| 摘要 |
A spirit level which can be offered up to a job, set and then removed for inspection or later reference, comprising a tubular fluid container (10c) partially filled with liquid (21) and having two arms or sides (150, 152) separated by one or more valves (26 and 26b) operable to prevent liquid flow between the arms. Preferably, the container is a closed loop and may be of rectangular, circular or D-shape. It is also preferable that, with such a closed-loop container, two valves are used to separate the arms, one at each end of each arm. And it is preferable that the two valves be operated in unison to jointly permit or prevent fluid exchange between the arms. |
