How to conduct a self-start test for the main pump, which is a shaft-mounted pump, and the auxiliary oil pump
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Our high-pressure ammonia pump’s main oil pump is a shaft-mounted pump, while the auxiliary oil pump is separate and features automatic start-up when oil pressure drops. How should the automatic start-up test for the auxiliary oil pump be carried out? Thank you to all fellow sailors…
It is an interlock; first, disconnect the auto-start interlock, then supply power to the auxiliary oil pump and activate the interlock. If the auxiliary oil pump starts, the auto-start function is working properly. An oil pressure input can also be used as an analog signal, and experiments can be conducted by changing this analog signal.
Thank you, I understand. What you mean is that without activating the interlock first, the pump operates in automatic mode; once the interlock is activated, the pump starts. So, can pumps with a low-level interlock also be started in this way when they are in automatic mode? Thank you
I am against providing analog signals. Start up as practically as possible on its own. This not only solves instrument-related issues but also addresses mechanical problems as well as operational issues that may arise in practice.
The design value is for the backup pump to start when the oil pressure drops to 0.1 Mp. How is this automatic start-up test carried out? Please give me some advice, thank you
The supervisor said to start the backup pump first, and once it’s running properly, switch it to automatic mode quickly before shutting down the pump to conduct this experiment. Is that acceptable?
Yes, that’s what we have been doing for many years; however, the auxiliary pump must first be tested individually to ensure it works properly before the experiment.
This experiment is easy to carry out: first, use electricity to activate the auxiliary oil pump for the experiment, and once all startup conditions are met, simulate the start of the main engine. After it starts, turn off the pressure control devices and use the two-out-of-three interlock system along with the manual valves at various measurement points to maintain the pressure. Turn off the auxiliary oil pump. At this time, since the pressure maintenance main pump is still operating, open the manual valves at any two measurement points to release pressure; once the pressure drops to the auto-start level, the auxiliary oil pump will start automatically.
We use analog signals for some of the instruments to achieve this. After all, since it is a chain debugging process, high-pressure pumps are generally not started in order to take the risk of carrying out debugging.
It is usually done through analog signals; otherwise, you should slightly open the pressure relief valve at the outlet of the main oil pump to reduce the oil pressure and see if the backup pump starts.