Pressure Relief Valves

//Cartridge Style, Direct Operated DBD10, 20 Hydraulic Pressure Relief Valve

Cartridge Style, Direct Operated DBD10, 20 Hydraulic Pressure Relief Valve


PRODUCT TYPE: DBD Cartridge Relief Valve
VALVE SIZE:  DBD 6, 8, 10, 15, 20, 25, 30
CONTROL METHOD: Direct Operated
APPLICATION Hydraulic Machines
CONNECTION TYPE: Threaded Connection
APPROXIMATE WEIGHT: Size10=0.5Kgs/1.1Lbs; Size20=1.0Kgs/2.2Lbs;
Relief Valve Block G Type
Hydraulic Relief Valve Block P Type
– Cartridge valve, threaded connection
– High strength carbon steel materials for high pressure
– Six pressure presetting stage available

DBD Direct Operated Relief Valve PDF

DBD Cartridge relief direct operated pressure valve is designed to limit hydraulic pressure to its presetting pressure. When the pump is starting, the oil is pressurized into to P port,  then the hydraulic oil lifts up the piston pressed by a spring, until hydraulic oil squeezes out from the T port, the system pressure remains to presetting pressure(normally operation pressure).

Finotek tests DBD cartridge relief valve one by one as per Equipment Directive 97/23/EC before delivery, every valve needs to be tested higher pressure nearly 15%-30% than their own max. operation pressure, the valve should be no noise while adjusting the sleeve. The popular adjustable type of our products is DBD6, DBD10, DBD15, DBD20, DBD25, DBD30 series for most of the units as safety valves.

DBD Direct Action Relief Valve -DBD Structure

Picture A-1 & A-2: Cushioning Spool, Damping Piston Of Direct Acting Relief Valve With Cartridge Style
1. Spring seat   |   2. Cushion spool    |   3. Pin

The DBD type is the cushioning spool, damping piston of direct acting relief valve with cartridge connections. It is important to understand the DBD series by the part of cushioning spool, please see the Picture A-2, the enlarged head part view of the structure.

The valve seat against cushion spool not only has dynamic hydraulic damping effect when the cushioning spool in a closed or open position so that to improve the vavle operation stability, but also is used to ensure the straight movement of cushion spool in order to improve the static characteristics of the DBD valve.

Due to cone shape between the connection of cushion spool and seat, therefore, the steady fluid force of flow in inlet and outlet port keeps equilibrium when the cushion spool in an open position. The part of pin “3” has and annular groove for switching the flow direction at outlet port and generated a jet force against the force from the valve spring, to counteract the spring increment force caused by increasing flow rate, so that the inlet pressure is less affect to flow changes and obtaining a pressure – flow characteristics with high-pressure and large flow level, which will increase the amount of flow rate through the pressure relief valve. In addition, the seat supports a larger diameter spring, and for higher pressure, to facilitate spring structure design and extend the presetting pressure range of DBD direct acting relief vavle.


DBD Valve Ordering Code

Example (Normal code): “FT-DBDS 6 K 1X/315 ”
Explanation As Below:

FT- DBD S 6 K 1X / 315    
(1) (2) (3) (4) (5) (6) (7) (8)

(1) Producer code= FT
(2) H= Hand wheel
  S= Screw adjustment and protective cap
(3) Size= 6; 8; 10; 15; 20; 25; 30
(4) K= Cartridge mounting
  G= Threaded connections
  P= Subplate mounting
(5) 1X= Valve series

(6) 315= Pressure presetting Bar(Psi):315(4600)
  25= Pressure presetting Bar(Psi):25(365)
  50= Pressure presetting Bar(Psi):50(725)
  100= Pressure presetting Bar(Psi):100(1450)
  200= Pressure presetting Bar(Psi):200(2900)
  400= Pressure presetting Bar(Psi):400(5800)
(7) No code= Inch thread
  2= Metric thread
(8) No code = NBR seals for petroleum oil
  V = FPM seals for phosphate ester

DBD Valve Technical Information

Main Raw Materials: 45# Carbon Steel(Valve House)
Power: By hydraulic
Brand: Finotek or OEM
Max. Operation Pressure: 6 Pressure presetting stages
Max. Flow Rate: 50-350L/min.

Oil Medium Temperature: -30 to +80(°C)for NBR O-rings
Oil Medium: Mineral oil as per DIN51 524, VDMA 24 568 or rapeseed oil, Viscosity 10 – 400 CST
Recommended Medium Filtration: ISO 4406 Standard, cleanliness class:20/18/15

DBD Valve Characteristic Curves


DBD Valve Function Symbol


DBD Valve Installation Dimensions


  D D1 D2 D3 L L1 L2 L3 L4 L5
6 M28×1.5 25H8 15 6 65 56.5±1 45 35 19 15
10 M35×1.5 32H8 18.5 10 80 67.5±1 52 41 23 18
20 M45×1.5 40H8 24 20 110 91.5±1 70 54 27 21
30 M60×2 55H8 38.75 30 140 113.5±1 84 60 29 23

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