How to distinguish whether the high and low pressure of an industrial chiller is in the normal range

The high pressure meter shows that 15-19Kgf/C㎡ is the best when the ice water machine compressor normally uses the suction pipe, but not higher than 21Kgf/C㎡. When the high pressure is higher than 25Kgf/C㎡, the high pressure switch trips, please follow Note 1 For treatment, the best low pressure is 3-4.5Kgf/C㎡, but not less than 3Kgf/C㎡. Please follow Note 3 for low pressure trip. When the compressor is running, when the differential pressure between the high pressure and the low pressure is very small or equal, it means that there is a problem with the compressor. Please stop the operation and notify the company to send someone to deal with it. Please note that the following conditions are when the compressor is running normally, such as The high and low pressure balance is still normal without operation.