Choose Litre Meter for the measurement of low flow liquids and gasses. Contact the Specialists and ask for advice on flowmeter selection - especially for low flow. Litre Meter meters have the widest range of measurable flow rates of any flowmeter company in the world. The VFF measures low flow and wide ranges of liquid. Ritter produce gas flowmeters down to 1 millilitre per hour. Sierra have flow meters for pipes up to 5m diameter.