Hydraulic Terminology

Question 1

Gauge Pressure

Answer 1

Is the pressure measured relative to local atmospheric pressure.

Atmospheric pressure is zero gauge.

Question 2

Absolute Pressure

Answer 2

The sum of atmospheric pressure and gauge pressure. The absolute pressure is in a perfect vacuum is zero.

Absolute pressure of the atmosphere of the atmosphere at sea level is 14.7 psi or 0 psi gauge.

Question 3

Vapor Pressure

Answer 3

The pressure exerted when a solid or liquid is in equilibrium with its own vapor.

Vapor pressure is a function of the substance and of the temperature.

Question 4

Vacuum

Answer 4

Frequently used in referring to pressure below atmospheric.

Vacuum is commonly expressed in inches of mercury.

14.7 psi atmospheric pressure equivalent to 30 inches of mercury at sea level

Question 5

Head

Answer 5

The vertical

Question 6

Potential Head

Energy of Position

Answer 6

The work required to elevate a weight to a certain height above some datum or reference plane.

Datum: a fixed starting point of a scale or operation. A piece of information.

Question 7

British Thermal Unit (BTU)

Answer 7

The amount of heat required to raise the temperature of one pound of water from 63 to 65 degrees of Fahrenheit. BTU’s are the unit commonly used to express the potential energy of fuels used in internal combustion engines.

Question 8

Shut Off Head

Answer 8

Shut-off Head is the head generated by a pump with the discharge valve closed (pump running at zero capacity)

Question 9

Static Pressure Head

Answer 9

(Energy per pound due to pressure)

The height to which liquid can raised by a given pressure.

Question 10

Velocity Head

Kinetic energy per pound

Answer 10

The vertical distance a liquid would have to fall to acquire the velocity “V”.

Question 11

Bernoulli’s Theorem

Answer 11

The sum of the three types (elevation, pressure, & velocity) of energy (Head) at any point in a system is the same at any other point in the system assuming no friction losses or the performance of work.

Question 12

Static Suction Lift

Answer 12

The vertical distance in feet, when the source of supply is below the pump, from the surface of the liquid to the pump centerline.

Question 13

Static Suction Head

Answer 13

When the liquid supply is above the pump. The vertical distance from the pump centerline to the surface of the liquid.