For more information about Custom processing: Brand: Siemens / Siemens Model: qbm81 type: mechanical pressure switch Siemens QBM81 series differential pressure switch for ventilation and air conditioning systems ? For monitoring of air filters, air flow, fan belts ? For monitoring the clean room, kitchen and so easy to install and use pressure · QBM81 ... pressure detector for monitoring ventilation and air conditioning system pressure, low pressure or overpressure. By measuring differential pressure, monitoring air filters, leading airflow, damaged belts and other clean room and kitchen room overvoltage. Function pressure generated at different pressures linked elastic deflection of the diaphragm. This special diaphragm ensures long-term stability of switching points. Each model is engraved with a separate scale for precision regulation. Optional regulation