Screw-In Cartridge Valves E-VLSC-MC001-E December 2009 K-380.A
An Eaton Brand
K
Where measurements are critical request certified drawings. We reserve the right to change specifications without notice.
1UL255 - Unloading Valve
Two pump
Up to 200 L/min (40 USgpm) • 350 bar (5000 psi)
Description
Two-pump unloader valves
are used in systems with
combinations of two (or more)
pumps to give high flow at low
pressure and high pressure
at low flow. The valves
bypass the flow from the low
pressure pump(s) to tank at a
pre-set pressure. This allows
pump selection to give, for
example, rapid advance and
high power compaction with
the most economic usage
of system components and
energy requirements.
Operation
Pump inlet to P1 and P2 is
combined to give maximum
flow at low pressure. When
the load pressure increases to
the valve setting the high flow
(low pressure) pump is
bypassed from P1 to tank
allowing nearly all system
power to be used for the high
pressure pump.
(See graph for the pressure
drop of the dumped flow). The
system relief valve provides
protection by limiting the
maximum pressure in the
system line.
Features
This is a self contained system
including two replaceable
cartridges with full adjustment
through their respective
ranges. Hardened working
components give long,
trouble-free life and single
body reduces plumbing to a
minimum.
Ratings and Specifications
Performance data is typical with fluid at 32 cST (150 SUS)
Rated flow low flow/high pressure (P2 150 L/min (40 USgpm)
high flow/low pressure (P1)) 200 L/min (52 USgpm)
Max setting 350 bar (5000 psi)
Cartridge material Working parts hardened & ground steel
External surface zinc plated
Body material Standard - steel
Mounting position Unrestricted
Weight 3.15 kg (6.93 lbs)
Seal kit number SK671 (Nitrile) SK671V (Viton)
Recommended filtration level BS5540/4 Class 18/13 (25 micron nominal)
Operating Temp -30°C to +90°C (-22° to 194° F)
Nominal viscosity range 5 to 500 cSt
Viton is a registered trademark of E.I. DuPont
Performance Data
Pressure Drop
P1
T
SYSTEM
P2
0 10 20 30 40 50 60
Flow - US gpm
0 40 80 120 160 200 240
Flow - L/min
50
100
150
200
250
300
3.5
6.9
10.3
13.8
17.2
20.7
Pressure - psi
Pressure - bar
P1 - T
EATON Screw-In Cartridge Valves E-VLSC-MC001-E December 2009 K-381.A
An Eaton Brand
K
Where measurements are critical request certified drawings. We reserve the right to change specifications without notice.
1UL255 - Unloading Valve
Two pump
Up to 200 L/min (40 USgpm) • 350 bar (5000 psi)
Model Code
2 3 4 51
1UL255
P
6W-4W
20
35
5
Adjustable High
Pressure Range
Note: Code based on pressure
in bar.
17 - 35-175 bar.
Std setting 105 bar
28 - 75-285 bar.
Std setting 175 bar
35 - 114-350 bar.
Std setting 280 bar
7
Seals
S - Nitrile (For use with
most industrial hydraulic
oils)
SV - Viton (For high tem-
perature and most
special uid applica-
tions)
Dimensions
mm (inch)
6
S
Complete Valve
Basic Code: 1UL255
1
Basic Code
1UL255 - Complete Valve
2
Adjustment Means
P - Leakproof Screw
Adjustment
3
Port Sizes -
4
Adjustable Low
Pressure Range
Note: Code based on pressure
in bar.
20 - 30-210 bar.
Std setting 100 bar
35 - 150-350 bar.
Std setting 200 bar
– – /
Code System PI & T P2 Housing Number (Steel)
6W-4W 3/4" BSPP 1/2" BSPP BXP24051-6W-4W-S-377
130
(5.12)
58
(2.28)
T
P1
25.4
(1.0)
179 MAX
(7.05)
Low Pressure
Unloading Cartridge
1PUL200-P-20-S-JL
110
(4.33)
10
(0.39)
2 Holes Ø9.0
(0.35) Thro’
T
P1
P2
92
(3.62)
65
(2.56)
26
(1.02)
Check Valve
HighPressure
Relief Cartridge
1LR100-F-**-S
SYSTEM
50.8
(2.0)
25.4
(1.0)
169 MAX
(6.65)
101.6
(4.0)
21.0
(0.83)
