Applications where a low NPSH is required, are very challenging for pump manufacturers. It is often necessary to take structural precautions to increase NPSHa values and thus ensure the safe operation of the pumps.
Especially in the oil and gas industry, liquids close to vapor pressure have to be conveyed regularly. Therefore, applications with low NPSHa are daily business. This requirement makes the design of pumping systems more complex. Often, either plant-side adjustments or NPSH optimized costly design adjustments have to be made to the pump system. By choosing the right pump technology however some complicating factors can be eliminated from the beginning. Often, progressing cavity pumps are only used for highly viscous or solid-laden media. However, they offer numerous advantages especially for applications with low NPSHa.
1. Very low NPSHr
Compared to other pump technologies progressing cavity pumps you can handle a very low NPSHa without expensive constructional adjustments. In the standard design, the values for horizontal pumps are well below 1.5 meters. With NPSHr optimized pump selections, values of well below 0.5m are possible.
2. Cost-effective and space-saving
Some pump types can only cope with a low NPSH in special versions or with special designs, resulting in high acquisition costs for you as a customer. The progressing cavity pump is often a more cost-effective alternative, as it already covers a wide range of NPSH critical applications in standard design. In addition, you can often use the progressing cavity pump in a horizontal design even with low NPSHa values. This saves additional costs for you compared to other pump types that are already designed submerged in these cases. Easy access for repair and maintenance work is guaranteed. Especially for larger installations, you no longer need to use cranes to lift submerged equipment. On-site adjustments to increase the NPSHa, such as installing pumping technology in shafts or the elevated installation of containers, are completely eliminated for you as a customer.
3. Handling changing viscosity and solids
You can handle media containing solids several centimeters in diameter with progressing cavity pumps. This is a decisive advantage for you in applications where solids are expected because other types of pumps often clog. Furthermore, you can cover a wide viscosity range with our progressing cavity pumps without losing efficiency.
4. Easy maintenance
At low NPSHa vertical submerged pumps are often used. The low NPSHr of progressing cavity pumps allows you to use dry-installed pumps in many applications. A horizontal installation allows you to replace wearing parts such as the rotor or stator easily and cost-effectively. Other systems often have to be installed vertically so that maintenance is usually only possible using a crane. This represents an enormous logistical, time and cost effort.
5. Inlet condition
Compared to other technologies, progressing cavity pumps can handle gas bubbles in the conveyed medium. Time-consuming venting and pump failures due to trapped gas bubbles are thus a thing of the past for your application.
6. Gentle conveyance
Progressing cavity pumps are characterized by low-shear and low-pulsation conveyance. Especially with shear-sensitive media that have to be separated in later process steps (e.g. oil-water mixture), this makes subsequent separation much easier and thus saves costs.
7. Robust design
Pumps are not allowed to be operated under cavitation. In the case of continuous operation under cavitation failure of progressing cavity pumps cannot be avoided, just as with other pump systems. However, progressing cavity pumps are more tolerant to cavitation. Cavitation bubbles implode when they are transported to an area with higher pressure. This happens in the rotor/stator system of progressing cavity pumps. Since the stator is made of elastomer it dampens the cavitation effect. This means that if cavitation occurs in your application, the pump does not fail immediately. You can normally restart the progressing cavity pump without repair after switching it off and eliminating the fault. This means that you can save the system and avoid significant damage with a proper monitoring.
As you can see, progressing cavity pump technology is a real alternative to some of the better-known pump technologies in the field of low NPSH applications.
Decades of experience in manufacturing progressing cavity pumps, combined with innovative approaches and continuous improvement, enable us to offer you a customized solution for your application that meets the highest standards.