PDRC01 and PDRO01 Differential Pressure Regulators: Closing and Opening Types Suit Different Connection Methods

At a Glance

Products: VALVEPARK differential pressure regulators PDRC01 (closing type) and PDRO01 (opening type)

Operation: self-acting, no external power required

Controlled variable: differential pressure between the inlet and outlet pressure points

Specifications: 1/2"~10" (15A~250A), flange, BW and SW, ASME Class 150~300 (PN16~40)

Industrial heating pipelines, such as district heating systems and large-building heating networks, have points where the pressure difference (differential pressure) between the inlet and outlet pressure points must be held constant. When the pressure difference between the supply and return sides grows, the piping is put under strain and the flow rate fluctuates. The VALVEPARK PDRC01 and PDRO01 are self-acting differential pressure regulators whose valves open and close on changes in differential pressure alone, without electricity or compressed air. The one that closes as differential pressure rises is the PDRC01 (closing type), and the one that opens is the PDRO01 (opening type).

The English product names of the two models are Pressure Differential Regulator Closing Type (PDRC01) and Opening Type (PDRO01). The C and O after the shared PDR distinguish the closing type (Closing) from the opening type (Opening).

How It Works and Where It Sits in the Pipeline

The regulator body sits in the middle of the heating pipeline. When the impulse tube (a connecting line that transmits pressure) carries pipeline pressure to the control actuator, the pressure on the diaphragm works against the spring force and moves the plug inside the body. When system pressure changes, this balance shifts and the plug position follows automatically.

Closing type for direct connection, opening type for indirect connection

Where to Apply the Closing and Opening Types

PDRC01 differential pressure regulator (closing type)

PDRO01 differential pressure regulator (opening type)

Both models work from the same differential pressure, but the valve moves in opposite directions: the closing type guards against excessive differential pressure, and the opening type reduces the pressure difference.

The PDRC01 suits a direct connection (heating water circulates directly through the building's heating pipes). The PDRO01 suits an indirect connection (only heat is passed to the building side through a heat exchanger). The PDRO01 is generally installed on the return pipeline and has a fully balanced bellows/diaphragm structure that cancels the pressure force acting on the plug.

There are piping examples where the PDRC01 is installed on either the supply side or the return side, so it can be placed to match where the differential pressure is taken. However, for a pipeline where only the downstream pressure needs to be held constant, a pressure reducing regulator (PRR01) is the right choice, not a differential pressure regulator.

Common Specifications and Allowable Differential Pressure

The two models share the same size, connection type, pressure class and materials.

The allowable differential pressure (the pressure difference that can be applied across the valve) decreases as the size increases, so for large bores check the operating differential pressure first. Values by pressure class are as follows.

Dimensions

PDRC01 and PDRO01 Valve Body

Differential Pressure Actuator (by Effective Area)

Unit: mm, tolerance ±0.5 mm

Frequently Asked Questions Before Adoption

Q. Can it be installed where there is no power or compressed air?

A. Yes. Both models are self-acting and need no power, but the impulse tube must be connected. The impulse tube is installed between the supply or return pipeline and the control actuator.

Q. Are there restrictions on installation orientation?

A. It depends on the fluid temperature. If the fluid temperature is 120°C or below, sizes 15~80A can be installed in any orientation. For 100~250A, or when the fluid temperature exceeds 120°C, install on a horizontal pipeline only, with the pressure actuator facing downward.

Q. Can it replace an existing differential pressure regulator in the same position?

A. Replacement can be considered only when the connection type, size and pressure class are the same and the L value in the dimension table matches. The set differential pressure and actuator size are checked separately.

Information to Prepare for a Quote Request

1. Application: whether it is a district heating direct or indirect connection, and whether the installation point is on the supply side or the return side

2. Model: PDRC01 (closing type) or PDRO01 (opening type)

3. Size and connection: bore (A), whichever of flange or weld is needed, and pressure class (ASME Class 150 or 300)

4. Operating conditions: set differential pressure, operating differential pressure range, fluid type and temperature

5. Installation conditions: pipeline orientation (whether horizontal) and the position where the impulse tube will be connected

Other models in the same regulator line are introduced by purpose: PRR01 and PRR02 for pipeline pressure control, TR01 and TR02 for temperature control, and MPR01 and MPR02 for tank micro-pressure control.

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