PTR Maintenance and facts

The Pulsed Tube Refrigerator (PTR), a closed-loop Helium system used with NOTCam, is an Iwatani CryoMini and consists of:

1. a Compressor (Model: CW303, Serial Number: MW32842-78) located in the machine room.
   It contains an oil filter which should be exchanged every 15000 hours.
   
   Exchanged in August 2006, after a run time of 28316 hours.
   Exchanged in July 2011 after a total run time of 63199 hours.
   Exchanged in June 2017 after a total run time of 121045 hours.
   
   We have extended the time before exchange of oil adsorber up to 60000 hours with no problems.

   
   
   

2. a Cold Head (P201) which is mounted onto the NOTCam cold table.
   
   
3. a Rotary Valve (Model: M201, Serial Number: MM20004-7Y), also called Motor Unit, which is connected with a short tube to the Cold Head (this one should be sent for maintenance every 15000 running hours).
   
   
4. Stiff copper tubes for Helium flow inside neoprene rubber covering, alltogether 7.5m (one part between the Cold Head and the Rotary Valve, and another part from the compressor in the machine room and up to the dome floor.
   
   
5. Flexible braided stainless steel hoses, 20mm diameter, alltogether 12.5m long, which are connected from the copper tubes coming from the compressor and attached to the Rotary Valve on the instrument, allowing for the rotator and altitude movements.
   
   
6. End couplings of the type Aeroquip 5400-8 couplings also referred to by KIC as Aeroquip 0.5 inch female ends

The helium hoses should be delivered clean, vacuum-baked and charged with
Ultra-High Purity (UHP) Helium gas, i.e. 99.9995% Helium (five nine's)
to a pressure of 275-300 psig (or 2.1 MPa).

When ordering Helium in La Palma the above UHP helium gas is referred to as:
Alphagaz Helium 2