External Pressure Relief Valves

Best Available Technology in Rail Tank Car PRVs

The Kelso pressure relief valve for low-pressure, class 117 tank cars raises the bar on the best available technology for the rail transportation industry.  With thousands of units in service the Kelso external PRV has demonstrated reliable operations in many tough service conditions without need of maintenance or unscheduled repair.


The Kelso external pressure relief valve design replaces the internal helical spring, internal valve stem and internal spring guide tube with up to 38 external constant force springs that place an external valve stem in compression.  The older style of internal PRVs have the active components inside the tank car which can cause issues; they are exposed to chemicals that may degrade the valve components over time; the maintenance requirements are more frequent due to contact with the goods inside the car; and the inspection process each time the tank car is loaded is more time-consuming due to the PRVs location inside the car.  Any degradation of the internal active valve components may result in a reduced level of reliability and overall value performance.  The Kelso external PRV for general purpose tank cars represents a substantial improvement over the current industry standard internal pressure relief valve.