Danfoss Upgrades AB-QM Valve Range with Higher Nominal Flow Rates

According to Refindustry, Danfoss has reworked its AB-QM Pressure Independent Control Valve range in sizes DN 125 to 250, lifting nominal flow rates by 5 to 60% across the line — and if you've ever watched a commissioning engineer stare at a valve landing 12% short of its published curve, you already know why that average 30% bump matters far beyond the datasheet. The redesign also cuts the differential pressure the system needs to deliver before the valve behaves like one.

What changed in the AB-QM

The redesign isn't just numbers moving on a datasheet. The required starting pressure drops to 40 kPa (about 5.8 psi) for standard-flow models and 60 kPa (8.7 psi) for the High Flow variants. If you've ever chased a chiller plant's pump selection because the valve demanded too much head, that's the kind of detail that quietly reshapes your whole equipment schedule — the pump curve, the strainer sizing, the way you stage the risers.

The valves keep their pressure-independent behavior, with valve authority staying close to 100% and a control range of 1:1000. In practice, that means stable control even when system pressure drifts. If you're balancing a building loop late at night with the air-handling units fighting you, that's a useful promise to have on the nameplate.

A small but welcome change for the install crew: DN 200 and DN 250 valves no longer require the NovoCon XL digital actuator — the redesigned valves can run on the smaller NovoCon L instead. In a retrofit chiller room or a tight ceiling cavity where rigging time is always the bottleneck, that swap is the kind of detail that quietly trims an afternoon off a job. The maximum permitted differential pressure has also climbed from 600 kPa (87 psi) to 800 kPa (116 psi), giving specifiers more headroom in tall buildings or long district loops.

New top-end models for very large jobs

For projects where a single main line is doing serious duty, Danfoss has added two DN 250 Super High Flow variants. The DN 250 SHF delivers about 600 m³/h (roughly 2,642 US gpm) at 80 kPa starting pressure, and the SHF+ pushes that to around 670 m³/h (about 2,950 US gpm) at 100 kPa. If you're working on a hyperscale data center or a district cooling substation, this is where the redesign starts to look less like an upgrade and more like a different category of valve.

What to verify before you swap a spec

A few things worth checking before you pencil these into a submittal:

• Actuator compatibility. If your existing drawings call for NovoCon XL on DN 200 or DN 250, confirm the redesigned line supports NovoCon L against your full control sequence. The actuator change is a real spec line item, not just a hardware swap.
• Pump headroom. The lower starting pressure is real, but it's a minimum, not the operating point. If you're chasing energy savings, re-run your pump selection against the new valve curve instead of just shaving head off the old calculation.
• Where the 30% lands for your size. The range is 5 to 60%. If your old AB-QM was sitting near the bottom of its size class, the gain can be dramatic; if it was already near the top, you're looking at a smaller relative bump.
• SHF and SHF+ availability. DN 250 Super High Flow valves aren't typically shelf stock at every distributor. Worth confirming lead times before you tie them to a milestone date.

Refindustry notes that the redesigned line is aimed at HVAC, data center and district cooling applications — exactly where pressure-independent control tends to do the most work for the least operational fuss.

A lot of valve news reads like a bullet list of numbers, and the temptation is to skim it. But for the people who actually have to commission these valves in a live plant, a 30% average flow lift isn't a marketing claim — it's one fewer workaround in a long day of workarounds.