Does the installation position need to be considered? 2015/12/14 Does the installation position need to be considered? Does a massflow unit need a warm up time? What information do we need for selecting and sizing the mass flow meters and controllers? Posted in FAQs Overview On principle, the devices can be installed in every mounting position. However we always recommend to inform us in advanced when you purchase the unit. Position can depending on the gas and the pressure cause some shift in the zero.