Medem gas pressure proving systems use ‘true differential’ gas pressure proving, measuring inlet/outlet pressure using micro-transducers (patented by Medem UK). The differential gas pressure proving method as developed and patented by Medem operates by measuring the pressure differentially across the inlet and the outlet of a gas isolation valve using micro transducers. All other systems can only see the gas pressure when the valve is open. All Medem proving systems have an LCD readout to make them very easy to use. The LCD displays step by step instructions as well as current status and suggestions to resolve issues such as inadequate ventilation or gas issues. Medem pressure proving systems offer teacher control along with the safety and protection of students in the classroom.