Due to physical and chemical properties of the agent, pressure in the tube can vary depending on the ambient temperature. The higher the ambient temperature, the higher pressure in the tube and vice versa at very low temperatures the pressure of agent vapours can be seen as zero.
The Indicator on the pressure gauge can vary from 0 bar (0 psi) when temperatures are very low to 17 bar (247 psi) when temperatures are very high. This is not a sign of defect in the system.
See our video for the inspection of the T series for further details