Donaldson HRS-L+ 1000-8750 Closed-Loop Adsorption Dryer

A large heat-regenerated dryer with a closed-loop cooling circuit

The Donaldson Ultradryer HRS-L+ 1000-8750 is the large-flow member of the Ultradryer family, with ten sizes from 1,000 to 8,750 m3/h. Its distinguishing feature is closed-loop cooling during regeneration, which lets it reach a pressure dew point of -70 C at 7 bar(g) (or -40 C) even where the plant ambient air is warm and humid.

Like the other heat-regenerated models it uses ambient air for heating and runs a six-hour cycle under Ultraconomy dew point control. Carbon steel vessels, flanged main pipes and a Siemens S7-1215C controller with KTP700 display are standard.

Technical specifications

Size table

• 1000: Air volume m3/h 1,000; Flange DN 80; Electrical load kW 18.5; Pressure drop mbar 110
• 1950: Air volume m3/h 1,950; Flange DN 100; Electrical load kW 32.5; Pressure drop mbar 120
• 2750: Air volume m3/h 2,750; Flange DN 100; Electrical load kW 42.5; Pressure drop mbar 180
• 4000: Air volume m3/h 4,000; Flange DN 150; Electrical load kW 67.5; Pressure drop mbar 80
• 6000: Air volume m3/h 6,000; Flange DN 150; Electrical load kW 86.0; Pressure drop mbar 100
• 7000: Air volume m3/h 7,000; Flange DN 180; Electrical load kW 95.0; Pressure drop mbar 120
• 8750: Air volume m3/h 8,750; Flange DN 200; Electrical load kW 115.0; Pressure drop mbar 80

Both inlet and outlet are on the back of the dryer for all HRS-L+ sizes.

Where closed-loop cooling pays off

In open ambient-air cooling the blower air needs to be cool and dry enough to take the heat out of the bed; the sheet states a limit of 35 C at 45 percent relative humidity down to 30 C at 60 percent. Closed-loop cooling is the answer for the -70 C duty and for sites with a demanding climate, which is why the printed operating inlet temperature is limited to 30 C for the deepest dew point.

Donaldson names industrial machinery, food processing, electronics and automotive as industries. Verify the dew point class (-40 C or -70 C), the inlet temperature and the available electrical supply against the sheet before specifying a size. As on the other Ultradryers, the controller offers a potential-free alarm contact, a remote on/off contact and a main switch as standard, and the sheet lists options such as ENERSAVE, vessel insulation, flow and energy monitoring and Modbus or Profibus data links. The dryer is meant for indoor installation, and the adsorber vessels are designed and tested to EN 13445 under the Pressure Equipment Directive.

Documents and quotation

Interested in HRS-L+ 1000-8750? Send the full code and quantity. Please confirm the dew point class, inlet temperature and electrical supply using Donaldson Ultradryer HRS-L+ 1000-8750 data sheet (F119012, 11/2025), attached to the page. Related: Compressors.