In 1958, R.H. Welker designed the first rubber plug type control valve to meet the demands of the gas industry for a quiet, versatile control valve. The many refinements and improvements made since that time have been incorporated into the current line of Welker Jet® Control Valves.
The proven design consists of a rubber plug which is expanded by a hydraulically operated piston and cylinder system. As the hydraulic force on the plug increases, it expands radially until it seals against the inside of a fixed liner. Hydraulic pressure is provided by a pneumatically operated diaphragm motor.
This streamlined, aerodynamic design generates a unique flow path that is unmatched by any other control valve on the market today.
Standard instrumentation consists of a filter dryer, first and second stage regulation with appropriate relief valve, and a pneumatic controller. The pressure sense line should be mounted as far downstream as possible.
An amplifying relay is used when the pressure requirements for positive shut off exceed the controller output or when greater response time is required. The amplifying relay is mounted between the controller output and the diaphragm motor.
A pilot operator is used for pressure control. Sensor line should be mounted as far downstream as possible. Filtered and regulated supply should be used to operate pilot.
I/P operation is used for flow or pressure control. a 4-20 mA of 1-5 V signal from the flow computer operates the control valve.