R978911172 - BuyRexroth

Manufacturer: Bosch Rexroth

Material #: R978911172

Model : DB20-2-5X/50/12 SO43A-199

$1,067.00 USD

More are expected on August 5, 2026

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Qty	Price	Savings
5-24	$1,040.32 USD	$26.68 USD
25+	$1,013.65 USD	$53.35 USD

Status: This product is temporarily out of stock.

Qty: Delivered as early as August 5, 2026 when ordered in

This product is eligible for factory repair.

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For subplate mounting Porting pattern according to ISO 6264-06-09 (NG10), ISO 6264-08-13 (NG25) and ISO 6264-10-17 (NG32) For threaded connection As screw-in cartridge valve (cartridge) 4 adjustment types for pressure adjustment, optionally
• Rotary knob
• Sleeve with hexagon and protective cap
• Lockable rotary knob with scale
• Rotary knob with scale 5 pressure ratings Corrosion-protected design

Pressure valve type DB is a pilot-operated pressure relief valve. It is used for limiting the operating pressure.

The pressure relief valves (DB) basically consist of the main valve (1) with main spool insert (3) and pilot control valve (2) with pressure adjustment element.

The pressure applied to channel P acts on the main spool (3). At the same time, pressure is applied to the spring-loaded side of the main spool (3) and to the ball (8) in the pilot control valve (2) via the control lines (6) and (7) which are equipped with nozzles (4) and (5). If the pressure in channel P exceeds the value set at the spring (9), the ball (8) opens against the spring (9). The corresponding signal comes internally, via the control lines (10) and (6) from channel P. The hydraulic fluid on the spring-loaded side of main spool (3) now flows via the control line (7), nozzle bore (11) and ball (8) into the spring chamber (12). From here, it is fed into the tank, either internally for type DB …– via control line (13), or externally for type DB…Y via control line (14). Nozzles (4) and (5) cause a pressure drop to occur at the main spool (3), hence the connection from channel P to channel T opens. Now, the hydraulic fluid flows from channel P to channel T maintaining the set operating pressure.

The pressure relief valve can be unloaded or switched to another pressure (second pressure rating) via port X (15).

01	02	03	04	05	06	07	08	09		10	11	12	13	14	15	16	17	18	19	20	21	22
DB								5X	/													*

01	Pressure relief valve	DB
02	Without directional valve	no code
03	Pilot-operated valve (complete)	no code
	Pilot control valve without main spool insert (do not enter any size)	C
	Pilot control valve with main spool insert (enter size 10 or 30)	C
	Pilot control valve without main spool insert for subplate mounting (do not enter any size)	T 1)
04	Size 10
	Subplate mounting "no code"	10
	Threaded connection "G"	10 (G1/2)
	Size 16
	Threaded connection "G"	15 (G3/4)
	Size 25
	Subplate mounting "no code"	20
	Threaded connection "G"	20 (G1)
	Threaded connection "G"	25 (G1 1/4)
	Size 32
	Subplate mounting "no code"	30
	Threaded connection "G"	30 (G1 1/2)
05	Without directional valve	no code
Type of connection
06	Subplate mounting or cartridge valve	no code
06	For threaded connection	G
Adjustment type for pressure adjustment
07	Rotary knob (not for version "C" and "T")	1
	Sleeve with hexagon and protective cap	2
	Lockable rotary knob with scale	3 2)
	Rotary knob with scale	7
08	Main spool Ø24 mm (all sizes)	–
08	Main spool Ø28 mm (only for NG32)	N
09	Component series 50 … 59 (50 … 59: unchanged installation and connection dimensions)	5X
10	Set pressure up to 50 bar	50
	Set pressure up to 100 bar	100
	Set pressure up to 200 bar	200
	Set pressure up to 315 bar	315
	Set pressure up to 350 bar	350
Pilot oil flow
11	External pilot oil supply, internal pilot oil return	X 3)
	Internal pilot oil supply, external pilot oil return	Y
	Pilot oil supply and pilot oil return external	XY 3)
12	Standard version	no code
12	Valve for minimum cracking pressure (not for versions "without main spool insert" and not suitable for mutual relief)	U 4)
13	Without switching shock damping	no code
14	Without directional valve	no code
15	Without directional valve	no code
16	Without manual override	no code
Electrical connection
17	Without directional valve	no code
18	Without directional valve	no code
Corrosion resistance
19	None	no code
19	Improved corrosion protection (240 h salt spray test according to EN ISO 9227)	J3 5)
Seal material
20	NBR seals	no code
	FKM seals	V
	Observe compatibility of seals with hydraulic fluid used. (Other seals upon request)
Equipment Directive
21	Without type-examination procedure	no code
21	Type-examination tested safety valve according to Pressure Equipment Directive 2014/68/EU	E
22	Further details in the plain text	*

1)	DBT corresponds to DBC, however with closed central bore
2)	H-Key with material no. R900008158 is included in the scope of delivery.
3)	Not with version "DBC"
4)	Only possible up to pressure rating 315 bar
5)	Only version "2", however without protective cap

Type-examination tested safety valves type DB…E

(Component series 5X according to Pressure Equipment Directive 2014/68/EU)

NG	Type designation	Component marking	Maximum flow qVmax in l/min with pilot oil return		Set response overpressurep in bar
NG	Type designation	Component marking	external "Y"	internal "–"	Set response overpressurep in bar
10		TÜV.SV.▢ – 851.12.F.G.p	170 230 230 230	130 200 200 200	30 ... 60 61 ... 110 111 ... 210 211 ... 350
25		TÜV.SV.▢ – 852.22.F.G.p	250 270 420 450	180 210 320 400	30 ... 60 61 ... 110 111 ... 210 211 ... 350
32		TÜV.SV.▢ – 853.32.F.G.p	600 600 650 700	225 340 540 580	30 ... 60 61 ... 110 111 ... 210 211 ... 350

1	For subplate mounting	no code
1	For threaded connection	G
Adjustment type for pressure adjustment
2	Hand wheel (pressure adjustment sealed, unloading or setting of a lower response pressure possible!)	1
2	With sealed protective cap (no adjustment/unloading possible)	2
Pressure
3	To be entered by the customer, e.g. pressure adjustment ≥ 30 bar and possible in 5 bar steps.	e.g. 150
Pilot oil flow
4	Pilot oil supply internal, pilot oil return internal	no code
4	Pilot oil supply internal, pilot oil return external (Recommendation)	Y 1)
5	NBR seals	no code
5	FKM seals	V
▢	Value entered at the factory

1)	Pilot oil supply external "X" not possible

general

Size				10	16	25		32
					DB.. 15	DB.. 20	DB.. 25
Weight	Subplate mounting	DB...	kg	2.6	-	3.5	-	4.4
		DBC...	kg	1.2
		DBC 10 or 30 ...	kg	1.5
	Threaded connection	DB...G	kg	5.3	5.2	5.1	5	4.8
Installation position				any
Ambient temperature range	NBR seals		°C	-30 … +80
	FKM seals		°C	-15 … +80
Minimum stability of the housing materials				Housing materials are to be selected so that there is sufficient safety for all imaginable operating conditions (e.g. with regard to pressure resistance, thread stripping strengths and tightening torques).

hydraulic

Size			10	16	25	25	32
Maximum operating pressure	Port P	bar	350
	Port X	bar	350
	Port T	bar	315
Maximum counter pressure	Port Y (DC solenoid)	bar	315
Minimum set pressure			flow-dependent, see characteristic curves
Maximum set pressure		bar	50 100 200 315 350
Maximum flow	Subplate mounting	l/min	250	-	500	-	650
	Threaded connection	l/min	250	500			650
Hydraulic fluid			see table
Hydraulic fluid temperature range	NBR seals	°C	-30 … +80
	FKM seals	°C	-15 … +80
Viscosity range		mm²/s	10 … 800
Maximum admissible degree of contamination of the hydraulic fluid 1)			Class 20/18/15 according to ISO 4406 (c)

1)	The cleanliness classes specified for the components must be adhered to in hydraulic systems. Effective filtration prevents faults and simultaneously increases the life cycle of the components. For the selection of the filters, see www.boschrexroth.com/filter.

Note:

Tank preloading adds to the minimum set pressure (ports T and Y)

Hydraulic fluid		Classification	Suitable sealing materials	Standards	Data sheet
Mineral oils		HL, HLP	NBR, FKM	DIN 51524	90220
Bio-degradable 1)	Insoluble in water	HETG	FKM	ISO 15380	90221
		HEES	FKM
	Soluble in water	HEPG	FKM	ISO 15380
Flame-resistant	Water-free	HFDU (glycol base)	FKM	ISO 12922	90222
		HFDU (ester base) 1)	FKM
	Containing water	HFC (Fuchs Hydrotherm 46M, Petrofer Ultra Safe 620)	NBR	ISO 12922	90223
Important information on hydraulic fluids: For further information and data on the use of other hydraulic fluids, please refer to the data sheets above or contact us. There may be limitations regarding the technical valve data (temperature, pressure range, life cycle, maintenance intervals, etc.). The ignition temperature of the hydraulic fluid used must be 50 K higher than the maximum solenoid surface temperature. Flame-resistant – containing water: Maximum operating pressure 210 bar Life cycle as compared to operation with mineral oil HL, HLP 30 … 100 % Maximum hydraulic fluid temperature 60 °C Bio-degradable and flame-resistant: If this hydraulic fluid is used, small amounts of dissolved zinc may get into the hydraulic system.

1)	Not recommended for corrosion-protected version “J3”

Deviating technical data: Type-examination tested safety valves type DB…E

(Component series 5X according to Pressure Equipment Directive 2014/68/EU)

hydraulic

Version			Pilot oil flow "no code"	Pilot oil flow "Y"
Maximum counter pressure	Port Y	bar	-	0
	Port T		See characteristic curves and explanatory notes for maximum counter pressure	PT < 15
Maximum flow			See ordering code, safety instructions and characteristic curves "Type-examination tested safety valve"
Hydraulic fluid			Mineral oil (HL, HLP) according to DIN 51524 and DIN 51524-1
Hydraulic fluid temperature range			-10 … +60 °C
Viscosity range		mm²/s	12 … 230

For applications outside these parameters, please consult us!

(measured with HLP46, ϑOil = 40 ±5 °C)

Standard version

Minimum set pressure and circulation pressure dependent on the flow 1)

1)	The characteristic curves apply to an output pressure pT =0 bar in the entire flow range.

Version “U”

Minimum set pressure and circulation pressure dependent on the flow 1)

Inlet pressure dependent on the flow

Notice:

The characteristic curves were measured with external, depressurized pilot oil return.

Due to the internal pilot oil return, the inlet pressure increases by the output pressure present in port T.

Pilot flow

Type-examination tested safety valves

(Component series 5X, according to Pressure Equipment Directive 2014/68/EU)

Counter pressure in the discharge line

Basically, the valve should be operated without counter pressure in the discharge line, if possible. With counter pressure in the discharge line, the maximum flow possible is reduced. There is a relation between the maximum counter pressure pT in the discharge line and flow qV, which can be seen from the following characteristic curves. Characteristic curves for intermediate values of the response pressure which are not listed must be determined by means of interpolation.

With a flow approaching zero, the maximum counter pressure pT is in each case 10 % of the response pressure. With increasing flow, the maximum counter pressure pT is reduced.

Interpolation of intermediate values from the diagram

At the pT axis, mark 1/10 of the value of pA. Determine the next lower and the next higher characteristic curve for this point. The point marked at pT divides the section between lower and higher characteristic curve on the pT axis with a certain percentage. At the qVmax axis, divide the section between next lower and next higher characteristic curve in the same percentage as the section at the pT axis. From the zerocrossing on the qVmax axis determined in that way, draw a straight line to the value on the pT axis marked before. Mark the system flow to be secured at the qVmax axis. Read off the maximum counter pressure for this value using the line at the pT axis drawn before.

Determination of the maximum counter pressure

Example 1 (with already existing characteristic curve):

Flow of the system / accumulator to be secured:qVmax = [si]300 l/min[/si][imp]79.3 USgpm[/imp Safety valve set to: pA = [si]80 bar[/si][imp]1150 psi[/imp]. Read off the maximum counter pressure pT of approx. [si]12 bar[/si][imp]175 psi[/imp] from the diagram (see arrows, dashed line " ").

Example 2 (with interpolated characteristic curve):

Flow of the system / accumulator to be secured: qVmax = [si]300 l/min[/si][imp]79.3 USgpm[/imp Safety valve set to: pA = [si]80 bar[/si][imp]1150 psi[/imp] Value to be marked at the axis referred to as pT: 1/10 x [si]80 bar[/si][imp]1150 psi[/imp] = [si]8 bar[/si][imp]115 psi[/imp]. Read off the maximum counter pressure pT of approx. [si]1 bar[/si][imp]15 psi[/imp] from the diagram (see arrows, dashed/dotted line " ").

Size 10

Diagram for determining the maximum counter pressure pT in the discharge line at port T of the valve dependent on the flow qVmax for valves type DB(W)...E with different response pressures pA.Intermediate values may be determined by means of interpolation. Regarding the procedure for interpolation refer to "Interpolation of intermediate values from the diagram".

Size 20

Size 30

pA	Response pressure in bar
pT	Maximum counter pressure in the discharge line (port T) in bar (sum of all possible counter pressures; also see AD2000 data sheet - A2)
pT max	10% x pA (with qV=0 l/min) according to Pressure Equipment Directive 2014/68/EU
qV max	Maximum flow in l/min

Type DB…–…	Type DB…X…	Type DB…Y…	Type DB…XY…

Threaded connection "G"

Dimensions in mm

1	Name plate
2	X port for pilot oil supply, external
3	Y port for pilot oil return, external
4	Adjustment type "1"
5	Adjustment type "2"
6	Adjustment type "3"
7	Adjustment type "7"
8	Hexagon SW10
9	Space required to remove the key
11	Valve mounting bores
19	Omitted with internal pilot oil return

Version	D1	ØD2	T1
Version		mm	mm
"DB 10 G"	G1/2	34	14
"DB 15 G"	G3/4	42	16
"DB 20 G"	G1	47	18
"DB 25 G"	G1 1/4	58	20
"DB 30 G"	G1 1/2	65	22

Subplate mounting "no code"

Dimensions in mm

1	Name plate
2	X port for pilot oil supply, external
3	Y port for pilot oil return, external
4	Adjustment type "1"
5	Adjustment type "2"
6	Adjustment type "3"
7	Adjustment type "7"
8	Hexagon SW10
9	Space required to remove the key
10	Locking pin
11	Valve mounting bores
19	Omitted with internal pilot oil return
35	Lock nut SW17, tightening torque MA = 10+5 Nm

Version	L1	L2	L3	L4	L5	L6	L7	L8	L9	B1	B2	ØD1
Version	mm	mm	mm	mm	mm	mm	mm	mm	mm	mm	mm	mm
"DB 10"	91	53.8	22.1	27.5	22.1	47.5	0	25.5	2	78	53.8	14
"DB 20"	116	66.7	33.4	33.3	11.1	55.6	23.8	22.8	10.5	100	70	18
"DB 30"	147.5	88.9	44.5	41	12.7	76.2	31.8	20	21	115	82.6	20

Pilot control valve with ("DBC 10 or 30") or without main spool insert ("DBC, DBT")

Dimensions in mm

Installation bore

Dimensions in mm

1	Name plate
3	Y port for pilot oil return, external
5	Adjustment type "2"
6	Adjustment type "3"
7	Adjustment type "7"
8	Hexagon SW10
9	Space required to remove the key
11	Valve mounting bores
20	Seal ring
21	Main spool insert
22	Bore Ø32 mm can cut Ø45 mm at any point. However, it must be observed that the connection bore X and the mounting bore are not damaged!
23	Support ring and seal ring are to be inserted into this bore before assembly of the main spool.
24	Nozzle (separate order; recommended nozzle Ø1.0 mm)
25	Seal ring
26	Seal ring
27	Seal ring
28	Support ring
29	Support ring
35	Lock nut SW17, tightening torque MA = 10+5 Nm

Valve mounting screws (separate order)

For reasons of stability, exclusively the following valve mounting screws may be used:

Version "DB 10"
4 x ISO 4762 - M12 x 50 - 10.9-flZn/nc/480h/C
with friction coefficient μtotal = 0.09 … 0.14
tightening torque MA = 75 Nm ±10%
material no. R913015611 Version "DB 20"
4 x ISO 4762 - M16 x 50 - 10.9-flZn/nc/480h/C
with friction coefficient μtotal = 0.09 … 0.14
tightening torque MA = 185 Nm ±10%
material no. R913015664 Version "DB 30"
4 x DIN 912 - M18 x 50 - 10.9-flZn/nc/480h/C
with friction coefficient μtotal = 0.09 … 0.14
tightening torque MA = 248 Nm ±10%
material no. R913015903 Version "DBC", "DBC 10", "DBC 30" and "DBT"
4 x ISO 4762 - M8 x 40 - 10.9-flZn/nc/480h/C
with friction coefficient μtotal = 0.09 … 0.14
tightening torque MA = 31 Nm ±10%
material no. R913015798

Notice:

The tightening torques stated are guidelines when using screws with the specified friction coefficients and when using a manual torque wrench (tolerance ±10%).


Required surface quality of the valve contact surface

Safety instructions: Type-examination tested safety valves type DB…E

(Component series 5X according to Pressure Equipment Directive 2014/68/EU)

Before ordering a type-examination tested safety valve, it must be observed that for the desired response overpressure p, the maximum admissible flow qV max of the safety valve must be larger than the maximum possible flow of the system. According to Pressure Equipment Directive 2014/68/EU , the increase of the system pressure by the flow must not be higher than 10 % of the set response pressure (see component marking). Discharge lines (ports T and Y) of safety valves must end in a risk-free manner. The accumulation of fluids in the discharge lines must not be possible (AD 2000 data sheet A 2). If a lead seal at the safety valve is removed, the approval according to the PED! Basically, the requirements of the Pressure Equipment Directive 2014/68/EU and of data sheet AD 2000 A 2 have to be observed.

It is imperative to observe the application notes!

In the plant, the response pressure specified in the component marking is set at a flow of 2 l/min.

The maximum admissible flow stated in the component marking (= numerical value instead of the character "G" in the component marking, see ordering code, type-examination tested safety valves) must not be exceeded.

It applies to:

Pilot oil return “external” (= Y in the ordering key) without counter pressure in the discharge line Y, admissible counter pressure in the discharge line (port T) < 15 bar Pilot oil return “internal” (= no code in the ordering key). The maximum admissible flow is only admissible without counter pressure in the discharge line (port T).

With internal pilot oil return, the system pressure increases by the counter pressure in the discharge line (port T) with increasing flow (observe AD2000 - data sheet A2 - item 6.3!).

To ensure that this increase in system pressure caused by the flow does not exceed the value of 10% of the set response pressure, the admissible flow has to be reduced dependent on the counter pressure in the discharge line (port T) (see diagrams (Safety instructions, Type-examination tested safety valves)).

It is imperative to observe the application notes!

In the plant, the response pressure specified in the component marking is set with a flow of 11 l/min. The maximum admissible flow stated in the component marking (= numerical value instead of the character "G" in the component marking, see ordering code, type-examination tested safety valves) must not be exceeded.
It applies to: Pilot oil return external ("Y") without counter pressure in the discharge line Y; admissible counter pressure in the discharge line (port T) < 15 bar Pilot oil return internal ("no code"). The maximum flow is only admissible without counter pressure in the discharge line (port T).

With internal pilot oil return, the system pressure increases by the counter pressure in the discharge line (port T) due to the increasing flow (observe AD2000 - data sheet; A2, item 6.3!)

To ensure that this increase in system pressure caused by the flow does not exceed 10% of the set response pressure, the admissible flow has to be reduced dependent on the counter pressure in the discharge line (port T) (see diagrams (Safety instructions, Type-examination tested safety valves)).

Notice:

Possible unloading via the directional valve must not be applied for safety-relevant functions! If unloading is required for safety-relevant functions, an additional unloading valve must be installed.

General information

The unloading function (directional valve function with version "DBW") must not be used for safety functions! With version "B", the lowest adjustable pressure (circulation pressure) is set in case of power failure or cable break. With version "A", the pressure limiting function is set in case of power failure or cable break. Hydraulic counter pressures in port T with internal pilot oil return and/or port Y with external pilot oil return add 1:1 to the response pressure of the valve set at the pilot control.
Example: Pressure adjustment of the valve by spring preload (item 9 "Product description") in the pilot control valve/adjustment type pspring = 200 bar Hydraulic counter pressure in port T with internal pilot oil return phydraulic = 50 bar => Response pressure = pspring + phydraulic = 250 bar

Manufacturer: Bosch Rexroth

Material #: R978911172

Model : DB20-2-5X/50/12 SO43A-199

More are expected on August 5, 2026

This product is eligible for factory repair.

Type-examination tested safety valves type DB…E

general

hydraulic

Deviating technical data: Type-examination tested safety valves type DB…E

hydraulic

(measured with HLP46, ϑOil = 40 ±5 °C)

Standard version

Version “U”

Inlet pressure dependent on the flow

Pilot flow

Type-examination tested safety valves

Counter pressure in the discharge line

Size 10

Size 20

Size 30

Type DB…–…

Type DB…X…

Type DB…Y…

Type DB…XY…

Threaded connection "G"

Subplate mounting "no code"

Pilot control valve with ("DBC 10 or 30") or without main spool insert ("DBC, DBT")

Installation bore

Safety instructions: Type-examination tested safety valves type DB…E

General information

Related Products

Information

Account

Manufacturer: Bosch Rexroth

Material #: R978911172

Model : DB20-2-5X/50/12 SO43A-199

More are expected on August 5, 2026

View Bulk Pricing Discounts

This product is eligible for factory repair.

Type-examination tested safety valves type DB…E

general

hydraulic

Deviating technical data: Type-examination tested safety valves type DB…E

hydraulic

(measured with HLP46, ϑOil = 40 ±5 °C)

Standard version

Version “U”

Inlet pressure dependent on the flow

Pilot flow

Type-examination tested safety valves

Counter pressure in the discharge line

Size 10

Size 20

Size 30

Type DB…–…

Type DB…X…

Type DB…Y…

Type DB…XY…

Threaded connection "G"

Subplate mounting "no code"

Pilot control valve with ("DBC 10 or 30") or without main spool insert ("DBC, DBT")

Installation bore

Safety instructions: Type-examination tested safety valves type DB…E

General information

Related Products

Information

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