• Out of Stock
    Hydra Part Inline Pressure Relief Valve 1/2" Bsp 80Lpm 350 Bar Max - Approved Hydraulics
    Regular price From £40.14
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    Inline Pressure Relief Valves 1/2" BSP 70-80Lpm

    Key Features

    • Port size: 1/2' bsp
    • Max flow: 70 to 80 l/min
    • Adjustment range: 5 to 50 bar ; 100 to 350 bar options
    • Max working pressure: 350 bar
    • Use: line mounting system overpressure protection
    Regular price From £40.14
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  • Hydra Part Inline Pressure Relief Valve 3/4" Bsp 80Lpm 350 Bar Max - Approved Hydraulics
    Regular price From £62.28
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    Inline Pressure Relief Valves 3/4" BSP

    Key Features

    • Port size: 3/4\" bsp
    • Max flow: 80 lpm
    • Pressure range: 100 to 350 bar
    • Function: inline pressure relief ; system overpressure protection
    • Mounting: in line valve body
    Regular price From £62.28
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  • Out of Stock
    Hydra Part Inline Pressure Relief Valve 3/8" Bsp 35Lpm 350 Bar Max - Approved Hydraulics
    Regular price From £107.42
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    Inline Pressure Relief Valves 1" BSP

    Key Features

    • Type: direct acting inline pressure relief valve
    • Ports: bsp per size
    • Setting: adjustable with locknut
    • Use: over pressure protection for circuits
    • Pressure: 315 to 350 bar typical
    Regular price From £107.42
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  • Out of Stock
    Hydra Part Inline Pressure Relief Valve 1 1/4" Bsp 150Lpm 350 Bar Max - Approved Hydraulics
    Regular price £158.46
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    Inline Pressure Relief Valve 1 1/4" Bsp 150Lpm 350 Bar Max

    Key Features

    • Type: inline pressure relief valve
    • Port size: 1 1/4" bsp
    • Max flow: 150 lpm
    • Set pressure range: up to 350 bar
    • Adjustment: screw ; locknut
    • Function: overpressure protection ; bypass to tank when set pressure reached
    • Mounting: in line
    • Typical applications: pump protection ; circuit safety ; mobile hydraulics
    Regular price £158.46
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  • Adam Hindle

    Sales Director

    I began my engineering career at Stockport College in around 2005, first completing a National Diploma in Electrical Engineering, followed by a Higher National Diploma in Mechanical Engineering. I then progressed to the University of Salford, where I earned a BEng (Hons) degree in Mechanical Engineering.

    After graduating, I started my professional career with Approved Hydraulics. I initially gained a combination of hands-on workshop experience and telephone-based sales experience. In later years, I moved into a full-time sales role and led the new crane and excavator attachments department that the company had recently established.

  • Hydra Part 3/8"BSP Dual Cross-over 35Lpm Relief Valve - 100-350Bar - Approved Hydraulics
    Regular price £99.42
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    3/8"BSP Dual Cross-over 35Lpm Relief Valve - 100-350Bar

    Key Features

    • Type: dual cross line relief valve
    • Port size: 3/8"bsp
    • Rated flow: 35 lpm
    • Adjustment range: 100 to 350 bar
    • Function: protects hydraulic motors from shock loads ; cross connected relief
    • Mounting: in line ; flangeable to motor on some models
    • Typical use: omp ; omr ; omh motor protection ; overrunning load control
    Regular price £99.42
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    • Order by 3pm for Next Day Delivery
  • Out of Stock
    Hydra Part 1/2"BSP Dual Cross-over 80Lpm Relief Valve - 130-350Bar - Approved Hydraulics
    Regular price £116.65
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    • Delivery to UK & Ireland

    1/2"BSP Dual Cross-over 80Lpm Relief Valves

    Key Features

    • Type: dual cross line relief valve
    • Port size: 1/2"bsp
    • Rated flow: 80 lpm
    • Adjustment range: 100 to 350 bar
    • Function: protects hydraulic motors from shock loads ; cross connected relief
    • Mounting: in line ; flangeable to motor on some models
    • Typical use: omp ; omr ; omh motor protection ; overrunning load control
    Regular price £116.65
    • All Items Guaranteed
    • Delivery to UK & Ireland
    • Order by 3pm for Next Day Delivery
  • Hydra Part 3/4"BSP Dual Cross-over 80Lpm Relief Valve - 130-350Bar - Approved Hydraulics
    Regular price £87.61
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    • Delivery to UK & Ireland

    3/4"BSP Dual Cross-over 80Lpm Relief Valve - 130-350Bar

    Key Features

    • Type: dual cross line relief valve
    • Port size: 3/4"bsp
    • Rated flow: 80 lpm
    • Adjustment range: 130 to 350 bar
    • Function: protects hydraulic motors from shock loads ; cross connected relief
    • Mounting: in line ; flangeable to motor on some models
    • Typical use: omp ; omr ; omh motor protection ; overrunning load control
    Regular price £87.61
    • All Items Guaranteed
    • Delivery to UK & Ireland
    • Order by 3pm for Next Day Delivery
  • Hydraulic Differential Type Relief Valve, VMPP 3/4" (20-200 Bar Adjustment) - Approved Hydraulics Limited
    Regular price £94.90
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    Hydraulic Differential Type Relief Valve, VMPP 3/4" (20-200 Bar Adjustment)

    Key Features

    • Type: differential poppet pressure relief valve VMPP
    • Ports: 3/8" BSPP P ; T
    • Setting range: 100–250 bar adjustable
    • Nominal flow variants: 20 l.min ; 50 l.min options
    • Leakage: guided poppet ; negligible leakage
    • Materials: zinc plated steel body ; hardened internals
    Regular price £94.90
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    • Order by 3pm for Next Day Delivery
  • 3/4" BSP IN-LINE 80 lpm RELIEF VALVE - 100-350 bar
    Regular price £102.06
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    3/4" BSP IN-LINE 80 lpm RELIEF VALVE - 100-350 bar

    Key Features

    • Ports: 3/4" BSPP inline
    • Flow: 80 l.min
    • Adjustment range: 100–350 bar
    • Function: direct acting relief ; protects downstream circuits
    • Construction: zinc plated steel body ; hardened internals
    Regular price £102.06
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    • Order by 3pm for Next Day Delivery
  • 3/4 BSPP Relief Valve - 80 l/min - 50/350 bar - Steel Body
    Regular price £44.22
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    3/4 BSPP Relief Valve - 80 l/min - 50/350 bar - Steel Body

    Key Features

    • Type: pressure relief valve; direct line mounting
    • Ports: 3/4 BSPP
    • Max flow: 80 L/min
    • Adjustable range: 50–350 bar
    • Function: protects circuit by limiting pressure to setpoint
    • Body: steel with corrosion-resistant plating
    Regular price £44.22
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  • 3/8" Dual Cross Line Relief Valve (V0440/180) 35 lpm - 100-180 Bar - With Protection Caps
    Regular price £66.06
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    3/8" Dual Cross Line Relief Valve (V0440/180) 35 lpm - 100-180 Bar - With Protection Caps

    Key Features

    • Thread size: G 3/8 BSPP
    • Setting range: 10 to 180 bar adjustable
    • Max flow: 35 l.min ; 45 l.min variants
    • Max pressure: 350 bar
    • Construction: zinc plated steel body ; hardened internal parts
    • Seals: NBR Buna N standard
    • Function: dual cross line relief with crossed tank
    • Typical use: motor or cylinder shock protection with independent port settings
    Regular price £66.06
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    • Delivery to UK & Ireland
    • Order by 3pm for Next Day Delivery
  • Out of Stock
    In-Line Pressure Reducing And Relieving Valve Direct Acting with Check
    Regular price £115.56
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    In-Line Pressure Reducing And Relieving Valve Direct Acting with Check

    Key Features

    • Max Flow: 30LPM
    • Max Pressure REG: 140 Bar
    • Max Pressure IN: 350 Bar
    • Function: Pressure reducing and relief regulation with check; protects downstream circuit
    • Notes: Specification information is limited in source listing; confirm dimensions and compatibility before purchase
    Regular price £115.56
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  • 1/2 BSPP Double Cross Relief Valve 50 L/Min 70/350 Bar - Steel Body
    Regular price £67.92
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    1/2 BSPP Double Cross Relief Valve 50 L/Min 70/350 Bar - Steel Body

    Key Features

    • Type: BSP tee adaptor
    • Connections: BSP threading per title
    • Threads: 1/2 thread
    • Material: plated carbon steel for hydraulic service
    • Use: split or combine lines; add instruments or auxiliary circuits
    Regular price £67.92
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  • Double cross relief valve 60L 1/2 BSPP 210 bar - steel body for OMP or OMR Hydraulic motors - Approved Hydraulics Limited
    Regular price £51.64
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    Double cross relief valve 60L 1/2 BSPP 210 bar - steel body for OMP or OMR Hydraulic motors

    Key Features

    • Type: double cross-line relief valve for hydraulic motors
    • Ports: 1/2 BSPP
    • Flow rating: per model
    • Max pressure: 210 bar
    • Compatibility: direct fit for Danfoss OMP/OMR style motors
    • Function: protects motor from shock and overpressure on both A/B lines
    • Body: steel; zinc plated
    Regular price £51.64
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    • Order by 3pm for Next Day Delivery
  • Out of Stock
    MV Hydraulic Motor Mounted Dual Cross Line relief valve 1" Ports - Approved Hydraulics Limited
    Regular price £397.86
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    MV Hydraulic Motor Mounted Dual Cross Line relief valve 1" Ports

    Key Features

    • Mounting: flanged directly to MV ; OMV ; CPMV motor port pattern
    • Port size: 1 in ports on MV variant
    • Setting ranges: 30 to 100 bar ; 50 to 210 bar ; 20 to 250 bar options
    • Max flow: up to 120 l.min
    • Function: dual cross port relief for overpressure ; shock protection
    • Construction: zinc plated steel body ; hardened internal components
    • Seals: NBR Buna N standard
    • Options: anti cavitation check valves available in related families
    Regular price £397.86
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    • Delivery to UK & Ireland
    • Order by 3pm for Next Day Delivery
  • BSPP Relief Valve upto 30 L/min - Steel Body
    Regular price From £24.27
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    BSPP Relief Valve upto 30 L/min - Steel Body

    Key Features

    • Type: hydraulic component
    • Design: built for mobile hydraulic service
    • Use: as specified by product title
    • Body: corrosion protected steel or aluminium per model
    Regular price From £24.27
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    • Delivery to UK & Ireland
    • Order by 3pm for Next Day Delivery
  • BSPP Relief Valve upto 50 L/min - Steel Body - Approved Hydraulics Limited
    Regular price From £37.18
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    • Delivery to UK & Ireland

    BSPP Relief Valve upto 50 L/min - Steel Body

    Key Features

    • Type: hydraulic component
    • Design: built for mobile hydraulic service
    • Use: as specified by product title
    • Body: corrosion protected steel or aluminium per model
    Regular price From £37.18
    • All Items Guaranteed
    • Delivery to UK & Ireland
    • Order by 3pm for Next Day Delivery

Relief Valves

Common Calculations FAQs

Calculating force, speed, pressure, power, and efficiency in hydraulic applications.

How do you calculate actuator speed?

Actuator speed is determined by flow rate and cross-sectional area:

Speed = Flow rate ÷ Area

Flow rate is the volume of fluid delivered (in L/min or GPM).

Area is the cross-sectional area of the actuator piston: π × (diameter ÷ 2)².

How do you calculate cylinder force?

Cylinder force can be calculated using:

Force = Pressure × Area

Pressure is the system pressure (in psi or bar).

Area is the cross-sectional area of the cylinder bore (in square inches or square centimeters).

Area = π × (bore diameter ÷ 2)².

How do you calculate pressure drop across a valve?

Pressure drop can be calculated using the valve flow coefficient (Cv):

Pressure Drop (ΔP) = (Flow Rate)² ÷ (Cv² × Fluid Density)

Flow Rate is the fluid flow (in GPM or L/min).

Cv is the valve flow coefficient.

Fluid Density is the density of the hydraulic fluid.

How do you size an accumulator?

Accumulator sizing considers required flow, pressure, and pre-charge:

Accumulator Volume = Flow Rate × Time ÷ Pressure

This determines how much fluid must be stored to maintain system pressure.

How to convert psi to bar?

Use the conversion factor: 1 bar = 14.5 psi.

To convert psi to bar, divide psi by 14.5.

Example: 200 psi ÷ 14.5 = 13.79 bar.

What is pre-charge pressure in an accumulator?

Pre-charge pressure is the initial gas pressure in the accumulator before fluid enters.

It helps maintain system pressure as the accumulator discharges.

Typically set to 70–80% of system operating pressure.

What is specific gravity of hydraulic fluid?

Specific gravity is the ratio of hydraulic fluid density to water.

A value of 1 means equal density.

Less than 1 means the fluid floats; greater than 1 means it sinks.

What is torque in a hydraulic motor?

Torque is the rotational force produced based on system pressure and motor displacement:

Torque = Pressure × Displacement ÷ 2π

Pressure is the operating system pressure.

Displacement is the volume displaced per revolution (in cubic inches or cubic centimeters).

What unit is hydraulic power measured in?

Hydraulic power is measured in horsepower (HP) or kilowatts (kW).

Hydraulic horsepower can be calculated using:

HP = (Pressure (psi) × Flow rate (GPM)) ÷ 1714.

What’s the relationship between pump speed and flow?

Flow rate is directly proportional to pump speed.

If pump speed doubles, flow rate doubles (assuming constant displacement).

This is important when adjusting flow or selecting a pump for varying speeds.