Pipe Drop

The Pipe Drop calculator computes the drop needed at the end of a run for a pipe to be laid with a desired grade.

INSTRUCTIONS: Choose units and enter the following:

• (G) Drop per 12" (e.g., 1/8" = 0.125  1/4" = 0.25 1/2" = 0.5)
• (R) Run of Pipe
• (W) Outer width of the pipe
• (x) Adder

Depth of Trench (D):  The calculator returns the depth in inches.  However, this can be automatically converted to compatible units via the pull-down menu.

The Math / Science

For a waist pipe to drain properly, there needs to be slope with a drop of 1/4" to 1/2" inch for every foot (12") of run.  With less of a slope, there is inadequate drainage.  With more slope, the liquids drain too fast and leave the solids behind.

The depth (d) of the fall is a function of the Run (R) and the grade (G):

         d = G/(12 inches) *R

where:

• d = vertical displacement
• G = grade in inches drop per foot
• R = horizontal displacement

The end depth of the trench is:

          D = d + W + x

where:

• D = Depth of Trench
• d = drop over the run
• W = outer diameter of the pipe
• x = adder for fittings

Plumbing Calculators

• Rolling Offsets (Run and Travel)  – The Rolling Offset Rolling Offset Lengths Pipe Grading function computes the run and travel length a rolling offset based on the offsets and fittings. (see diagram).
• Pipe Grading - Compute the drop needed over a run to maintain a grade (e.g., 4" over 12')
• Diagonal of a Square - This is a simple calculation to assist in computing the diagonal of a square.
• Diagonal of a Box - This computes the length of the diagonal of a box (T) based on sides of length R, S and U.
• Flow Rate - This computes flow rate based on the total volume and the time it took to accumulate.
• Pipe Flow Volume  - This computes the total volume from a pipe based on the flow rated and the duration of flow.
• Weight of Water in a Tank - Computes the weight of water in a cylindrical tank based on the radius and height (or length).
• Weight of Water in a Pipe - Computes the weight of water or other substances in a pipe based on the dimension and material density.
• Weight of Sea Water in pipe - Computes the weight of sea water in a cylinder based on the radius and height (or length)
• Pressure Head - The Potential Gravity-Fed Water Pressure from a Tank (a.k.a. Pressure Head) based on the height of storage.
• Pipe Volume - Computes the volume in a pipe.
• Pipe Surface Area - Computes the surface area of a pipe.
• Pipe Coating Amount - Computes the volume of coating material for a pipe such as paint, polyethylene, polyurethane, zinc, bitumen, FBE or mortar.
• Volume of Water in a Tank (e.g. hot water tanks),
• Volume of a Spherical Container
• Weight of Water in a Spherical Container
• Volume of Water in Rectangular Tank 
• Weight of Water in a Rectangular Tank
• Capillary Rise - The height of water in a small tube due to capillary force.
• Snow Water Equivalence - The volume of water created by an area and depth of snow.
• Pore Water Pressure - Pressure of uplift from the water table.
• Pipe Stress Budget - Computes the pressure that a pipe can withstand based on the allowable stress, wall thickness and outside diameter.
• Water in Basement Volume: Computes the volume of water in an area such as a basement based on the dimensions and the time required to pump it out based on a sump pump rate.
• Paint for Pipes: Computes the amount of paint needed to cover the exterior surface area of one or more pipes based on the pipe diameter, length, number of coats, number of pipes and the recommended area coverage of the paint. 
• Time to Fill: Computes the amount of time necessary to fill something (e.g., tank or pool) based on the volume and flow rate.
• Pipe Insulation Calc: Computes the number of bags of pipe insulation needed for a run of pipes based on the 12' of length per bag and the length of pipe run to be insulated.