Danfoss AB-PM Combined Automatic Balancing Valve DN 10-100

Overview

The Danfoss AB-PM is a combined automatic balancing valve that brings together a differential pressure controller, a flow limiter and a control valve with linear characteristic in one compact body. Instead of controlling a single terminal unit, it keeps a stable differential pressure across a whole circuit, such as an apartment connection, a floor heating or cooling manifold, or a zone branch that feeds several fan coils, and it limits the maximum flow into that circuit. The range covers DN 10 to DN 32 for loop and apartment connections and DN 40 to DN 100 for larger HVAC zones, all rated PN 16.

Seven Star LLC supplies the Danfoss AB-PM and its accessories to MEP contractors, consultants and building owners across Oman and the GCC, with engineering support in Muscat. The valve is particularly useful in malls, shell and core office towers and mixed-use developments, where the base building is commissioned long before tenants install their own terminal units.

Operating Principle

The Danfoss AB-PM is installed in one pipe of the circuit, and an impulse tube connects its diaphragm to the opposite pipe, typically through a partner valve such as an ASV-BD or the supplied 1/16 inch adapter. The diaphragm compares the pressures on both sides and moves the pressure controller cone to hold the differential pressure across the circuit constant. When thermostatic valves or fan coil valves in the circuit close, the valve throttles; when they open, it opens, so each terminal unit always works against the same stable pressure difference. This keeps thermostatic and control valves quiet and in their working range, even where a higher pump head is needed for the rest of the system.

At the same time, the flow limiter caps the flow to the circuit at the preset value, so a zone that is oversized or poorly balanced cannot steal water from others. On DN 40 to 100, the flow limitation is set from 40 to 100 % on a scale where one turn equals 10 %, and the differential pressure setting uses 0 to 20 turns (DN 40 to 50) or 0 to 40 turns (DN 65 to 100). Regardless of the setting, the valve can modulate below 1 % of set flow, and shut-off is to ISO 5208 class A with no visible leakage.

Engineering Design of the Danfoss AB-PM

Danfoss AB-PM valves in DN 10 to 32 have DZR brass bodies (CW 602N), EPDM membranes and O-rings, stainless steel springs and cones, and external threads to ISO 228/1 from G½A to G1½A. They come with a 1.5 m impulse tube and adapter, and are available in a standard version and an HP (high pressure) version for larger floor heating loops that need a higher differential pressure. Maximum differential pressure across the valve is 400 kPa, and the minimum available differential pressure is 18 kPa for the standard version and 28 kPa for HP. The control valve stroke is 2.25 or 4.5 mm depending on size, with an M30 x 1.5 actuator connection.

The Danfoss AB-PM DN 40 to 100 range is supplied with a 2.5 m impulse tube, a brass handle and an impulse tube connector, and offers test plugs for measuring the differential pressure for flow verification during handover or troubleshooting. Its control valve stroke is 10 mm (DN 40 to 50) or 15 mm (DN 65 to 100), and connections are external thread or EN 1092-2 flanges depending on size. All sizes work with water and water mixtures in closed heating and cooling systems at medium temperatures from -10 to 120 °C.

Key Features

Each Danfoss AB-PM replaces several separate components in each circuit:

• Differential pressure control, flow limitation and a linear control valve in one valve body.
• Zone control capability with a TWA-Q on/off actuator (DN 10 to 32) or an AME 435 QM modulating actuator (DN 40 to 100).
• Stable differential pressure across thermostatic and control valves for quiet operation at all loads.
• Flow limitation adjustable from 40 to 100 % on DN 40 to 100, with factory presetting at 100 %.
• HP versions of DN 10 to 32 for loops that need a higher differential pressure.
• Test plugs on DN 40 to 100 for differential pressure measurement and flow verification.
• Compact body suited to manifold cabinets and riser connections with limited space.
• Shut-off function to ISO 5208 class A.

Industrial Applications

In shopping malls, office towers and mixed-use projects in Muscat and across the GCC, the Danfoss AB-PM DN 40 to 100 is installed at each tenant or floor branch of the chilled water riser. During the first stage of the project it guarantees the design pressure and flow to each empty zone, and when tenants complete their fit-out, the base building remains balanced without re-commissioning. Unoccupied zones do not disturb other users, and the test plugs let the facility team verify that each tenant receives the contracted flow.

The smaller Danfoss AB-PM sizes, DN 10 to 32, suit apartment connections in residential towers, manifold-fed floor cooling or heating loops, and any circuit where several terminal units share one supply and need a stable differential pressure. Seven Star LLC supplies the Danfoss AB-PM with impulse tubes, tailpieces and actuators, and helps engineers size the valve from the design flow and the pressure drop of the zone for projects in Oman.

For control of individual terminal units, see the Danfoss AB-QM pressure independent control valve.

Technical Specifications

The Danfoss AB-PM data below combines the Danfoss data sheets AI177686474377en-010704 (DN 10-32) and AI557828912007en-010102 (DN 40-100):

How to Order

To request a quotation for the Danfoss AB-PM, send Seven Star LLC the design flow and pressure drop for each zone, pipe sizes, heating or cooling service and the actuator or control requirement. Our Muscat team will confirm sizes and settings, advise on stock and lead time for Oman and the GCC, and provide the two official Danfoss data sheets. For differential pressure measurement and regulation on the same systems, see the WIKA DPGT43 differential pressure gauge, the Setra 264 low differential pressure transducer and the Masoneilan 172-50 differential pressure regulator.