Import pump nameplate

Thank you. What is the relationship between this pressure and the pressure required for the necessary net positive suction head? I need to install a feed pump for this pump; should the pressure provided by the feed pump before it reaches the main pump be sufficient to meet the requirements of the net positive suction head, or does it need to meet the requirements related to the suction pressure?

This post was last edited by 3983596_FPPZ on 2018-11-25 at 14:54. How can you ensure that the net positive suction head is satisfied? This requires calculation; therefore, the inlet pressure must be satisfied. However, you can check whether cavitation will occur in the first-stage impeller: the saturated vapor pressure of the oil at that temperature + the pump’s NPSHr + 0.5 (safety margin)

Thank you. However, this pump is used for transporting gasoline and diesel; if only the minimum NPSH is required, a very low pressure before the pump will suffice – 5 bar is not necessary. Then what is the purpose of this suction pressure?

Should it be the maximum allowable inlet pressure?

This post was last edited by 3983596_FPPZ on 2018-11-25 at 18:25. It should be the minimum pressure; pump manufacturers are also concerned about cavitation, so a larger margin is reserved. If the inlet pressure truly cannot be achieved, then calculations need to be done – operating at the limit is very unsafe, as fluctuations in operating conditions can lead to problems. This equipment is quite large and likely expensive as well; it’s best to follow the regulations. Otherwise, if the pump gets damaged, the pump manufacturer will not be held responsible, and one will have to bear the consequences themselves. It is recommended to inform or discuss the actual situation with the relevant supervisors, who will make the decision. Otherwise, if things go wrong due to reckless actions, ordinary people like us cannot afford to take responsibility for that.

This post was last edited by 3983596_FPPZ on 2018-11-25 at 18:41. Meeting the requirement for a sufficient net positive suction head means avoiding cavitation; however, it is not clear what exactly constitutes sufficient net positive suction head, which makes it difficult to apply in practice. Moreover, the net positive suction head is an inherent parameter of the pump itself, and it remains unchanged regardless of whether such a requirement is met or not. However, the required inlet pressure is a value that includes a safety margin; it is a specific figure that is easy to understand and work with. Therefore, the operating conditions specified for ordering are based on the minimum required inlet pressure to ensure that the pump does not experience cavitation. In fact, it’s definitely the operating conditions and performance parameters on site that come first; the pump manufacturer selects an appropriate pump based on the data you provide. Now that the parameters of the pump itself are fine, you still fail to meet the original operating conditions – there’s nothing else to say but haha

It refers to the rated inlet pressure, which can be calculated using the formula: ρgh (852.4*9.81*1300) = 108.7 barg = 113.7 – 5. It should be a Ruultsen BB3 pump, of the double-suction type for the first stage

NPSHr is the required net positive suction head of the pump; the value that follows it is the inlet pressure