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Large Scale Conservation Part 2

Recently we did some work on Monitor’s twin vibrating side-lever steam engine (seen here submerged in its treatment tank).

This engine is almost the size of my kitchen. Made mostly of cast and wrought iron it weighs approximately 30 tons. In order to keep it submerged in treatment solution this 40,000 gallon tank (the square tank in the middle of the pic) was constructed for us by the folks at the Northrop Grumman shipyard here in Newport News.

The tank has to be big enough not only to keep the whole engine submerged, but also to allow plenty of room for conservators to get in and work around the engine. It has a watertight door fitted for easy access, and a set of sprinklers plumbed around the top to keep the engine wet even when the tank is drained for a work session.

But getting a big enough tank isn’t the only requirement. Nearly 40,000 gallons of deionized water is no laughing matter. Thus far the engine has been kept in tap water, which has been adequate for the preliminary stages of the treatment. Tap water after all has only a tiny fraction of the chloride content of sea water. Now that treatment is progressing however we need to start using deionized water and that means upgrading our current deionizing system, capable of generating “only” about 6000 gallons at a time. Of course the existing system (in the pic to the right) is at least an order of magnitude larger than any deionizing system I had seen before working on this project, but it needs to be even bigger for the demands we will soon be placing on it.

Into those 40,000 gallons of water we add 150 lbs of sodium hydroxide. This lab buys sodium hydroxide and other treatment chemicals by the pallet full. Whenever we change out the solution in the tank we have to contact the city waterworks in advance to let them know that we are sending a big dose of very alkaline water their way. Fortunately the people at the waterworks actually find that a large dose of hydroxide from time to time helps them keep their system well balanced, so we can dispose of our solution that way. These can all be minor issues when your artifact will fit into a Tupperware container. They become much bigger issues when you have BIG artifacts like these.

Now that’s the engine and its treatment tank. Take a look at that big octagonal tank behind the engine tank. In there is the Monitor’s famous revolving gun turret. It weighs about 120 tons and sits in 90,000 gallons of water!


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