Microhidráulica Industrial

# Flow Factor (Multi-Orifice)

When multiple orifices appear in series or when a restrictor has several stages, there is a non-uniform distribution of the overall pressure drop through the restrictor. Click here for additional discussion of series gas flow.

The effect of the above flow behavior is that the gas flow rate of a multi-orifice device is higher than would be expected from a single-orifice device of the same lohm rate, and at the same pressure conditions. This characteristic is reflected in the flow factor, “ fM", which reaches a maximum value of 1.3 at a pressure ratio of 3/1. See the graph on page 171 for values of “ fM", at any pressure ratio for multi-orifice restrictors. EXAMPLE: What multi-orifice restriction will permit a flow of 0.5 std L/min. of hydrogen at 70°F, with supply pressure at 40 psig, discharging to atmosphere.

K = 1030 (click here) = 70°F, fT = 1.0 (click here) = 40.0 + 14.7 = 54.7 psia = 14.7 psia = 54.7 / 14.7 = 3.72 = 1.30 (click here) = 0.50 std L/min When multiple orifices appear in series or when a restrictor has several stages, there is a non-uniform distribution of the overall pressure drop through the restrictor. Click here for additional discussion of series gas flow.

The effect of the above flow behavior is that the gas flow rate of a multi-orifice device is higher than would be expected from a single-orifice device of the same lohm rate, and at the same pressure conditions. This characteristic is reflected in the flow factor, “ fM", which reaches a maximum value of 1.3 at a pressure ratio of 3/1. See the graph on page 171 for values of “ fM", at any pressure ratio for multi-orifice restrictors. EXAMPLE: What multi-orifice restriction will permit a flow of 0.5 std L/min. of hydrogen at 70°F, with supply pressure at 40 psig, discharging to atmosphere.

K = 1030 (click here) = 70°F, fT = 1.0 (click here) = 40.0 + 14.7 = 54.7 psia = 14.7 psia = 54.7 / 14.7 = 3.72 = 1.30 (click here) = 0.50 std L/min 