•Flowrate
- is the volume of fluid or mass that passes a certain area per time unit.
- Unit used : m³/hr, LPM, GPM……
•Pressure / Head
- a force per unit area.
- Unit used : Bar, PSI, Kg/cm², Kpa….
•Viscosity
- a measure of how resistive the fluid is to flow
- Unit used : Centipoise (cPs), mPas (milliPascal), Centistokes (cst), SSU..
•Density
- is a fluid mass per unit of volume
- Unit used : kg/m³
- Example :
1 m³ of ethyl alcohol has a mass of 789kg, i.e. Density = 0.789 kg/m³

•Specific Gravity SG
- is the ratio of a fluid’s density to the density of water
- Example
1 liter of H²O when is weigh it will have 1kg of weight. So it has a SG of 1
1 liter of fluid when is weigh it shows 1.2kg of weight, means that it has a SG of 1.2
- No unit is use as it is a ratio of weight(kg) / 1 liter of fluid
•Temperature
- a measure of the internal energy level in a fluid.
- Unit used : Celsius (°C), Fahrenheit (°F), Kelvin (K)
•Gauge Pressure
- Using atmospheric pressure as a zero reference, gauge pressure is the pressure within
the gauge that exceeds the surrounding atmospheric pressure. It is a measure of the
force per unit area exerted by a fluid, commonly indicated in units barg or psig.
•Absolute Pressure
- is the total pressure exerted by a fluid, indicated in units bar a or psia
- Absolute Pressure = Gauge Pressure + Atmospheric Pressure

•Vacuum
- Describe as pressure in a pumping system below normal atmospheric pressure.
- a measure of the difference between the measured pressure and atmospheric
pressure
- Unit in mmHg or inHg
•Inlet (Suction) Pressure
- is the pressure at which the fluid is entering the pump
•Outlet (Discharge) Pressure
- is the pressure at which the fluid leaves the pump
•Differential Pressure
- is the difference between the inlet & outlet pressures.
- For inlet pressure above atmospheric pressure,
Differential Pressure = Out Pressure – Inlet pressure.
- For inlet pressure below atmospheric pressure,
Differential Pressure = Outlet Pressure + Inlet pressure

•Flooded Suction
- Used to describe a positive inlet pressure/head, whereby fluid will readily flow into
pump inlet at sufficient pressure to avoid cavitation.
•Static Head
- is a difference in fluid level
•Static Suction Head
- is the difference in height between the fluid level and the center line of the pump inlet
on the inlet side of the pump
•Static Discharge Head
- is the difference in height between the fluid level and the center line of the pump inlet
on the discharge side of the pump
•Total Static Head
- is the difference in height between the static discharge head & the static suction head
of a system.

•Friction Head
- is the pressure drop on both inlet & discharge sides of the pump due to frictional losses
in fluid flow
•Dynamic Head
- is the energy required to set the fluid in motion and to overcome any resistance to that
motion.
•Total Suction Head
- is the static suction head less the dynamic head. Where the static head is negative, or
where the dynamic head is greater than the static head, this implies the fluid level will
be below the center line of the pump inlet (ie suction lift)
•Total Discharge Head
- is the sum of the static discharge & dynamic heads.

•Total Head
- is the total pressure difference between the total discharge head & the total suction
head of the pump
- Total Head = Ht – (± Hs)
Total Discharge Head Ht = ht + hft + pt
Total Suction Head Hs = hs – hfs + (± ps)
Where H = Total Head
Hs = total Suction Head
Ht = Total Discharge Head
hs = Static Suction Head
ht = Static Discharge Head
hfs = Pressure Drop in Suction Line
hft = Pressure Drop in Discharge Line
Ps = Vacuum or Pressure in a tank on suction side
Pt = Pressure in a tank on discharge side

•Pressure Drop
- manufacturer of processing equipment usually have data available for pressure drop.
These losses are affected by fluid velocity, viscosity, tube diameter, internal surface
finish of tube and tube length.
•Cavitation
- Cavitation is an undesirable vacuous space in the inlet port of the pump normally
occupied by fluid. The lowest pressure point in a pump occurs at the pump inlet – due
to local pressure reduction part of the fluid may evaporate generating small vapour
bubbles. These bubbles are carried along by the fluid and implode instantly when they
get into areas of higher pressure.
- If cavitation occurs this will result in loss of pump efficiency & noisy operation. It will
shortened the pump life.
•Net Positive Suction Head (NPSH)
- The condition at the inlet of a pump is critical.
- The system on the inlet side of the pump must allow a smooth flow of fluid to enter the
pump at a suffciently high pressure to avoid cavitation. This is called the NPSH.

•Net Positive Suction Head (NPSH)
- Pump manufacturers supply data about the NPSH required (NPSHr) by their pumps for
satisfactory operation.
- When selecting a pump, it is critical the NPSH available (NPSHa) in the system is greater
than NPSHr.
- NPSH = NPSHa > NPSHr