Liquid nitrogen (Ln2) loss reduction at testing operation

The cold testing is performed at test area. Normally, portable liquid cylinders (PLC) are used to supply liquid nitrogen (Ln2) to test handlers. One full PLC of Ln2 will normally last up to 6 to 8 hours of production. Normally, it requires three to four changeovers of PLCs per day for each cold test station. So, it is needed to fill thousands of PLCs per month for cold testing operation. Typically hundreds of PLCs are manually filled and the other PLCs are filled via the low-Loss filling station. The manual filling of Ln2 into PLCs causes 40 to 50% loss of Ln2. The low-loss system also makes 15 to 25% losses of Ln2 or more. There are test stations, which are connected from the PLC to the multiplexer and then to the test handler. The multiplexer is foam insulated, which has very high heat loss. It also requires labor and time to set up connections. So, there is a loss of tester utilization. So, there are great opportunities for cost saving. The good solutions must be selected for implementation. We have taken several steps to stop Ln2 loss and increase tester utilization. We have improved the low loss control system to stop over flow. The flash loss has brought down by reducing pressure of the main tank from 120 psi to 50 psi. We are also installing the direct dynaflex pipeline system to deliver Ln2 directly to test handlers. So, we have reduced the loss of Ln2 from 35-40% to 2-5 %. The tester utilization is also increased.