Use Of Top-Off Charges - Telemark Cryogenics 1200 Instruction Manual

Telemark Cryogenics Microprocessor Based Cryochillers
4.4 The Use of "Top-off" gas Charges
The use should periodically shut the system down and check the
balance pressure of the unit. The unit should be sit down for a period
of 24 hours to allow the unit to warm up. Ideally the CT (coldest
temperature) should be between 15° C - 20° C. The b alance pressure
should be in the region of 180Psi to 240 PSI (12.4 bar to 16.5 bar)
depending upon the unit model. See specifications in Section one of
this manual for balance pressures.
The main cause for loss of pressure is due to coupling leaks.
If the balance pressure is too low it can adversely affect the
performance of the Cryochiller (mainly cool and defrost times) and
below the minimum pressure care should be taken in deciding
whether to add a top-off gas charge or to completely recharge the unit.
On this point, it's VERY important to be aware of the history of the unit,
as the unit may have been topped off previously.
Note: The unit can only be topped of a finite number of
times and is also dependent upon the balance pressure
at time of topping off the unit. As a rule of thumb if the
BP drops to about 170—180 PSI you can normally
carry out two top-off procedures. Below 170 PSI
Telemark recommends that the unit be recharged to
prevent damage to the Cryochiller. After the unit has
been top-off more than twice, Telemark recommends
that the unit is fully re-charged. Re-charging the unit
should only be carried out by trained personnel.
Top-off charges are availed from Telemark and or our world-wide
representatives. Part numbers as below
75-1100-00
75-1000-00
US EPA Compliant top-off charge
Kyoto/CE Mark "Green" top-off charge
Page 53 of 63
Revision 1.0.7 October 2018