This news article was originally written in Spanish. It has been automatically translated for your convenience. Reasonable efforts have been made to provide an accurate translation, however, no automated translation is perfect nor is it intended to replace a human translator. The original article in Spanish can be viewed at Precisión y rapidez en el análisis de gases medicinales en Praxair

The company implements an automatic analysis of gases (oxygen, nitrous and air)

Precision and speed in the analysis of medicinal gases at Praxair

Drafting QU26/04/2007

Electronic Engineering (LEI, S.L.) lines has been developed for Praxair, one of the leading companies in production of packaging and sale of gas, an automated system that allows to analyze gases oxygen, nitrous and air for their plants of Madrid (Villaverde)Vigo, Gijón, Valencia, Cordoba and Granada. To automate this system has been used a programmable automaton CJ1M of Omron, which achieves greater speed in the analysis of different gases and more control in the processing of data.

The operation of the system is based on carrying gas from bottles, or directly from the tank, through a series of valves, to analyzers that measured the concentration which has the gas. To automate this system has been used a programmable automaton CJ1M of Omron.

The monitoring system that is used for control, data acquisition and management of events and alarms is software SCADA of Factorylink version 3.5, with a license for 75 points. The Scada, in turn, is connected to an IBM AS400 platform to save the results of the analysis.

Its operation

The process begins when the analyst reads the number from the bottle by a reader of bar code that is sent to the Scada and this, in turn, transmits to the AS400. This answer with information relating to that bar code reporting whether the analysis may be performed or not.

Once the process begins, the Scada sends the information to the automaton to start the specified sequence of analysis. Different processes occur depending on the type of bottle or tank. To get the correct measurement of the Analyzer, is first performed a check of the team through a botellas-patrones to be used as references. The Analyzer compares the value of the sample with the stored reference value, thus showing the concentration of the sample gas. The sequence begins with the opening of the electro-válvulas gas reaches up to the Analyzer where the value of the sample will be collected.

This value will be checked if it lies within the established parameters. If so, the value is recorded and stored in the AS400 through the Scada, leaving the system ready for further analysis.

The following teams are used to analyze the medicinal gas:

Analyzer that measures the purities of O₂, CO and CO₂ of the sample.
Analyzer that measures the humidity which has sample.
Analyzer that measures concentrations of NO and no.₂ in N₂or.
Analyzer that measures the concentration of N₂or
Analyzer that measures the concentrations of CO and CO₂ into N₂or.

All these teams are controlled through the automaton with communications CJ1W-SCU21 cards and by means of a communication protocol for each one, developed in CX-Protocol. Through these communications you can collect the values of measurement of the analysers and perform remote equipment calibrations.

To ensure constant sample to the analysers, also you have to control the flow rate that is provided, where used some drivers of mass flow controlled by communications CJ1W-SCU21 card where the value of the flow of the sample is collected and you select the type of gas which will pass through the meter. The analog input card is used to collect the different values of temperature and pressure signals of 4 to 20 mA.