Omega Air RDS refrigeration dryers for compressed air
Omega Air RDS refrigeration dryers dry compressed air to a pressure dew point of +3 °C. The air cools down inside them, the water vapour condenses and the automatic drain discharges the water without letting compressed air escape. The dried air meets water class 4 according to ISO 8573-1.
The range comprises 18 sizes from 20 to 1,900 m³/h (333 to 31,667 l/min at 7 bar), with working pressure up to 16 bar and R513A refrigerant. All sizes have an automatic zero air loss condensate drain and a controller that displays the dew point.
What the RDS dryer can do
- Automatic zero air loss condensate drain
- Controller displays the dew point and reports faults
- MODBUS communication, remote switch-on and alarm output
- Pressure drop below 0.2 bar
- R513A refrigerant with no effect on the ozone layer
- Stable dew point even at low air demand
Sizes and technical data
The code links to the dryer’s product page, the second column to the bypass piping that belongs to it. The number in the code is the flow rate in m³/h.
| Dryer | Bypass piping | Flow rate m³/h | Flow rate l/min | Pressure bar | Power supply V/Hz | Power input / consumption kW | Connection | Dimensions A × B × C mm | Weight kg |
|---|---|---|---|---|---|---|---|---|---|
| RDS-20 | RDP-20-BP | 20 | 333 | 16 | 230/50 | 0.16 / 0.14 | G 3/4" | 352 × 485 × 592 | 25 |
| RDS-35 | 35 | 583 | 16 | 230/50 | 0.17 / 0.14 | G 3/4" | 352 × 485 × 592 | 25 | |
| RDS-50 | 50 | 833 | 16 | 230/50 | 0.2 / 0.18 | G 1" | 352 × 485 × 592 | 26 | |
| RDS-75 | RDP-75-BP | 75 | 1,250 | 16 | 230/50 | 0.4 / 0.25 | G 1" | 352 × 485 × 592 | 27 |
| RDS-100 | RDP-100-BP | 100 | 1,667 | 16 | 230/50 | 0.45 / 0.32 | G 1" | 355 × 550 × 592 | 32 |
| RDS-140 | 140 | 2,333 | 16 | 230/50 | 0.5 / 0.38 | G 1" | 355 × 550 × 592 | 50 | |
| RDS-180 | RDP-180-BP | 180 | 3,000 | 16 | 230/50 | 0.6 / 0.45 | G 1 1/2" | 495 × 558 × 826 | 52 |
| RDS-235 | 235 | 3,917 | 16 | 230/50 | 0.73 / 0.6 | G 1 1/2" | 495 × 558 × 826 | 56 | |
| RDS-300 | 300 | 5,000 | 16 | 230/50 | 1.0 / 0.7 | G 1 1/2" | 495 × 558 × 826 | 84 | |
| RDS-380 | 380 | 6,333 | 16 | 230/50 | 1.1 / 0.8 | G 1 1/2" | 495 × 558 × 826 | 90 | |
| RDS-480 | 480 | 8,000 | 16 | 230/50 | 1.2 / 1.0 | G 1 1/2" | 495 × 558 × 826 | 99 | |
| RDS-600 | RDP-600-BP | 600 | 10,000 | 16 | 230/50 | 1.3 / 1.1 | G 2" | 491 × 708 × 973 | 110 |
| RDS-750 | 750 | 12,500 | 16 | 400/50 | 2.0 / 1.5 | G 2" | 491 × 708 × 973 | 120 | |
| RDS-950 | 950 | 15,833 | 16 | 400/50 | 2.4 / 1.9 | G 2" | 491 × 708 × 973 | 150 | |
| RDS-1150 | – | 1,150 | 19,167 | 16 | 400/50 | 2.4 / 2.0 | G 2 1/2" | 662 × 856 × 1534 | 250 |
| RDS-1300 | – | 1,300 | 21,667 | 16 | 400/50 | 2.6 / 2.3 | G 2 1/2" | 662 × 856 × 1534 | 280 |
| RDS-1500 | – | 1,500 | 25,000 | 16 | 400/50 | 2.7 / 2.4 | G 2 1/2" | 662 × 856 × 1534 | 290 |
| RDS-1900 | – | 1,900 | 31,667 | 16 | 400/50 | 3.8 / 3.4 | G 2 1/2" | 662 × 856 × 1534 | 310 |
The flow rate applies to a room temperature of +25 °C, inlet air at +35 °C, a pressure of 7 bar and a pressure dew point of +3 °C ± 1 °C (atmospheric dew point −20.5 °C). Power input is the maximum electrical input; consumption applies at nominal conditions. With a 60 Hz power supply, the power input is 20% higher. Larger flow rates on request.
How to choose the size
The dryer must handle the full output of the compressor. The flow rate in the table applies to reference conditions; the actual flow rate changes with pressure, inlet air temperature, room temperature and the required dew point. Therefore, multiply the nominal flow rate by the manufacturer’s four correction factors:
actual flow rate = nominal flow rate × pressure factor × dew point factor × inlet temperature factor × room temperature factor
Example: the compressor delivers 3,000 l/min at 8 bar, the inlet air is at +40 °C and the room is at +30 °C. The RDS-180 with its nominal flow rate of 3,000 l/min handles 3,000 × 1.05 × 1.00 × 0.83 × 0.96 = 2,510 l/min, which is not enough. The RDS-235 handles 3,917 × 1.05 × 1.00 × 0.83 × 0.96 = 3,277 l/min and is sufficient.
Pressure factor
| Pressure bar | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Correction factor | 0.39 | 0.60 | 0.77 | 0.86 | 0.93 | 1.00 | 1.05 | 1.10 | 1.14 | 1.18 | 1.21 | 1.24 | 1.27 | 1.30 | 1.32 |
Dew point factor
| Dew point °C | 3 | 5 | 7 | 10 |
|---|---|---|---|---|
| Correction factor | 1.00 | 1.10 | 1.21 | 1.39 |
Inlet air temperature factor
| Temperature °C | ≤ 25 | 30 | 35 | 40 | 45 | 50 | 55 |
|---|---|---|---|---|---|---|---|
| Correction factor | 1.20 | 1.12 | 1.00 | 0.83 | 0.69 | 0.59 | 0.50 |
Room temperature factor
| Temperature °C | ≤ 25 | 30 | 35 | 40 | 45 |
|---|---|---|---|---|---|
| Correction factor | 1.00 | 0.96 | 0.90 | 0.82 | 0.72 |
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How the refrigeration dryer works
Warm, humid air passes through the three-stage heat exchanger module (1). In the first stage (a), it is pre-cooled by the cold dried air leaving the module. In the second stage, the evaporator (b), the refrigerant cools it and the water vapour condenses. In the third stage (c), the demister separates the water droplets from the air stream and the drain (9) discharges them.
The cold dry air is warmed up again in the first stage by the incoming air. This saves energy, and the outlet air is warm enough to prevent ambient moisture from condensing on the pipework. Pre-cooling also keeps the whole system operating stably.
Refrigerant circuit
The refrigerant is circulated by the hermetic refrigeration compressor (4). The compressed gas liquefies in the condenser (5), which is cooled by its fan, controlled by temperature or pressure. The liquid refrigerant passes through the filter (7), which traps contaminants, and through the capillary or thermostatic expansion valve (8). There its pressure drops and its temperature with it, so it absorbs heat from the air in the evaporator. The evaporated refrigerant returns to the compressor.
The dryer operates non-cyclically: when air demand drops or stops, the hot gas bypass valve (6) returns part of the hot gas from the compressor discharge back to the suction side. The pressure and temperature in the evaporator remain at the set value and the condensate on the evaporator does not freeze.
Dryer components
The numbers on the photos correspond to the diagram above.
Control and protection
The control panel holds the main switch and the controller, which displays the pressure dew point and signals alarms: high or low temperature and temperature sensor failure. The front of the panel has IP 65 protection.
The dryer communicates via MODBUS, can be switched on and off remotely and has an alarm output. Smaller dryers have a basic controller that mainly monitors the dew point; larger ones have more powerful controllers with additional monitoring functions.
Condensate drain
Water from the demister is discharged by an automatic zero air loss condensate drain: it releases only the condensate, and no compressed air escapes.
Construction
The cabinet is made of carbon steel with epoxy powder coating. The condenser has aluminium fins and copper tubes and is air-cooled, the refrigerant piping is copper and the evaporator is insulated with flexible elastomeric foam.
The evaporator is made of aluminium; from RDS-380 upwards, it is a brazed plate exchanger made of stainless steel. Dryers up to RDS-100 can be carried by hand; from RDS-140 upwards, they are moved by forklift. The proven design is quick to install and easy to maintain.
R513A refrigerant
In the improved range, the manufacturer has made the dryers smaller, improved their components and final testing, and replaced the R134a and R407C refrigerants with R513A. It is azeotropic, has low global warming potential and zero ozone depletion potential, is energy-efficient and is non-flammable in air under normal conditions.
Dew point and air purity
Compressed air carries water, oil and solid particles. The ISO 8573-1 standard specifies how much of them may remain, depending on the application – for an overview of the classes, see industrial filters according to ISO 8573-1. The water content is expressed as the pressure dew point: the temperature at which the air is saturated with moisture. When the air cools to the dew point or below, water condenses.
A refrigeration dryer achieves a dew point of +3 °C, i.e. water class 4. For a dew point below 0 °C, for example in an air line running outdoors in winter, you need a desiccant dryer.
Technical data of the RDS range
| Parameter | Value |
|---|---|
| Maximum working pressure | 16 bar |
| Pressure dew point | +3 °C (water class 4 according to ISO 8573-1) |
| Inlet air temperature | up to +55 °C (temperature other than +35 °C = correction factor) |
| Room temperature | +1 to +45 °C (above +25 °C = correction factor) |
| Storage | +1 to +65 °C, relative humidity up to 90% |
| Filter upstream of the dryer | 3 µm pre-filter |
| Pressure drop | < 0.2 bar |
| Noise level at 1 m | < 65 dB(A) |
| Refrigerant | R513A |
| Refrigeration compressor operation | non-cyclic |
| Condensate drainage | automatic, zero air loss |
| Condenser cooling | air |
| Communication | MODBUS |
| Digital input and output | remote on/off, alarm |
| Control panel protection | IP 65 |
| Power supply | 230 V / 50 Hz (RDS-20 to RDS-600), 400 V / 50 Hz (RDS-750 to RDS-1900); 60 Hz on request, power input 20% higher |
| Cabinet | carbon steel, epoxy powder coating |
| Evaporator | aluminium, from RDS-380 brazed stainless steel plates; flexible elastomeric foam insulation |
| Condenser | aluminium fins and copper tubes |
| Handling | by hand up to RDS-100, by forklift from RDS-140 |
Bypass piping
The bypass piping routes the air around the dryer, so you do not have to shut down the air line during maintenance and servicing. Each size has its own piping, listed in the second column of the table: RDP-20-BP for RDS-20 to RDS-50, RDP-75-BP for RDS-75, RDP-100-BP for RDS-100 and RDS-140, RDP-180-BP for RDS-180 to RDS-480 and RDP-600-BP for RDS-600 to RDS-950. The largest sizes, RDS-1150 to RDS-1900, have no bypass piping.
Ventilek’s tip
Install a 3 µm pre-filter upstream of the dryer. It captures solid contaminants and oil droplets before they clog the heat exchanger, and the manufacturer requires it for RDS dryers. Downstream of the dryer, add a fine pre-filter and a microfilter, depending on the required purity.
- How do I choose the dryer size?
- By the compressor output. Multiply the nominal flow rate from the table by the correction factors for your pressure, inlet air temperature, room temperature and dew point, and choose a dryer that can handle the full output of the compressor.
- What dew point does the RDS dryer reach?
- Pressure dew point +3 °C, i.e. water class 4 according to ISO 8573-1. For a dew point below 0 °C, you need a desiccant dryer.
- What goes upstream of the dryer?
- A 3 µm pre-filter. It protects the dryer’s heat exchanger from solid contaminants and oil droplets, and the manufacturer requires it.
- Where can the dryer be installed?
- In a room with a temperature of +1 to +45 °C; above +25 °C, the flow rate is reduced by a correction factor. It can be stored at +1 to +65 °C and relative humidity up to 90%.
- How much electricity does the dryer use?
- From 0.135 kW for the smallest size to 3.4 kW for the largest at nominal conditions; the maximum power input of each size is given in the table. With a 60 Hz power supply, the power input is 20% higher.
- What is the bypass piping for?
- It routes the air around the dryer, so you do not have to shut down the air line during maintenance and servicing.
The technical data of RDS dryers are based on the product data sheet of the manufacturer Omega Air (2024).
For other types of dryers, see compressed air dryers.
Product sorting
List of products
Sell-off (remaining stock). The RDP-50 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-50.Condensation...
Bypass piping for Omega Air RDP-50, RDP-75 and RDP-100 refrigeration dryers being sold off. It makes maintenance and servicing of the dryer easier, without shutting down the air...
Sell-off (remaining stock). The RDP-35 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-35.Condensation...
Bypass piping for Omega Air RDP-140, RDP-180 and RDP-235 refrigeration dryers being sold off. It makes maintenance and servicing of the dryer easier, without shutting down the...
Bypass piping for Omega Air RDS-20, RDS-35 and RDS-50 refrigeration dryers and for RDP-20 and RDP-35 dryers being sold off. It makes maintenance and servicing of the dryer...
Bypass piping for Omega Air RDP-300 and RDP-380 refrigeration dryers being sold off. It makes maintenance and servicing of the dryer easier, without shutting down the air line.
Bypass piping for Omega Air RDP-480 refrigeration dryers being sold off. It makes maintenance and servicing of the dryer easier, without shutting down the air line.
Bypass piping for Omega Air RDS-600, RDS-750 and RDS-950 refrigeration dryers and for RDP-600, RDP-750 and RDP-950 dryers being sold off. It makes maintenance and servicing of...
Sell-off (remaining stock). The RDP-20 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-20.Refrigerant...
Sell-off (remaining stock). The RDP-300 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-300.Refrigerant...
Sell-off (remaining stock). The RDP-75 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-75.Condensation...
Sell-off (remaining stock). The RDP-480 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-480.Refrigerant...
Sell-off (remaining stock). The RDP-100 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-100.Condensation...
Sell-off (remaining stock). The RDP-1150 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the...
Sell-off (remaining stock). The RDP-1300 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the...
Sell-off (remaining stock). The RDP-140 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-140.Condensation...
Sell-off (remaining stock). The RDP-1500 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the...
Sell-off (remaining stock). The RDP-180 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-180.Condensation...
Sell-off (remaining stock). The RDP-1900 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the...
Sell-off (remaining stock). The RDP-235 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-235.Refrigerated...
Sell-off (remaining stock). The RDP-380 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-380.Condensation...
Sell-off (remaining stock). The RDP-600 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-600.Condensation...
Sell-off (remaining stock). The RDP-750 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-750.Refrigerant...
Sell-off (remaining stock). The RDP-950 dryer is the previous version (14 bar, R134a refrigerant, EMD12 drain). Its successor with the same flow rate is the RDS-950.Refrigerant...
Bypass piping for Omega Air RDS-100 and RDS-140 refrigeration dryers. It makes maintenance and servicing of the dryer easier, without shutting down the air line.
Bypass piping for Omega Air RDS-180, RDS-235, RDS-300, RDS-380 and RDS-480 refrigeration dryers. It makes maintenance and servicing of the dryer easier, without shutting down...
Bypass piping for Omega Air RDS-75 refrigeration dryers. It makes maintenance and servicing of the dryer easier, without shutting down the air line.
Omega Air RDS-100 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 100 m³/h (1,667 l/min) at 7 bar, working pressure up to 16...
Omega Air RDS-1150 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 1,150 m³/h (19,167 l/min) at 7 bar, working pressure up...
Omega Air RDS-1300 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 1,300 m³/h (21,667 l/min) at 7 bar, working pressure up...
Omega Air RDS-140 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 140 m³/h (2,333 l/min) at 7 bar, working pressure up to 16...
Omega Air RDS-1500 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 1,500 m³/h (25,000 l/min) at 7 bar, working pressure up...
Omega Air RDS-180 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 180 m³/h (3,000 l/min) at 7 bar, working pressure up to 16...
Omega Air RDS-1900 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 1,900 m³/h (31,667 l/min) at 7 bar, working pressure up...
Omega Air RDS-20 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 20 m³/h (333 l/min) at 7 bar, working pressure up to 16...
Omega Air RDS-235 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 235 m³/h (3,917 l/min) at 7 bar, working pressure up to 16...
Omega Air RDS-300 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 300 m³/h (5,000 l/min) at 7 bar, working pressure up to 16...
Omega Air RDS-35 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 35 m³/h (583 l/min) at 7 bar, working pressure up to 16...
Omega Air RDS-380 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 380 m³/h (6,333 l/min) at 7 bar, working pressure up to 16...
Omega Air RDS-480 refrigeration dryer for compressed air with a pressure dew point of +3 °C (water class 4). Flow rate 480 m³/h (8,000 l/min) at 7 bar, working pressure up to 16...