Hydraulic Servo Valves – S4 Pro

The S4 Pro is a compact hydraulic servo valve designed for S01 ports. Its performance includes a flow range of 0.1-4.8 gpm (0.5-18 lpm), frequency over 200 Hz, and a fast response time of <3 ms. It is the smallest direct drive valve on the market with a low weight of 0.64 lbs (290 g) and port circle of 12.2 mm port circle. It is well suited for space-conscious applications like robotics, industrial, and motorsports.

Delivering superior performance, dynamics, and reliability in an ultra-compact package, it introduces a new era of control and productivity with the Domin S4 Pro series.

Available on S01 port pattern as standard.

For applications with a higher flow rate, view our most popular model, the S6 Pro, which has a maximum flow rate of 15.9 gpm (60 lpm).

Popular Upgrade Models:

Key Specs:

Key Features:

Standard Modification Options:

Technical Data

General Data

Design		Direct Drive Servo Valve
Actuation		Rotary-Rotary
Size		Miniature
Mounting Interface		ISO 10372-01-01
Ambient Temperature	ºC (ºF)	-20 to +60 (-4 to +140)
Mass	kg (lb)	0.29 (0.64)
Vibration Resistance	g	35, 3 axes
Shock Resistance	g	50

Hydraulic Data

Max. Operating Pressure (P, A, B, T)	Bar (psi)	350 (5,000)
Fluid		Hydraulic Oil DIN 51524-535
Fluid Temperature	ºC (ºF)	-20 to +80 (-5 to +175)
Viscosity	cSt	5 to 500
Rated Flow	l/min (US gal / min)	0.5 to 6 (0.2 to 1.6) / 6 to 11 (1.6 to 2.9) / 11 to 18 (2.9 to 4.8)
Flow Maximum	l/min (US gal / min)	1.4 to 12 (0.4 to 3.2) / 12 to 22 (3.2 to 5.8) / 22 to 36 (5.8 to 9.6)
Leakage at 100 bar	l/min (US gal / min)	<0.2 (0.05) / <0.45 (0.12) / <0.45 (0.12)
Filtration		ISO 4406 (1999) 18/16/13

Static/Dynamic Data

Response Time at 100% Step Input	ms	<3
Frequency Response (-3dB gain, ±25% signal)	Hz	>200
Frequency Response (-90deg phase, ±25% signal)	Hz	>110
Hysteresis	%	<1
Threshold	%	<1
Null Shift	%	<1

Performance Graphs

View performance graphs for the S4 Pro Domin Servo Valve below including Step Response, Flow vs Command, Frequency Response, and Pressure Gain:

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Electronics Data

Ratings of the valve electronics vary based on selected command input. Note that input ranges of Code E (±5 mA) are unavailable for S4 Pro.

±10 V (Code A)

Absolute Maximum Ratings*		Min.	Typ.	Max.
Supply Voltage	V	0	–	30
Differential Input Signal	V	-10.5	–	10.5
Input Signal Common Mode Offset	V	-10	–	10

Normal Operating Conditions		Min.	Typ.	Max.
Supply Voltage	V	22	24	30
Peak Current Consumption**	A	–	–	3.3
Differential Input Signals	V	-10	–	10
Input Impedance	KΩ	200	–	–

±20 mA (Code B)

Absolute Maximum Ratings*		Min.	Typ.	Max.
Supply Voltage	V	0	–	30
Differential Input Signal	mA	-25	–	25
Input Signal Common Mode Offset	V	-10	–	10

Normal Operating Conditions		Min.	Typ.	Max.
Supply Voltage	V	22	24	30
Peak Current Consumption**	A	–	–	3.3
Differential Input Signals	mA	20	–	20
Input Impedance***	Ω	–	392	–

+4 to +20 mA (Code C)

Absolute Maximum Ratings*		Min.	Typ.	Max.
Supply Voltage	V	0	–	30
Differential Input Signal	mA	-25	–	25
Input Signal Common Mode Offset	V	-10	–	10

Normal Operating Conditions		Min.	Typ.	Max.
Supply Voltage**	V	22	24	30
Peak Current Consumption	A	–	–	3.3
Differential Input Signals	mA	4	–	20
Differential Input Signals for drive off****	mA	-20	–	2
Input Impedance***	Ω	–	392	–

±5 V (Code D)

Absolute Maximum Ratings*		Min.	Typ.	Max.
Supply Voltage	V	0	–	30
Differential Input Signal	mA	-5.5	–	5.5
Input Signal Common Mode Offset	V	-5	–	5

Normal Operating Conditions		Min.	Typ.	Max.
Supply Voltage	V	22	24	30
Peak Current Consumption**	A	–	–	3.3
Differential Input Signals	mA	-5	–	5
Input Impedance	KΩ	200	–	–

* Conditions outside of the absolute maximum ratings may cause permanent damage to the valve. Operation of the product outside of the nominal operating conditions is not guaranteed and may affect product reliability.

** The valve supply must be protected with a 4 AT fuse or equivalent overcurrent protection device.

*** Valves with a current command signal use a 0.1% tolerance shunt resistor to measure demand current.

**** For 4 to 20mA command signal, a current in this range will disable the motor drive until a current outside this range is received at the command input.

Enable Function

Valves can be provided with an enable function. This allows the valve to be enabled or disabled by varying the voltage into the enable pin. Note that valves with code C command type can also be enabled or disabled using the command signal; see the corresponding table for further details.

Normal Operating Conditions		Min.	Typ.	Max.
Voltage for Drive Enable	V	9	–	28
Voltage for Drive Disable	V	0	–	5
Input Impedance	Ω	50	–	–

Electronic Interface Diagrams

Please note pin orientation. Not to scale. Flying leads that terminate in bare wires do not have associated diagrams. In these cases, please refer to the wire color to determinate the correct pin out.

4 Contact, Unterminated fly lead (Code B4)

Type: Flying Lead (300 mm length)
Termination: Bare Wires

Wire Color	Function	Desc.
White	Supply 0 V	0 V
Black	Supply +	+24 V
Green	Input – (Ground Ref)	Differential Input Signal, –
Red	Input +	Differential Input Signal, +

6 + PE Circular Connector (Code E)

Type: Case Mounted
Termination: Connector according to EN 175201-804/MIL 5015 equivalent, shell size 14

Pin	Function	Desc.
A	Supply +	+24 V
B	Supply 0 V	0 V
C	Output – Enable Input	Output 0 V Reference Drive Enable Input*
D	Input +	Differential Input, +
E	Input –	Differential Input, –
F	Output +	Output Signal
G	Earth	–

* When the enable function is selected, the function of pin C is the enable input. This replaces the standard pin function.

4 Pin Circular Connector (Code E4)

Type: Case Mounted
Termination: Connector according to EN 175201-804/MIL 5015 equivalent, shell size 14
Number of Contacts: 4

Pin	Function	Desc.
A	Supply +	+24 V
B	Input +	Differential Input, +
C	Input –	Differential Input, –
D	Supply 0 V	0 V

G4 Rack and Panel Connector (Code G)

Type: Flying Lead
Termination: Winchester™ G4-20P

Pin	Function	Desc.
A	Supply 0 v	0 v
B	Supply +	+24 V
C	Input – (Ground Ref)	Differential Input, –
D	Input +	Differential Input, +

Unit Dimensions + Mounting Dimensions

Unit Dimensions – Connector Code G and B4

Unit Dimensions – Connector Code E and E4

Nominal dimensions are displayed in mm. Bracketed dimensions are in inches. Not to scale.

Mounting Surface Pattern Dimensions

	Dia Ø mm	X Position mm	Y Position mm
F1	M4	0	0
F2	M4	23.8	0
F3	M4	23.8	26.2
F4	M4	0	26.2
P	3.8	11.9	19.2
A	3.8	18.0	13.1
B	3.8	5.8	13.1
T	3.8	11.9	7.0

Bolts (F1, F2, F3, F4)

Type: M4 x 55 DIN EN ISO 4762-10.9
Required Torque: 2.5 Nm (5.53 ft-lbf)

O-Rings (P, A, B, T)

Type: 4.47 x Ø 1.78 (ISO 3601-1-008)
Material: NBR, EPDM or Viton, 70 Shore A
Hardness: 70 Shore A

Standards Compliance

EMC Regulations: EN 61000-6-2 / EN55011:1998+A1
Performance Tests: ISO 10770-1
Pressure Rating: EN 10771
Hydraulic Interface: ISO 10372-01-01-0-92

Not to scale.

Ordering Code

S4 Pro 1 2 3 4 5 6 7 8 9

Variants on Request

Domin is proud of their ability to offer tailored solutions that meet customers’ specific needs. If you require a non-standard configuration, or a bespoke modification, we are confident we can provide you with the best solution. Talk to us here and one of our team will respond as soon as possible.

Domin is a supplier and servo valve manufacturer for various applications including automotive/motorsports, aerospace, animatronics, simulation, robotics, and marine.