【Q&A】July 8, 2017
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How to prevent cavitation in centrifugal pumps? Answer: 1. The installation height of the pump must not exceed the allowable suction height. 2. When the liquid flow rate and resistance in the suction pipeline are too high, the installation height should be reduced. 3. Strictly control the material temperature. http://down.hcbbs.cc/attachment/forum/201706/10/203353z7y06fdo70r6eod0.jpg Petrochemical Zone—New Ideas for Energy Saving: The “Creative Thinking” Campaign (The second phase of this campaign is in full swing) http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1666758 (Source: Haichuan Chemical Industry Forum)
(1) During installation, the distance between the pump’s suction inlet and the liquid surface should be as low as possible to reduce suction pressure losses； (2) Increase the diameter of the pump suction pipe to reduce the resistance loss in the suction line ； (3) Under the condition of meeting the requirements for head and flow rate, the lower the rotational speed, the better, as this reduces the vacuum level at the pump’s suction inlet ； (4) Use a double-suction pump or a centrifugal pump equipped with a preliminary impeller to improve the suction conditions ； (5) Where process conditions permit, avoid an increase in the temperature of the liquid being transported to prevent its vaporization
Select an appropriate centrifugal pump to improve its own cavitation resistance
The installation height of the centrifugal pump should not be too high; increase the diameter of the suction pipe appropriately
Ensure an adequate head; the components at the pump inlet should not be too light, and the component density, inlet temperature, etc. should remain within the design ranges, while the outlet flow rate should not be too low
1. The installation height of the pump must not exceed the allowable suction height. 2. When the liquid flow rate and resistance in the suction pipeline are too high, the installation height should be reduced. 3. Strictly control the material temperature.
When there is air inside the centrifugal pump casing, the lower density of air compared to that of the liquid results in a smaller centrifugal force. As a result, the pressure difference between the surface of the liquid in the tank and the pump’s suction inlet is not sufficient to force the liquid in the tank into the pump; in other words, the centrifugal pump does not have self-priming capability, which prevents it from pumping liquid. This phenomenon is known as \"cavitation\". The installation height of the pump must not exceed the allowable suction height. When the liquid flow rate and resistance in the suction line are too high, the installation height should be reduced.
The inlet pressure must be greater than the saturated vapor pressure of the fluid
When there is air inside the centrifugal pump casing, the lower density of air compared to that of the liquid results in a smaller centrifugal force. As a result, the pressure difference between the surface of the liquid in the tank and the pump’s suction inlet is not sufficient to force the liquid in the tank into the pump; in other words, the centrifugal pump does not have self-priming capability, which prevents it from pumping liquid. This phenomenon is known as \"cavitation\". 1. The installation height of the pump must not exceed the allowable suction height. 2. When the liquid flow rate and resistance in the suction pipeline are too high, the installation height should be reduced.
To prevent cavitation, the main measures that should be taken are: 1. During installation, the distance between the pump’s suction inlet and the liquid surface should be as low as possible to reduce suction pressure losses. 2. Increase the diameter of the pump suction pipe to reduce the resistance loss in the suction line. 3. Subject to meeting the requirements for head and flow rate, the lower the rotational speed, the better, as this reduces the vacuum level at the pump’s suction inlet. 4. Use a double-suction pump or a centrifugal pump equipped with a pre-inducer wheel to improve the suction conditions. 5. Where process conditions permit, avoid an increase in the temperature of the liquid being transported to prevent its vaporization.
(1) During installation, the distance between the pump’s suction inlet and the liquid surface should be as low as possible to reduce suction pressure losses； (2) Increase the diameter of the pump suction pipe to reduce the resistance loss in the suction line ； (3) Under the condition of meeting the requirements for head and flow rate, the lower the rotational speed, the better, as this reduces the vacuum level at the pump’s suction inlet ； (4) Use a double-suction pump or a centrifugal pump equipped with a preliminary impeller to improve the suction conditions ； (5) Where process conditions permit, avoid an increase in the temperature of the liquid being transported to prevent its vaporization