The duct should comprise a plastic tube that gets surrounded by concrete then screed and flooring finishes are applied above. The air and suction lines remain accessible via access covers.
Of the 6 fixings to hold the chair down, you'll probably find that only 3 actually do any work as when you tighten one, the adjacent ones slacken off. By repeated torquing, you'll get them close to equal tightness but it'll still just be close. That's why installers use break-back torque wrenches (if they're following the instructions) rather than dial-indicators which should only be used by people who actually understand what they're looking at.
I loaned an installer a dial-indicator once. Several hours later, he'd managed to pull all the fixings out without having exceeded the recommended torque.
Back to the issue of fixings coinciding with the channel, just make sure that they're deeper than the channel. And miss the duct, obviously.
Lowest bidder syndrome, eh!It will not have escaped the regular visitors to this thread that the refurbishment work is being complicated by a combination of factors.
So if you recall that a channel had to be dug out of the floor for the air and suction lines.
This has created a duct which is to be topped with a thin piece of chipboard, a levelling scree and then vinyl.
Those who were paying attention and supplied all the various helpful tips will recall that the previous chair was bolted to the concrete floor.
Obviously that was before someone dug out a duct which is to be covered in chipboard.
Dreading the answer, I asked the other day what the plan was for bolting the new chair to the floor.
A template was produced of the new chair.
Of the 6 bolts which should go into concrete, 3 will do so.
3 will go into a thin sheet of chipboard.
Nice to see you've got hold of John Smith's excellent book. Worth getting the CD-ROM of Falkland islands Journal back issues from the Museum too as it's got some interesting stuff on the ESRO station, the Hovercraft and loads more.