How to Calculate a Water Hammer

Last summer I built an underground sprinkler system for my lawn. As I flipped the switch for the first time and beamed with pride at my wonderful creation, I couldn’t help but notice the loud thud whenever one of the valves closed. Lo and behold (insert joke about engineer building projects here), this is a […]

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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. […]

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. If a stream of dye is inserted into the flow and it disperses and mixes, the flow is turbulent. When the flow is turbulent, […]

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. If a stream of dye is inserted into the flow and it continues in a straight, unbroken line, the flow is laminar. Flow Types The opposite of […]

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. The equation is: Where: De = Hydraulic Diameter (ft or m) v = velocity of the fluid […]

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 […]

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. […]

How to Calculate Hydraulic Radius

hydraulic radius

Hydraulic radius is used in various engineering applications, particularly in the calculation of pipe and channel flow. It is defined as the flow area divided by the wetted perimeter. Flow Area This is the cross-sectional flow area of the channel or pipe. When a pipe is flowing under pressure, this is the full internal area […]

How to calculate Tailwater

tailwater

Tailwater is defined as the depth of flow in a channel immediately downstream of a drainage facility. Since a drainage structure can create a constriction, the tailwater is usually a starting point, from which the resulting headwater is calculated. Early in my career I was confused by this, because it would seem that building a […]