This is the way to our colleagues, which specifies the "tricky" questions – they say, why drive the truck tractor MAZ works when installed on it counters VZO 8 (Maximum capacity of 200 liters per hour) at idle, but can not move and deaf. Consider the most common and distinctive option – when in the measured range values of flow in the fuel line supply has an error, close to the maximum of "+" sign, and return – as close to the maximum allowed, but with a negative sign (-). Thus, when the flow of 240 l / h and consumption of 30 liters / hour, we have the flowmeter A V1 = 240 * 1.01 = 242.4 l / h flow readings 2 V2 = (240-30) * 0,99 = 207,9 l / h Fuel consumption 34.5 l / h Fuel actual 30.0 l / h. The error In fact, until: (34,5-30,0) / 30.0 * 100% = + / – 15% In general, the overall accuracy of the system of two fuel flow meters forward and reverse flow is given by: + / = + Rsistemy / – R x (Vpryamoy Vobratny +) / (Vpryamoy – Vobratny), (2) where Rsistemy – total system error, R – relative (passport) the accuracy of flow in the system (assuming its the same), Vpryamoy – direct fuel consumption, Vobratny – the reverse flow of fuel. Of This formula is obvious that at low costs and high flow without any additional measures the error of such a system would seek to huge values in order exceeding the claimed accuracy of the actual flowmeters. .