What are the typical total and half stroke lengths for multi-stage feed water pumps? Is 1 mm a reasonable value?

The total and half stroke of multi-stage feed water pumps depend on specific design requirements and operating conditions, so a fixed value cannot be simply assigned. A common design method is to calculate the total lift and half lift based on the head loss in the water supply system. As for whether 1 mm is reasonable, it needs to be evaluated based on specific circumstances, such as the layout of the water supply network, water flow rate, pressure, and other factors, as well as the requirements regarding head loss. Generally speaking, a total stroke of 1 mm and a half-stroke are reasonable in some cases, but may not be sufficient in others. .

It is best to assemble it in accordance with the equipment’s instructions or using the data provided by the manufacturer. Then, compare the actual operating parameters with those specified for the device to see if they meet the requirements. There is no need to worry too much about the value of the installation clearance. For reference.

This post was last edited by Xiuxiangxi who fixes pumps on 2023-5-17 at 17:05. 1. A total displacement of 1 mm is unreasonable; a half-displacement of 1 mm may occur, but it isn’t necessarily within the standard range. This value needs to be adjusted. It is acceptable when the pump size is small, but not so when the pump size is large. The total axial displacement can be considered as the axial movement of the impeller within the middle section of the housing. For example, when the impeller is pushed towards the inlet side, and the front and rear plates of the impeller or the inlet ring come into contact with the guide vanes in the front part of the middle section, it represents the shortest distance between the rear plate of the impeller and the back part of that middle section. This distance is determined based on the actual design dimensions of the pump; please share the pump’s drawings so I can take a look – I don’t know what the size of your pump is at the moment. 2. By 1mm, I’m not sure if you mean the total stroke distance or half of it. If the actual total stroke distance of your pump is not 1mm, and you still measure 1mm, then there are several possible explanations: 1) The rotor has not been pushed or pulled to its full extent; 2) If it cannot be pushed or pulled any further, it’s possible that the rotor is rubbing against stationary parts of the pump, such as the guide vane rings, guide vanes, impeller, shaft sleeves, balance drum, etc., due to wear or damage. 3. The shaft is severely bent; you can eliminate this issue by checking for vibration. 4. There were errors in the measurements and calculations, as the measurement points were not at the same location. If the measured half-axis movement is 1 mm, while the total axis movement is 6 mm, then the half-axis movement should actually be 3 mm, which indicates that the rotor as a whole has shifted towards the outlet side. The following steps can be taken to make adjustments: 1. Take repeated measurements and move the shaft back and forth to ensure the readings are accurate. 2. Once the measurements are correct, make adjustments by checking whether the balance ring or balance sleeve is properly installed and not missing any parts. 3. After confirming proper installation, adjustments can be made by removing shims behind the balance ring or thinning out the balance ring, or by installing 2 mm of adjusting shims on the shaft before attaching the balance disc, with the goal of moving the rotor another 2 mm forward so that the half-axis movement returns to 3 mm.

1. A total stroke of 1 mm is unreasonable; a half-stroke of 1 mm may occur, but it is not necessarily within the standard range. This half-stroke needs to be adjusted. It is acceptable when the pump size is small, but it is unreasonable for larger pumps. The total axial displacement can be considered as the axial movement of the impeller within the middle section of the housing. For example, when the impeller is pushed towards the inlet side, and the front and rear plates of the impeller or the inlet ring come into contact with the guide vanes in the front part of the middle section, it represents the shortest distance between the rear plate of the impeller and the back part of that middle section. This distance is determined based on the actual design dimensions of the pump; please share the pump’s drawings so I can take a look – I don’t know what the size of your pump is at the moment. 2. By 1mm, I’m not sure if you mean the total stroke distance or half of it. If the actual total stroke distance of your pump is not 1mm, and you still measure 1mm, then there are several possible explanations: 1) The rotor has not been pushed or pulled to its full extent; 2) If it cannot be pushed or pulled any further, it’s possible that the rotor is rubbing against stationary parts of the pump, such as the guide vane rings, guide vanes, impeller, shaft sleeves, balance drum, etc., due to wear or damage. 3. The shaft is severely bent; you can eliminate this issue by checking for vibration. 4. There were errors in the measurements and calculations, as the measurement points were not at the same location. If the measured half-axis movement is 1 mm, while the total axis movement is 6 mm, then the half-axis movement should actually be 3 mm, which indicates that the rotor as a whole has shifted towards the outlet side. The following steps can be taken to make adjustments: 1. Take repeated measurements and move the shaft back and forth to ensure the readings are accurate. 2. Once the measurements are correct, make adjustments by checking whether the balance ring or balance sleeve is properly installed and not missing any parts. 3. After confirming proper installation, adjustments can be made by removing shims behind the balance ring or thinning out the balance ring, or by installing 2 mm of adjusting shims on the shaft before attaching the balance disc, with the goal of moving the rotor another 2 mm forward so that the half-axis movement returns to 3 mm.

The total stroke is 1 mm, which is a bit small. With centering done in this way, the half-thrust amount is only 0.5 mm; generally, the gap between the balance disk and the balance ring also needs to be taken into account, which results in a relatively small thrust clearance remaining. If the thrust clearance is not adjusted properly, it will cause friction and scraping between the impeller and the stator.

Half of the amount of movement is equal to half of the total amount of movement; for the floating end of high-temperature pumps, this amount of movement can be increased by 0.50–1 mm. The total amount of movement should be determined based on the data provided, ranging from 6–12 mm depending on the size of the pump.