Regenerative Desiccant Dryers

KAD, KED, and KBD Series

kaeser.com
Desiccant Air Dryers
The right dryer for you
Most compressed air applications can achieve the required air quality by using a refrigerated dryer
in combination with proper filtration. However, in cases where compressed air is exposed to freez-
ing temperatures or where the product, process, or equipment is highly sensitive to moisture, Kaeser
offers a complete line of desiccant dryers specifically designed to meet low dew points and deliver
energy savings.

Innovation you can trust Savings with proper application

With a cutting edge research and development team committed Proper planning with the help of Kaeser’s system design
to building industry-leading products, Kaeser continues to engineers can save you money on capital and energy costs.
deliver better solutions to meet our customers’ compressed Desiccant dryers have a higher purchase price and overall
air needs. Kaeser’s expertise and world-wide reputation for operating costs than refrigerated dryers and should be applied
superior reliability and efficiency offer great performance and to the portions of a system requiring dew points below that
peace of mind. of a refrigerated dryer. Kaeser can design a system that will
efficiently deliver air quality suitable for your application.
Quality in every detail
Desiccant dryer performance and reliability are driven by Desiccant dryer basic operation
component quality. Kaeser’s valves and actuators are designed Kaeser desiccant dryers use the principles of adsorption and
for consistent dew point performance and low pressure drop. desorption and alternately cycle the compressed air through
Additionally, desiccant bed symmetry is selected to ensure twin desiccant towers. As the vapor-laden air flows through one
uniform flow distribution and maximize contact time, while the tower, the moisture is adsorbed onto the desiccant. Meanwhile,
spherical activated alumina desiccant allows for long service in the other tower, “purge air” flows through, evaporates the
life and minimizes dusting. It also has a high surface-to-volume water on the desiccant, and carries it out of the tower as vapor.
ratio and great affinity for water vapor for superior adsorption.

The benefits of counterflow regeneration

Kaeser’s upflow drying and downflow regeneration extends desiccant service life
and ensures consistent outlet dew points.

Upflow drying also controls the accumulation of liquid water in the desiccant
beds. Regardless of design, liquid water will accumulate in the piping between the
prefilters and the dryer inlet. Eventually, the air stream will carry a “slug” of water
into the desiccant bed.

Counterflow design ensures that the driest portion of the desiccant bed is nearest
the dryer outlet at switchover, and allows purge air to be evenly distributed
A Inlet valve D & E Purge
throughout the desiccant bed, providing more effective regeneration.
B Outlet valve valves
C Muffler
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3
Heatless desiccant dryer (KAD)
KADs produce pressure dew points as low as -100°F at rated conditions
(see Dew Point Options on page 5).
Sizes: 40 – 5400 scfm Standard purge pressure
adjusting valve
• Offers convenient purge
rate adjustment

Inlet and outlet shuttle

Controls and
valves
instrumentation
• Nylon shuttle
• Tower pressure gauges
• Tested to over 500,000
• Tower status lights cycles
• Switching failure alarm* • Corrosion resistant
• Purge flow indicator aluminum housing
• NEMA 4 electrical enclosure • Single moving part has
very long life
• RS232 comm port*
• No maintenance
*Not available on KAD E
• No check valves

Standard moisture
indicator
• Color change indicates
Separate top fill and
elevated outlet dew point
bottom drain ports
• Easy desiccant replacement
and removal
Standard stainless steel
support screens and air
diffusers
• Located internally at top
and bottom of each vessel
• Easy to remove and clean
• Efficiently filters out large
contaminants and protects
outlet shuttle valve
• Effectively prevents
channeling

ASME stamped pressure Structural steel frame complete

vessels with floor stand for easy
• Fabricated per Section VIII of the installation
boiler and pressure vessel code • Lifting lugs for easy handling
• ASME pressure relief valve • Optional factory mounting of
pre- and after-filters
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Heatless desiccant dryer (KAD) (Table 1)

Purge Rate @ Outlet Air Flow Inlet and Filter Total

Inlet Flow 100 psig Rate Dimensions*
All Models Power Outlet Weight Package Replacement
@ 100 psig (scfm) (scfm) WxDxH
(E and PS) Supply Connection* (lb.) Capacity Desiccant
(scfm) (inches)
Avg Max Avg Min (inches) (scfm) (lb.)
KAD 40 40 5.8 7 34.2 33.0 31 x 32 x 49 365 60 52
KAD 60 60 8.6 10.5 51.4 49.5 31 x 32 x 64 445 60 80
KAD 90 90 13 15.8 77.0 74.2 31 x 32 x 81 1 NPT 575 100 110
KAD 115 115 16.6 20.1 98.4 94.9 685
42 x 38 x 57 170 210
KAD 165 165 23.8 28.9 141 136 685
KAD 260 260 37.4 45.5 223 215 47 x 38 x 75 1010 375 318
KAD 370 370 53.3 64.8 317 305 55 x 38 x 65 1215 375 458
KAD 450 450 64.8 78.8 385 371 100-240 V 55 x 38 x 73 1350 485 542
2 NPT
KAD 590 590 85 103 505 487 49 x 48 x 103 1473 625 708
1 Ph
KAD 750 750 108 131 642 619 50 x 48 x 107 2134 780 906
KAD 930 930 134 163 796 767 50 or 60 Hz 55 x 56 x 112 2414 1000 1180
KAD 1130 1130 163 198 967 932 59 x 56 x 115 2875 1250 1420
3 FLG
KAD 1350 1350 194 236 1156 1114 60 x 56 x 120 3722 1875 1846
KAD 1550 1550 223 271 1327 1279 66 x 56 x 116 4167 1875 2064
KAD 2100 2100 302 368 1798 1732 72 x 56 x 119 4 FLG 4417 2500 2520
KAD 3000 3000 432 525 2568 2475 76 x 62 x 125 9010 3125 3734
KAD 4100 4100 590 718 3510 3383 85 x 62 x 124 9900 5000 5398
6 FLG
KAD 5400 5400 778 945 4622 4455 96 x 66 x 124 12,000 6875 7200

Note 1: KAD dryer inlet flow capacities are established in accordance with CAGI (Compressed Air and Gas Institute) Standard ADF-200: Inlet air pressure 100 psig,
inlet air temperature 100°F, saturated.
Note 2: The purge flow rate of any pressure swing (heatless) desiccant dryer is not constant throughout the purge cycle. The purge cycle consists of a maximum
purge flow period when the purge valve is open and a reduced flow period during repressurization. The total air consumption during the purge cycle is the average
purge flow and is based on a 10 minute cycle time (-40°F PDP).
Note 3: Maximum working pressure: 150 psig standard; 250 psig optional. Maximum working pressure to 500 psig available for most models. Consult factory.
*Dryer only. May vary with filter package.

Flow capacities KAD inlet pressure correction KAD dew point options
Maximum inlet flow capacities at factor (Table 2) meet ISO 8573.1 air quality
various pressures: Inlet Inlet standards (Table 3)
To determine a dryer’s inlet flow capacity Pressure Multiplier Pressure Multiplier
(psig) (psig) Models KAD and KAD PS allow the user
at inlet pressures other than 100 psig, 60* 0.65 125 1.10 to select outlet pressure dew points
multiply the dryer’s rated inlet flow 70 0.74 130 1.12 corresponding to four of the different ISO
(found in Table 1) by the multiplier from 80 0.83 140 1.16
8573.1 air quality classes.
90 0.91 150 1.20
Table 2 that corresponds to the system
100 1.00 175 1.29
pressure at the dryer inlet. KAD E models are preset to deliver the
110 1.04 200 1.37
115 1.06 225 1.45 commonly used ISO 8573.1 Class 2 outlet
Outlet flow capacities: 120 1.08 250 1.52 pressure dew point.
For dryers operating at less than *For operation at pressures lower than 60 psig, please
contact factory.
maximum flow and using the Purge
Economizer feature and/or operating at (Table 3)
pressures other than 100 psig, contact
Cycle Time and Mode
factory for correct purge flow. ISO 8573.1 Class Dew Point with Optional Purge
Standard
Saver**
1 -100°F (-73°C)* 4 min. fixed N/A
2 -40°F (-40°C) 10 min. fixed Yes
3 -4°F (-20°C) 16 min. fixed Yes
Specifications are subject to change 4 +38°F (+3°C) 24 min. fixed No
without notice. * This performance exceeds Quality Class 1 set at -94°F (-70°C)
** The Purge Saver controller also offers fixed cycle settings 5
Heated desiccant dryers (KED & KBD)
Kaeser Heated Purge Dryers (KED) are heated regenerative dryers that use only 7% of compressed air
for purging. They heat the dry purge air to increase its capacity to hold moisture and to regenerate. KED’s
provide lower operating costs by reducing the amount of expensive purge air used to regenerate. Standard
design outlet pressure dew point at rated conditions: -4°F (-40°F with the optional purge booster).
Sizes: 300 – 3200 scfm

Kaeser Blower Purge Dryers (KBD) use little or no purge air by introducing atmospheric air and heating
it. The heated air has a higher capacity for absorbing water and provides effective regeneration. KBD’s
provide the greatest energy savings by eliminating the need to use costly compressed air for purging.
Standard design outlet pressure dew point at rated conditions: -40°F.
Sizes: 500 – 4300 scfm standard. Up to 10,000 scfm available, consult factory.

Standard stainless steel support

screens and air diffusers
Standard pressure relief
• Located internally at top and bottom of
valve Standard moisture each vessel
• Meets ASME Section VIII indicator • Easy to remove and clean
• Samples outlet air • Efficiently filters out large contaminants
• Color change indicates and protects outlet shuttle valve
elevated outlet dew point • Effectively prevents channeling
(not shown)

Standard purge flow valve

(KED only)
• Offers convenient purge rate
adjustment

Controls and
instrumentation
• Tower pressure gauges
• Tower status lights
• Switching failure alarm
• Purge flow indicator (KED only)
• NEMA 4 electrical enclosure
• RS232 comm port

KED Dryer ASME stamped pressure

vessels KBD Dryer

• Fabricated per Section VIII of the

boiler and pressure vessel code

Long life non-lubricated inlet and

purge control valves standard
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Kaeser heated purge dryers (KED) (Table 4)
Inlet flow High-Temp Total
KED Purge Air Available Dimensions Approx. In/Out Pre-filter
@ 100 psig Heater After-filter Replacement
Model Flow Rate Average WxDxH Weight Connection (KB Series)
100°F (HTA Series) Desiccant
Number (scfm) (scfm) (in.) (lb.) (in.) (scfm)
(scfm) (nom kW) (Avg kW) (scfm) (lb.)
300 300 21 279 5 2.0 50 x 46 x 98 1400 375 400 420
1.5 NPT
400 400 28 372 7 2.7 55 x 52 x 104 1800 625
600 708
500 500 35 465 7 3.3 55 x 52 x 105 1880 625
2 NPT
600 600 42 558 8 4.0 57 x 53 x 108 2000 780 906
750 750 53 697 10 5.0 62 x 59 x 114 2400
1000P 1200 1180
900 900 63 837 12 6.0 62 x 59 x 114 2480
1050 1050 74 976 14 7.0 66 x 62 x 113 2900 1250P 1420
3 FLG
1300 1300 91 1209 17 8.7 68 x 63 x 118 3400 1846
1500 1500 105 1395 19 10.0 82 x 66 x 119 5100 1875P 1800
2518
1800 1800 126 1674 23 12.0 82 x 66 x 119 5180
2200 2200 154 2046 28 14.7 85 x 73 x 127 7800 2500P 2400
3734
2600 2600 182 2418 32 17.4 85 x 73 x 127 7880 4 FLG 3125P 3000
3200 3200 224 2976 40 21.4 97 x 82 x 125 9000 5000P 4800 4754
Average Heater kW (fixed cycle) = [kW required to produce 280°F temperature rise] x [235 min. max heat time] / [240 min. drying time]
Actual kW is less and proportional to the average water load presented to the dryer.

Kaeser blower purge dryers (KBD) (Table 5)

Inlet flow High-Temp Total
KBD Blower Blower Heater Dimensions Approx. In/Out Pre-filter
@ 100 psig After-filter Replacement
Model Flow Rate WxDxH Weight Connection (KB Series)
100°F (HTA Series) Desiccant
Number (scfm) (in.) (lb.) (in.) (scfm)
(scfm) (nom hp) (Avg kW) (nom kW) (Avg kW) (scfm) (lb.)
500 500 94 2.5 1.6 10 6.4 55 x 59 x 105 1866 625 600 708
2 NPT
600 600 113 2.5 12 7.7 57 x 60 x 108 2111 780 906
750 750 140 4 2.2 14 9.6 62 x 68 x 114 2465
1000P 1200 1180
900 900 158 2.0 17 10.8 62 x 68 x 114 2412
1050 1050 183 5 2.6 19 12.5 66 x 72 x 113 2981 1250P 1420
3 FLG
1300 1300 227 7.5 4.9 23 15.5 68 x 73 x 118 3576 1846
1500 1500 281 7.8 28 19.3 82 x 79 x 119 5359 1875P 1800
2518
1800 1800 317 10 7.3 33 21.7 82 x 79 x 119 5490
2200 2200 403 5.9 40 27.6 85 x 86 x 127 8018 2500P 2400
4 FLG 3734
2600 2600 449 15 9.8 45 30.7 85 x 89 x 127 8123 3125P 3000
3200 3200 552 5 2.4 54 37.7 97 x 107 x 127 9333 4/6 FLG* 4754
3600 3600 614 3.1 60 42.0 97 x 116 x 133 9833 5000P 4800 5220
7.5 6 FLG
4300 4300 732 4.2 70 50.1 109 x 123 x 132 12,350 5650
Average Heater kW (fixed cycle) = [kW required to produce 280°F temperature rise] x [235 min. max heat time] / [240 min drying time]
Average Blower kW (fixed cycle) = [Blower kW] x [235 min. max heat time] / [240 min dryer time]
Average Dryer kW (fixed cycle) = [Average Heater kW] + [Average Blower kW]
Actual kW is less and proportional to the average water load presented to the dryer.
*KBD 3200 has a 4” FLG inlet and 6” FLG outlet connection.

Inlet flow KED/KBD inlet conditions correction factors (Table 6)

Inlet Flow capacities shown in the Inlet Inlet Temperature °F (°C)
Pressure 60 70 80 90 100 110 120
Important:
Specifications Table have been
(psig) (15.6) (21.1) (26.7) (32.2) (37.8) (43.3) (48.9)
established at an inlet pressure of For inlet temperatures
60 1.03 1.01 0.99 0.80 0.58 0.43 0.32
100 psig (7 bar) and a saturated above 100°F, we
70 1.10 1.08 1.07 0.94 0.68 0.50 0.37
inlet temperature of 100°F (38°C). strongly recommend
80 1.17 1.15 1.14 1.08 0.79 0.58 0.43
installing a trim cooler.
To determine maximum inlet flow 90 1.24 1.22 1.20 1.18 0.89 0.66 0.49
100 1.30 1.28 1.26 1.24 1.00 0.74 0.55
Please note that
at other conditions, multiply the for every 20°F inlet
110 1.36 1.34 1.32 1.30 1.11 0.82 0.61
inlet flow from the Specifications temperature increase,
115 1.39 1.37 1.35 1.33 1.16 0.86 0.64
Table by the multiplier from Table 120 1.42 1.40 1.38 1.36 1.22 0.90 0.67 moisture load/dryer size
6 that corresponds to your operat- 125 1.45 1.43 1.41 1.39 1.27 0.94 0.70 approximately doubles.
130 1.48 1.46 1.44 1.42 1.33 0.99 0.74
ing conditions.
140 1.53 1.51 1.49 1.47 1.44 1.07 0.80
150 1.58 1.56 1.54 1.52 1.50 1.16 0.87
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Controls and instrumentation
Heatless desiccant dryers
P3 P4

P1 P2

P3

P1 P2

70%
ISO 8573.1
Class 60
1 -100 F / -73 C 50
2 -40 F / -4 C 40
kW
3 -4 F / -20 C 30
4 +38 F / +3 C 20
10
0%

RS232

Standard control Purge saver control Basic timer control

(KAD) (KAD PS) (KAD E)
The standard controller, with process To precisely and automatically match The Basic Timer Control is a reliable
flow schematic and LED’s, makes purge air consumption to a changing fixed cycle timer with LED’s indicating
status checks of control sequence, load, Kaeser offers the Purge Saver which tower is drying. This controller
valves, and filters simple and allows the Control. Having the same features as maintains a fixed 10-minute cycle
user to program reminders for routine the Standard Control (except the Purge delivering an ISO Class 2 pressure dew
maintenance intervals. A diagnostic Economizer Switches), the Purge Saver point (-40°F). Choose this controller
mode steps through the dryer’s monitors temperature changes within when air demand is uniform and closely
operational sequence to verify proper the desiccant bed when the dryer is matches dryer capacity.
function and performance. The display operating at less than its full capacity
clearly notifies the user if a malfunction and keeps the towers on-line until the
occurs. full drying capacity is reached. This
reduces the number of purge cycles and
This controller has four fixed cycle
ensures that only the necessary volume
operating modes corresponding to four
of purge air is consumed.
of the ISO 8573.1 air quality classes
for moisture content. In addition, the In the event of a malfunction with the
standard controller includes a manually Purge Saver Control, standard fixed
selectable purge saving feature. The cycle operation is automatically initiated.
Purge Economizer Switches allow the Dryer operating status is displayed on a
user to reduce purge consumption two-line vacuum fluorescent text display
in increments of 10% of full purge with choice of three languages: English, Energy savings of Purge Economizer
requirement and down to 30% of dryer Spanish, or French.
capacity, to closely match a constant,
fixed load.

8
 Optional controls
Externally heated desiccant dryers Heated purge (KED)

Energy management control Purge booster

(KED and KBD) Without increasing the use of
The Energy Management Control for compressed air,
heated dryers monitors the moisture purge flow can be
level in the desiccant bed and keeps increased from
a tower on-line drying compressed air 7% to 12% with
until the desiccant’s adsorptive capacity the optional Purge
has been fully utilized. Regeneration Booster. This
is then initiated and completed in the device reduces
following four hours. The regenerated compressed air consumption from 7%
tower repressurizes then sits idle until to 6% and draws in an equal volume of
Standard control ambient air mixing it with the purge air.
the Energy Management Control detects
(KED and KBD) The increased purge airflow produces
full use of the adsorptive capacity of the
The standard controller for heated drying tower and brings the regenerated lower outlet dew points and minimizes
dryers operates the dryer on a fixed tower back on-line. For operation at dew point spikes.
eight-hour cycle. A tower is on-line less than full capacity, the Energy
(drying compressed air) for four
Heated purge and blower
Management Control will match power
hours and then taken off-line to be
purge (KED and KBD)
requirement to demand by reducing
regenerated during the remaining four the frequency of regeneration. Heater Energy Saver
hours. Heater operation is terminated operation is terminated when temperature
The Energy Saver Option integrates
when temperature sensors detect that sensors detect that desiccant bed
moisture and temperature sensors to
desiccant bed heating is complete. heating is complete. The standard
monitor the humidity level near the
The standard controller’s process controller’s process flow schematic and
outlet end of the desiccant beds. During
flow schematic and LED’s make LED’s make status checks of control
periods of reduced flow, the Energy
status checks of control sequence, sequence, valves and filters simple, and
Saver extends the drying cycle thereby
valves, and filters simple and allow allow the user to program reminders
reducing the number of regeneration
the user to program reminders for for routine maintenance intervals. A
cycles, saving energy. For KED models,
routine maintenance intervals. A diagnostic mode steps through the
the Energy Saver Option also includes
diagnostic mode steps through the dryer’s operational sequence to verify
the Purge Booster.
dryer’s operational sequence to verify proper function and performance. The
proper function and performance. The display clearly notifies the user if a Energy Management
display clearly notifies the user if a malfunction occurs. Dryer operating
The Energy Management Option includes
malfunction occurs. Dryer operating status is displayed on a two-line vacuum
the Energy Saver Option above and a
status is displayed on a two-line vacuum fluorescent text display with choice of
digital dew point monitor. This feature
fluorescent text display with choice of three languages: English, Spanish, or
displays the dryer’s outlet dew point
three languages: English, Spanish, or French.
and allows the user to prevent tower
French.
changeover until a user specified outlet
dew point has been achieved, or lets
the Energy Management determine the
length of the drying period. For KED
models, the Energy Management Option
also includes the Purge Booster.

9
Choosing the right desiccant dryer
When selecting desiccant dryers, assess the dew point required for your application and size the dryer for only the part of the
system that needs the low dew point.

Heatless dryers (KAD) can achieve the lowest dew points (as low as -100°F) and have lower initial cost, but have higher operating
costs. Exhaust purge and blower purge dryers are more efficient, but have higher initial costs can only reach dew points as low as
-40°F. See the charts below for comparison.

Operating costs comparison

Total cost of purchase, operation, and maintenance of desiccant dryers

10
Options Filtration

Insulation for heated Wall-mounted heatless

desiccant air dryers desiccant air dryers (KADW) All desiccant dryers require proper

(KED and KBD) filtration. Coalescing pre-filters prevent

Compact and convenient, these wall-
contamination of desiccant beds by
Insulation with protective jacket for mounted dryers are available in seven
hydrophobic aerosols. Particulate after-
heater and heater discharge piping is models from 7 to 50 scfm all with factory
filters collect traces of desiccant dust
standard; however, insulation for the supplied filter packages. Four minute
that may exit the dryer. Maintaining
desiccant vessels is optional. Vessel fixed cycle timer produces standard
these filters extends service intervals
insulation offers protection for personnel -40°F pressure dew point at rated flow
and provides excellent air quality. All
and reduces operating costs. Vessel conditions. Lower pressure dew points,
Kaeser desiccant dryers offer optional
insulation is flexible open-cell melamine to -100°F, are achieved by reducing air
filter packages with or without block and
foam having a permanently bonded PVC flow rate.
bypass valves.
film laminated polyester fabric jacket.
This insulating system absorbs impact
and returns to its original shape, thus
maintaining its insulating qualities.

Other options
• High humidity alarm
• Dew point monitor
• Stainless steel or copper pilot and instrument air tubing and fittings
• NEMA 4 low ambient protection packages
• NEMA 7 Explosion-proof electrical packages (KAD only)
• Parallel piped pre-filters and after-filters

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 The world is our home
As one of the world’s largest compressed air
systems providers and compressor manufacturers,
Kaeser Compressors is represented throughout the
world by a comprehensive network of branches,
subsidiary companies and factory trained partners.

With innovative products and services, Kaeser

Compressors’ experienced consultants and
engineers help customers to enhance their
competitive edge by working in close partnership
to develop progressive system concepts that
continuously push the boundaries of performance
and compressed air efficiency. Every Kaeser
customer benefits from the decades of knowledge
and experience gained from hundreds of thousands
of installations worldwide and over ten thousand
formal compressed air system audits.

These advantages, coupled with Kaeser’s worldwide

service organization, ensure that our compressed
air products and systems deliver superior
performance with maximum uptime.

www.kaeser.com

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