General Machine Products 89300 AirStream Cable Blowing Machine - Manual (Page 32)

Page 32 of 44
The air box and tube clamp are now set up to blow air through the tube. Connect the air as for normal blowing.
Make sure there are personnel at the other end of the tube run, and that they are aware that the air is to be
turned on. Make sure that a suitable device is fitted to prevent injury should any object be expelled from the far
end of the tube.
The far end of the tube run should be monitored, air should be leaving the tube under reasonable pressure.
The minimum pressure required will vary with the length of tube in the run, the friction characteristics of the
tube and the cable and the lubrication being used. However, as a starting point the air leaving the far end of
the tube should be (at least) similar to a light breeze. Bear in mind that if the tube run is of considerable
distance, it may take a few minutes for the air to reach the far end of the tube.
If after waiting a suitable time there is no air leaving the far end of the tube, this would indicate that there is a
blockage or similar obstruction in the tube run, or, that the tube is fractured. In either case the fault should be
corrected before any attempt is made to blow cable down the tube.
Once the tube integrity has been confirmed by the method outlined above. The tube may be lubricated.
Open the air box and tube clamp assembly, as shown in the sketch above, withdraw the tube and raise it so
that the lubricant will pour into it easily and not overflow from the top. Pour lubricant of recommended quality
and quantity down the tube (A recommended quantity is 100ml per 1km of tube length). Insert a suitable foam
plug into the tube and put the tube back into the air box and tube clamp as shown in the sketch above.
The air box and tube clamp assembly are now set up to blow the foam plug through the tube, the foam plug will
help to deposit an even coating of lubricant to the inside walls of the tube. Connect the air as for normal
blowing. Make sure there are personnel at the other end of the tube run, and that they are aware that the air is
to be turned on. Make sure that a suitable device is fitted to prevent injury should any object be expelled from
the far end of the tube. When the foam plug has been expelled from the far end of the tube run, cable can be
installed into the tube.
Note: when the air is turned off, after checking the tube integrity and sending the foam plug down the tube to
spread the lubricant, it may take some time for the pressure in the tube to dissipate. Time must be allowed for
the pressure to fall back to low levels.