At the start-up of circuit the color of test paper can be yellow, in consequence of atmosferic humidity or humidity contamination of plant where the indicator is installed.
When the humidity level of refrigerant fluid is steady, by the action of dryer filter, the color of test paper becomes green, because the equilibrium conditions are reached.
Normally, the time required to reach the stationary condition of circuit is 12 hour; if the yellow color of test paper remains, it means that is necessary a further action to eliminate the humidity presence inside the circuit.
The braze welding of indicators equipped by copper tubes should made by special alloy, with low melting point.
The flame should not be directed toward the glass or body of indicator, because it can damage the indicator in
consequence of overheating.