The Mass Flow method is the most straightforward way of measuring leaks. It is based on the mass conservation law which states that the mass of material entering a volume (once the system is in equilibrium) equals the amount leaving it. 

This method offers measurable leak rates to approx. 10^-2 std. cc/sec in high volume production applications.  This technique features medium sensitivity and flexibility within the limits of temperature dependency.  In order to achieve reliable readings, the flow must be allowed to stabilize, adding time to the cycle time. The method offers advantages in that it requires no roughing vacuum (lower cost and maintenance), and will therefore tolerate a much more hostile environment (slightly dirty or wet parts).  This is a relatively rugged technique, and does not require highly skilled maintenance.

Disadvantages include: a lower sensitivity than other Amount of Leak Methods; temperature and stabilization time dependency

The test typically consists of the following steps:

	Quick-filling the part to desired test pressure
	Measuring the mass flow rate into the part while maintaining pressure inside the part

Sensitivity range [std.cc/sec]
Temperature dependence
Operator dependence
Main factors affecting sensitivity	Part volume (stabilization required)
Test pressure range	any
Maintenance required	Skilled maintenance is required
Cost