Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 22-04-2013, 08:49   #31
Do or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 9,198
Re: Installing New Hatches In Fuel Tanks

This is how it was when I learned this; may be they now put stuff in diesel that changes it but I don't think so:

- diesel fuel flash point is well above 50 Celsius.
- standing diesel fuel below that temperature (without being atomized by injectors inside cylinders etc.) will not ignite by spark or flame. Only when the liquid diesel fuel becomes warmer than 52 Celsius or so, it starts creating vapors that can ignite.

that is how it was and I believe still is.

p.s. Also, OP has an aluminium tank, not a steel tank, so when drilling this there should not even be any sparks.

p.p.s. I believe many are confusing this with welding on a diesel tank, which process can heat the liquid diesel above it's flash point.
__________________

__________________
s/v Jedi is offline   Reply With Quote
Old 22-04-2013, 09:36   #32
Registered User

Join Date: Dec 2009
Location: Los Angeles
Boat: sportscraft,30-power
Posts: 107
Re: Installing New Hatches In Fuel Tanks

Quote:
Originally Posted by s/v Jedi View Post
This is how it was when I learned this; may be they now put stuff in diesel that changes it but I don't think so:

- diesel fuel flash point is well above 50 Celsius.
- standing diesel fuel below that temperature (without being atomized by injectors inside cylinders etc.) will not ignite by spark or flame. Only when the liquid diesel fuel becomes warmer than 52 Celsius or so, it starts creating vapors that can ignite.

that is how it was and I believe still is.

p.s. Also, OP has an aluminium tank, not a steel tank, so when drilling this there should not even be any sparks.

p.p.s. I believe many are confusing this with welding on a diesel tank, which process can heat the liquid diesel above it's flash point.
My vote goes to the Jedi. I would follow his advice.
__________________

__________________
Ofer is offline   Reply With Quote
Old 22-04-2013, 09:45   #33
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,586
Images: 240
Re: Installing New Hatches In Fuel Tanks

Quote:
Originally Posted by s/v Jedi View Post
... - diesel fuel flash point is well above 50 Celsius.
- standing diesel fuel below that temperature (without being atomized by injectors inside cylinders etc.) will not ignite by spark or flame. Only when the liquid diesel fuel becomes warmer than 52 Celsius or so, it starts creating vapors that can ignite...
... p.p.s. I believe many are confusing this with welding on a diesel tank, which process can heat the liquid diesel above it's flash point.
Indeed.

Flash point is determined by heating the fuel in a small enclosed chamber until the vapours ignite when a small flame is passed over the surface of the liquid. The temperature of the fuel at this point is the flash point.

Diesel Flash point 40 - 62C (144 F)
Biodiesel Flash point >130 C (266 F)
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 22-04-2013, 18:47   #34
Registered User

Join Date: Nov 2012
Posts: 40
Re: Installing New Hatches In Fuel Tanks

Remember, those flash points are in AIR. If you fill the tank with argon or carbon dioxide first (both of which are heavier than air), the tank won't ever go boom, even if you cut the hole with a plasma cutter.

We routinely weld diesel fuel tanks without much more than filling them with argon and/or CO2. But they are emptied of fuel.
__________________
dannobee is offline   Reply With Quote
Old 22-04-2013, 23:22   #35
Do or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 9,198
Quote:
Originally Posted by dannobee View Post
Remember, those flash points are in AIR. If you fill the tank with argon or carbon dioxide first (both of which are heavier than air), the tank won't ever go boom, even if you cut the hole with a plasma cutter.

We routinely weld diesel fuel tanks without much more than filling them with argon and/or CO2. But they are emptied of fuel.
Yes correct, it is all about reaching the explosive limit with right amount of oxygen in the vapor. However, the OP is not going to weld or use plasma cutters. He is going to use a drillbit to drill a hole for a pickup into the top of an aluminium diesel tank in cold England. Unless he puts propane burners under the tank, he is never going have diesel at 50 degrees Celsius with this project, nor is he going to have sparks.

The safest thing to do is to fill the tank with sand before drilling. It is also the most time consuming method.

p.s. with some grease or other sticky stuff on the drillbit, most if not all chips should stick to that instead of dropping in the tank.
__________________
s/v Jedi is offline   Reply With Quote
Old 23-04-2013, 00:06   #36
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,751
Re: Installing New Hatches In Fuel Tanks

Quote:
Originally Posted by s/v Jedi View Post
This is how it was when I learned this; may be they now put stuff in diesel that changes it but I don't think so:

- diesel fuel flash point is well above 50 Celsius.
- standing diesel fuel below that temperature (without being atomized by injectors inside cylinders etc.) will not ignite by spark or flame. Only when the liquid diesel fuel becomes warmer than 52 Celsius or so, it starts creating vapors that can ignite.

that is how it was and I believe still is.

p.s. Also, OP has an aluminium tank, not a steel tank, so when drilling this there should not even be any sparks.

p.p.s. I believe many are confusing this with welding on a diesel tank, which process can heat the liquid diesel above it's flash point.
Indeed.

I'm sorry to have offended the sensibilities of the marine school graduate, but I do think he is confusing the protocol for welding tanks with that for merely cutting one. I am pretty confident that just cutting holes in alu plate does not require any special anti-explosive precautions.

Before actually doing so, I will read up on it again, to be absolutely sure.
__________________
Dockhead is offline   Reply With Quote
Old 23-04-2013, 02:04   #37
Armchair Bucketeer
 
David_Old_Jersey's Avatar

Join Date: Oct 2006
Posts: 10,013
Images: 4
Re: Installing New Hatches In Fuel Tanks

............and get someone to shoot some youtube - just in case!
David_Old_Jersey is offline   Reply With Quote
Old 26-04-2013, 23:03   #38
Registered User
 
Bambolera's Avatar

Join Date: Nov 2012
Posts: 79
Re: Installing New Hatches In Fuel Tanks

I just cut access holes in my aluminium tanks. Although most of the fuel was pumped out, there must have been fumes present. No problem.

I used a 4" hole saw, an electric drill and a shop-vac. If you remove the chips (w/shop-vac) as you drill, there will be very little debri in the tank.

Good luck
__________________
Bambolera is offline   Reply With Quote
Old 26-04-2013, 23:18   #39
Registered User
 
Bambolera's Avatar

Join Date: Nov 2012
Posts: 79
Re: Installing New Hatches In Fuel Tanks

Since I also needed to add fittings to the tanks, I had them welded to the access plates with pickup tubes.

Hope that helps
__________________

__________________
Bambolera is offline   Reply With Quote
Reply

Tags
fuel, tanks

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 08:45.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.