The LLS 4000/4000U liquid level switch is designed to detect the state (gas or liquid) of the refrigerant in front of the sensing head, while installed in a wide range of refrigeration applications. The LLS level switch comes in 2 variants, LLS 4000 and LLS 4000U. They are identical except for the connector thread interface to the system. The LLS 4000 is provided with G 3⁄4” thread, while the LLS 4000U is provided with NPT 3⁄4” thread. The LLS 4000/4000U liquid level switch is based on the proven reflectometry measuring technology (microwave level measurement) adapted specifically for the new LLS 4000/4000U switch. LLS 4000/4000U liquid level switches can be used to control the liquid level of many different refrigerants in vessels, accumulators, receivers, standpipes, etc. The switches are normally installed in a pair of two, controlling the upper liquid level and the lower liquid level.