The 1640 Liquid Level Actuator provides a simple, reliable way to trigger an Isco sampler to begin a sampling routine when the liquid level reaches a predetermined height. The 1640 comprises a conductivity probe that mounts above the stream, a control box that mounts on the sampler, and connecting cable. It can be used in conjunction with other devices such as a rain gauge or flow meter to trigger sampling on multiple conditions.

With the control switch set to LATCH, the 1640 will actuate the sampler when the liquid rises to the probe assembly, and the sampler remains actuated when the liquid level recedes. In TOGGLE/RESET mode, the 1640 actuates the sampler only while the liquid is touching the probe, and sampling is suspended if the liquid level recedes.