Connection housings

up to 420 barup to 120 l/min

Pressure Relief ValveDB12

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A Adjustment device with lift stopB Valve bodyC SpringD Spring plate with hydrodynamic

lift supportE Valve seatF Closing cone with damping

piston

1. DESCRIPTION1.1. GENERAL

According to DIN-ISO 1219,HYDAC pressure relief valvesDB12 are valves for oil hydraulicsystems to limit pressure acrossthe inlet by opening the outletagainst a spring force. The valveis designed as a direct-operatedpressure relief valve in seat valveconstruction. This provides verygood opening/closingcharacteristics and enables userunits to be sealed leakage-free.Further advantages of thesevalves are as follows:

– cavity dimensions to ISO 7789– low hysteresis and high stability

ensure accurate pressure control– optimum system adaptation owing

to various pressure ranges– limited setting range means that

the spring cannot be blocked,thereby maintaining the pressurerelief function

– the damping unit ensures thatstable operation is maintainedover the whole capacity rangeand that the noise level is kept toa minimum

– small pressure increase atincreased flow rate over thewhole application range due tohydrodynamic lift support on thespring plate

– mechanical lift stop ensuresoperational safety even whenpressure peaks cause anoverload

– their compact design saves spacewhen installing in connectionhousings, control blocks etc.,especially in confined installationconditions.

– simple installation due to service-friendly cartridge valve technology

1.2. FUNCTIONHYDAC pressure relief valvesDB12 are direct-operated,spring-loaded cone seat valvesfor oil hydraulic systems.The valve consists essentially of avalve body with built-in valve seat,a hardened and polished closingcone and the adjustment devicefor setting the initial springtension. The spring applies thisforce to the closing cone andpushes it against the valve seat.On the opposite side of theclosing cone, the system pressureacts via port 1 of the valve. If thehydraulic pressure force is belowthe pre-set spring tension, thevalve is closed. If the hydraulicpressure force exceeds the pre-set spring tension, the closingcone is lifted off the valve seatand the operating fluid flows frompressure port 1 to tank port 2.This limits the pressure acrossport 1. To ensure that stableoperation is maintained, theclosing cone is rigidly connectedto the damping piston which hasto displace oil via an aperture witheach movement of the closingcone. Each time, this producesan opposing damping force to thedirection of movement.

1.3. APPLICATIONHYDAC pressure relief valvesDB12 are used:

– as safety valves to limit pressureto the maximum permissible

– for pressure relief on pressurevessels

– as safety valves for cylinders,pumps and other pressuregenerators

– for limiting pressure in hydraulicunits and control blocks

– for pressure control of hydrauliccircuitsAreas of application are, forexample:

– hydraulic units– elevating platforms– mobile hydraulics– clamping hydraulics– force or torque limiting on drive

elements– accumulator stations– hydraulic systems with

accumulators1.4. NOTES

When fitting the valves intocontrol blocks and housings therecommended torque ratingsmust be observed.Note port configuration.Please note:If the connections are incorrect,the safety function of the valve isdisabled.Please note:The opening pressure of the valveincreases by the amount ofpressure across tank port 2 (p2)!DB12: p2max = 100 bar

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2.1.2 Model code(also order example)

DB 12120A - 01 X - 350 V 315

Pressure relief valve

Cavity

Type01 = technical specifications as per this brochure

Series(determined by manufacturer)

Setting pressure range150 = up to 150 bar250 = up to 250 bar350 = up to 350 bar420 = up to 420 bar

Type of adjustmentV = adjustable with tool (standard models)

Cracking pressure settingNo details = cracking pressure approx. 10 bar (spring relaxed)Pressure value = customer-specific cracking pressure

(min. order quantity 50 pieces)

2. TECHNICALSPECIFICATIONS

2.1. GENERAL2.1.1 Designation and symbol

Pressure relief valve

Please quote material number when ordering.Delivery for non-standard models is longer and the price is higher.

Please note:It is possible for the customer to lead-seal the valve using a cap,stock no. 397 397 (see point 3. Dimensions).

Standard models

2.1.3 Type of constructionCone-seat valve, direct-operated

2.1.4 Type of mountingCartridge valve

2.1.5 Mounting positionOptional

2.1.6 Weight0.42 kg

2.1.7 Direction of flowFrom 1 to 2, pressure relieffunctionFrom 2 to 1, shut-off leakage-free

2.1.8 Ambient temperature rangemin. - 20 °Cmax. + 80 °C

2.1.9 MaterialsValve body: high tensile steelClosing element: hardened andpolished steel, wear-resistantSeals: FPM and Teflon

2.1.10 Type of connectionSuitable connection housings withcavity 12120A are available.See separate housing brochureno. E 5.252../..

Stock no. (= order no.) Model code

552 805 DB12120A-01X-150V

552 806 DB12120A-01X-250V

552 807 DB12120A-01X-350V

552 836 DB12120A-01X-420V

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2.2. HYDRAULIC DETAILS2.2.1 Nominal pressure

inlet (port 1): up to 420 baroutlet (port 2): DB12: up to 100 bar

2.2.2 Operating pressure rangesup to 150 barup to 250 barup to 350 barup to 400 barFor lowest setting pressures, see 2.2.7 Pressure,dependent on flow rate.

2.2.3 Pressure fluidMineral oil to DIN 51524, part 1 and 2

2.2.4 Operating fluid temperature rangemin. - 20 °Cmax. + 80 °C

2.2.5 Viscosity rangemin. 10 mm²/smax. 380 mm²/s

2.2.6 FiltrationMax. permissible contamination level of the operatingfluid to ISO 4406 class 21/19/16 (NAS 1638 class 10).We therefore recommend a filter with a minimumretention rate of β20 = 100.The fitting of filters and regular replacement ofelements ensures correct functioning, reduces wear &tear and increases the service life.

2.2.7 Pressure, dependent on flow ratemeasured at ν = 28 mm2/s and toil = 50 °C

Pressure range . . . 250 bar

Pressure range . . . 150 bar

Pressure range . . . 350 bar

Pressure range . . . 420 bar

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lowest setting pressure

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lowest setting pressure

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Cartridge form tools

with cap,material no. 397397,for lead-sealingby customerstandard

3. DIMENSIONSDB12

torqueSW32 50+10 Nm

CAVITY DIMENSIONS 12120A (TO ISO 7789)Geometry

Tool Stock no.Countersink 175 002 / 162 128Reamer 174 874Tap 1002625Plug gauge in preparation

4. NOTEThe information in this brochure relates to the operating conditions and applications described.For applications or operating conditions not described, please contact the relevant technical department.Subject to technical modifications.

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