During a recent plant upgrade, a large asphalt equipment manufacturer purchased the ONE series differential pressure switch to monitor flow through a helical heating coil on their hot oil heater skids. In this application, the flow rate of the thermal fluid must be maintained in order to prevent damage to the heater coil from overheating. Overheating causes the thermal fluid to break down and form as coke, creating deposits inside the coil. Eventually the coil can rupture, allowing the thermal fluid to enter the combustion chamber and cause an uncontrolled fire.
The ONE series differential pressure sensor’s high side is connected to the inlet of the helical coil. The low side is connected to the outlet of the coil. The ONE series calculates the differential pressure between the high and low side and compares it to the programmed set point. The 10A, 280 VAC solid state relay inside remains closed if the differential pressure is higher than the set point, allowing the burner to provide heat to the coil. If the differential pressure falls below the set point, the relay opens and shuts down the burner immediately.
The operator can monitor the ONE series digital display to determine if the flow through the heater coil is normal. The adjustable set point and deadband facility allows for factory presets suitable for various oil heating capacities and reduced cycling. The ONE series also has self-diagnostics to provide a fail safe open switch if a switch fault or power failure occurs, preventing a runaway condition, and its reliable solid state design eliminates wear from high cycling rates.
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