Nitrogen Tank Accessories
Accelerated Genetics has a complete line of dewars (liquid tanks) and vapor-shippers
(dry shippers) to meet the storage and shipping needs of any breeder. We are proud
to offer only the highest quality tanks from the world's leading manufacturers.
Tank Accessories: Accelerated Genetics also carries replacement
parts for most tanks including: Neck corks canisters center canisters lids and lid-assemblies.
40433 LN2 Measuring Stick.
40429 MVE Small Plastic Shipping Carton for SC 4/2V and SC 4/3V.
40430 MVE Large Plastic Shipping Carton for XC 20/3V.
It's Time To Replace Your Old Tank If:
- The time between fills is becoming shorter.
- You notice an increase in liquid nitrogen usage.
- Frost is forming around the neck area.
- Condensation is forming on the outside of the tank.
- The vacuum plug is missing or is loose in vacuum port.
- The tank is 10 years or older.
Tank Holding Times
Semen tank manufacturers often specify "Static Evaporation Rate" and "Normal Working Time" in their literature as an indication of a tank's holding time. Static Evaporation Rate (SER) is a calculated measurement of the expected loss of liquid nitrogen over a specific time period - usually measured in liters per day. For example, an SER of 0.095 liters per day, means this tank will lose 0.095 liters of nitrogen each day. If the tank holds 20.5 liters of nitrogen the expected holding time would be 216 days (20.5 ÷ 0.095). However, SER should not be used to determine the length of time between nitrogen fills. SER's are usually calculated with no semen or canisters in the tank. Additionally, SER's are calculated without any movement or opening of the tank. Therefore, SER is not a realistic expectation of the holding time for on-farm tanks. That is why the industry has adopted "Normal Working Times" which is an estimation of a tank's holding time under normal working conditions. "Normal Working Times" are usually calculated by taking 65% of the SER. For the above example of a tank with an SER holding time of 216 days the estimated "Normal Working Time" would be 140 days (216 x 0.65).
So, why is it that sometimes tanks do not seem to meet the "Normal Working Time" published by the manufacturer? Some possible answers could be the age and condition of the tank. Older tanks may be losing their vacuum and therefore the SER is greater than when originally purchased and will not hold as efficiently. This gradual reduction in holding time may not be noticeable at first - but over the years it can become an issue. Generally, you should consider replacing your semen tank after 8 years of use. Also with older tanks we generally see neckcorks that are worn and extremely loose fitting. Severely worn neckcorks can increase SER by up to 30% and these should be replaced with a new neckcork that is designed specifically for the tank in question. Another possible answer could be the tank was mishandled and there could be a sudden loss of vacuum. Under this circumstance the tank will frost up - especially around the neckcork, the nitrogen loss will be rapid and the contents could be compromised in a matter of hours. Tanks should be lifted by both handles, kept upright when emptied, stored on a pallet to avoid contact with concrete and water, and if transported secured in the vehicle and set on a padded surface. Another possible reason for a shorter than expected working time could be tampering with the tank. This may be unintentional - for example, some children are fascinated by the physical properties of liquid and may be using it for their impromptu experiments. That's why it is important to always secure and lock the lid and only allow authorized persons access to the tank.
But more than likely, the reason a tank doesn't meet the "Normal Working Time" is that your operation may not be "normal". Conditions that will affect the working time are neckcorks being removed for extended periods of time - which we often see on larger herds and with time breeding programs. Tanks left in extremely warm conditions or in a draft will have shorter than expected working times. Tanks completely filled with semen have less nitrogen capacity and therefore would have a shorter working time. Accelerated Genetics has conducted several in-house test of tanks and found under certain conditions "Normal Working Time" may be as low as 50% of the SER.
The answer to the question "What is my tank's working time?" can be easily assessed by keeping records of nitrogen use. Each week record the liquid level in the tank using a measuring stick. After a few months, you will be able to assess your average nitrogen loss and will be able to estimate your tank's holding time. Also, this will allow the early detection of changes in nitrogen loss which could be an indication that the tank's vacuum may be failing and allow you to take preventative action to protect your genetic investment. Your Accelerated Genetics representative can assist you with calculating your tank's "Normal Working Time" and is a source for replacement neckcorks, tanks and other breeding supplies.
