Hydraulic Technical Info. > Forumulas

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Basic Formulas
Formula For:	Word Formula	Letter Formula
Fluid Pressure In Pounds/Square Inch	Pressure =	P = or psi =
Fluid Fow Rate In Gallons/Minute	Flow Rate =	Q =
Fluid Power In Horsepower	Horsepower =	HP =

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Fluid Formulas
Formula For:	Word Formula	Letter Formula
Velocity Through Piping In Feet/Second Velocity	Velocity =	V =
Compressibility of Oil In Additional Required Oil To Reach Pressure	Additional = Volume	VA = * Approximately 1/2 % per 100 psi
Compressibility of a Fluid	Compressibility =	C(ß)=
Specific Gravity of a Fluid	Specific = Gravity	SG =
Valve (Cv) Flow Factor	Valve Factor (Cv) =	Cv =
Viscosity in Centistokes	For Viscosities of 32 to 100 Saybolt Universal Seconds: Centistokes = .2253 x SUS -	CS = .2253 SUS -
Viscosity in Centistokes	For Viscosities of 100 to 240 Saybolt Universal Seconds: Centistokes = .2193 x SUS -	CS = .2193 SUS -
Viscosity in Centistokes	For Viscosities Greater Than 240 Saybolt Universal Seconds: Centistokes =	CS =
NOTE: Saybolt Universal Seconds is often abbreviated SSU.

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Pump Formulas
Formula For:	Word Formula	Letter Formula
Pump Outlet Flow In Gallons/Minute	Flow =	Q =
Pump Input Power In Horsepower Required	Horsepower Input =	HPIN = or
Pump Efficiency Overall in Percent	Overall Efficiency = X 100 Overall Efficiency = Volumetric Eff. x Mechanical Eff.	EffQV=  x  100 EffQV =  EffVOL x EffMECH
Pump Efficiency Overall in Percent	Volumetric Efficiency = x 100	EffVOL = x 100
Pump Efficiency Mechanical in Percent	Mechanical Efficiency = x 100	EffMEC = x 100
Pump Life B10 Bearing Life	B10 Hours of Bearing Life = Rated Life Hours x x	B10  x x

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Cylinder Formulas
Formula For:	Word Formula	Letter Formula
Cylinder Area In Square Inches	Area =  x Radius2 (Inches) Area =   x Diameter2 (Inches)	A = r2 A =   or  A = .785D2
Cylinder Force In Pounds, Push or Pull	Force = Pressure (psi) x Net Area (Square Inches)	F = psi x A or F = PA
Cylinder Velocity or Speed n Feet/Second	Velocity =	V = or V =
Cylinder Volume Capacity In Gallons of Fluid	Velocity = Velocity =	V = V =   / = Length of Stroke
Cylinder Flow Rate In Gallons Per Minute	Flow Rate =	Q = or  Q = 3.117vA
Fluid Motor Torque In Inch Pounds	Torque =  Torque = Torque =	T = or T = T = T = or T =
Fluid Motor Torque/100 psi In Inch Pounds	Torque/100 psi =	T100psi =
Fluid Motor Speed In Revolutions/Minute	Speed =	n =
Fluid Motor Power In Horsepower Output	Horsepower =	HP =

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Thermal Formulas
Formula For:	Word Formula	Letter Formula
Reservoir Cooling Capacity Based on Adequate Air Circulation	Heat (BTU/HR) = 2 x Temperature Difference Between Reservoir Walls And Air (ºF) x Area of Reservoir (Sq.Ft.)	BTU/Hr = 2.0 x T x A
Heat in Hydraulic Oil (approx.) Due to System Inefficiency(SG=.89-.92)	Heat (BTU/HR) = Flow Rate (GPM) x 210 x Temperature Difference (ºF)	BTU/HR = Q x 210 x T
Heat in Fresh Water (approx.)	Heat(BTU/HR) = Flow Rate (GPM) x 500 x Temperature Difference (ºF)	BTU/HR = Q x 500 x T
Note: One British Thermal Unit (BTU) is the amount of heat required to raise the temperature of one pound of water one degree.   Once Horsepower = 2545 BTU/HR.

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Accumulator Formulas
Formula For:	Word Formula	Letter Formula
Pressure or Volume w/ Constant "T" (Temperature)	Original Pressure x Original Volume = Final Pressure x Final Volume	P1 V1  =  P2 V2   Isothermic
Pressure or Temperature w/ Constant "V" (Volume)	Original Pressure x Final Temperature = Final Pressure x Original Temperature	P1 T1  =  P2 T2   Isochoric
Volume or Temeprature w/ Constant "P" (Pressure)	Original Volume x Final Temperature =       Final Volume x Original Temperature	V1 T1  =  V2 T2   Isobaric
Pressure or Volume w/temperature Change to Heat or Compression	Original Pressure x Original Volumen = Final Pressure x Final Volumen   =    =	= =
Note: One British Thermal Unit (BTU) is the amount of heat required to raise the temperature of one pound of water one degree.   Once Horsepower = 2545 BTU/HR.

[Basic]   [Fluid]   [Pump]   [Cylinder]   [Thermal]   [Accumulator]
[Volume & Capacity Equivalents]  [Top of Page]

[Basic]   [Fluid]   [Pump]   [Cylinder]   [Thermal]   [Accumulator]
[Volume & Capacity Equivalents]  [Top of Page]