Liquid helium transport/laboratory storage Dewars
The Cryofab CMSH helium Dewar is designed for minimum loss storage, transportation, and dispensing of liquid helium. The CMSH container employs state of the art vapor cooled multishield technology in conjunction with superinsulation to effect the lowest guaranteed loss rates in the industry on comparable units. The advanced insulation system results in quicker, more efficient cool down without the need for nitrogen pre-cooling. In addition, the elimination of LN2 or helium gas circulation shielding means that the CMSH is virtually maintenance-free.
These units have the same general areas of use as old-style, 4-wall helium containers but permit large storage capacities in small packages with lighter weight.
|Model||Gross Capacity||Daily Boil Off Rates||Overall Height*||Body Diameter||Empty Weight||Transfer Line Fittings|
|CF-30||34 L||2.75%||48 in||20 in||131 lb||3/8 in or 1/2 in|
|CF-60||65 L||1.5%||51 in||24 in||192 lb|
|CF-100||110 L||1%||59 in||24 in||210 lb|
|*NOTE: Overall height includes 4 in casters.|
Liquid helium storage Dewar insert
Janis offers a variable temperature exchange-gas storage dewar insert (VTI) designed for use in 60 L or 100 L LHe storage Dewars. It can operate from <5 K to 500 K.
Design features include:
- Exchange gas manifolds include separate valves for gas inlet and outlet, so it is simple to tell which position is open and closed.
- Safety pressure relief on the central rod of the sample positioner prevents the sample positioner from being launched upward if an ice blockage forms.
- Capacitance vacuum/pressure gauge for monitoring the pressure in the sample tube. This is a digital gauge that can display the pressure in a variety of units and also has an analog bar to show dynamic changes in the pressure. Capacitance gauges work in any environment, including helium, so the pressure measurement is accurate.
- Sliding seal on the outer vacuum shroud allows the VTI to be slowly inserted into the LHe Dewar without having cold helium gas rapidly escape.
This simple liquid helium probe provides an accurate indication of the liquid level in a storage Dewar or research cryostat. The configuration on the right has a thin rubber diaphragm o-ring sealed over the upper portion of the dipstick. The assembly is connected to a small diameter stainless steel tube that is inserted into the liquid helium. The overall length of the stainless steel tube is designed to the customer's specification. The dipstick produces a steady low-frequency pulsation when immersed in liquid helium, which can easily be felt at the diaphragm with a fingertip. When the dipstick is raised just above the liquid level, a high-frequency pulsation occurs. The stainless steel tubing is attached to the diaphragm assembly by a threaded fitting and is easily replaceable.