If the wave guide is very tight, there is too little suppletion of dry air to the wave guide. Therefore Delair has developed two systems to prevent the disadvantages of this phenomenon. One of these is a bleeding system by means of an exhaust assembly.
MOIST AIR Wave guides are normally pressurized with dry air to prevent the disadvantages of moist air and condensate resulting in corrosion and loss of signal. Although the water vapour transmission of the windows of the wave guide is very low, a continuous diffusion of water molecules from the moist ambient air will diffuse through the window material.
EXHAUST ASSEMBLY If the wave guide is very tight, there is too little suppletion of dry air to the wave guide. Therefore Delair has developed two systems to prevent the disadvantages of this phenomenon. One of these is a bleeding system by means of an exhaust assembly. In case of application of an exhaust assembly a very small amount of air is continuously exhausted from the antenna to the atmosphere, so removing possibly introduced water vapour. Dry air is supplied by the dryer again.
CAPILLARY TUBE The exhaust assembly consists of a rigid stainless steel housing, in which a very precisely calibrated orifice is mounted. It should be fitted to the end of the wave guide, a combination of two wave guides or otherwise. This special orifice is not adjustable. The amount depends on the wave guide pressure.
TYPES There are several types available. The smallest one is suited to exhaust 0.5 l/h at 10-15 mbar, intended for the smallest wave guides. The selection of the type depends on the volume and the operating pressure of the wave guide and the capacity of the dryer.
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