Issues with the pipe diameters and valves before, after, and in the bypass of the mass flow meter
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What is the purpose of installing a bypass on a mass flow meter? If it fails and cannot measure flow, then using the bypass means that accurate measurement is no longer possible, which has a significant impact on the measurement process. If a bypass is used, is it necessary to choose the diameter of the pipe as well as that of the bypass pipe in the same way as with control valve assemblies? Is it necessary to install a shut-off valve on the bypass? A mass flow meter isn’t used to regulate flow rate.
This post was last edited by ylb913 on 2015-7-26 at 10:50. One of our mass flow meters has a main pipe diameter of DN200, while the flow meter itself has a diameter of DN80. Sometimes, when the flow rate is high, there is backpressure, so we are forced to use a bypass line. The other one is for fuel gas; since there is coking dry gas present, it gets easily blocked, so it has to be isolated for cleaning. 1. Process requirements are more important than accurate measurement; a gate valve is indeed sufficient for the bypass line. 2. A short-term cessation of measurement is better than prolonged inaccurate measurement.
If a secondary line is used, then a portion of the flow won’t be measured, right? That means the measurement won’t be accurate. If the measurement isn’t accurate, it’s not necessary to use a mass flow meter – after all, mass flow meters are quite expensive
It is not recommended to use a bypass; the control valve for the mass flow meter can be designed as part of the bypass system.
The bypass is used for cleaning the mass flow meter, and a valve must definitely be installed on the bypass.