Setting the Foxboro/Schneider Electric IDP10-A Differential Pressure Transmitter for Measuring Flow

This tutorial explains the setup for the Foxboro / Schneider Electric differential pressure transmitter model IDP10-A when used in a flow monitoring application.

When you need the flexibility and performance of a customizable, intelligent transmitter but do not need a digital output signal, these transmitters give outstanding value at a low cost. 

The Foxboro® brand Model IDP10 is a two-wire d/p Cell® Transmitter with an analog output that enables accurate, dependable differential pressure measurement and transmits a 4 to 20 mA analog output signal. 

The IDP10 is a comprehensive series of d/p Cell, gauge, absolute, multirange, multivariable, and premium performance transmitters. All use field-proven silicon strain gauge sensors and standard top works. 

Included in this transmitter is the -A electronics module. It is a low-cost analog output transmitter with complete configurable capabilities. This transmitter offers the most ability at the lowest possible cost to you. It even allows you to re-calibrate to new calibrated ranges using the conventional LCD indication without the requirement for calibration pressure. 

It is intended for use in Division 1 hazardous locations and meets Division 2 standards. Versions that fulfill agency flameproof and zone criteria are also available.

For more information, contact Mead O'Brien. Call (800) 874-9655 or visit https://meadobrien.com.

Measuring the Flow of Vaporized Liquid Natural Gas

Veris Accelabar installed on vaporized liquid natural gas line.

Application

A liquid natural gas plant in the Midwest needed to measure gas flow to heaters that vaporize LNG to gaseous natural gas for use during peak periods in the winter season. The company stores LNG in two 12,000,000-gallon tanks and uses gas-fired heaters to vaporize it as required to meet customer demand. For most of the year demand is low (1,000 SCFH); however, during the coldest winter months gas consumption jumps to 60,000 standard cubic feet per hour (SCFH) in a 3” sch 40 line at 80 psig/70° F.




Problem

The plant must account for the gas usage over the entire range as it is part of the operating cost during LNG vaporization, as well as when it is used for plant heating. The customer could not find one meter to accommodate the entire range accurately. The plant had attempted to measure the flow rate with a Roots turbine meter sized for the maximum flow rate, but could not get accurate flow readings at the low end of the measurement range, making it impossible to determine actual usage during the off-peak periods. In addition to accuracy limitations, turbine meters have moving parts that wear and require expensive maintenance. The customer’s operating cost was estimated and charged against the bottom line. In addition, as you can see from the photo, there was no straight run available which hindered a conventional meter’s ability to perform accurately.

Accelabar

Solution

A Model AF 3” 150-H-M Accelabar was installed immediately downstream of a pipe reduction, control valve and pressure regulator. The Accelabar had two Foxboro IDP50 high accuracy DP transmitters directly mounted to the top of the Accelabar sensor. Stacked outputs were required to accommodate the wide turndown in DP of 308.2” w.c. at max and 0.08” w.c. at min.

Results

The Accelabar performed as advertised with ±0.75% accuracy over the entire range of 1,000 to 60,000 SCFH—a flow turndown of 60:1. Because the Accelabar and transmitters have no moving parts to wear or seize, maintenance is minimal. The LNG supplier has found that the flow metering system is user friendly and easy to operate, especially since DP flow measurement is one of the most easily understood of any flow measurement technology available. To the LNG provider, this translates into improved material accountability and lower operating costs to increase profitability.

Reprinted with permission by Veris, a division of Armstrong International.