Linear Flow Orifice Meter Designs for Pre-set Flow Rates

Introduction

The LFOM mimics the Sutro weir with a series of holes positioned vertically on a riser pipe. Due to the approximation, and rounding errors, it is currently assumed that several preset designs are more accurate than a program that accepts any plant flow rate. The pre-set designs will ensure the optimal orifice configuration. A common error is an orifice pattern of 1, 1, 0, 2, 1. This occurs because in the second row the number of holes requested was a fractional amount and then in the subsequent row the program calls for 1 and a fractional hole which rounds to two holes. Installation of a LFOM for a higher flow rate than necessary won't degrade the performance and it is a way to ensure quality in the design. Criteria by which the designs are evaluated include: maximum error, number of rows, and the presense of the rounding error.

Designs for Pre-Set Flow Rates

The Mathcad Entrance Tank Code was run for seven flow rates, three Pi_LfomOrifice values, and two initial values for the H.flowloc array. The excel spreadsheet with the original data is available here. The Entrance Tank Code is available throught the SourceForge repository, a storage system. To access the code .............