Why does the Ingersoll Rand centrifugal 3C type compressor oil station not require a high-level emergency oil tank?
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Why does the Ingersoll Rand centrifugal 3C type compressor oil station not require a high-level emergency oil tank? If there is a sudden power outage and both the main and auxiliary oil pumps stop working, with the motor rotating at 2970 r/min, the three-stage rotor could reach 18,000 r/min – isn’t there a risk of it being damaged? Dear experts, what is the principle behind this? Let’s discuss it together. Thank you.
Generally, there are two reasons why gas stations are not equipped with high-mounted fuel tanks: 1. Gas stations are fitted with emergency fuel pumps, which use DC motors or dual-circuit systems to ensure that the compressor stops running gradually even if the main and auxiliary pumps fail； 2. The main pump is a shaft-mounted pump; the compressor can keep operating without the main pump.
The compressor does not have a high-level, emergency, or accumulator tank. The main oil pump is a shaft-mounted pump (double screw type); when there is a major power outage, the auxiliary oil pump stops working, and the main oil pump continues to operate mainly due to inertia. The instructions state that an international standard low-pressure lubrication system (around 2 kg/cm2) is used; the lubricating oil pump is designed to be oversized, ensuring sufficient lubrication of the gears and bearings even in the event of a sudden power outage, thus guaranteeing safe operation. The fuel supply pressure is indeed below 2 kilograms, usually around 1.8 kilograms.
The main and auxiliary oil pumps in Ingersoll Rand centrifuges are typically twin-screw or triple-screw oil pumps. Normally, the auxiliary oil pump starts to operate before the main motor is fully started up or after the stop button is pressed, thereby maintaining a pressure of around 2 bar in the lubrication oil circuit. Once the main motor is running properly, the main oil pump takes over to maintain this pressure, and the auxiliary oil pump stops, thus helping to achieve energy savings. In the event of power outages or other unexpected situations, it takes approximately 360 seconds for the main motor to stop operating. The main oil pump driven by the motor is sufficient to maintain the pressure in the lubrication system, thereby ensuring proper lubrication and cooling of the bearings. This was taken into account during the design phase, and it is also the reason why there is no high-level oil tank; basically, imported air compressor units do not have high-level oil tanks.
Thank you for the reply. Yes, it’s sufficient to ensure lubrication during power outages.
360 seconds is 6 minutes; how is it possible for the motor to keep rotating for another 6 minutes after it stops?
The 360 seconds I’m referring to is the time from when the main motor loses power until it comes to a complete stop. I have also conducted tests on this time period, and it indeed takes 360 seconds; moreover, this time can be seen on the panel as well