Given the choices;
a) Bourdon gauge flowmeter
b) Hudson gauge flow meter
c) Constant flow selector
d) pressure compensated flowmeter.
The one that can only be used upright is the pressure-compensated flowmeter. Compensated flowmeters work with a variable orifice and fixed pressure. They read back pressure, and take into account resistance changes down stream from the needle valve. If pressure exceeds 50psig downstream, flow ceases.
