How to calculate NPIPA & NPIPR for PD pumps

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In summary, NPIPA (Net Positive Inlet Pressure Available) and NPIPR (Net Positive Inlet Pressure Required) are two important parameters used to determine the performance of a positive displacement (PD) pump. NPIPA is the difference between the inlet pressure and the vapor pressure of the pumped liquid, while NPIPR is the minimum inlet pressure required for the pump to operate properly. To calculate these values, the vapor pressure of the liquid, inlet pressure, and pump specifications must be known. NPIPA and NPIPR are crucial for ensuring the proper operation of PD pumps and can be optimized by adjusting pump speed and size, as well as monitoring and maintaining these parameters. Other factors that can affect NPIPA and N
  • #1
jaybikes
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How do I determine NPIPA and NPIPR for PD oil pumps. I understand from limited research that suction condition is critical to the success of each application, but I do not know the formulas.
 
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  • #2
Have you taken a look through this article? The parameters you are looking for are analagous to NPSH and NPSHR in centrifs.

http://findarticles.com/p/articles/mi_qa5350/is_/ai_n21301101
 
  • #3
Thanks Fred. Article on testing PD pumps really helped.

Jay
 

1. What is NPIPA and NPIPR for PD pumps?

NPIPA (Net Positive Inlet Pressure Available) and NPIPR (Net Positive Inlet Pressure Required) are two important parameters used to determine the performance of a positive displacement (PD) pump. NPIPA is the difference between the inlet pressure and the vapor pressure of the pumped liquid, while NPIPR is the minimum inlet pressure required for the pump to operate properly.

2. How do you calculate NPIPA and NPIPR for PD pumps?

To calculate NPIPA, you will need to know the vapor pressure of the pumped liquid and the inlet pressure. NPIPA = Inlet Pressure - Vapor Pressure. To calculate NPIPR, you will need to know the pump specifications, such as pump speed, flow rate, and pump efficiency. NPIPR = (Flow rate x Pump speed x Pump efficiency) / (3600 x Pump displacement).

3. Why are NPIPA and NPIPR important for PD pumps?

NPIPA and NPIPR are important because they help ensure the proper operation of PD pumps. If NPIPA is too low, it can cause cavitation, which can damage the pump and decrease its efficiency. If NPIPR is not met, the pump may not be able to deliver the desired flow rate, resulting in poor performance.

4. Are there any other factors that can affect NPIPA and NPIPR?

Yes, there are other factors that can affect NPIPA and NPIPR. These include the type of liquid being pumped, the temperature and viscosity of the liquid, and the elevation of the pump. It is important to consider these factors when calculating NPIPA and NPIPR for accurate results.

5. How can NPIPA and NPIPR be optimized for PD pumps?

NPIPA and NPIPR can be optimized by adjusting the pump speed, as well as the size and type of pump. Increasing the inlet pressure and decreasing the vapor pressure of the pumped liquid can also improve NPIPA and NPIPR. It is important to regularly monitor and maintain these parameters to ensure the efficient operation of PD pumps.

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