| 摘要 |
<p>The present invention is directed to environmentally friendly levels. Through the use of renewable resource or environmentally friendly liquids in the transparent tubes of a level, it is possible to provide a level that will not harm the environment if the liquid escapes from the tubes as well as reduce the use of petroleum based fluids. In one embodiment, the level contains non-petroleum based hydrocarbons and a water-based solution of dissolved ionic solids. In other embodiments, the level contains non-petroleum based hydrocarbons and water-based solutions of dissolved ionic solids with increased boiling points and lowered freezing points. In other embodiments the level contains arced tubes, standard tubes and combinations of both wherein the liquid in the tubes may be the same or different.</p> |
