Sunday, January 31, 2010

Antartic Fire Department Supply Line Debate

From: Bragg, Captain (Contractor) Sent: Saturday, January 30, 2010 12:56 AMTo: MCM-Firehouse-All: AFD Supply line survey

Below I have attached a document that I put together to try to help determine objectively what supply line should be carried and used by the AFD in the future. This is what I could put together quickly, please review it if you would and reply with any comments and/or corrections that you might have. I am looking for opinions and suggestions that will help with the process. As always 50 minds should be better than 1 looking at this. And I do have to thank Lt. Hinshilwood and FF/DO Walsh for the assistance and comments.

Please review and send me any comments by Tues. February 2nd.

Thanks.

Antarctic Fire Department Supply Line Survey
January 29, 2010

The selected maximum supply hose line length for these calculations is 1400’. This was selected based upon the distance from hydrant #4 at MMI to building 191 the Carpentry Shop. There are buildings in McMurdo that are further from a hydrant, but this is the furthest regularly occupied building from a water supply.

The calculations are based on available water flow from the hydrant. The ISO method shows a required fire flow of 2850 gpm for total involvement. So obviously the available water flow from the water system is the limiting factor. The latest hydrant flow data from hydrant #4 is 600 gpm. This data is from March of 2008 and the test was conducted with no additional pumping assistance from the water plant. Therefore, we could get 600+ gpm from this hydrant; the actual flow will require further testing.

With our current fleet in full operating condition we can support this operation at 600 gpm. It would require a dual 3” hose lay and an intermediate engine to relay pump to achieve this goal. Thing go down hill quickly at flows past 600 gpm.
Now jumping to a single lay 4” LDH we can expect some different results. At the 600 gpm flow rate, a single 1400’ line will be more than adequate. The limit for and 4” or 5” supply hose is 165 psi FL due to the maximum allowable pressure of an LDH of 185 psi and the required residual intake pressure of 20 psi. Using these numbers, you can see that the 4” hose begins to limit hose lengths at higher flows. At 800 gpm the maximum allowable length is 1300 feet. And at 1000 gpm the maximum allowable length is 900 feet.


And next with 5” single lay LDH we can expect even more distance and/or water flow. At flows up to 1000 gpm a 1400 foot line can be supported without any additional supply engines.

The other factor that I did not include in these calculations is elevation gain from hydrant #4 to building 191. The gain is approximately 80 feet, which equates to 40 psi of additional friction loss. This makes the 4” line a little sketchier in this example.

As I see it for the AFD there are several pros and cons for each type of supply line.
Pros:
Dual 3” – can be used with all existing adapters, hydrants, and hose.
– total weight of 50’ roll is 38 pounds.
LDH 4 or 5” – more water flow and/or longer lays with less apparatus.
– sexless coupling require no double male/female adapters.
Cons:
Dual 3” – high friction loss and limited flow/lengths.
– dual lays require additional coordination and setup.
LDH 4 or 5” – added expense of additional adapters and couplings.
– total weight of 100’ of 4” is 68 pounds and 5” is 84 pounds.

R.J. Bragg
Captain
Antarctic Fire Department


AFD Supply Line Debate Continues

Reply:

My fellow hose jockeys, through scientific studies, equations, and diagrams I will show you why smaller supply lines are in our favor rather than large diameter hose. Thank you to Walt the plumber and Kiwi Army Blackie & Nicole for their valued assistance.


To determine how much a hose line weighs we will complete the simple math equations to find out the specific weight of each hose diameter in question. In order to find the amount of water in a charged hose line we will use the Volume of a Cylinder Equation,
V = π x r² x h

V = Volume π = 3.14 r = Radius h = Height

First we must identity the characteristics of the hose in question.

5in Large Diameter Hose (LDH): π = 3.14 r = 2.5in h = 100ft

4in LDH: π = 3.14 r = 2in h = 100ft

3in: π = 3.14 r = 1.5in h = 100ft

All measurements must be converted to the same units to equate. Convert feet to inches.

Set up the problem for each hose diameter and solve.

V = 3.14 x 2.5² x 1200 = 23550in³

Using the cancellation table to cancel out all units, except the desired gallons.

V = 3.14 x 2² x 1200 = 15072in³

V = 3.14 x 1.5² x 1200 = 8478in³

Now water weighs roughly 8.33lbs/US Gallon. Figuring this and the weight of the hose will give us the total weight of the hose when full of water.

8.33 x 102 + 84 = 934 lbs for 5”
8.33 x 65 + 68 = 610 lbs for 4”
8.33 x 38 + 38 = 355 lbs for 3”

With temperatures regularly being below 32ºF/0ºC, the freezing point of water, it is common for hose lines in Antarctica to build ice accumulation. The ultimate question is this: would you rather try and maneuver the frozen 5” hose weighing 934 pounds or the 3” hose weighing only 355 pounds?

Conclusion: Frozen 3” is less than frozen 5” or 4” supply lines. Thank you.

(Courtesy of Lt Hardrick)










Tuesday, January 26, 2010

Monday, January 25, 2010
















Surely New Zealand is the best place in the world to make one's home...

Friday, January 22, 2010

R&R New Zealand




Surely New Zealand is the best place in the world to make one's home...

Tuesday, January 12, 2010

24 hr flight delay due to Con 4 weather!

Monday, January 11, 2010

28 hours til R&R in New Zealand!

Thursday, January 7, 2010

Saturday, January 2, 2010

sunny
winds ~30mph
temp 30 degrees

47 days til sunset
4 months til last sunset
8.5 months til first sunrise and arrival of Winfly personnel

Take my psych test next week and find out for sure if I'll winter or not!

At station 2- the ARFF station- today. It's a town holiday so there are no flights. Our only duties today are truck checks. The Pegasus shortcut road is closed (~8 miles), and no shuttles are running, so we borrowed a van with big tires and drove ourselves out at 1030 this morning. Tried for a land speed to Pegasus record yesterday.. but we were observed by watchers from LDB and trouble ensued. Being scrutinized very carefully this morning so 25 mph it is, and no faster. Hope to go out and see the old Pegasus crash.
Reading Polar Journeys, spending time online, calculating taxes, eating dim sum from brunch.

Friday, January 1, 2010

IceStock!

14 hours of live local bands. Stage set up outside from noon-1800 (interesting fact about adapting to Antarctica- I eat about twice as much as at home, my body temp was normal at 96.7 degrees at last check, and now I can stand around outside in jeans and a sweatshirt in 30-40 degree temps for 6 hours without getting cold. Aided by lots of coffee with baileys.)
Happy New Year from Antarctica!