Leak-Free Load-Control Valve, Size 6
Q
max
= 50l/min (13 gpm),p
max
= 420bar (6000 psi)
leak-proof, pilot operated, flange- or pipe design
Series BBV 6...
1/9
Reference: 300-P-9050020-EN-04
Issue: 08.2020
S Two-stage load-control valve and bypass check valve
are functionally combined in one coaxial valve assembly
S Leak-free load holding
S The load pressure has very little influence on the pilot
pressure required → area ratio 1:66
S Guaranteed closing force for the load-control assembly
→ reliable shut-off even with a broken spring
S Thanks to the various pilot control styles, the valve can
always be adapted to the system requirements
S Hardened, ground and lapped seat valve components
ensure permanent leaktightness and long service life
S Optionally with pilot operated secondary pressure relief
valve
S All external parts with zinc-nickel coating according to
DIN EN ISO 19598
1 Description
Load-control valves in this series prevent hydraulic actua
tors from running ahead of the available oil supply. In one
valve, they combine the functions of load-holding, safety
and pipe-rupture protection. These hydraulic load-control
valves from the series BBV 6… are pilot operated as well as
high performance valves of size 6 and available as flange
and piping valves. They are ideally suited for use in high-
pressure applications up to 420 bar (6000 psi). Thanks to
the various pilot control variants, the cartridge can be opti
mally adapted to the system requirements. The compact
design allows for minimum installation space. All external
parts are zinc-nickel plated, and are thus suitable for use in
the harshest operating environments. These valves mainly
used in mobile and stationary applications (e.g. for speed
control of cylinders, hydraulic motors or on the luffing mech
anisms).
2 Symbol
without secondary pressure relief valve with secondary pressure relief valve
A
B
X
A1
B1
A
B
X
A1
MB
300-P-9050020-EN-04/08.2020
Series BBV
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3 Technical data
General characteristics Description, value, unit
Designation leak-free load-control valve
Design leak-proof, hydraulically pilot operated, flange or
pipe design
Size size 6
Mounting method flanged (SAE 6000 psi) or piped
Main ports A, A1
Main port B
Main port B, B1
Control port X
Measuring port MB
G ⅜", ISO 1179-1
SAE ½" 6000 psi (mit SV)
ISO 6162-2 DN13 M8
(SAE J518 Code 62-8, M8x1.25)
G ⅜", ISO 1179-1 (ohne SV)
G ⅜", ISO 1179-1 (ohne SV)
G ¼", ISO 1179-1
G ¼", ISO 1179-1
Weight without SV: 2.0 kg (4.40 lbs)
with SV: 2.9 kg (6.39 lbs)
Mounting attitude unrestricted
Ambient temperature range -25°C … +80°C (-13 °F … +176 °F)
(others on application)
Surface corrosion protection all external parts with zinc-nickel coating according to
DIN EN ISO 19598
Hydraulic characteristics Description, value, unit
Maximum operating pressure 420bar (6000 psi)
Maximum flow rate 50 l/min (13 gpm)
Flow direction A → B, free flow through check valve
B → A, controlled flow
Operator type hydraulic proportional
Opening pilot ratio 1:66
Hydraulic fluid HL and HLP mineral oil to DIN 51 524;
for other fluids, please contact BUCHER
Hydraulic fluid temperature range -25°C … +80°C (-13 °F … +176 °F)
Temperature rating of seals NBR
FKM
MIL
-25°C … +100°C (-13 °F … +212 °F)
-20°C … +200°C (-4 °F … +392 °F)
-55°C … +80°C (-67 °F … +176 °F)
Viscosity range 2.8…1500 mm
2
/s (cSt), recommended 10…380 mm
2
/s (cSt)
Minimum fluid cleanliness
Cleanliness class to ISO 4406:1999
class 20/17/14
300-P-9050020-EN-04/08.2020
Series BBV
3/9
4 Construction and function
4.1 Neutral position (load pressure at B, ports A and X depressurized)
In the neutral position, there is zero leakage from B → A. The valve is held closed by the check valve spring, which acts the
pilot valve ball and thus on the control spool, and also by the load pressure, which acts on the rear side of the pilot valve ball
and the control spool.
4.2 Check valve function (flow from A → B)
To raise the actuator, pump pressure is applied via port A to the valve seat area of the control spool and causes the control
spool together with the pilot ball to open, pushing against the check valve spring. Due to the small effective area of the pilot
ball, when the control spool moves in the opening direction during the check valve function the pilot ball moves with it, and
does not lift from its seat in the spool.
4.3 Lowering function (flow from B → A)
Initial decompression
The pilot pressure at port X moves the pilot piston in opposition to the pilot spring, lifting the pilot ball from its seat in the control
spool. The load pressure behind the control spool now decays as it escapes past the pilot ball seat to port A.
Opening the control spool
With further increase in the pilot pressure, the pilot piston compresses the pilot spring still more. It then makes direct contact
with the control spool and pushes it open aigainst the check valve spring.
The pilot pressure acting on the pilot piston therefore controls the open metering area of the control spool, and consequently
the flow rate from B → A.
Damping
The system can be protected against oscillations by using suitable damping orifices. The effect of the bypass orifice from
X → A is to make it necessary to use higher pilot pressures (pressure divider function) and this improves the damping
behaviour.
The orifices are protected against contamination by a mesh filter at port X and a check valve that prevents flow from A.
4.4 Secondary pressure relief valve (SV)
The secondary pressure relief valve is connected directly to the cylinder port B. When the pressure setting (which is externally
adjustable) is reached, the relief valve poppet opens to creat a flow path to the pilot chamber X. This causes the pressure
in the pilot chamber to rise, which moves the pilot piston in the opening direction. The excess pressure in B is now relieved
to A though the open control spool.
IMPORTANT!:
For more information on the secondary pressure
relief valve (SV) see documentation
300-P-9050065 on our website.
300-P-9050020-EN-04/08.2020
Series BBV
4/9
5 Performance graphs
measured with oil viscosity 33mm
2
/s (cSt)
Δp = f (Q) Pressure drop - Flow rate characteristic
Check valve function, A → B
0
(140)
(285)
(430)
Q [l/min (gpm)]
50403020100
(570)
(700)
(13)(11)(8.0)(5.3)(2.6)
10
20
30
40
50
(860)60
P0051.ai
1
2
3
4
5
p = f (Q) Pressure - Flow rate characteristic
Pilot pressure pX @ 200 bar load pressure, B → A
(with damping orifice, without bypass orifice)
0
(140)
(285)
(430)
Q [l/min (gpm)]
50403020100
pX [bar (psi)]
(570)
(13)(11)(8.0)(5.3)(2.6)
10
20
30
40
P0053.ai
1
2
3
4
5
Δp = f (Q) Pressure drop - Flow rate characteristic
Lowering function, B → A, fully open
0
(285)
Q [l/min (gpm)]
50403020100
(570)
(13)(11)(8.0)(5.3)(2.6)
20
40
(860)60
(1150)80
(1400)100
P0052.ai
1
234
5
p = f (Q) Pressure - Flow rate characteristic
Secondary pressure relief valve (SV)
0
(5700)
Q [l/min (gpm)]0
A [bar (psi)]
400
(4300)300
(5000)350
(3600)250
(2900)200
(2100)150
(1400)100
(700)50
2FL: 7.5 l/min (1.98 gpm)
4FL: 15 l/min (3.75 gpm)
4FS: 30 l/min (7.5 gpm)
4SL: 50 l/min (13 gpm)
8FS: 50 l/min (13 gpm)
P0056.ai
a
b
c
Legend:
(applies to all characteristic curves)
1 piston type 4SL
2 piston type 4FS
3 piston type 4FL
4 piston type 2FL
5 piston type 8FS
a Setting 130 bar (1900 psi)
b Setting 230 bar (3300 psi)
c Setting 330 bar (4700 psi)
300-P-9050020-EN-04/08.2020
Series BBV
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5.1 Orifice names
A
B
X
A1
B1
1
2
1 damping orifice
2 bypass orifice
5.2 Table of opening pressures
Opening pressure at 200 bar load pressure (theoretical values).
pX
pre-opening
[bar / (psi)]
pX
start of opening
[bar / (psi)]
pX
fully open
[bar / (psi)]
Bypass orifice
[mm]
damping orifice
[mm]
9.0 / (130.5) 16.0 / (232.0) 33.0 / (478.6) Ø0.00 Ø0.25…0.40
12.0 / (174.0) 21.0 / (304.5) 45.0 / (652.6) Ø0.30 Ø0.40
14.0 / (203.0) 25.0 / (362.5) 52.5 / (761.4) Ø0.30 Ø0.35
14.0 / (203.0) 25.0 / (362.5) 54.0 / (783.2) Ø0.35 Ø0.40
18.0 / (261.0) 32.0 / (464.1) 67.5 / (979.0) Ø0.30 Ø0.30
18.0 / (261.0) 32.0 / (464.1) 67.5 / (979.0) Ø0.35 Ø0.35
18.0 / (261.0) 32.0 / (464.1) 67.5 / (979.0) Ø0.40 Ø0.40
23.0 / (333.5) 42.0 / (609.1) 88.5 / (1283.5) Ø0.45 Ø0.40
24.0 / (348.0) 43.0 / (623.6) 91.5 / (1327.0) Ø0.40 Ø0.35
26.0 / (377.0) 46.0 / (667.1) 97.5 / (1414.1) Ø0.35 Ø0.30
34.0 / (493.1) 60.0 / (870.2) 126.0 / (1827.4) Ø0.45 Ø0.35
37.0 / (536.6) 67.0 / (971.7) 141.0 / (2045.0) Ø0.40 Ø0.30
54.0 / (783.2) 97.0 / (1406.8) 205.5 / (2980.5) Ø0.45 Ø0.30
IMPORTANT!: The opening pressure can be
adjusted to the system by changing the orifices.
300-P-9050020-EN-04/08.2020
Series BBV
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6 Dimensions & sectional view
Example for the dimensional units:
0.79 = 0.79mm [millimeter]
(.031) = 0.031“ [inch]
Without secondary pressure relief valve (SV)
100
(3.93)
10
(.393)
7
(.275)
28
(1.10)
56
(2.20)
35
(1.37)
64.8
(2.55)
8
(.314)
124
(4.88)
167.5
(6.59)
35.5
(1.39)
20
(.787)
40
(1.57)
300−4−3109051−A
With secondary pressure relief valve (SV)
300-P-9050020-EN-04/08.2020
Series BBV
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7 Installation information
IMPORTANT!:
Designing load-control valves requires specialist
technical knowledge and product knowledge.
Safety applications must be verified by adequate
tests to ensure safety in actual use.
ATTENTION!
Only qualified personnel with mechanical skills
may carry out any maintenance work. Generally,
the only work that should ever be undertaken is to
check, and possibly replace, the seals. When
changing seals, oil or grease the new seals tho
roughly before fitting them.
IMPORTANT!:
The valve may only be used for its intended pur
pose within its nominal rating. If you plan to use it
outside the nominal rating, you must contact the
valve manufacturer.
The ultimate responsibility for safety in the instal
lation and use rests with the end-machine manu
facturer of the mobile application.
IMPORTANT!:
The port threads conform to DIN 3852 T1.
Use screws to DIN 912, grad 12.9, to mount the
valve.
Tightening torques as per the manufacturer's in
structions.
IMPORTANT!:
Protect seals and flange faces from damage.
The mating flange face must be of the quality
spedified in the data sheet!
Pay attention to the port designations.
IMPORTANT!
Seal kit with the external seals is available on app
lication.
300-P-9050020-EN-04/08.2020
Series BBV
8/9
8 Application examples
8.1 Speed control of a cylinder
Further possible applications are:
S Safety function for booms, derricking gear, etc.
S Speed control of hydraulic motors and derricking gear
300-P-9050020-EN-04/08.2020
Series BBV
9/9
9 Ordering code
BBV = leak-free load control valve
6 = size 6
2FL = piston type 2FL
4FL = piston type 4FL
4FS = piston type 4FS
4SL = piston type 4SL
8FS = piston type 8FS
0.30 = damping orifice Ø0.30
0.35 = damping orifice Ø0.35
0.40 = damping orifice Ø0.40
BY = with bypass (standard)
0.00 = bypass orifice Ø0.00 (closed)
0.30 = bypass orifice Ø0.30
0.35 = bypass orifice Ø0.35
0.40 = bypass orifice Ø0.40
0.45 = bypass orifice Ø0.45
(blank) = without secondary pressure relief valve (SV)
SV with secondary pressure relief valve (SV)
… = setting of the secondary pressure relief valve (SV)
50…500 bar (700…7200 psi)
N = NBR (Nitrile) seals (standard)
V = FKM (Viton) seals
T = MIL (low temperature) seals
(special seals - please contact BUCHER)
/
N
e.g.
-BBV 6 0.00-
BY
/
0.30/2FL
___
/
IMPORTANT!:
Additional documentation and 3D models
(.stp or .igs format) can be downloaded from
www.bucherhydraulics.com
(LOGintern area; registration is necessary)
IMPORTANT!:
We also offer customised solutions.
Please talk to our sales team.
E 2020 by Bucher Hydraulics AG, CH-6345 Neuheim
www.bucherhydraulics.cominfo.ch@bucherhydraulics.com
All rights reserved.
Data is provided for the purpose of product description only, and must not be construed as warranted characteristics in the legal sense. The
information does not relieve users from the duty of conducting their own evaluations and tests. Because the products are subject to continual
improvement, we reserve the right to amend the product specifications contained in this catalogue.
Classification: 430.325.360.305.315.325.305.310