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Resources - Disk Pumps

The ultimate disk pump solution

When your challenge is pumping abrasives, corrosive fluids, slurries or sludge, the Southwestern Controls/Adaptek Disk Pump solution is the answer to your problem. In addition, our disk pump solution allows for delicate shear sensitive fluids and other products to stay intact. Also, consider the Adaptek design for the following requirements:

  • Low NPSH requirements
  • The need to handle large particles
  • The need to handle viscous fluids

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Resources - Useful Fluid Power Formulas

General Formulas:

Work, foot-pounds = force x distance

Horsepower = work/(time, seconds x 550)


Southwester Controls - Pumps
Hydraulic Formulas:

Force, pounds = (pressure, lbs/sq-in)(area, sq-in)

Area of cylinder, square inches = (force, lbs)/(pressure, lbs/sq-in)

Pressure, lbs/square-inch = (force, lbs)/(area, sq-in)

Intensifier:  P1 A1 = P2 A2 and P1 D12 = P2  D22
where: D1 is diameter of large piston; D2 is diameter of small piston; P1 is pressure applied to large piston; P2 is pressure applied to small piston

Pump flow rate, gpm = DNEV/231
where: D = displacement, cu-in/rev; N = speed, rev/min: EV = volumetric efficiency

Pump output horsepower = PQ/1714 = TNEO/63025
where: T = torque, lb-in; Q = pump flow rate, gpm; P = pressure, psi; N = speed, RPM; EO = overall efficiency

Lift pressure, pounds/square inch = (fluid column height, feet)(62.4)(SG)/144

Velocity of fluid in a tube, feet/second = 0.321 Q/A

Max fluid velocity allowed by National Fluid Power Society = 20 feet/second for pressure lines
= 15 feet/second for return lines
= 5 feet/second for suction lines

Tube inside diameter, inches = 0.639(Q/Vmax)1/2

Maximum pressure for pipe threads = 200 psi   Reference ANSI/(NFPA/JIC) T2.24.1 - 1991

Approximate tube stress, psi = P ID/(2 T)
where: T = tube wall thickness, inch; P = pressure, psi; ID = inside diameter of tube, inch

Factor of safety = ultimate tensile strength, psi/allowable stress, psi

Cylinder speed extending, inches/second = 3.85 Q/AE

Cylinder speed retracting, inches/second = 3.85 Q/AR

Hydraulic motor torque, pound-inches = P D EM/(2 p)
where: P = pressure, psi; D = motor displacement, in3/rev; EM = mechanical efficiency

Hydraulic motor speed, rpm = Q EV 231/D
where: Q = flow rate, gpm; D = displacement, inches3/revolution; EV = volumetric efficiency

Hydraulic motor horsepower output = P Q EO/1714
where: P = pressure, psi; Q = flow rate, gpm; EO = overall efficiency

EO = EV x EM
where: EV, volumetric efficiency: EM, mechanical efficiency: EO, overall efficiency

Oil flow rate across an orifice, cu-in/sec = 100 AO (DP)1/2
where: AO = area of orifice, in2 ;DP = pressure differential across orifice, psi


Southwestern Controls - Pumps
Pneumatic Formulas:

PSIA = PSIG + 14.7

Vacuum pressure, PSI =(0.491)(H, inches of mercury vacuum)

Compression ratio = (final pressure, PSIA/initial pressure, PSIA)
Example: CR = (90 PSIG +14.7)/14.7

Time a receiver can deliver flow between two pressures, minutes = (VR x (P1 – P2))/(14.7 x Q)
where: VR is volume of receiver, cu ft; Q is flow rate out, CFM; (P1-P2) is starting pressure – ending pressure

Perfect gas law: P1 V1/T1 = P2 V2/T2
where: T = degrees Rankin; P1 & P2 = PSIA; units of volume V unimportant
Constant temperature, P1 V1 = P2 V2
Constant volume, P1/T1 = P2/T2
Constant pressure, V1/T1 = V2/T2

DP pressure loss in air line, psi = (0.1025 x L x (Q/60)2)/(CR x d 5.31)
where: L is length of pipe, feet; d is inside diameter of pipe, inches; Q is air flow rate, SCFM; CR is compression ratio

Volume of free air required to raise pressure in a receiver = (P2V2/P1) – V2
where: P1 =14.7 PSIA; P2 = final pressure, PSIA; V2 = receiver volume, ft3; V = volume of air that must be added by compressor, ft3

Displacement of a compressor, in3/revolution = number of pistons x (p/4)(piston diameter2, in2)(stroke, inches)