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This flow rate is used to calculate the number of Flow Control Valves needed in the system (N.Fcm). It is calculated by dividing the maximum FCM flow rate (Q.FcmMax) by the maximum flow rate allowed through the valve (rounded up to the nearest whole number). The maximum flow rate through the valve is calculated using the flow rate through a pipe with minor losses equation found in the Fluids Functions (Q.PipeMinor).
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Next, the maximum allowable flow rate through the valve must be calculated based on the maximum laminar flow through a reasonable length tube, the maximum head loss through the float valve (given in Design Assumputions), and available tube diameters. The allowable flow rate is based on eliminating the diameter from the Hagen-Poiseuille equation by using the maximum Reynolds number constraint. For higher flows multiple parallel tubes could be used. However the maximum flow rate that can be handled by the float valve needs to be considered.
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Note that the minimum length of the tube is equal to the maximum head loss to be at least as great as the maximum head loss with some additional length to be able to reach the ports.
The tube diameter is then selected based on the diameter required for laminar flow and the diameter required for head loss. The largest of the two is chosen. Note that the maximum diameter is not compared because this was already taken into account for the minimum diameters. From there the inner diameter of the FCM tube is found by comparing the minimum diameter to the available diameters. The diameter for the flow control module is designated as ID.FcmTube.
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