We will post items that might help you diagnose and repair your cryogenic vessels.
Symptoms - Liquid nitrogen squirting from area between solenoid valve coil and valve body. The liquid fill line connection will be constantly frosted and LN2 consumption rates will increase. Chipped tile under unit at left rear corner.
Repair - Replace Valcor valve with other brand of valve. (About $265.00 for parts - $150 for labor)
Parts - call 1-888-CRYO-999 for a new solenoid valve (about $295 us).
Ease of Repair - Not very easy. Get a qualified technician to do work
Symptoms - Excessive ice forming on rear of inner tub area. Ice forms around sensor tube and blocks vent tube of sensor tube.
Repair - regular removal of ice from tub and from side/rear of booted lid. Keep the ice from building up on rear of tub by removing it as it forms.
Parts- None. Use a plastic paint scraper to remove lid ice.
Ease of Repair - easy
Breakdown of Duct-Seal on older MVE-XLC Series freezers
It's about time to check the condition of the Duct-seal caulking that is keeping the water out of your MVE XLC series sensor tubes. In the rear of your older MVE XLC- series cryogenic freezer you will find an access port that allow access to the top of the tube that houses the level sensors. Removal of the two small screws will reveal the top of the sensor tube and the wire leads of the sensors. The sensors should be tightly sealed with the gray/black caulk material. There should also be a small copper "J" shaped vent tube packed into the tube along side of the sensor wires. If the caulking material is broken down or has fallen away from the top of the tube it needs to be replaced and re-packed around the sensor tube. This material keeps water from flowing down into the sensor tube and forming an ice block in the tube. Ice will block the exit of the vapors within the tube and cause the controller to read the level incorrectly. Pack the duct-seal around the wires and "J" tube so that water will not drain down the sensor tube. Do not allow water to drip down the tube while re-packing the material....use a paper towel to remove the pooled water before repacking the material.
Parts - New duct-seal or 100% silicone caulk.
Cautions - make sure the "J" tube is properly installed. It's purpose is to vent the vapor that travels up the sensor tube. The sensor tube must not be sealed without a vent tube installed.
Ease of repair - Moderate
Drifting Level Readings on MVE Tech-2000 Controller
I you are experiencing a problem with an incorrect readout from a MVE Tech-2000 controller then you could possibly have a leak in the sensor system. The symptoms are overfilling, low level display readings when compared to the actual LN2 level. A small 1/8 MPT to 1/4 FPT fitting that connects the sensor tube assembly to the clean out purge valve assembly could have developed a crack in the casing and is causing the pressure in the sensor tube to read low. To inspect the fitting you must gain access to the purge valve assembly and leak check all the fittings with a soap and water solution. If any of the connections show bubbles, then either tighten or replace the leaking connection/fitting. If the brass adaptor mentioned above leaks, replace it rather than trying to fix it. You can get the fitting from us or at the local hardware store. The unit should show the correct level once the leak is repaired.
Broken Hinge Tabs on MVE XLC Series Freezers
The hinge must me replaced wit reinforced hinges (Welded back plate). The job is difficult and requires an experienced service technician with special tools. Call us and we will speak with you about the complexities of replacing the hinges.
Worn Out Pneumatic lid Support Struts
After about 5-7 years the pneumatic strut assemblies on some TW K-series freezers loose their ability to hold the lid up in the open position. The struts will have to be replace with new struts. Different K-series models use different force value struts. Call with your model number and we will get you the proper part numbers.
Constantly Frosted hose and excessive LN2 Consumption
If your transfer line is always frosted and your LN2 consumption rate has increased dramatically, it is probable that you have a loose connection or a weeping relief valve. Tighten the connections while they are not frosted. If the problem persists replace the relief valve with a 50psi relief valve. The TW K-series are especially prone to leaking relief valves. Cracked tile under the vessel is a good sign that the relief valve is leaking. The valves are easy to replace and cost about $50 (see accessories page).
Incorrect Level Readings on MVE XLC Series Containers
Some of the level reading gauges on MVE XLC- series container read off-the-scale rather than displaying the true level. I suggest ignoring the gauge and manually checking the level with a wooden yard stick.
Common Human Error Related Issues on Dewars/Refrigerators/Freezers
Connecting Fill hose to "vent" connection on supply tank - Automatic filling unit will not fill and hose is frosted all the time. Fix problem by changing the hose to the "Liquid" connection fitting.
Overfilling and transporting Cryoseries refrigerators- The Cryoseries line of freezers should not be filled into the neck tube area. Let the unit sit at the fill site for one hour before transporting the unit back to the lab location.
Connecting the autofill unit to a high pressure ln2 tank- All autofilling cryogenic freezers should be connected to a LOW PRESSURE (22psi) liquid nitrogen supply tank. Collecting the unit to a high pressure (235psi) will cause the 50 psi relief valve to open and vent the liquid into the lab. Fix the problem by calling your LN2 vendor and have them deliver a "low pressure" tank.
Placing cryogenic equipment in high airflow areas - Cryogenic equipment is sensitive to strong air currents. The currents will cause the units to ice up quickly. The air around the unit should be calm and dry. Keeping units in walk in freezers and next to mechanical refrigerators should be avoided if possible.
