It's Megan from the LIFCO content team. I sat down with Fraser we dove deeper into our recent video about a Linde HPR 135 that was going over pressure. Read below and be sure to check out our video for the full breakdown, also linked below.
Video Link: Linde HPR 135 Troubleshooting
Megan: In the beginning of this inspection, we see the burnt oil, what typically causes the oil to get like that? And does that do any damage to the pump?
Fraser: Heat from either a lack of lubrication or high pressure going to low pressure without work being performed (most common example is going over a relief valve or through an orifice). Burnt oil is one of the few situations where oil needs to be replaced. It is a chemical change in the oil and it will have lost its lubrication properties. Usually the burnt oil gets mixed in with the good oil and its damaging effects can be diluted over the long run.
Megan: In this case the pump was going over pressure at 6500psi but it needed to be at 3000-3400psi. The customer said it was not able to be compensated but you said that's because the pump can't actually do that. Can you explain that more?
Fraser: There are three main types of compensation but we will discuss two of them: one changes the flow by reading the system pressure in the pump outlet, and the other changes the flow by receiving a signal from a load sense line. Extremely common for a pump to have both controls at once. However this unit only has the load sense. So the pump would not pressure compensate on its own. It would need to get a signal to increase or decrease the flow. Meaning, we simply need to confirm that the pump was reacting to the signal correctly. Which it was. So if it is not reducing the flow then the signal is faulty. Like if your tv doesn't work, in this case it is the cable provider who has the problem. Not the TV.
Megan: In the end we found out the problem was contamination, but we don't actually see the contamination so where was this conclusion drawn from?
Fraser: Contamination is a system problem. We examined one component in that system and it had concrete evidence of contamination. What you mean to say is "We didn't see the contaminates" but they are in the oil, we did not do any oil testing. In severe cases we would see it even in the small amount of oil still in the component, or jammed inside.
Megan: Last question, what is the next step for the customer when receiving this pump to avoid any further contamination?
Fraser: I didn't like the inspection report as it did not make it perfectly clear [it should say] "The pump was still capable of doing what it was signaled to do. It had signs of the symptoms, but was not the cause. There is something else malfunctioning and the pump is not being told to stop producing flow. Look to some valving and it likely is suffering from the same contaminates."
The customer told us that the machine had a catastrophic failure in another circuit which shared the same oil reservoir. It was not cleaned out 100% after.
They still had some work to do, but the source of the problem was established: it needed a more thorough cleaning after that catastrophic failure.