
content (>50% water content) on
request
1.10 IMPORTANT INFORMATION
Filter housings must be earthed.
When using electrical clogging indicators,
the electrical power supply to the system
must be switched off before removing the
clogging indicator connector.
1.3 FILTER SPECIFICATIONS
Nominal pressure 10 bar
Temperature range -30 °C to +100 °C (short-term: -40 °C)
Material of lter head Aluminium
Material of lter bowl Steel (all RKM except RKM 300)
Polyamide (RKM 300)
Material of cover plate Polyamide (RKM 80 to 251, 350)
Aluminium (RKM 300, 400, 800)
Type of clogging indicator VMF – Connection thread G 1/8
Pressure setting of the clogging indicator -0.2 bar (vacuum pressure)
2 bar (back-pressure)
(others on request)
Bypass cracking pressure (V2) 2.5 bar (others on request)
Setting for back-pressure valve (V1) 0.5 bar (others on request)
Symbol for hydraulic systems
RKM
80
RKM
100
RKM
120
RKM
151
RKM
201
RKM
251
RKM
201/-TH
RKM
300
RKM
400
RKM
800
HYDAC lter elements are validated
and their quality is constantly
monitored according to the following
standards:
ISO 2941, ISO 2942, ISO 2943,
ISO 3724, ISO 3968, ISO 11170
ISO 16889
Filter elements are available with the
following pressure stability values:
Mobilemicron
®
(MM): 10 bar
1.4 SEALS
Perbunan (=NBR)
1.5 MOUNTING
Tank-top lter
1.6 SPECIAL MODELS AND
ACCESSORIES
with bleed valve
with multiport head (only RKM 80 to
251; see point 2.4)
with integral thermal bypass valve
(only RKM 151, 201, 251; see point
2.5)
with anti-cavitation valve (V3)
1.7 SPARE PARTS
See Original Spare Parts List
1.8 CERTIFICATES AND APPROVALS
On request
RKM
350
VA = clogging indicator
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2
RKM MM 300 B T F 10 W 0 . X /-NR-EV
Filter type
RKM
Filter material of element
MM Mobilemicron
Size of lter or element
RKM: 80, 100, 120, 151, 201, 251, 300, 350, 400, 800
Operating pressure
B = 10 bar
V = 7 bar (for RKM with clogging indicator up to max. 7 bar operating pressure)
Type and size of suction line
Type Connection Filter size
80 100 120 151 201 251 300 350 400 800
T 2 x CS1¼
V 2 x G1
X 1 x G1
Y 1 x G¾
Z to customer spec.
* * *
Type and size of return line
Type Connection Filter size
80 100 120 151 201 251 300 350 400 800
C 1 x G¾
D 1 x G1
E 1 x G1¼
F 1 x CS1½
G 1 x G1½
Z to customer spec.
° ° ° *° *° *°
Filtration rating in µm
MM: 8, 10, 15
Type of clogging indicator
W without port for clogging indicator
Y plastic blanking plug in indicator port
A steel blanking plug in indicator port
F pressure switch
K return line & vacuum pressure gauge for other clogging indicators
R return line pressure gauge see brochure no. 7.050../..
UF vacuum switch
Type code
0 no indicator
1-5 see point 2.6
Modication number
X the latest version is always supplied
Supplementary details
no details = standard (without anti-cavitation valve; seals NBR; bypass valve 2.5 bar; back-pressure valve 0.5 bar)
B3-CV3.5 bypass valve with 3 bar cracking pressure and back-pressure valve with 3.5 bar cracking pressure (only RKM 350)
B6-CV3 bypass valve with 6 bar cracking pressure and back-pressure valve with 3 bar cracking pressure (only RKM 100, 300)
ES vent plug
EV air bleed valve
NR anti-cavitation valve (not on RKM 350)
NRF125 anti-cavitation valve and coarse strainer 125 µm (not on RKM 350)
for symbols
ND pressure release valve in back-pressure valve
see point 2.7
UT lter suitable for use when immersed horizontally in oil
V FPM seals
xxxxx only RKM 80 to 251 (see point 2.4)
xxxxxxxx only RKM 400 and 800 (see point 2.4)
THxx only RKM 151, 201, 251 (see point 2.5)
2. MODEL CODE (also order example)
2.1 COMPLETE FILTER
0300 RK 010 MM /-V
Size
0080, 0100, 0120, 0151, 0201, 0251, 0300, 0350, 0400, 0800
Type
RK
Filtration rating in µm
MM 008, 010, 015
Filter material
MM
Supplementary details
V FPM seal
2.2 REPLACEMENT ELEMENT
2.3 REPLACEMENT CLOGGING INDICATOR VMF 2 F . X
The return line indicator monitors the level of contamination in the element.
The vacuum indicator monitors the suction side pressure.
Type
VMF thread G 1/8
Pressure setting
0.2 -0.2 bar (vacuum pressure)
others on request
2 2 bar (back-pressure)
Type of clogging indicator (see Point 2.1)
Modication number
X the latest version is always supplied
Supplementary details
V only for types B, BM, LE, LZ and C /-EX2G (all other clogging indicators have FPM seals as standard)
* only in conjunction
with thermal
bypass valve
° only in conjunction
with multiport head
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2.4 PORT CONFIGURATION RKM 80 TO 251 MULTIPORT HEAD AND RKM 400 AND 800
Since there are numerous options for machining the ports on the multiport head and the head of the RKM 400/800, the
general code BZZ is selected here. In order to determine the position and size of the ports, a 5-digit or a 9-digit code is added
as a supplementary detail. This is determined using the table below. Unused ports are indicated by a "0".
R = return port; S = suction port
S2
Port conguration RKM 80, 100, 120 Multiport
Position in code 1 2 3 4 5
Connection R1 R2 R3 S1 S2
G ½ B B B B
G ¾ C C C C C
G1 D
Port plugged 0 0 0 0 0
Special port Z Z Z Z Z
Example: RKM MM 100 BZZ 15 W 1.0 /-CBBCC
Port conguration RKM 151, 201, 251 Multiport
Position in code 1 2 3 4 5
Port R1 R2 R3 S1 S2
G ¾ C C C C
G 1 D D D D D
G 1¼ E
Port plugged 0 0 0 0 0
Special port Z Z Z Z Z
Example: RKM MM 201 BZZ 15 W 1.0 /-ECCDD
Port conguration RKM 400 and 800
Position in code 1 2 3 4 5 6 7 8 9
Port R1 R2 R3 S4 S5 S6 S7 S8 S9
SAE DN 50 1
SAE DN 65 2
G1 1 1 A A 1 1 A A
G1¼ 2 2 B B 2 2 B B
G1½ 3 3 C C 3 3 C C
Port plugged 0 0 0 0 0 0 0 0
Special port Z Z Z Z Z Z Z Z
Example: RKM MM 400 BZZ 15 A 1.0 /-102CC2200
R1
S1
R2
R3
S2
R1
S1
R2
R3
S6 S7
R1
S5
S4
R3
R2
S8
S9
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2.5 PORT CONFIGURATION RKM 151, 201, 251 WITH
THERMAL BYPASS VALVE
The part ow which requires cooling can be directed via
separate ports via the thermal valve. During a cold start, the
spool of the thermal valve shuts off the ow to the cooler so
that the uid ows directly through the lter element. The
position of the spool is regulated by the oil temperature.
From approx. 50-60 ºC the inlet to the cooler is completely
open (diagram 1).
Alternative connection option according to diagram 2: A hose
connects the inlet line of the cooler to the thermal valve.
The connection conguration is determined by agreement
with the customer.
Diagram 1
Diagram 2
suction port
G1
temperature switch
M 14x1.5
return line
(direct to the element)
G¾ or G1
connection for
clogging indicator
G1/8
inlet to the cooler
G¾
return line
(direct to the element)
G¾
return line
(via thermal valve)
G3/8
return line
(via thermal valve)
e.g. M36x2
return line
(direct to the element)
G¾ or G1
return line
(via thermal valve)
G3/8
suction port
G1
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2.6 TYPE CODE
RKM 80, 100, 120
RKM 151, 201, 251
RKM 300
Type Type of Measuring
code clogging indicator
1.X Return line Before lter element
2.X Return line Before lter element
3.X Vacuum After lter element
4.X Vacuum After lter element
5.X 2 indicators: Before & after element
Return line
& vacuum
Type Type of Measuring
code clogging indicator
1.X Return line Before lter element
2.X Return line Before lter element
3.X Vacuum After lter element
5.X 2 indicators: Before & after element
Return line
& vacuum
Type Type of Measuring
code clogging indicator
1.X Return line Before lter element
2.X Return line Before lter element
3.X Vacuum After lter element
4.X Vacuum After lter element
5.X 2 indicators: Before & after element
Return line
& vacuum
RKM 400, 800
Type Type of Measuring
code clogging indicator
1.X Return line Before lter element
2.X Return line Before lter element
3.X Vacuum After lter element
4.X Vacuum After lter element
5.X 2 indicators: Before & after element
Return line
& vacuum
2.7 SYMBOLS
/-ND/-NR
/-NRF125
RKM 350
Other indicator congurations on request!
A
B
V2
V1
3 bar
(2.5 bar)
3.5 bar
(0.5 bar)
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3. FILTER CALCULATION /
SIZING
The total pressure drop of a lter at a
certain ow rate Q is the sum of the
housing ∆p and the element ∆p and is
calculated as follows:
∆p
total
= ∆p
housing
+ ∆p
element
∆p
housing
= (see Point 3.1)
∆p
element
= Q •
SK*
•
viscosity
1000 30
(*see point 3.2)
For ease of calculation, our Filter
Sizing Program is available on request
free of charge.
NEW: Sizing online at www.hydac.com
3.1 GRADIENT COEFFICIENTS (SK)
FOR FILTER ELEMENTS
The gradient coefcients in mbar/
(l/min) apply to mineral oils with a
kinematic viscosity of 30 mm²/s. The
pressure drop changes proportionally
to the change in viscosity.
RKM MM
8 µm 10 µm 15 µm
80 2.70 2.70 1.60
100 1.80 1.80 1.10
120 1.40 1.40 0.90
151 1.00 1.00 0.65
201 0.75 0.75 0.47
251 0.58 0.58 0.36
300 0.62 0.62 0.39
350 0.30 0.30 0.20
400 0.56 0.56 0.35
800 0.44 0.44 0.27
3.2 ∆p-Q HOUSING CURVES
INCLUDING ELEMENT BASED
ON ISO 3968
The housing curves apply to mineral oil
with a density of 0.86 kg/dm³ and
a kinematic viscosity of 30 mm²/s.
In this case, the differential pressure
changes proportionally to the density.
∆p [bar]
Q [l/min]
RKM 80
∆p [bar]
Q [l/min]
RKM 100
∆p [bar]
Q [l/min]
RKM 251
∆p [bar]
Q [l/min]
RKM 300
∆p [bar]
Q [l/min]
RKM 120
∆p [bar]
Q [l/min]
RKM 151
∆p [bar]
Q [l/min]
RKM 400
∆p [bar]
Q [l/min]
RKM 800
∆p [bar]
Q [l/min]
RKM 201
∆p [bar]
Q [l/min]
RKM 350
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4. DIMENSIONS
RKM 80, 100, 120
outlet
RKM 80, 100, 120 Multiport
Weight incl.
element [kg]
Volume of
pressure
chamber [l]
RKM 80 1.5 0.80
RKM 100 1.7 1.00
RKM 120 1.9 1.20
Weight incl.
element [kg]
Volume of pressure
chamber [l]
RKM 80 1.8 0.80
RKM 100 2.0 1.00
RKM 120 2.2 1.20
inlet
outlet
inlet
inlet
inlet
outlet
Tank requirements
1. In the lter contact area, the tank ange should have a
maximum atness of 0.3 mm and Ra 3.2 µm maximum
roughness.
2. In addition, the contact area should be free of damage
and scratches.
3. The xing holes of the tank ange must be blind, or
stud bolts with threadlocker must be used to x the
lter.
As an alternative, the tank ange can be continuously
welded from the inside.
4. Both the tank sheet metal and/or the lter mounting
ange must be sufciently robust so that neither deform
when the seal is compressed during tightening.
5. When using a dipstick through a mounting screw,
threadlock the screw into the thread, using Loctite 243,
for example, or a similar threadlocker..
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RKM 151, 201, 251
RKM 151, 201, 251 Multiport
Weight incl.
element [kg]
Volume of pressure
chamber [l]
RKM 151 3.1 2.20
RKM 201 3.7 2.50
RKM 251 4.0 3.00
Weight incl.
element [kg]
Volume of pressure
chamber [l]
RKM 151 3.5 2.20
RKM 201 4.2 2.50
RKM 251 4.5 3.00
outlet
inlet
inlet
inlet
outlet
inlet
outletoutlet
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RKM 151, 201, 251 with Thermal Bypass Valve
RKM 300
Weight incl.
element [kg]
Volume of pressure
chamber [l]
RKM 151 4.6 2.20
RKM 201 5.2 2.50
RKM 251 5.5 3.00
Weight incl.
element [kg]
Volume of pressure
chamber [l]
RKM
300
4.6 4.00
outlet
inlet
View from below
outlet
inlet
outlet
inlet
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10
NOTE
The information in this brochure relates to the operating conditions and applications
described.
For applications and operating conditions not described, please contact the relevant
technical department.
Subject to technical modications.
HYDAC Filtertechnik GmbH
Industriegebiet
D-66280 Sulzbach/Saar
Tel.: 0 68 97 / 509-01
Fax: 0 68 97 / 509-300
Internet: www.hydac.com
E-Mail: lter@hydac.com
RKM 400, 800
RKM 350
Weight incl.
element [kg]
Volume of
pressure
chamber [l]
RKM 400 6.5 8.50
RKM 800 7.5 10.00
Weight incl.
element [kg]
Volume of
pressure
chamber [l]
RKM 350 6.3 6.00
outlet
inlet
View from below
outlet
outlet outlet
inlet
inlet
outlet
outlet
Flange interface
SAE 2" 3000 psi or
SAE 2 1/2" 3000 psi