Technical Information - Fig No. 414

The chart (below) shows max. capacities for reduced pressures 58% or less than inlet pressure. Where reduced pressure is greater - multiply by given factor.

Superheated Steam capacity is reduced by multiplying by the required factor.

Both factors must be used if appropriate.

The ‘ROMA’ Type R Pressure Reducing Valve is a pilot-operated, full bore, single seated valve capable of passing larger quantities of steam or air than a direct-acting type of equal size.

Control of reduced pressure is adjustable from about 90% of inlet pressure to any lower pressure above 100 kPa, and will maintain that pressure regardless of fluctuations in inlet pressure or capacity demands.

A minimum operating differential pressure of 100 kPa is required.

Operation

The reduced pressure acting upon the diaphragm balances the adjustable regulating spring loading. As the reduced pressure falls, the spring forces open the pilot valve to allow upstream pressure to be imposed upon the piston.

The piston in turn forces the main valve open, thus supplying more steam to the downstream line to maintain the required downstream setting.

The valve modulates to supply the flow requirements under actual working conditions.