During a tightness test, a pressure drop may be observed without an actual leak being present. One of the primary causes is the change in temperature of the gas and the piping.
Temperature effect
If the temperature decreases, the pressure in the closed section may also decrease. The opposite can happen with an increase in temperature.
Stabilization before measurement
The network must have time to stabilize before the actual pressure trend is evaluated.
Instrument check
A low-accuracy pressure gauge or one with a zero-point issue can create a false impression.
When do we suspect an actual leak
A continuous drop that is not explained by temperature variations requires further detection and inspection of connections.
Best practice
Pressure, temperature, and time are recorded simultaneously so that the evaluation is data-driven.
