The condensate pump does not deliver flow after maintenance, and the outlet pressure fails to increase – seek a solution
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Dear sea friends: Our company has a multi-stage condensate pump manufactured by Zhejiang Pump Factory. The normal operating pressure for this pump is 12 kilograms, but over a period of almost half a year, the outlet pressure dropped to 7 kilograms. We carried out a major repair on the pump, during which the sealing rings were measured and replaced; now the clearance on each side of these rings is within 0.30 mm. We also checked the motor current, the inlet and outlet pipes, as well as the pump’s exhaust system, and found no issues. Yet, even after installation, the outlet pressure remains the same as it was before the repair. Also, after starting the pump, if the outlet valve is not opened, the pressure cannot rise and remains at only 7 kilograms. I hope fellow sailors can help analyze what might be causing this. Below are pictures of the pump’s external structure; please analyze them. Reply reward: My topic reward: 0% of the tasks completed on that day. My reply reward: 0% of the tasks completed on that day. *If a topic posted by you yourself receives more than 10 replies from others each day, you can claim a reward of 1 charm. * By replying to others’ “posted today” topics 31 times per day, you can also receive a reward of 6 wealth points. * Repeated replies on the same topic are not counted; one reply per day is allowed. * Meaningless spam posts result in higher point deductions. Points rules for this forum: Post a message, Save a draft, Share with listeners, Sync this topic to: Tencent Weibo, Close, Upload an image, Album images, Online images
If it’s installed correctly, there’s no reason why pressure shouldn’t be applied; one thing that must be ensured is that there’s no place for air to enter, such as at the mechanical seal.
Check the multi-stage pump for the clearance of each stage’s ring.
Have those process parameters such as inlet pressure remained unchanged? Has the motor power remained unchanged? Has the opening degree of the circulation valve changed? Is the mechanical seal damaged?
What is the temperature of the medium transported by the condensate pump? In general, the fluid transported by pumps under such operating conditions is often in a critical state, which makes it easy to cause vacuum formation or cavitation. In my opinion, it’s better to look for the reasons in terms of the manufacturing processes, of course on the premise that the assembly clearances you mentioned are all within the required limits.
Please check if the flow channel is aligned? Is the impeller installed in reverse? Is the internal mouth ring clearance too large?
Firstly, the current single-sided gap of the mouth ring is generally within 0.30 mm, which is a bit large; secondly, it is necessary to check for any leaks between the stages and at the connection tubes. In terms of the process, if it is permissible, wait until the other pump stops (make sure it stops completely) and then try starting this pump.
There should be no air leakage, because after the tank pump is in use, the mechanical seal prevents leaks
The clearances between the impeller shroud and the back ring at each stage were checked, with the maximum unilateral clearance not exceeding 0.30 mm
The process parameters at the inlet remained unchanged; the motor was also inspected. Attempting to use the motor of the backup pump in reverse didn’t work either, and even after starting the pump and closing the outlet valve, no pressure was generated. The mechanical seal was checked and it’s not damaged. The sealing is normal
This condenser has two pumps, but the pressure and flow rate of the other pump are both normal. So it’s a bit puzzling that all the other gaps meet the requirements.