Because most people in FLG have day jobs only a very few attend the workshop (known as the Box Shop) during the day. The majority attend from the late afternoon from around 4pm until 11pm.
Which leaves some time for sight-seeing in the morning before work!
So in order to get the tourist sights out of the way I took the Bay Area Rail Transit (BART) downtown to the Ferry Building and went for a stroll. My walk guided me to Coit Tower a 1930s Art Deco tower that overlooks the bay.
 |
| Golden Gate Bridge in fog |
Downtown SF with Trans-American pyramid in background
Inside Coit Tower
I then traipsed down the hill and caught a cablecar. These were designed around the 1870s as a manually operated cable-driven system. The driver needs to pull a brake onto the cable to stop/start. They also only go in one direction and must be manually turned around at the end of each line.
Having fulfilled my touristly duties it was off to work.
Manual Cablecar Turnaround
Cablecar driver operating brakes
View from outside cablecar
Wednesday night is the FLG recruiting night where volunteers can come and try out the organisation and see if it suits them. There's a lot of manual labour involved. A lot of hammering, beating and welding but also some tinkering, electronics and gas plumbing. Volunteers often don't return but a steady stream of short-term volunteers provides the raw manpower to get the job done.
This Wednesday there were about 30 volunteers (old and new). We all gathered in the yard and were given an outline of the structure of FLG. The organisation is essentially divided into 3 groups - the fabricators (welding, grinding and metalwork), the Geeks (electronic lighting and control) and the Plumbers (gas fittings and fire effects).
Xylophage construction plan
Since I am interested in learning about fire effects I joined the Plumbers. They made an effort to point out that this was possibly the least glamorous part of the build and most people get bored with it pretty quickly.
We then went on to spend about 2 hours screwing together brass fittings.
The plumbers are in the process of designing the plumbing for the mushrooms that will form part of Xylophage.
Each Mushroom will be constructed of six segments forming a mushroom cap. Each of these 6 segments will have a gas "poofer" that blows a ball of fire into the air. Since there are six poofers the Plumbers are referring to it as a "sex-a-poof". The fittings we were screwing together go into forming the six outlets from the gas holding tank.
I learned a lot about propane gas and fire safety that night. From experience FLG now only use fittings and tubing rated for propane. The cost of the parts multiplied by the cost of a lawsuit if the fire effect goes awry makes using rated fittings better value than made up fittings.
FLG also use a vapouriser to distribute the propane. When the propane gas under pressure leaves the vessel it cools due to endothermic processes and because the temperature drops the effectiveness of delivery ceases. To prevent the flames from going out they vapourise the liquid propane prior to distribution to the gas lines making the gas flow even and constant.
We then went on to test a pilot light for the sex-a-poof. This is essentially a piec of slotted steel tube at the end of a gas line. As part of the work they want the pilot lights to burn with a blue flame. That means allowing oxygen to mix with the propane. To do this they purchased a barbecue fitting called a venturi that mixes air and propane. This was fitted at the pase of a tube with a t-piece at the top that fed two pilot lights. The gas line was attached to the venturi, and the venturi to a gas bottle and regulator. Gas was released into the regulator and as many joins as possible were sprayed with soapy water to determine if there were any leaks. If a leak appears it will show up as a gas-filled bubble. There were no leaks.
A butane torch was then lit with strict instructions given not to open the propane valve until the signal. The propane was released and the pilot light worked first time!
So ended that evening's work.
No comments:
Post a Comment