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General Machine Products (KT), LLC
4.
The far end of the duct run should be monitored, air should be leaving the duct under reasonable pres-
sure. The minimum pressure required will vary with the length of duct in the run, the friction character-
istics of the duct and the cable and the lubrication being used. However, as a starting point the air
leaving the far end of the duct should be (at least) similar to a light breeze. Bear in mind that if the duct
run is of considerable distance, it may take a few minutes for the air to reach the far end of the duct.
5.
If after waiting a suitable time there is no air leaving the far end of the duct, this would indicate that
there is a blockage or similar obstruction in the duct run, or, that the duct is fractured. In either case the
fault should be corrected before any attempt is made to blow cable down the duct.
6.
Once the duct integrity has been confirmed by the method outlined above. The duct may be lubricated.
10.1 LUBRICATION
“
Polywater Duct Prelube
®
”
lubricant can greatly improve the cable lengths installed if used correctly,
therefore the following procedure should be employed.
Warning: Do not exceed the stated volumes as this can reduced the installation lengths
1. The table below indicates the volume of lubricant necessary given common duct sizes and lengths.
Distance to Blow
500m
1000m
1500m
2000m
Duct Size
Duct Fill
Length (cm)
Duct Fill
Volume (mL)
Duct Fill
Length (cm)
Duct Fill
Volume (mL)
Duct Fill
Length (cm)
Duct Fill
Volume (mL)
Duct Fill
Length (cm)
Duct Fill
Volume (mL)
12 x 10mm
4
3.2
8
6.3
12
9.5
16
12.6
10 x 8mm
5
2.6
10
5.1
15
7.6
20
10.1
8 x 6mm
7
2.0
13
3.7
20
5.7
27
7.7
7 x 5.5mm
8
2.0
15
3.6
22
5.3
29
6.9
2. Inset foam projectile into duct a distance lower
than the above required fill length. Pour lubricant
into duct, fill and fit second foam profile.
3. Install duct into air chamber of Hurricane
Cable Blowing Machine; insert seal/plug in
chamber; charge system with air.
•
Make sure there are personnel at the other
end of the duct run, and that they are aware
that the air is to be turned on. Make sure that
a suitable device is fitted to obviate injury
should any object be expelled from the far
end of the duct.
4. Once both projectiles have exited the duct, the
exhaust system. Installation duct is now ready
for cable blowing.
•
Note:
when the air is turned off, after checking the duct integrity and sending the foam plug down the
duct to spread the lubricant. It may take some time for the pressure in the duct to dissipate,
time must be allowed for the pressure to fall back to low levels.
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