Archives for October 2013

Pipe Standards

There are many different standards governing the different types of pipe material, diameters and wall thicknesses. The following are a list of standards in place in the United States: Gasketed PVC sewer pipe Smaller than 15 in. diameter: ASTM D3034. Greater than 15 in. diameter: ASTM F679. PVC pressure pipe for water distribution: AWWA C900. […]

Types of Pipe Material

Pipe materials are chosen to withstand internal pressures, external loads from backfill and traffic, smoothness, corrosion resistance, chemical inertness, cost, and other factors. The major types of pipe material that are in use today are: Plastic Steel Concrete Copper and brass Cast iron Vitrified clay Plastic Pipe Subdivided into PVC and ABS pipe, plastic pipe […]

How to calculate Turbulent Flow

Turbulent flow is rough and choppy. Turbulent flow is the opposite of laminar flow, which is straight line flow. In pipelines, laminar flow occurs when Reynolds number is greater than 4,000. $latex R_e > 4,000&s=2$ If a stream of dye is inserted into the flow and it disperses and mixes, the flow is turbulent. When […]

How to determine Laminar Flow

Laminar flow is smooth flow in a straight line. Laminar is the opposite of turbulent flow. In pipelines, laminar flow occurs when Reynolds number is less than 2,100. $latex R_e < 2,100&s=2$ If a stream of dye is inserted into the flow and it continues in a straight, unbroken line, the flow is laminar. Flow […]

How to Calculate Reynold’s Number

The Reynolds number of a fluid is a dimensionless constant which allows you to determine whether the flow of a fluid is laminar or turbulent. It represents the ratio of inertial forces to viscous forces in the fluid. $latex R_e = \frac{inertial forces}{viscous forces}&s=2$ The equation is: $latex R_e = \frac{D_ev}{\upsilon}&s=2$ Where: De = Hydraulic […]

How to Calculate Hydraulic Diameter

The hydraulic diameter is a term used in fluid mechanics and thermodynamics. It is a measure of the efficiency of a section to pass flow by relating the cross-sectional area of flow to the wetted perimeter of the cross-section. The hydraulic diameter of a round pipe is simply its diameter. The equations for hydraulic diameter […]

What is a Pitot Tube and How does it Work?

Pitot tubes are small, right angle shaped tubes that can measure the velocity of a fluid.  They are an important part of an airplane, where they are used to provide the pilot with in-flight velocity measurements. When the fluid enters the pitot tube, it is forced to come to a stop.  At some point in […]

Bernoulli Equation Examples

For reference, the Bernoulli equation is: $latex E_t = E_p + E_v + E_z\newline \indent =\frac{p}{\rho}+\frac{v^{2}}{2}+zg\hspace{20px}^{(SI)}\newline \indent =\frac{p}{\rho}+\frac{v^{2}}{2g_c}+\frac{zg}{g_c}\hspace{20px}^{(US)}&s=2$ Example 1 A reservoir contains an outlet that consists of a pipe that discharges water 50 ft below the top of the reservoir. What is the velocity of the water exiting the pipe (at point B)? Solution […]

How to Use the Bernoulli Equation

The Bernoulli equation states that the total energy possessed by a fluid is the sum of its pressure, kinetic, and potential energies. $latex E_t = E_p + E_v + E_z\newline \indent =\frac{p}{\rho}+\frac{v^{2}}{2}+zg\hspace{20px}^{(SI)}\newline \indent =\frac{p}{\rho}+\frac{v^{2}}{2g_c}+\frac{zg}{g_c}\hspace{20px}^{(US)}&s=2$ Using this starting point, we can calculate the total head, ht, and total pressure, pt, that the fluid is under: $latex […]

How to Calculate Fluid Energy

The energy of a fluid comes in the following forms: Kinetic Energy (if it is moving) Potential Energy Pressure Energy Kinetic Energy Since energy is required to accelerate a stationary body, a moving mass of fluid flow possesses more energy than an identical, stationary mass. This energy difference is the kinetic energy of the fluid. […]