Once there was an application on a steel mill where they enriched the furnace oxygen levels by injecting oxygen into it by means of lancing. The liquid Oxygen plant with vaporizers was over 300 meters away and it then feeds to the plant with a 6 in line at 8 Barg.

Then the pressure was reduced to 5 Barg with a 5% accuracy. The line split into a manifold that went to two panels from where they controlled the flow to the two-lances into the two separate furnaces each about 40 meters apart from each other. The original plant design was to install a Globe Control Valve with a pneumatic blind pressure controller which act as a pressure reducing station. This pressure reducing regulator station was installed 10 meters before the manifold and the sensing line was just downstream of the Control valve.

The problem the customer had was that the set-point was changing as soon as the second kiln was brought online and the accuracy they could allow was +/-5%. The second issue was as soon as they adjusted the flow in the one panel it influences the pressure set-point. Since the flow meters was sized at a specific inlet pressure as soon as the pressure changes the flow-rate changed and they had to re-adjust the hand valve.

We looked at the application and realized that we can better it by implementing better technology and minor changes to the installation without the need of feedback loops to a PLC. We decided to change to a pilot operated pressure reducing regulator, but we also decided to change the sensing line sensing position to a position where the manifold split to the two panels.

Due to a change in the sensing line sensing location where the pressure was sensed we probably beat the competition. The speed of response of the pressure reducing regulator was much faster than that of the globe control valve with the blind pressure controller, although the customer considered using a control loop from the PLC we convinced them that the Pilot Operated Regulator's speed of response was still faster than a control valve with a Transmitter, PLC and positioner.

We have seen several times that if the location of the valve or as in this case the sensing point, is correct it will make a huge difference in the overall performance of the control valve.

We believed that if the competition or the customer had just moved the sensing point they would have solved the problem, but because we had the know how, we had the opportunity to sell the customer a solution.