FREQUENTLY ASKED QUESTIONS
Stainless Steel Products
None of the products manufactured or sold by phaseTwo require a Safety Data Sheet; there are no hazardous materials used in our manufacturing processes.
– An SDS for liquid nitrogen is normally required under OSHA regulations and can be obtained from your LN2 supplier.
– UN1977 Nitrogen, Refrigerated Liquid
o Hazard Overview
§ Liquid nitrogen is very cold (-196oC / -320oF) and direct contact with cryogenic fluids (liquid or gas phase) can cause severe personal injury including burns, frostbite, eye damage and asphyxiation. Appropriate PPE must be used when handling liquid nitrogen.
– 1. Temperature – in vapor phase storage, stored samples are kept in the cold vapor (gas) above the liquid nitrogen pool. The nitrogen gas (the ’vapor’) is warmer than the liquid pool; nitrogen gas stratifies above the liquid pool, and therefore temperatures are warmer the further from the liquid pool. In liquid phase storage, the cryogenic vessel is typically filled nearly full, so that all stored samples are submerged in liquid nitrogen.
2. Cross contamination – Vapor phase storage greatly reduces the risk of cross contamination in the event of a leak or storage mode failure (cryovials, blood bags, ampules, straws, etc.) that releases stored material into the cryogenic storage chamber.
3. Storage Mode – Check with the manufacturer of the storage mode used to confirm if the mode used is suitable for immersion in liquid nitrogen.
4. Racks – For full access freezers, the use of aluminum racks is strongly recommended; aluminum is much more thermally conductive than stainless steel and the use of aluminum racks will reduce the temperature in vapor phase substantially. Limited access freezers (HCHE) have an aluminum carousel, or turntable, that serves the same purpose as aluminum racks
– Replace it; relief valves should be replaced every 2-3 years as a matter of routine maintenance.
– Using a hair dryer of commercial heat gun (set on LOW – Do Not Exceed 160oF / 71oC), direct the warm air flow around the underside of the lid for 5-10 minutes so the air flow contacts the lid gasket. Repeat as necessary until the lid opens.
– It’s recommended to clean the foam core and gasket regularly to remove any frost or ice.
– During normal operation, the solenoid valve will make a soft humming noise. If the noise is excessively loud, turn the valve on and off using the controller. If a soft humming noise is heard, the valve should continue to operate normally. If the humming noise is excessive, replace the solenoid valve. Solenoid valves should be replaced every two (2) years.
– If the solenoid valve is chattering or rattling, and the freezer continues to fill, check the solenoid valve orientation. There is a directional flow arrow in the brass body of the valve; the arrow should always point toward the vessel, NOT the LN2 source.
– Gas Bypass Systems, aka hot gas bypass, are designed to vent nitrogen gas trapped in the fill hose or manifold to avoid introducing these gases into the liquid nitrogen pool inside the freezer. In theory, the warm gases trapped in the hose or manifold will introduce warmer gases into the liquid pool and increase evaporation rate while putting stored samples at risk due to temperature rise.
– Gas bypass systems are effective when an LN2 freezer is connected to a manifold with a remote LN2 source (bulk or micro-bulk) or longer than normal fill hose but are not typically necessary when a freezer is connected to a dedicated LN2 source via a standard 4-6 foot fill hose.
– Gas bypass systems utilize a second dedicated solenoid valve and sensor that monitors the gas bypass vent. When a fill is initiated, either manually or automatically, the gas bypass solenoid opens and vents the trapped nitrogen gas until the system senses liquid flow; the controller then closed the gas bypass solenoid valve and opens the primary fill valve, allowing liquid to flow into the freezer.
– Gas bypass systems are typically fitted with a compression fitting on the vent outlet to accommodate copper tubing for an external (outdoor) vent.
– Always use an oxygen monitor inside the LN2 freezer area. Nitrogen gas will displace normal room air and deplete the oxygen supply.
– Vacuum-insulated hoses are recommended for large manifold-type LN2 supply systems where the supply source is remote, or when a single dedicated LN2 source is more than 10 feet from the freezer and will help reduce fill time and overall LN 2 consumption over the life of the freezer.
– Recommended inlet pressure is between 10-22psig (0.7–1.5 bar). Higher pressure will increase turbulence inside the freezer, increase LN2 usage overall and can affect solenoid valve performance. Lower pressure will increase the length of time it takes to fill the freezer.
Aluminum Products
None of the products manufactured or sold by PhaseTwo require a Safety Data Sheet; there are no hazardous materials used in our manufacturing processes.
– An SDS for liquid nitrogen is normally required under OSHA regulations and can be obtained from your LN2 supplier.
Dewars are only used for the storage and dispensing of liquid nitrogen. Freezers are used for storing biological samples and are equipped with either round canisters or square racks for vial storage.
Increased LN2 consumption can be caused by a couple of issues:
1. A poorly fitting neck tube core (foam plug). Check to make sure the neck tube core is in good shape and isn’t damaged. Also make sure it’s clean and not covered with frost.
2. Loss of vacuum. A tank that is losing its vacuum will evaporate more LN2 than usual. Tanks will usually exhibit signs of a vacuum loss, including sweating or frosting of the outside, moisture collecting underneath the tank, frosting, or icing of the cap, and vapor escaping from the tank.
UN1977 Nitrogen, Refrigerated Liquid
o Hazard Overview
§ Liquid nitrogen is very cold (-196oC / -320oF) and direct contact with cryogenic fluids (liquid or gas phase) can cause severe personal injury including burns, frostbite, eye damage and asphyxiation. Appropriate PPE must be used when handling liquid nitrogen.
– Fifteen (15) years.
– Monitor your LN2 level and never let it get below 25%.
Letting a tank run empty is how most samples are lost and is the most preventable reason. Set up a regular schedule to check your level. You can also add an optional low-level alarm to most tanks which will alert you when the level is low.
– Secure your tank when transporting.
Don’t let your tank roll around or end up on its side. Movement of your tank when filled causes the inner vessel to swing & sway. While normal sway is accommodated in tank design, long-term excessive movement of the tank can cause the neck tube to crack or break. Tanks are not designed to be laid on their side. This adds additional stress to the neck tube and will cause premature failure. Keep your tank uptight at all times.
– Don’t store your tank on a concrete floor.
Aluminum reacts with the alkalis (OH) found in Portland cement concrete. When these two chemicals are combined, the reaction produces hydrogen gas. Ultimately this will deteriorate the bottom of your tank and thus ruin its ability to hold a vacuum. Store your tank on an optional roller base, in the cardboard shipping box or on a wood pallet.
– Keep your Vapor Shipper filled so it’s ready to use when needed.
Keeping heat out of your Vapor Shipper by keeping it filled with LN2 is a best practice. When you’re ready to load the shipper, just pour off the excess and it’s ready to ship. No waiting time required.
– Always keep your tank cold!
LN2 tanks will last longer if they are kept cold with liquid nitrogen, even when you are not storing samples. Allowing them to warm up and filling them only when needed will shorten the life of your tank.