Relieving 1 to 3
Reducing 2 to 1
248/3600
186/2700
124/1800
62/900
15
4
0
0
33
21
05
15
4
30
8
45
12
61
16
FLOW RATE lpm/gpm
PRESSURE bar/psi
Typical Relieving and Reducing Pressure vs. Flow
at Maximun Pressure Setting for Different Spring Ranges
32 cSt/150 sus oil at 40°C
76
20
30
8
45
12
61
16
76
20
310/4500
15
PERFORMANCE (Cartridge Only)
DESCRIPTION
A screw-in, cartridge-style, direct-acting, spool-type, hydraulic pressure reducing/
relieving valve, with internal spring-chamber drain and spool damping chamber. It is
designed to act as a pressure regulating valve for secondary circuits. Internal
damping makes this valve particularly suitable for use in circuits with unstable input
flows in demanding applications requiring enhanced stability.
OPERATION
In its steady state, the PR50-38 allows flow to pass bidirectionally from port 2 to
port 1, with the spring chamber constantly drained at port 3. Upon attainment of
a predetermined pressure at 1, the spool shifts to block flow at 2, thereby
regulating pressure at 1. In this mode, the valve will also relieve from port 1 to port 3,
at a variable value over the set reducing pressure. Tank port pressure is additive to
the pressure setting at a ratio of 1:1.
FEATURES
• Adjustments cannot be backed out of the valve.
• Adjustments prohibit springs from going solid.
• Optional spring ranges to 227.5 bar (3300 psi).
• Optional 233 micron screen at port 2.
• Industry common cavity.
RATINGS
Pressure Rating: 345 bar (5000 psi) at ports 1 and 2; 68.9 bar (1000 psi) at port 3;
241 bar (3500 psi) max for F and H Adjustment options.
Proof Pressure: 48.2 bar (7000 psi) at ports 1 and 2; 68.9 bar (1000 psi) at port 3
Burst Pressure: 1034 bar (5000 psi)
Regulated Pressure Range: 10.3 to 227.5 bar (150 to 3300 psi)
Maximum Rated Flow: See Performance Chart
Maximum Internal Leakage to Port 3: 82 ml per minute (5.0 cu. in. per minute)
Temperature: -40 to 100°C (-40 to 212°F) with standard Buna N seals;
-26 to 204°C (-15 to 400°F) with fluorocarbon seals;
-54 to 107°C (-65 to 225°F) with polyurethane seals
Filtration: See page 9.010.1
Fluids: Mineral-based or synthetics with lubricating properties at viscosities of
7.4 to 420 cSt (50 to 2000 sus); See Temperature and Oil Viscosity, page 9.060.1
Installation: No restrictions; See page 9.020.1
Cavity: VC10-3; See page 9.110.1
Cavity Tool: CT10-3XX; See page 8.600.1
Seal Kit: SK10-3X-BM; See page 8.650.1
PRESSU
ISO SYMBOL
6.454.1
2
3
1
PR50-38 Pressure Reducing/Relieving Spool Valve
HYDRAFORCE
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®
RE CONTROLS
9.7/140
8.3/120
6.9/100
5.5/80
4.1/60
15.1
4
22.7
6
30.3
8
FLOW lpm/gpm
PRESSURE bar/psi
Fully Open Pressure Drop
Port 2 to Port 1 & Port 1 to Port 3
32 cSt/150 sus oil at 40°C
37.9
10
7.6
2
0
Screen
No Screen
1.4/20
138/2000
110.3/1600
82.7/1200
55.2/800
27.6/400
0.1000
0.200
TIME seconds
PRESSURE bar/psi
Response To Inlet Pressure Step
Time (sec.) Step Up: 0.040
Inlet Pressure Port 2 to Port 1
Supporting Valve Upstream Inlet Pressure Steps
Between 241.3 bar (3500 psi) and 10.3 bar (150 psi)
Pressure Step Response
in Reducing Mode Time (sec)
Step Up: 0.014 Step Down: 0.043
Inlet Pressure Port 2 to Port 1
Supporting Valve Downstream Reducing Flow Steps
Between 0 lpm (0 gpm) and 18.9 lpm (5 gpm)
138/2000
110.3/1600
82.7/1200
55.2/800
27.6/400
0.0500
0.100
TIME seconds
PRESSURE bar/psi
Blue rectangles are links to other catalog pages.
Setting in bar
†
(Blank) for Adjustable, or
Specify, for example:
M25 25 bar
M100 100 bar
Setting in psi
†
(Blank) for Adjustable, or
Specify, for example:
9.0 900 psi
21.5 2150 psi
DIMENSIONS
* 241 bar (3500 psi) max for F
and H Adjustment options.
MATERIALS
TO ORDER
PR50-38
__ - __ __ __ __ - __ - __ __ / __ __ __ __
Adjustment Option
1/4 in. Hex Allen Head A
1-1/2 in. Dia. Alum. Knob B
Option A w/Cover Cap C
Factory Preset Non-Adj. F*
Factory Preset Hidden Adj.
(See page 6.003.1) H*
Option C w/Lockwire Holes L
Spring Range
05 10.3 to 37.9 bar
(150 to 550 psi)
15 6.9 to 103 bar
(100 to 1500 psi)
21 27.6 to 144.8 bar
(400 to 2100 psi)
33* 55.2 to 227.5 bar
(800 to 3300 psi)
Seals
Buna N (Std.) N
Fluorocarbon V
Polyurethane P
PR50-38
6.454.2
TORQUE:
25–27 ft-lbs
(33.9–36.6 Nm)
0.75
19.1
ACROSS
FLATS
Ductile iron
body shown
Thru
2 Places
Orifice Disc should not
be used with this valve.
Note: Polyurethane seals
are required for operation
over 241 bar (3500 psi).
*For adjustment options "H" and "F" spring
will become overstressed if pressure set
above specified limit
Damped, Direct-Acting
Porting
Cartridge Only 0
SAE 6 6T
SAE 6 6TD
SAE 8 8T
SAE 8 8TD
1/4 in. BSP* 2B
1/4 in. BSP* 2BD
3/8 in. BSP* 3B
3/8 in. BSP* 3BD
*BSP Body; U.K. Mfr Only
®
HYDRAFORCE
HYDRAFORCE
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®
Cartridge: Weight: 0.27 to 0.31 kg.
(0.59 to 0.69 lbs.) depending
on adjustment type. Steel with
hardened work surfaces. Zinc-
plated exposed surfaces. Buna N
O-rings and polyester elastomer
back-ups standard. Anodized
aluminum knobs and caps.
Standard Ported Body:
Weight: 0.36 kg. (0.80 lbs.)
Anodized high-strength 6061 T6
aluminum alloy, rated to 207 bar
(3000 psi). Ductile iron (code D)
bodies are required for operation
over 207 bar (3000 psi), dimen-
sions may differ; consult factory.
See page 8.010.1
Screen
No Screen (blank)
233 Micron Screen S
†
Adjustable valves will be pre-
set to approx. 50% of spring
max. potential.
Blue rectangles are links to other catalog pages.
