Solid particles such as dust, water droplets, oil aerosols, and gaseous contaminants such as oil and hydrocarbon vapors present in your compressed air network will cause all manufacturing processes to operate inefficiently. This will result in increased costs, more down time due to excessive maintenance and lower quality in terms of spoilt products and adverse machinery wear.

The condensation present in the compressed air network work is the cause of : increased wear and corrosion within the pneumatic equipment used, higher running expenses and damage to machinery.

Faulty or spoilt products, lower quality, higher costs of spare parts and loss of production for repair works are the usual consequences!

In order to appreciate the quantity of water generated by the air compression process one should consider that a 50 HP (37 kW) compressor which delivers 6,000 Litre/min (212 cfm). free air at 7 Bar at an ambient temperature of 25°C and with 70 % relative humidity will produce 5.4 Litres per hour of vaporized water. After compression on entry to your network some of this vapor will condense allowing small droplets of water to be formed.

The use of after coolers, separators and condensate drains make it is possible to eliminate up to 70 % of the condensate. The remaining condensate may only be removed by using a refrigerant type compressed air dryer which will enable the temperature of the compressed air to be reduced significantly, in such a way it will be possible to eliminate all the remaining humidity. The dew point is the temperature at which the water contained in the compressed air begins to condense.

A lower dew point temperature will generate a larger quantity of condensate. To determine the required dew point at which to operate the dryer it is useful to take into consideration the minimum ambient temperature the compressed air system is exposed to. A dew point temperature of a few degrees lower than the minimum expected ambient temperature will allow the efficient removal of condensation and therefore maximum protection to the machinery and equipment used and to the distribution pipe work itself.

The new machines, thanks to new and patented solutions are capable of a high level performance whilst being extremely reliable. The use of high efficiency combined aluminium heat exchangers together with a new maintenance free condensate separator mean that this range of Air Dryers represent leading technology in the industry. 

Air at the intake to the air compressor, especially in industrial areas, contains various kinds contamination. A combination of these particles with droplets of oil and water will seriously damage the compressed air system. This will cause excessive wear to moving parts, clog orifices in precision instruments and contaminate products and processes.

Filters installed at compressor intake will only remove the larger particles and are used to specifically to protect the compressor. They offer no protection for the removal of contaminants for the compressed air system at large. 

Compressed air, leaving the after cooler of the compressor at a temperature of 35°C can contain more water (39.9 gr) than air at 18°C (15.2gr). This means condensation between after cooler and point of use would be 24.1 gr of water per m3 of compressed air.

Most compressors ‘carry over’ a substantial quantity of oil into the compressed air particularly in the case of older reciprocating compressors. The quantity depends on operating temperature, type and age of compressor and type of oil used.

Once the oil is transferred to the network from the compressor it has lost any beneficial lubricating properties and is therefore no benefit in lubricating any downstream equipment, furthermore the residual oil mixes with the condensate to form an acidic emulsified paste. This material is particularly aggressive to most industrial materials causing significant damage and disruptions to all industrial processes. 

The choosing of the correct size and type of dryer is essential to ensure reliable operation whilst avoiding additional and unnecessary costs. Therefore its useful to note that:

• An undersized dryer will not be able to dissipate the heat of the air and therefore the efficiency of the dryer will be seriously impaired.
   
• On the other hand, an oversized unit will cause continuous modulation in order to maintain stability in the cooling process, this will cause operational problems and increased wear and tear to components within the dryer.

In order to select the right dryer it is important to know the actual working condition and air consumption of the system. More precisely it is necessary to know:

By keeping in mind that the standard working conditions listed in the technical data (according to ISO 7183) are:
 

Should be the working condition differ the correction factors detailed below will allow the selection of the correct model to be made for the application.
 

For example: 

A 45 kW screw compressor delivers 6,000 1/min of compressed air at 7 bar. by measuring the inlet air temperature (for example 45°C) and the max ambient temperature (30°C) proceed as follows: 6.000 :1 (cf1) : 0,98 (cf2) : 0,75 (cf3) = 8,163 I/min.

A suitable installation is as the correct selection of the appropriate model. The scheme below depicts a typical well designed instillation. Depending on customer requirements it is possible to adapt this to different applications.

If there are any other queries you have concerning air systems our technical support team will be glad to help. You can e-mail your questions to us at: support@abac.co.uk or phone on +44 01869 326 226.
 

 
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