An Experimental Study on the Effects of an Upstream Gate Valve on the Accuracy of an Insertion Type Flowmeter

Abstract

Flowmeters measure the consumption of chilled water or hot water in buildings. Depending on the accuracy, cost consideration, and available space, the flowmeter selected could be an insertion type or fixed type such as orifices or venturi meters. Insertion flow sensors or flowmeters are mostly preferred for use in existing buildings because of their ease of installation, removal and reinstallation. Two types of commercially available insertion type flowmeters, series 225B and SDI-000125, both from Data Industrial[TR], were tested at different angles of orientation (0⁰, 45⁰, and 90⁰) and at different locations downstream of a 4-inch gate valve in straight sections of PVC pipe with flow rates between 80 gpm (2 ft/s) and 320 gpm (8 ft/s). The measured flow rates were compared to the flow rates obtained with a standard orifice meter. The effects of the gate valve on the accuracy of each flowmeter were investigated. A baseline test was conducted with no gate valve upstream of meter 1 (series 225B). Results from this test showed that the presence of the gate valve distorts flow meter readings. Measured flow rates were decreased with meter orientations of 0⁰, 45⁰, and 90⁰ when the gate valve was present, indicating that the gate valve partially blocks the flow in the upper region of the pipe. Accuracy increases as the flow meter is moved to locations further downstream. Performances of both flowmeters have been compared and contrasted.