The cause of the lag of the spray bottle.

Update:29 Dec 2018
Summary:

When using the spray bottle for the first time, press t […]

When using the spray bottle for the first time, press the wrench a few times before ejecting the cleaning liquid.
There are two reasons for this lag:
When the liquid is started to be pumped, the trigger begins a downward stroke instead of the upstroke (the piston is outside the hydraulic chamber). When the wrench was pulled back for the first time, the piston was pushed in, but no liquid was withdrawn; there was only air in the hydraulic chamber. The piston slides out of its own to draw liquid from the reservoir. When the piston begins its first upstroke, the pump begins to draw cleaning fluid from the reservoir. At the same time, however, it also sucks up the air in the plastic tube that connects the reservoir. Before starting to spray the cleaning solution, the pump mechanism should be used to remove the air. Therefore, it may be necessary to pull the wrench back and forth several times. This simple pump design is called a reciprocating piston pump and has a wide range of applications. In addition to pumping out water, air and other liquids, this design can also be used to extract water and oil from the ground.