A full-size bottle of nitrogen is supplied by the Palomar staff, usually in response to a corresponding request on the green sheet. When the flow rate is properly adjusted, a single bottle should be sufficient for a 3-4 night run. At the 60-inch telescope, the Palomar staff normally ties the nitrogen bottle to the railing near the SE end of the telescope pier. At the 200-inch telescope, the bottle will be fastened to the floor of the Cassegrain cage (Figure 2).
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A regulator and rubber connection hose can be found amongst the Fabry-Perot equipment. Often the Palomar crew will have already connected the regulator to the nitrogen bottle. If they have not, first unscrew the protective cap that sits over the valve and valve handle of the bottle. Using a large wrench, fasten the regulator to the bottle. Be careful to not exert excessive force on the soft brass fittings. You may then open the valve on the nitrogen bottle, i.e., not the regulator valve. The right-hand regulator gauge should then register 1600-2000 PSI, if the bottle is full.
Finally, insert the clear plastic tube into the end of the regulator nozzle and tighten the fitting with a small wrench. This arrangement doesn't use a proper fitting, so you will probably need to use tape to secure the hose to the regulator and ensure against leaks. It may also help to tape a length of the hose to the nitrogen bottle, to relieve strain from the fitting.
For use in blowing off optical components, you will probably then want to open the regulator valve to create a moderate flow of nitrogen. You may regulate this flow more precisely using the small needle valve near the etalon end of the hose.