Tech Tips for the 8329 Laser Ceilometer

by Dan Roberts, Field Service Technician, All Weather, Inc.

This short collection of 8329 Laser Ceilometer tips is designed for people who are installing, maintaining, or operating the equipment. The ceilometer is a relatively care free device for the airport and little maintenance is required. But even the simplest of maintenance still has "finer points" (like avoiding being stung by wasps)!

Installation Tips for Installers

1. When installing the ceilometer, it's best to orient the machine so that the desiccant cartridge is on the north side of the machine (or the south side, in the southern hemisphere). This cartridge has an indicator paper that can become bleached by the sun so that instead of blue or pink, all you see is gray.  The cartridge will last much longer if it's exposed to less direct sunlight.
   
   
2. The easiest way to locate the bolts for mounting the ceilometer to the foundation is to stand it in place and drill through the existing holes on all three legs using a 3/8" masonry bit in a hammer drill. After drilling each hole, drop one of your 'wedge bolts' upside down through the ceilometer foot into the hole so that the machine doesn't move while you're starting the next hole. When all three holes are done, pull out the bolts and rotate the machine a few degrees to expose the holes in the concrete (which should be at least 2-1/2" deep). Place a wedge bolt upright in each hole (they won't go in very far) and set the ceilometer back over the bolts. Place a washer on each -remember to add a ground lug to the one nearest the ground wire- and a nut screwed on just far enough so that it exposes only the first thread on the top of the bolt. Hammer the bolts down into the concrete until the nuts contact the washers, and then tighten the nuts. As the bolts are pulled up, they will wedge themselves more tightly into the concrete and the nuts will become tight.
   
   
3. After the ceilometer is in place, connect the AC power connector to the bottom of the base casting; route the cable alongside one of the ceilometer legs and down through a strain relief into the pull box on the conduit. Cut off the excess and use wire nuts to connect it to the incoming power wires. Similarly, connect the larger cannon plug to the signal connector; route the gray signal wire down the leg with the power wire and tie-wrap them to the leg so that they don't swing in the wind. If allowed to move too much, the wires can work-harden and break, leaving a lost or intermittent connection.  Route the signal wire through the strain relief and into the conduit, where there should be a pull-rope to get the cable through the conduit to the next pull box near the tower. Don't cut off the excess yet, it'll eventually reach into the DCP.

Maintenance Tips for Field Service Technicians

1. The maintenance procedure calls for placing a paper over the ceilometer as a test, expecting it to report 100 feet. Sometimes, it doesn't work. Depending on the paper's color and texture, some white paper reflects too much light and saturates the photodiode in the ceilometer. Sometimes the only thing you get from a sheet of white paper is a successful test of the blower and the dirty window sensor. If you don't get an indication of 100 feet, try placing a clip board over the sensor, dark side down.  Another way is to throw your jacket over the sensor. These will provide a more diffuse reflection than a white sheet of paper and may give you better results.
   
   
2. Be aware that the ceilometer is the favorite part of an AWOS for wasps or hornets to build a nest. Sometimes the nest will be under the rim of the outer cover right where you want to grasp it to remove the cover. While it takes more effort, it's safer to just put one hand on each side of the cover and lift it off.
   
   
3. If the birds consider your ceilometer to be an ideal perch, the windows may be difficult to clean. The easiest way to deal with this is to abandon the windex and cleaning pad and slowly pour water over the windows as you swab them with a cloth or paper towel. After a moment, the blower will come on, blowing your water away as fast as you pour it. After they look clean, one last splash of water with a quick swab with your hand will leave them ready for the blower to remove the rest of the water, leaving them nice and clean.
   
   
4. If the blower filters on the bottom of the ceilometer are dirty, you should replace them. What if you don't have replacements?  In a pinch, you can wash them by hand in the sink with soapy water, then rinse and sling out as much water as you can. Lay them in the sun for a bit and you can put them back in the ceilometer. They'll still look like heck, but they'll be able to serve until you can get new ones. Note that one of them is denser than the other. That one goes on top. Don't leave the machine for extended periods without filters. Flying insects can get sucked into the blower, then blown up the manifold pipe to the thin slit nozzle above the windows, clogging it.

Operations Tips for Airport Managers

1. Sometimes the blower seems to be running for no apparent reason. This is no cause for concern; it can be triggered by very low clouds, fog, or dust in the air, or even by a spider web across the top of the outer cover. The blower is rated for continuous duty and there's no reason to be concerned about it wearing or burning out. If it actually does run 24/7, let our technician know about it when he's on site. He may be able to improve the situation.
   
   
2. If the indicator paper in the desiccant cartridge turns pink, it means that the desiccant is ready to be replaced. The desiccant is important not only to keep the electronics dry, but to keep the windows from fogging up inside.

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