4 ms·

What problem is solved by using aircraft-style toilets on Navy ships?

by guidedlight 7y ago

jonsen 7y ago
Stealth.
- erpellan 7y ago
  Aircraft toilets always sound pretty damn loud to me. And their main reason to exist on planes is the lack of available water. Pretty sure that is not an aircraft carrier’s constraint.
  - jonititan 7y ago
    Actually ships are very water constrained. Especially Nuclear as they can't risk sea water contamination to the reactor cooling.
    - Reason077 7y ago
      Modern aircraft carriers have reverse-osmosis desalination systems on board. These can supply hundreds (thousands?) of tons of potable water per day.
      - davidf18 7y ago
        Thank you for this information, for I was wondering why they wouldn't have desalinization technology on-board, and you've answered the question -- they do. Thus, I don't understand the lack of fresh water.
    - dctoedt 7y ago
      Yes, fresh water is a valuable commodity at sea; on U.S. Navy ships, water-flushed toilets are flushed with sea water, not fresh — or at least that's the way it used to be, and I can't imagine it'd be different today. (Source: Three years' sea duty as an engineering officer in the aircraft carrier USS Enterprise, CVN-65.) EDIT: See https://www.navy.mil/submit/display.asp?story_id=103122 https://www.navy.mil/submit/display.asp?story_id=103122 for a 2017 press release describing how the Reactor Department produces fresh water aboard the aircraft carrier USS Abraham Lincoln (a Nimitz-class carrier, i.e., an old design). TL;DR: It's done with giant evaporators, that is, distilling units. Fun fact: At sea, one of the big uses of fresh water aboard a carrier is the repeated washing down of the aircraft to reduce corrosion from the salt air.
  - deleted 7y ago
    [deleted]
wmoser 7y ago
Well, the old way to do it is to use sea water flushing which leads to its own problems over the life of the ship with pipes corroding. New(ish) environmental regulations dictate that you can't just flush everything overboard anymore, it needs to be processed through a sewage plant. Despite probably being able to ignore most environmental laws, the Navy normally at least tries to abide by the current laws to be a good citizen and not pollute the oceans as well as having an easier time when visiting foreign ports. The process plants run better on fresh water but fresh water is expensive and heavy on a ship so a vacuum system allows for less water per flush and really works pretty well if people don't flush stupid things. Stupid things that my co-workers have fished from sewage plant besides the things mentioned in the article: Towels Screwdrivers Glasses Rags baby wipes/ flushable wipes Pens As long as only body waste and a small amount of toilet paper are used, the systems are actually fairly reliable. Teaching people that that is ALL that can be flushed is an on going problem. The chemicals seem to be another issue, possibly a design issue but there are ways around that too. Urine crystals build up on the walls of the pipes and reduce the diameter for the waste water to flow. The vaccum systems typically have smaller diameter pipes then the old style "gravity" flush systems. There are companies that make continuous dosing systems that go in the end of the branch lines to help keep them clear. A lot of issues with maintenance can be solved by design of branches in the piping system with isolation valves so the whole system doesn't have to be shut down to fix something. Even replacing a toilet means shutting off the branch or system since it opens a hole in the vacuum system and leads to loss of vacuum. Some more information: https://www.boatus.org/clean-boating/sewage/msd-types/ https://www.boatus.org/clean-boating/sewage/msd-types/ Manufacturers: https://jetsgroup.com/jets-group/the-highest-standards/the-heart-of-our-system https://jetsgroup.com/jets-group/the-highest-standards/the-h... https://evac.com/ https://evac.com/
- 101404 7y ago
  If all that can be flushed is human waste and paper, then why not put it directly into the ocean? It's quickly and completely bio degradable (eaten by fish and micro organisms).
  - wmoser 7y ago
jonsen 7y ago
There’s a substantial number of big passenger ships cruising the seas. One would think this was a solved problem.

What problem is solved by using aircraft-style toilets on Navy ships?

jonsen 7y ago

Stealth.

erpellan 7y ago
Aircraft toilets always sound pretty damn loud to me. And their main reason to exist on planes is the lack of available water. Pretty sure that is not an aircraft carrier’s constraint.
- jonititan 7y ago
  Actually ships are very water constrained. Especially Nuclear as they can't risk sea water contamination to the reactor cooling.
  - Reason077 7y ago
    Modern aircraft carriers have reverse-osmosis desalination systems on board. These can supply hundreds (thousands?) of tons of potable water per day.
    - davidf18 7y ago
      Thank you for this information, for I was wondering why they wouldn't have desalinization technology on-board, and you've answered the question -- they do. Thus, I don't understand the lack of fresh water.
  - dctoedt 7y ago
    Yes, fresh water is a valuable commodity at sea; on U.S. Navy ships, water-flushed toilets are flushed with sea water, not fresh — or at least that's the way it used to be, and I can't imagine it'd be different today. (Source: Three years' sea duty as an engineering officer in the aircraft carrier USS Enterprise, CVN-65.) EDIT: See https://www.navy.mil/submit/display.asp?story_id=103122 https://www.navy.mil/submit/display.asp?story_id=103122 for a 2017 press release describing how the Reactor Department produces fresh water aboard the aircraft carrier USS Abraham Lincoln (a Nimitz-class carrier, i.e., an old design). TL;DR: It's done with giant evaporators, that is, distilling units. Fun fact: At sea, one of the big uses of fresh water aboard a carrier is the repeated washing down of the aircraft to reduce corrosion from the salt air.
- deleted 7y ago
  [deleted]

wmoser 7y ago

Well, the old way to do it is to use sea water flushing which leads to its own problems over the life of the ship with pipes corroding. New(ish) environmental regulations dictate that you can't just flush everything overboard anymore, it needs to be processed through a sewage plant. Despite probably being able to ignore most environmental laws, the Navy normally at least tries to abide by the current laws to be a good citizen and not pollute the oceans as well as having an easier time when visiting foreign ports. The process plants run better on fresh water but fresh water is expensive and heavy on a ship so a vacuum system allows for less water per flush and really works pretty well if people don't flush stupid things. Stupid things that my co-workers have fished from sewage plant besides the things mentioned in the article: Towels Screwdrivers Glasses Rags baby wipes/ flushable wipes Pens As long as only body waste and a small amount of toilet paper are used, the systems are actually fairly reliable. Teaching people that that is ALL that can be flushed is an on going problem. The chemicals seem to be another issue, possibly a design issue but there are ways around that too. Urine crystals build up on the walls of the pipes and reduce the diameter for the waste water to flow. The vaccum systems typically have smaller diameter pipes then the old style "gravity" flush systems. There are companies that make continuous dosing systems that go in the end of the branch lines to help keep them clear. A lot of issues with maintenance can be solved by design of branches in the piping system with isolation valves so the whole system doesn't have to be shut down to fix something. Even replacing a toilet means shutting off the branch or system since it opens a hole in the vacuum system and leads to loss of vacuum. Some more information: https://www.boatus.org/clean-boating/sewage/msd-types/ https://www.boatus.org/clean-boating/sewage/msd-types/ Manufacturers: https://jetsgroup.com/jets-group/the-highest-standards/the-heart-of-our-system https://jetsgroup.com/jets-group/the-highest-standards/the-h... https://evac.com/ https://evac.com/

101404 7y ago
If all that can be flushed is human waste and paper, then why not put it directly into the ocean? It's quickly and completely bio degradable (eaten by fish and micro organisms).
- wmoser 7y ago

jonsen 7y ago

There’s a substantial number of big passenger ships cruising the seas. One would think this was a solved problem.