DIRECTIONAL DUST GAUGE TO BS1747 Pt5
FITTING REPLACEMENT COLLECTING TUBES
1. Unpack the replacement tube. The new bolt and plastic spacer are held in position by an M8 nut - this is only to keep everything together in transit and should be removed and discarded.
2. The old tube should be removed from the stand by unscrewing the two M8 bolts which are accessible through the main gauge aperture.
3. If possible, clean up the threads in the stand using an M8 x 1.25 tap.
4. Fix the new tube to the stand, taking great care to avoid crossing threads. The upper and lower bolts should be tightened gradually and alternately to ensure that the tube remains more or less vertical during assembly. Ignoring this advice can result in a broken bottle retaining ring. Do not overtighten the two screws; the rubber spacers should just mould themselves to the shape of the tube.
5. Clean the tube and bottle before using for the first time.