Select Page

# Hydraulic Calculator

Type in the textbox the known information. Leave only one field open in each formula and click the “calculate” button for the result of that field. The “reset” button will clear all fields. On the conversion table type in the textbox the units you want to convert.

## Pump Flow or Displacement

$$GPM(Flow) = \frac{RPM * DISPLACEMENT (Cu. In./Rev.)}{231}$$

 RPM DISPLACEMENT GPM (Flow)

## Pump Input Horsepower

$$HP(Power) = \frac{PSI(Pressure) * GPM(Flow))}{1714 * \text{% }Pump\text{ } Efficiency }$$

 PSI (Pressure) GPM (Flow) % Pump Efficiency HP (Power)

## Torque

$$Lb-in (Torque) =\frac{PSI (Pressure) * cu.in. / rev. (Displacement)}{2π}$$

 PSI(Pressure) cu.in./rev.(Displacement) Lb−in(Torque)

## Torque

$$Lb-in (Torque) =\frac{HP(Power) *63025}{RPM}$$

 HP(Power) RPM Lb−in(Torque)

## Cylinder Piston Area-Blind End (Extension)

$$in^2(Area) = in (Piston\text{ } Diameter) ^ 2 * (\frac{π}{4})$$

 in(Piston Diameter) in2(Area)

## Cylinder Piston Area-Rod End (Retraction)

$$in^2 (Area) = (in (Piston Diameter))^2 *(\frac{π}{4}) – (in(Rod Diam.))^2 *(\frac{π}{4})$$

 in(Piston Diameter) in(Rod Diam.) in2(Area)

## Cylinder Force

$$lbf. (Pounds\text{ }of\text{ }Force) = PSI (Pressure) * sq. in. (Area)$$

 PSI(Pressure) sq.in.(Area) lbf.(Pounds of Force)

## Cylinder Flow Rate and Velocity

$$GPM (Flow) = \frac{in.^2 (Area) * in. (Stroke Travel) * 60 }{sec (Time) * 231}$$

 in.2(Area) Stroke Travel sec(Time) GPM(Flow)

## Cylinder Volume

$$Gal (Volume)=\frac{in.^2 (Piston Area) * in. (Stroke)}{231}$$

 in.2(Piston Area) in.(Stroke) Gal (Volume)

## Pressure Loss Per Foot of Pipe (Laminar Flow Only)

$$PSI/ft(Pressure Loss)=\frac{SSU(Viscosity\text{ at }Oper. Temp.) * GMP}{18300*(in(I.D. of Pipe))^4}$$

 SSU(Viscosity at Oper.Temp.) GMP in(I.D. of Pipe) PSI/ft(PressureLoss)

## Velocity of Oil Flow in a Pipe

$$ft/sec(Velocity)=\frac{GPM (Flow)*0.3208}{(in(I.D. of Pipe))^2*0.7854}$$

 GMP in(I.D. of Pipe) ft/sec(Velocity)

## Reservoir Cooling Capacity (Steel w/ Adequate Air Circulation)

BTU/hr(Heat Loss) =2*sq. ft. (Surface Area of Reservoir) * (°F (Reservoir Wall Temp.)-°F (Air Temp.))

 sq. ft. (SA of Reservoir) °F (Reservoir Wall Temp.) °F (Air Temp.) BTU/hr(Heat Loss))

## Heat in a Hydraulic System From Unused Flow / Pressure

BTU/hr (Heat) = GPM (Flow)*1.485 *PSIG (Pressure Drop)

 GPM (Flow) PSIG (Pressure Drop) BTU/hr (Heat)

## Heat in a Hydraulic System (Hydraulic Oil)

BTU/hr (Heat Loss) = 210 * GPM (Flow) * (°F (Return Fluid Temp.) -°F (Pump Fluid Temp.))

 GPM (Flow) °F (Return pump Temp.) °F (Pump pump Temp.) BTU/hr (Heat Loss)

## Heat Required to Reach a Desired Temperature

$$kWh (Heat)=\frac{Lbs. of Hyd Oil*Specific Heat*(°F (End Temp.)-°F (Beg. Temp.))}{3413}$$

 Lbs. of Hyd Oil Specific Heat °F (End Temp.) °F (Beg. Temp.) kWh (Heat)

## Accumulator Make Up Oil Necessary to Stroke Cyl in “X” seconds

### Blind End

$$Oil Req. = \frac{3.14 * Cyl. Bore Dia.^2 * Stroke}{4}-\frac{GPM * 231 * Req. Stroke}{60}$$

### Rod End

$$Oil Req. = \frac{3.14*(Cyl. Bore Dia.^2-RodDia.^2)}{4}* Stroke-\frac{GPM * 231 * Req. Stroke}{60}$$

 Cylinder Bore Diameter (in) Stroke (in) Rod Diameter (in) Pump Flow GPM Required Stroke Time (sec) Blind End Accum. of Oil Required (in3) Rod End Accum. of Oil Required (in3)

## Accumulator Sizing

$$StoredOil = \frac{0.95 * Pre\text{-}charge * Vol.Size}{Min. PSI} – \frac{0.95*Pre\text{-}charge*Vol.Size}{System PSI}$$

Stored Oil if Accumulator Size is Larger Pre-charge Pressure (Nitrogen) Minimum System Pressure Maximum System Pressure Volume Size (cu. in.)/ Rated Gas Vol. for 1 Gallon Discharge in cu.in per 1 Gallon Size Accumulator 1 Gallon 2.5 Gallon 5 Gallon 10 Gallon 20 Gallon

Note:
Due to heating and cooling of the nitrogen during operation, a 5% allowance has been added to the formula. Allow enough extra capacity for contingencies.

## Calculating Flow Rates in Regeneration Circuits

DB = Diameter Blind End
DR = Diamter of Rod End
P = Pump Flow

### Cylinder Speed

$$Cylinder Speed (in/sec) = \frac{P * 231}{60 * (\frac{DR^2}{4} * π)}$$

### Flow Out of Rod End of Cylinder

$$Flow Rod End (GPM) = \frac{DB^2-DR^2}{DR^2}*P$$

### Combined Flow (Regen. Flow + Pump Flow)

$$Combined Flow (GPM) = \frac{DB^2}{DR^2}*P$$

### Retraction Flow (Flow Out of Blind End)

$$Retract Flow (GPM) = \frac{DB^2}{DB^2-DR^2}*P$$

 Diameter Blind End = DB Diamter of Rod End = DR Pump Flow = P Cylinder Speed (in/sec) Flow Rod End (GPM) Combined Flow (GPM) Retract Flow (GPM)

## Displacement

 cc cu. in. cu. in. cc

## Volume

 Liters Gallons Gallons Liters

## Distance

 cm Inches Inches cm

## Pressure

 BAR PSI PSI BAR MPa PSI PSI MPa

## Power

 BTU /hr hp BTU /hr kW hp BTU /hr hp kW kW BTU /hr kW hp

## Torque

 Nm lb-in lb-iN Nm

## Force

 N lb-ft lb-ft N

## Viscosity (100° F)

 SUS cSt cSt SUS

## Velocity

 cm/sec ft/sec ft/sec cm/sec

## Heat/ Energy

 BTUhphkWhkJ BTUhphkWhkJ

## Temperature

 °C °F °F °C

## Disclaimer

360-705-0918
sales@northpointeindustries.com
2918 Ferguson Street SW Suite C2
Tumwater, WA 98512 