Liquid nitrogen tanks are used for long-term storage of extremely valuable samples that are either difficult or impossible to replace, from research specimens in biorepositories to reproductive tissue in fertility cryostorage facilities. Due to the extreme consequences tied to sample loss, these facilities want to be sure they use the optimal monitoring approach to create a dependable safety net in the event of a liquid nitrogen tank issue.
To start, let’s look at the three main methods to monitor liquid nitrogen storage tanks.
1. Monitor the Temperature Inside a Liquid Nitrogen Tank
In this method, a temperature probe is typically inserted into the tank or dewar and measures the temperature of the LN2 vapor phase — normally a few inches above the actual LN2 level in the storage device.
If the vapor temperature climbs above the normal level, that means the LN2 level is getting low, and alerts are sent out to notify key personnel that the internal temperature inside the liquid nitrogen storage tank is elevated above its normal range. These real-time notifications give staff several hours to remedy the issue before the temperatures are elevated high enough to potentially damage the contents.
It is especially important for the LN2 monitoring system to provide an alert escalation capability so that additional alerts are transmitted as increasingly higher temperature limits are breached. That way, staff knows the situation is getting worse and it will require a quicker intervention.
2. Monitor the LN2 Level Inside the Liquid Nitrogen Tank
Most large storage rooms have an automated system for refilling liquid nitrogen in devices that are getting low. In these cases, a large storage facility with a large volume of liquid nitrogen is connected by a series of pipes and manifolds to the individual LN2 storage tanks.
Each liquid nitrogen tank or dewar has LN2 level sensors for both low and high levels. When the LN2 level reaches the low level, the auto-refill function starts. When the LN2 level reaches the high level, the auto-refill function stops. By having an independent LN2 level sensor in the liquid nitrogen tank, staff will be notified if the auto-refill did not occur and the LN2 level is approaching a dangerously low level.
While some LN2 tanks have auto-refill functions, others are manually filled. Staff needs to know when a manual fill tank needs to be refilled —perhaps sooner than anticipated for that tank. Monitoring the system provides staff with the alerts they need to take swift action.
Most liquid nitrogen tanks have a local alarm if the LN2 level gets too low; but in many facilities, there is often no staff around to hear the alarm. Therefore, an independent alerting system is crucial for notifying staff that there is a refill problem.
3. Monitor the Outside Temperature of the LN2 Tank or Dewar
It is rare for the vacuum insulation of a liquid nitrogen tank or dewar to be breached or damaged. But if either of these issues were to occur, the insulation value loss inside the tank would mean the interior’s extreme cold would make it to the exterior of the tank. (Most LN2 tanks and dewars rely on the vacuum between the inside and outside of the LN2 tank, which is the most effective type of insulation.)
By monitoring the exterior surface of an LN2 storage device, any rupture or damage to the tank that compromises its insulation integrity will be detected immediately and appropriate staff will be notified.
These insulation breaches are almost always a result of collisions between an LN2 storage device and metal carts or other devices on wheels that can collide.
So, What’s the Best Method to Keep Your LN2 Tanks Safe?
Have samples or specimens in your collection that are either impossible or very difficult to replace? If so, the best method to protect the contents of your LN2 storage tanks is to use all three monitoring methods. Together, they create a comprehensive safety net that effectively prevents the catastrophic consequences of LN2 storage failures.
By the same token, it’s recommended that each of these monitoring systems are installed for optimum reliability for that added peace of mind. This includes backup power and alert notifications capabilities so you can always stay connected to your tank’s safety.
At CORIS, we offer all three types of LN2 monitoring, providing our customers with the comprehensive protection that modern facilities require. Learn more about our system.
