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Technical Information - Fig No. 414

The ‘ROMA’ Type R Pressure Reducing Valve is a pilot-operated, full-bore, single-seated valve designed to pass larger volumes of steam than a direct-acting valve of the same size.

Control of reduced pressure is adjustable from approximately 90% of inlet pressure down to any pressure above 100 kPa, and the valve will maintain that setting regardless of fluctuations in inlet pressure or demand.

A minimum differential pressure of 100 kPa is required for operation.

Operation:

Reduced pressure acting on the diaphragm balances the loading of the adjustable regulating spring. When the downstream pressure falls, the spring opens the pilot valve, allowing upstream pressure to act on the piston. The piston then opens the main valve, admitting more steam to the downstream side to restore the required set pressure.

The valve continuously modulates to meet actual flow requirements under operating conditions.

Dimensions (mm)

Valve Size	15/20	25	50	80	100
‘A’	130	170	245	345	415
‘B’	55	55	70	80	178
‘C’	340	340	310	310	425

LP Over HP

The chart 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.

Pressure Ratio	0.58	0.74	0.82	0.87	0.91	0.94	0.96	0.98	0.99
Capacity Factor	1.0	0.9	0.8	0.7	0.6	0.5	0.4	0.3	0.2

^oC Superheat above Saturation	50^o	100^o	150^o	200^o	250^o	300^o
Superheat Factor	0.94	0.89	0.84	0.80	0.76	0.72