Colormetric detectors are rapid leak detectors and inexpensive to use.  They react
chemically with minute leaks causing a visible color change in the developer.
They can be used to detect leaks up to 1x10-7 Std cm3/s

WHERE ARE COLORMETRIC LEAK TESTERS USED?
Colormetric developers are used to leak test large single and double walled tanks, pressure and vauum vessels, laminated, lined or double-walled parts, complex piping systems, flexible containers (such as aircraft fuel tanks), glass-to-metal seals in hybrid packages and systems that inherently contain or will contain the tracer (water, ammonia, chlorine or oil).