Final answer:
The normal oil level in the sight glass of a reciprocating compressor depends on the specific model and design. It is typically maintained between the low and high marks indicated on the sight glass.
Step-by-step explanation:
In a reciprocating compressor, the normal oil level in the sight glass depends on the specific model and design of the compressor. However, the oil level is typically maintained between the low and high marks indicated on the sight glass. These marks ensure that the compressor has enough oil for proper lubrication and cooling.
For example, if the sight glass has a low mark at one-third of the glass and a high mark at two-thirds, the normal oil level should be maintained between these two marks. If the oil level falls below the low mark, it may indicate a need for oil replenishment.