DWL: I'm not sure.

TRQ: natural gas

RH: hot backwater

RDW: Not sure.

WL: sewage

The code name on the drawings of hydropower specialty generally uses pinyin initials. For example, generally speaking, rainwater is YL, sewage is WL, fire fighting is XL, and automatic spraying is ZP. . . Wait a minute. . Sometimes, if the project is particularly complex, you can also add a prefix before or after the number to distinguish it. However, no matter how it is named, there will be corresponding legends and explanations on general drawings to explain the meaning of numbers or graphics. You have to analyze the specific content of this number to know the exact meaning. Some of my answers can only be used as reference, I hope to help you ~ ~