Extending The Envelope Of Flow Control Capability

Monday, April 25, 2022

The Problem: A reliable flow control is increasingly more difficult the closer you reach the capability envelope

Whenever application details get further away from “normal” and closer to the edges of the capability envelope it becomes increasingly more difficult to establish a reliable flow control solution. Combinations of high pressure, high differential pressure, extremes of temperature, variable and/or extremes of flow rate and the aggressive nature of the media have previously resulted in some level of compromise, especially with the level of automation.

That has now changed as PCT are able to make the impossible, possible.

The Solution: There are three important contributions to making the whole solution successful

There are three important contributions to making the whole solution successful.

1. Firstly, a Coriolis sensor that is selected for its specific characteristics – perhaps ultra-low flow, perhaps constructed from an exotic alloy or perhaps for a cryogenic temperature.
2. Secondly, a multi-orifice dome loaded control valve that is perfectly suited to extreme applications as it has an extremely high flow turn-down ratio of up to 1 million to one, special construction and just one moving part.
3. Thirdly, an electro-pneumatic controller (E-PC) in dual valve format that converts a measured flow output signal into one-to-one pneumatic dome loading control within onboard customized firmware.

CODA Coriolis Standard Accuracy Flow Meter

The Coriolis sensor measures the flow and sends an electronic signal to the electro-pneumatic controller. Within the electro-pneumatic controller, the firmware translates the flow signal into a pressure output that, in turn, controls the dome-loading pressure. Custom firmware within the E-PC ensures a seamless conversion of the measured flow rate signal into a corresponding pressure set-point used to vary the over-pressure within the valve and hence the amount of flow being controlled. By varying the dome-loading, the diaphragm will flex thereby either covering or exposing the orifices to vary the flow rate to the desired level.

The Benefits

• Highly accurate and stable flow control of gases and liquids of unknown composition.
• Highly accurate and stable control of aggressive/corrosive gases and liquids.
• Smooth, repeatable operation within high pressure and especially high DP systems.
• High integrity and long life within the extremes of high to low temperatures.
• Being multi-orifice, the variable Cv ensures precise control across a huge range of flows.

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Posted by Andy Mangell, Co-Owner / Sales Director