Which instrument is used to check the liquidometer accuracy?

The weighted gauge tester is the correct instrument used to check the accuracy of a liquidometer. This device operates by verifying the readings of the liquidometer against a known standard. A weighted gauge tester typically involves a weight attached to a measuring tape, which is submerged in the liquid to determine the true level of the liquid versus what the liquidometer indicates. This process helps in identifying any discrepancies in the liquidometer's reading, ensuring that it is providing precise measurements for maintaining fuel or water levels.

Using a tape and bob, while potentially useful for measuring depths or levels manually, does not specifically test the accuracy of the liquidometer itself, and a liquid level gauge generally refers to the device being evaluated, rather than a tool for checking its accuracy. Similarly, a liquid level float might be part of the liquidometer system but does not serve the purpose of testing the liquidometer's accuracy directly. Thus, the weighted gauge tester is the optimal choice for this task.