Texan Petroleum Shipments Monitored for Superior Accuracy

MTS Systems Corp. Sensors Division (USA) is providing its MG Level Plus liquidlevel transmitters to Truman Arnold Companies (TAC) of Caddo Mills in Texas, to measure and monitor its daily shipments of more than one million gallons of petroleum.

When TAC management decided to implement a wireless solution that would allow them to monitor the shipments remotely while maintaining accuracy, they chose a method that combined MTS’ MG transmitters with
Siemens Energy & Automation’s wireless control capabilities. “TAC needed a solution that would accurately measure the petroleum, and the MG transmitter provides superior accuracy, field replacement and compatibility with the Siemens wireless control system, all of which allow for greater efficiency and costeffectiveness for TAC,” said Lee Aiken, Level Plus product marketing manager, MTS Sensors.

A petroleum terminal in Caddo Mills, Texas, connects TAC to the Explorer pipeline, which transports petroleum from the Gulf of Mexico to Indiana. For every ten day cycle, the Caddo Mills terminal receives an average of 200,000 barrels of petroleum that is stored in nine closed-roof storage tanks ranging in size from 20,000 to 110,000 barrels, with a total storage capacity of 650,000 barrels.

The challenge when moving such a large amount of petroleum products is maintaining accurate control of the process. TAC cannot afford to run out of any of the petroleum products they carry or have inaccuracies during custody transfer. Inaccuracy can result in TAC either paying for product that was not received or by not charging for product that was delivered. For every 0.5% in custody transfer error that TAC endures, the company loses 1,000 barrels of product per cycle at the Caddo Mills terminal. If this was spread out over the year, and included other terminals that TAC also operates, the cost of inaccuracy quickly reaches into the tens of millions of dollars.

A wireless interface was the key to TAC’s implementation. MTS Sensors worked with Siemens Energy & Automation to provide TAC with the ability to go wireless. The MTS / Siemens solution provided TAC with a highly accurate MTS digital transmitter and wireless connectivity to a central control panel in their office.

The Siemens transceivers and I/O modules work together with a selection of accessory equipment from Siemens to create a wireless network for any application. WiPS-Link configuration software is used to configure the transceiver and network parameters to utilize the Modbus output of the MG transmitter. TAC used the output from the transceiver to control a graphical display to allow the employees at Caddo Mills to easily view the tank levels from their office.

The most significant benefit seen by TAC was true cost savings. Because there were no signal wires running from the storage tank into a control room, TAC saved on costs for conduit, wire, installation, install time, etc. And because TAC engineers can now easily monitor all of the tanks from one central location without having to leave the office, they can spend more time focusing on other more productive aspects of their jobs.

TAC engineers experienced an easy installation process by using the MG transmitter and its stainless steel flexible hose, which allows a single person to carry the transmitter to the top of the tank and install it through any 1" process opening with an adjustable NPT fitting. A larger opening is needed to install the floats on the transmitter before insertion. TAC ordered its MG transmitter with Modbus output, which is available for vessels from 508mm to 18,288mm and is ideal for process control, bulk storage, precision inventory control and product level, interface level and temperature monitoring. Another key feature for TAC was field replacement of the transmitters without downtime. The MG achieves this through its modular construction, which allows the transmitter to be serviced or replaced without having to shut down the tank or process.

Customers choose the model MG transmitter due to its ability to provide 3-in-1 measurement of the product level, interface level and temperature. The model MG has built a reputation of high accuracy, reliability, simple installation, and field replacement. Every transmitter is built custom to the application and is available in lengths from 508 mm (20 in.) to 18,288 mm (720 in.). The model MG can operate on either 12 or 24 Vdc power via its 4-wire Modbus connection.