The SERIES RM Rate-Master? Flowmeters are a line of general use, direct reading precision flowmeters suitable for both gas and liquid applications. This Series consists of 2? (51 mm), 5? (127 mm) and 10? (254 mm) scales that can be panel or surface mounted with optional precision metering valves. Within a given Series, the Rate-Master? flowmeter bodies can be instantly interchanged, allowing the piping to remain undisturbed, interchangeability of the ranges, and easy cleaning