Semen/Nitrogen Tank Care
By : Dean Kreager, Licking County Agriculture and Natural Resources Educator
It is almost time to start breeding for the 2021 calf crop. Last week I talked about proper semen handling so this week I thought it was worth providing some information on care and handling of the liquid nitrogen tanks. The nitrogen tanks on our farms are likely storing semen and embryos that are very expensive to replace or maybe can’t be replaced. We need to take care of these tanks to make sure we don’t lose the contents.
Many people may be heading to the Ohio Beef Expo to pick up straws of semen and there are some things you should keep in mind.
Ideally you would have a dry shipper tank to pick up your straws. This is the small tanks they use to send semen to your farm. These are called “dry shippers” because they should not have liquid in them. They contain an absorbent material that soaks up the liquid nitrogen and can maintain a temperature close to the temperature of liquid nitrogen for 1 to 3 weeks. The problem is that these tanks will cost as much or more than your standard storage tank and you need to recharge them with liquid nitrogen before using them.
Legally you can not carry a tank containing liquid nitrogen in an enclosed vehicle such as a truck cab or car. The obvious reason is the risk of spillage in the event of a wreck or from falling over on a sharp curve. The liquid can cause severe injuries or death. The other issue that you may not think about is that nitrogen gas is constantly escaping. That’s why they have a loose-fitting plug and not a screw on cap on the tank. A little bit of liquid will turn into a lot of gas. A couple tablespoons full of liquid nitrogen will quickly inflate a large balloon when it evaporates out of a plastic bottle. This is a great science experiment to show students on how gas takes up more space than liquid. Nitrogen is always evaporating out of the nitrogen tank and can displace the oxygen in an enclosed truck cab. This can happen very quickly if nitrogen spills inside the vehicle. There is no odor to it so there is no warning when the oxygen reaches dangerously low levels.
The other reason you need to be careful when hauling the nitrogen tank is that while manufacturers work to make tanks sturdy, they are still oversized thermoses. If you look at the picture you can see that the inner container is only attached to the outer container at the neck. Rough treatment can cause a crack in this connection. Once the vacuum is lost through a crack the tank will fail rapidly leaving you with a total loss of the contents.
Tank care tips:
- If you must routinely take your tank between farms, make sure it is strapped down where it will not tip.
- Measure the nitrogen level and keep track of it. Ideally this would be daily but even if you could remember to do it once a week you might get an indication when the nitrogen use on a tank has increased so that you can move the semen to another tank. It can also let you know if you need to get the tank filled before it gets too low.
- Store the tank on a wooden platform. Do not store directly on concrete. Concrete can allow moisture to be wicked under the tank and moisture can cause corrosion. Concrete may also contain salts that could be corrosive to the tank.
- Keep the tank clean. There are times my tank is just outside of my working system when I am breeding cows. Splatters get on the side of the tank. We have all seen what happens to metal items exposed to manure for long periods of time. Clean the tank after use and store in a clean place.