Vacuum instruments installed on multiple lithium bromide units

The vacuum level of a lithium bromide chiller unit generally refers to the vacuum pressure at the absorber, as this is the main area where the unit’s evacuation system removes air. The unit typically uses U-type vacuum gauges and pressure sensors to display the pressure of the automatic pumping system as well as the pressure in the absorber. Although the designs vary among different manufacturers, the pressure at the location of the automatic exhaust system is of particular concern. In a situation like the one you described, excluding the possibility that a unit malfunction is causing the high-pressure alarm, the pressure that should be measured is the pressure of the automatic evacuation system. A vacuum pressure sensor can be installed at the top of the air storage chamber in the unit’s automatic exhaust system. The range can be set around 0-30 kPa. During installation, it is necessary to fill the unit with nitrogen, weld the sensor holder, and conduct a leak test using nitrogen pressure. Copper gaskets or PTFE gaskets should be used between the sensor and the holder; a leak-free condition must be achieved, otherwise it can cause significant damage to the unit. Sensors generally operate on 24VDC; the power supplied by the electrical control cabinet is sufficient. After being collected by an analog signal acquisition module, the data is transmitted to the control room via the 485 protocol.