FDI-LP Series (Low Pressure Range)
Based on the principle of cooling the air to near freezing point to remove the moisture
Range 720 m3/hr to 1700 m3/hr (424 CFM to 1000 CFM) (Low Pressure Range 1.6 to 4.0 kg/cm2)Our Airgineers Can Help You Select The Right Product!
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Working of Low-Pressure Compressed Air Dryer
A low-pressure compressed air dryer is specifically designed to remove moisture (water vapor) from compressed air operating at lower pressures. These dryers are essential in sectors like ash handling in power plants, cement plants, cleaning applications at pharmaceuticals, and general manufacturing, where moisture-free air is critical for:
- Protecting downstream equipment
- Ensuring reliable operation of pneumatic systems
- Maintaining product quality and hygiene standards
If moisture is not removed, it can lead to corrosion of pipelines, failure of pneumatic tools, and contamination of end products.
Working Principle – Refrigerated Type (Low Pressure)
The dryer operates on the principle of cooling the air to condense water vapor, which is then separated and drained. Here’s a step-by-step breakdown:
- Compressed Air Inlet
Low-pressure compressed air from the air compressor enters the dryer with high moisture content. - Pre-Cooling – Air-to-Air Heat Exchanger (Pre-Cooler)
The incoming warm compressed air passes through a heat exchanger, where it is cooled by outgoing dry air. This pre-cooling step reduces the load on the refrigeration system and initiates partial moisture condensation. - Deep Cooling – Air-to-Refrigerant Heat Exchanger (Evaporator)
– Air then enters the evaporator, where a refrigerant absorbs heat from the air.
– The temperature drops to around 3°C to 5°C, causing most water vapor to condense into liquid. - Moisture Separation – Centrifugal + Demister Pad Separator
– The condensed water is removed using a centrifugal separator combined with a demister pad.
– Water is discharged via automatic or manual drain systems. - Reheating (Optional) – Air-to-Air Heat Exchanger
The dry, cold air may be reheated slightly by exchanging heat with incoming air (via the air-to-air heat exchanger) to:
– Avoid condensation in downstream pipelines
– Improve energy efficiency - Clean, Dry Air Outlet
The dry and slightly reheated air exits the dryer and is delivered to the system, now free from harmful moisture.
Process Flow Diagram
| MODEL | Air flor (in m3/hr.) |
Working Pressure in.cm2(g) |
Dimensions ( L x W x H) (in mm) |
Weight (in Kg.) |
Water Qty. (in m3/hr.) |
Power Consumption (in KW) |
Air Connection (in inch) |
Water Connection (in inch) |
|---|---|---|---|---|---|---|---|---|
| FDI-1690W (LP) |
1450
|
4.0
|
2600 x 1000 x 1690
|
1500
|
5.00
|
5.00
|
4″
|
2″
|
| FDI-LP-1800W(SP) |
1803
|
1.7
|
2300 x 1100 x 1650
|
2800
|
9.00
|
9.00
|
6″
|
2″
|
| FDI-LP-2160W |
750
|
2.5
|
1800 x 950 x 1500
|
1050
|
4.00
|
4.00
|
4″
|
1.5″
|
| FDI-LP-2160W |
720
|
2.5
|
1800 x 950 x 1500
|
1050
|
4.10
|
4.10
|
4″
|
1″
|
| FDI-LP-2550W(S) |
1920
|
5.5
|
1800 x 850 x 1350
|
1200
|
25.00
|
25.00
|
4″
|
1.5″
|
| FDI-3000W(LP) |
2428
|
4.0
|
1800 x 850 x 1420
|
1200
|
6.00
|
6.00
|
4″
|
1.5″
|
| FDI-LP-4500W(S) |
4500
|
3.5
|
3200 x 1250 x 1925
|
2200
|
16.00
|
16.00
|
8″
|
2″
|
| FDI-LP-5400W(S) |
5400
|
1.5
|
3650 x 1250 x 2500
|
2500
|
13.00
|
13.00
|
10″
|
2″
|
| FDI-LP-5500W(SP) |
5100
|
2.2
|
3600 x 1500 x 2650
|
2300
|
15.00
|
15.00
|
10″
|
2″
|
| FDI-LP-5800W(SP) |
5800
|
1.7
|
4200 x 1600 x 2990
|
5000
|
29.00
|
29.00
|
12″
|
3″
|
| FDI-6000W (LP) |
6000
|
1.8
|
2400 x 1900 x 1835
|
5000
|
25.00
|
25.00
|
8″
|
3″
|
| FDI-LP-6000W (S) |
6000
|
2.3
|
2400 x 1900 x 1835
|
5000
|
25.00
|
25.00
|
8″
|
3″
|
| FDI-LP-6000W (SP) |
6000
|
1.5
|
4000 x 2000 x 2800
|
5400
|
18.00
|
18.00
|
12″
|
3″
|
| FDI-LP-6000W (SP) |
5800
|
3.3
|
3700 x 1250 x 2500
|
3000
|
15.00
|
15.00
|
10″
|
2″
|
| FDI-LP-6300W (SP) |
6300
|
2.0
|
3650 x 1250 x 2500
|
3000
|
15.00
|
15.00
|
10″
|
2″
|
| FDI-LP-6500W (SP) |
6200
|
2.8
|
3600 x 1500 x 2650
|
2500
|
16.00
|
16.00
|
10″
|
2″
|
| FDI-LP-6635W (SP) |
7000
|
2.0
|
2600 x 2000 x 2070
|
3000
|
25.00
|
25.00
|
8″
|
3″
|
| FDI-LP-6700W (SP) |
6306
|
2.7
|
3650 x 1250 x 2500
|
2500
|
15.00
|
15.00
|
10″
|
2″
|
| FDI-LP-6960W (SP) |
7000
|
1.5
|
2400 x 1900 x 1825
|
2500
|
25.00
|
25.00
|
8″
|
3″
|
| FDI-LP-6960W (SP) |
6600
|
2.8
|
2600 x 1900 x 1825
|
2500
|
25.00
|
25.00
|
8″
|
3″
|
| FDI-LP-7500W (SP) |
6710
|
2.5
|
4000 x 2000 x 2800
|
5400
|
34.50
|
34.50
|
12″
|
3″
|
| FDI-LP-7500W (SP) |
6100
|
1.6
|
4000 x 2000 x 2800
|
5400
|
24.00
|
24.00
|
12″
|
3″
|
| FDI-LP-7500W (SP) |
7200
|
1.3
|
4000 x 2300 x 2890
|
5400
|
19.00
|
19.00
|
14″
|
2.5″
|
| FDI-LP-9000W (SP) |
9000
|
4.3
|
4000 x 2000 x 2800
|
5400
|
21.00
|
21.00
|
12″
|
3″
|
|
Note: Higher capacities & Customised Requirements are available on request.
|
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Frequently Asked Questions
The FDI-LP Series compressed air dryer is designed to remove moisture from compressed air operating at lower pressures. It is suitable for applications such as power plant ash handling, cement plants, pharmaceutical cleaning, and general manufacturing where dry compressed air is required.
The low pressure refrigeration air dryer cools compressed air through an air-to-air heat exchanger and then an air-to-refrigerant heat exchanger, condensing the water vapour. This delivers a pressure dew point of +2 °C to +3 °C, and the condensed moisture is removed through a centrifugal cum demister pad separator.
Moisture separation helps protect downstream equipment and pneumatic systems from problems caused by condensed water. It can also help reduce pipeline corrosion, prevent pneumatic tool failures, and maintain product quality and hygiene in moisture-sensitive applications.
Delair builds low-pressure refrigerated air dryers in both air-cooled and water-cooled configurations, available in 16 standard models across a wide capacity band. Each unit combines refrigerated drying through a proprietary air-to-air and air-to-refrigerant heat exchanger and a centrifugal cum demister pad separator, and reheats the outgoing air via the air-to-air exchanger. Higher capacities and customised configurations are built to requirement.
The FDI-LP Series is available in 16 standard models and provides a pressure dew point of +2 °C to +3 °C. It is designed for tropical conditions with air inlet and ambient temperatures up to 50 °C, is built in accordance with ISO 8573-1, and carries approved design as per NTPC, BHEL, ONGC, and EIL norms. Higher capacities are available on request.
