Largest Fully Automated Gas Fill Plant Opens in Mexico.

Industrial, medical, and specialty gas fill system increases productivity, ensures product integrity

The Welding Company of America (Weldcoa) a Northlake, Ill., company, in conjunction with Praxair Mexico S.A. de C.V., recently completed installation and start-up of the largest fully automated palletized industrial, medical, and specialty gas filling facility in North America. This state-of-the-art fill plant located approximately 20 miles northwest of Mexico City, is owned and operated by Praxair Mexico Inc. The site, along with its sister facility in Monterrey, Mexico, also installed by Weldcoa in 2002, significantly enhances Praxair Mexico’s position as a supplier of mixed gas cylinders for industrial, specialty, medical, welding, and other industrial applications throughout Mexico.

Praxair Mexico´s recently inaugurated site is unique for several reasons. It is highly complex, since it fills more than 250 different products that meet stringent international standards, such as NIST, EPA protocols, and USP grades, as well as domestic regulations. Since this fill plant supplies customers around the world, the packaging, labeling, and the certification process requires careful coordination to stay in compliance with the wide range of quality, safety, and product integrity needs that vary from requirements of every customer.
The new Praxair Mexico automated fill plant in the outskirts of Mexico City designed and installed by Weldcoa, recently went online, raising the plant´s productivity, and maintaining consistent quality.

When Praxair Mexico began this expansive
undertaking, it requested the services of Weldcoa because of its extensive experience
in the field, as well as its overall system design. Weldcoa was also sensitive to the schedule demand. “Praxair Mexico was very clear regarding the time parameters,”
states Bud Klotz, VP of Operations at Weldcoa. “We knew that our success would be based on the relationships that we had formed with our key vendors, so when we concluded those early meetings with Praxair Mexico, we immediately alerted our vendors, who were kept in the loop throughout the year-long planning/
negotiation process.”

At Praxair Mexico´s request, one of Weldcoa’s key vendors, CPV Manufacturing Inc., was included in the project. “If our software could be called the brains, then the CPV valves would be the heart,” adds Hector Villarreal, Vice President of Sales and Marketing at Weldcoa. “CPV stepped up and made things happen. Praxair Mexico had some very tight specs, which prompted us to turn to CPV products”

Not only did CPV fulfill the specification needs of the task, they were able to work closely with Weldcoa and Praxair Mexico to develop a new configuration of the durable Flo-Master valve. The most current material specifications for valves in high pressure oxygen service in the gases industry dictate that naval brass be used rather than the classic aluminum bronze. CPV engineered, manufactured, and delivered the valves on schedule; those valves are now the standard usedby Weldcoa for oxygen service. The new Praxair Mexico system incorporates 180 of these valves in pipe sizes ranging from 1/8-in. to one inch.

Many innovations were included in the plant. The new palletized fill island has 18 automated fill heads, each of which controls the filling of 18 cylinders. Thus, theoretically, up to 324 cylinders can be filled simultaneously.

Fill heads are dedicated to either straight gas filling or mixture filling, and multiple heads can be programmed to operate simultaneously through the various filling steps. Straight gas filling is performed by the ressure/temperature method, while mixture filling utilizes a small reference cylinder on a weigh scale. The control system automatically controls the vacuum and gas supply resources between the filling heads. As a result, this station is said to be one of the most efficient filling stations in North America.

All venting, vacuum, purging, and cylinder filling operations on the station are administered and controlled by four on-board Mitsubishi Programmable Logic Controllers (PLCs), which incorporate proprietary software programming. The programming was developed and written by Weldcoa.

Villarreal adds: “Mitsubishi knew the pressure Weldcoa was under and provided us with the equipment and expertise that we needed to fulfill Praxair Mexico’s needs. The goal of a filling station with this level of sophistication is to ensure high productivity levels without compromising
safety and mix accuracy. At the same time, design required a configuration and operation that were sufficiently simple that employees would require little training to function as highly capable operators. This required safeguards to be programmed into the system that make it virtually impossible for employees to initiate incorrect filling operations of or call for unsafe mixes. The Mitsubishi equipment permits us to achieve all of these goals.

“The touch screen controls on the station ensure that operation is as simple aspharmaceuticalsthe touch screens used for order taking at a fast food restaurant. The sequence for filling gas mixes is pre-programmed and cannot be altered by an operator. However, since every gas filling station has slight variations in both control operations and formula mixes, a password permits management access to overrides when appropriate.”

The filling operation at the Mexico City facility can be monitored continuously by operators who can readily determine— to an exact degree—the completeness
of a fill process. Moreover, to ensure that time loss is minimized, the program also offers audible cues in English or Spanish.

These are used to alert workers of the approach to the completion of a specific fill sequence so they can be prepared to initiate the next step in a subsequent operation. The high level of automation and the filling station’s trouble-free operation can be credited for the reduction in the number of employees required to operate this facility at full capacity. Operator numbers are far less than required at other facilities.

When Praxair Mexico first approached Weldcoa about installing an automated fill system, the possibility appeared challenging. The economics and return on investment
were ultimately justified due toimproved quality of product, increased productivity, greater safety, cost reduction,
and ease of training. Thus, in light of these benefits, full automation was considered the most viable option.

In an era when so many companies are fighting for market share, Praxair Mexico has laid the seeds for future dominance in an economy that is daily growing closer to U.S. levels.