the connector includes a connector head a probe and a second key element the probe extends from the connector head and is insertable through a center of the cap and into the mouth of the container the probe has a flow passage the second key element is configured to mate with the first key element the system also includes a pump coupled with the probe and with the flow passage the pump pumps fluid through the probe and the flow passage the system also includes a sensor for sensing when the first and second key elements are mated and for sensing when the first and second key elements are not mated finally the system includes a controller coupled with the sensor and the pump the controller enables the pump when the sensor senses that the first and second key elements are mated and disables the pump when the sensor senses that the first and second key elements are not mated application_number US 81584297 A description fig1 shows a preferred embodiment of a liquid chemical dispensing system 10 in accordance with the present invention dispensing system 10 includes inner container 11 outer container 12 connector 14 control unit 16 and pump 18 connector 14 includes sensor 20 and port adaptor 22 sensor line 24 couples sensor 20 to control unit 16 adaptor tube 26 connects port adaptor 22 to pump 18 in operation of dispensing system 10 inner container 11 is housed within outer container 12 inner container 11 is made of a flexible material and outer container 12 is made of a rigid material inner container 11 contains a liquid chemical in its interior for example inner container 11 may contain a liquid chemical such as photoresist for use in.