Operating the outlet valve opening of the centrifugal pump

The regulation of flow rate is mainly done through the backflow control valve; it’s best not to adjust the inlets and outlets of the pump frequently, as they are usually left fully open. If the pump operates for a long time with a low outlet opening, the fluid continuously circulates within the pump, increasing the load; it is also prone to vaporization due to heat, and the seals are likely to leak. Furthermore, does having the outlet fully open mean that the pressure is distributed to the pipes at the back, while not having it fully open means that the pressure remains trapped in the pump? This post was last edited by wdepei on 2009-3-19 09:17.]

The pump outlet valve should be fully open to prevent pump blockage and throttling at the pump outlet.

In production units, pump outlet valves are generally not used to adjust flow rate. Sometimes, when the pump is oversized or operates for long hours, it becomes difficult to control the flow with control valves; in such cases, using the outlet valve to restrict flow can be considered for a short period of time.

It is better to keep it fully open and control it with the outlet valve. If it is not fully open, the medium will keep circulating inside the pump, increasing the load; it is also prone to vaporization due to heat, sealing issues may occur, and the pump’s outlet valve is susceptible to erosion as well

When operating a centrifugal pump, the outlet valve should be fully open, with backpressure controlled by a regulating valve. If it is not fully open, prolonged exposure to the medium can cause wear on the valve disc, resulting in the valve not closing properly.

In the case of a gate valve, it should be operated either fully open or fully closed. However, if the gate valve is of high quality or if it is another type of valve, an opening degree of 2/3 should suffice to achieve the maximum range of flow regulation; since operating it fully open at that point would be pointless, it is recommended to use an opening degree of 2/3 for safety and ease of operation.

Yes, it is best to keep the pump running at full capacity; especially for the outlet valves of the slurry pumps in the catalysis workshop, they should be kept fully open to prevent the catalyst contained in the slurry from wearing out the outlet valves.

The pump outlet should be fully open, with the flow rate controlled by a control valve.

The pump outlet valve should be fully open; for variable frequency control, use a frequency converter or a valve

　For the outlet valve of a centrifugal pump, it is generally required to be fully open. However, from a safety perspective, after the valve is fully opened, turning it another three or four turns – that is, opening it to 2/3 of its full position – essentially achieves the maximum flow rate of the valve.

For centrifugal pumps, the flow rate is regulated using the outlet valve, rather than the inlet valve! This must be followed!

The opening degree of the pump outlet valve is fully open, with the backstream controlled by a regulating valve. This is based on one principle: if there is more than one valve leading to an exit, the valve that is closest to the equipment, or what is known as the wall valve (in the case of a container), should be kept fully open, with the flow being controlled by the valve located further downstream. This approach is intended to prevent damage to this valve due to frequent operation, which could lead to leakage issues. Because replacing it is not convenient.

Open the pump outlet valve to one-third or one-half of its full opening; one-half is sufficient – there’s no need to open it completely, as that would be excessive. If the pump suddenly leaks, it will be troublesome to shut it down. The control valve is used to regulate the flow rate; having the outlet valve fully open exerts significant stress on the control valve, and over time this can lead to leakage from the control valve

If the pump is variable frequency, it’s better to use a pump – it saves electricity. This post was last edited by chengkang on 2009-3-27 at 22:21

Here, I’ll talk in detail about my work experience. For centrifugal pumps, it’s not necessary to keep the outlet fully open; there’s no such requirement. It’s sufficient to adjust it according to the flow rate. In normal operations, the flow rate doesn’t change significantly. When the outlet is opened wide, if the flow rate becomes too high, it’s necessary to use control valves to regulate it, so as to minimize damage to the pump. The pressure drop across the control valves will be higher in such cases. At my post in the catalytic unit, I kept the outlet valve of the centrifugal pump closed to a moderate degree. Generally, it’s around 15 deductions; as long as the flow rate is sufficient, that’s fine. We strive to keep the valve position at 50%. If there is any vaporization due to a small opening at the outlet, this won’t occur in our catalytic unit. Although theoretically, prolonged rotation leads to heating and makes vaporization more likely, in practice vaporization does not occur. This is my personal opinion, for reference only

Generally, we ask the workers to turn it fully open and then rotate it a few more times, as a gate valve that is fully open is prone to getting stuck or having its valve plate fall off. . . :lol

This is an extremely common issue. As for whether to turn it fully on, halfway on, or two-thirds on, I think it’s important first to understand how flow regulation is achieved. From the perspective of centrifugal pumps, it is undisputed that the pump’s inlet is fully open. But what about the opening degree of the outlet valve? In fact, there is a clear understanding regarding the operation of gate valves: they cannot be completely open with no remaining margin at all! If it’s closed, it’s impossible; they’re trying their best to close it. That’s it, okay. Knowing this, you should understand how much the outlet valve of the centrifugal pump should be opened! If there is a control valve to regulate the flow rate, keep the outlet valve as fully open as possible and use the control valve to regulate the flow; the advantages of this approach go without saying, as those who spoke earlier have explained them in detail. If not, one has to control the outlet valve based on the pump current, or use a gate valve upstream to control the flow rate.

Under normal circumstances, it is kept fully open, with the control valve used to regulate the flow rate

Generally, the outlet valve is opened fully, and then the flow rate is adjusted using a control valve on the backside. Without a backpressure control valve, the outlet valve opening is selected in coordination with manual operation.

The inlet valve of the centrifugal pump is fully open to reduce pipeline pressure loss and ensure the proper operation of the pump. It is not necessary to fully open the outlet valve; once the valve is opened to a certain degree and the downstream control valve is also fully open, a medium flow rate that is slightly above 100% of the design value is sufficient. Under normal circumstances, opening the pump outlet valve to 1/2 to 2/3 of its full opening is enough to meet the process requirements. Under normal operating conditions, vaporization inside the pump does not occur; on the contrary, the hazards of having the valve fully open are as follows: 1. If the control valve fails and remains fully open, the centrifugal pump is very likely to experience overcurrent, which can damage the pump. 2. Fully opening and closing increases the workload; it takes time to close the pump outlet valve in emergency situations.