Mechanical Challenge

Status
Not open for further replies.
T

That Man

Senior Member
Location
California, United States
Occupation
Electrical Designer
My electrical design group has been tasked to design a means by which an instrument (H2S Monitor), mounted 55' high (attached to the mouth of a vent stack), can be made accessible to a technician on the ground for callibration purposes.

Our client does not want the technician to climb to the level of the instrument, so the only option we appear to have is to mechanically lower the instrument to ground level. Our current design involves a hinged section of rigid conduit that has to be mechanically lowered and hoisted into position, but the design of such a device has grown enormously complex.

A far simpler method would be a simple halyard design, whereby we would raise and lower the instrument like a flag on a flag pole. Are there any exceptions in the code that accomidate a flexible cable outdoors for such an application?
 
That Man said:
Are there any exceptions in the code that accomidate a flexible cable outdoors for such an application?
Click to expand...


What type of power is this monitor useing? Is it the monitor that needs to go on the vent stack or just a sensor?

What I'm getting at is if this cable that you wish to raise and lower is part of a piece of equipment and not part of the building wiring system is that it wouldn't be covered by the NEC.
 
Last edited:
If you secure the flex to a messenger/support wire rated for the weight to be supported would that fulfill the requirements? Attached every 2.5 feet.
 
That Man said:
My electrical design group has been tasked to design a means by which an instrument (H2S Monitor), mounted 55' high (attached to the mouth of a vent stack), can be made accessible to a technician on the ground for callibration purposes.

Our client does not want the technician to climb to the level of the instrument, so the only option we appear to have is to mechanically lower the instrument to ground level. Our current design involves a hinged section of rigid conduit that has to be mechanically lowered and hoisted into position, but the design of such a device has grown enormously complex.

A far simpler method would be a simple halyard design, whereby we would raise and lower the instrument like a flag on a flag pole. Are there any exceptions in the code that accomidate a flexible cable outdoors for such an application?
Click to expand...

Retractable cable reel. How do you solve the placement and positioning of the instrument itself?
 
Another question: I have been looking at some H2S sensors on line. Maybe the one you are useing. Is this Sensor to be used in a class 1, division 1 or hazardous location? This could effect the use of cables greatly.
 
without knowing the specifics of the device at the top of the tower, i would run a track up the tower using the bosch or item structural aluminum extrusions, with a trolly that rides up and down the track (these are captive in the slots of the track and cannot come out) that holds the device. The top of the track has a headblock with a pulley. Aircraft cable is connected to the top of the trolley, through the headblock, and back to a winch on the ground that is used to raise and lower the assembly. Then you have a 2nd aircraft cable hanging from the bottom of the trolly which is connected to smaller trollys every couple feet all the way to the bottom. These smaller trollys in turn support a run of 1/2" sealtite. With this arrangement the entire assembly of sensor and conduit is ridgidly supported on the tower yet can be raised and lowered at will. The whole thing would be very clean, and shouldnt cost too much.

If you like I can provide a complete solution with 3d cad drawings for a "small" fee :grin:
 
Just higher a technician with really, really long arms.
 
80/20 stock, liner slide, and cable track, and a flagpole pulley:


trackgroups.gif


Linear-Motion-1.jpg

rope15.jpg
 
How do those large lighting poles at Interstate interchanges work? They have a ring of large lights. Some sort of remote control that lowers the whole ring to replace the bulbs.
 
Could you leave the equipment on the ground and use a tube and a vacuum system to bring the sample down to it? that way it would be a permanent installation with a lot fewer parts.
 
Having never been deterred from imparting my wisdom by not knowing what I was talking about ...

could you mount the detector down where you want it, and pump the emissions down to the sensor through some sort of tubing?
 
Last edited:
realolman said:
Having never been deterred from imparting my wisdom by not knowing what I was talking about ...

could you mount the detector down where you want it, and pump the emissions down to the sensor through some sort of tubing?
Click to expand...

you could but you might have to heat the sample lines.
 
Speedskater said:
How do those large lighting poles at Interstate interchanges work? They have a ring of large lights. Some sort of remote control that lowers the whole ring to replace the bulbs.
Click to expand...

The ones in my area require that you unbolt an access door on the side of the base, in there will be a disconnecting means for the electricity and a winch.

You attach a large drill motor onto the winch and lower the lights. But many of thees have been replaced with hinged poles that you attach hydraulic pistons to and lower the entire pole to the ground.
 
we worked at some gas substations not too long ago where we installed the detectors at design height, but put the remote transmitters at an accessible height. we installed pvc flex tubing to the sensors down to the accessible height so that calibration was able to be performed from the accessible (ground) station (even though it requires a somewhat larger gas sample. Those were ch4 sensors though - I'm not familiar with the H2S calibration, but if it is similar then that might be a possible solution. (although at 55' you might be out of luck). I am guessing that you have already contacted the manufacturer's rep to find out if there is a solution they have already seen for this problem ?
 
mdshunk said:
80/20 stock, liner slide, and cable track, and a flagpole pulley:

Click to expand...

A german firm that owns a floor paneling company, locally, used this "x" structure (small detail) in their kendorf applications. They also had alot of assorted attachments that they used, (caddie comes to mind) the like attachments held in by a mushroom bolt and threaded to the plate as shown. It was tight and a very clear looking application.
 
Status
Not open for further replies.
Top