# Determing GPM through PVC pipe (Gravity Drains)

• rwludman
In summary, GPM (gallons per minute) for PVC pipes is determined by the pipe size, slope, and water flow. A steeper slope and larger pipe diameter result in a higher GPM, while a longer pipe reduces the GPM due to friction and resistance. The maximum GPM for PVC pipes varies depending on the pipe diameter and slope, and it is important to consult local plumbing codes for specific guidelines. To calculate the GPM for a specific PVC pipe system, you will need to know the pipe diameter, slope, and length, and it is recommended to consult a professional plumber for accurate calculations. It is possible to increase the GPM by increasing the pipe diameter or slope, but this should be done in accordance with
rwludman
Does anyone know the equation to find the flow rate, in GPM, of water through a vertical pvc pipe? No pump, just gravity.

depends on the accuracy required for your answer. first approximation: the kinetic energy (velocity) at the bottom equals the loss of potential energy from top to bottom. that neglects friction losses. Try googling 'bernoulli equation' and 'moody friction' for more details.

There is no single equation that can accurately determine the flow rate of water through a vertical PVC pipe using only gravity. The flow rate is dependent on several factors such as the diameter and length of the pipe, the slope of the pipe, and the viscosity of the water. Additionally, the flow rate may also be affected by any obstructions or bends in the pipe. In order to accurately determine the flow rate, it is important to consider all of these factors and use a combination of equations, such as the Darcy-Weisbach equation and the Manning equation, to calculate the flow rate. It is also important to conduct experiments and gather data to validate the calculated flow rate.

## 1. How is GPM determined through PVC pipe?

GPM (gallons per minute) is determined by the size and slope of the PVC pipe, as well as the amount of water being drained. The steeper the slope and the larger the pipe diameter, the higher the GPM will be. Additionally, the longer the pipe, the lower the GPM will be due to friction and resistance.

## 2. What is the maximum GPM for PVC pipes?

The maximum GPM for PVC pipes varies depending on the pipe diameter and slope. Generally, a 4-inch diameter pipe with a slope of 1/8 inch per foot can handle a maximum GPM of 50. However, it is important to consult local plumbing codes and regulations for specific guidelines on maximum GPM for PVC pipes.

## 3. How do I calculate the GPM for a specific PVC pipe system?

To calculate the GPM for a specific PVC pipe system, you will need to know the pipe diameter, slope, and length. You can then use a GPM calculator or a formula (such as the Manning Equation) to determine the GPM based on these factors. It is recommended to consult a professional plumber for more accurate calculations.

## 4. Can I increase the GPM for a PVC pipe system?

Yes, the GPM for a PVC pipe system can be increased by increasing the pipe diameter or slope. However, this should only be done in accordance with local plumbing codes and regulations. Additionally, it is important to ensure that the increased GPM does not exceed the capacity of the overall plumbing system.

## 5. Are there any factors that can affect the GPM through a PVC pipe?

Yes, there are several factors that can affect the GPM through a PVC pipe. These include the condition of the pipe (such as clogs or damage), the type of fluid being drained (such as water or sewage), and the presence of any fittings or bends in the pipe. It is important to regularly inspect and maintain the PVC pipe system to ensure optimal GPM.

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