SPARO/Viper Maintenance Items

Monitoring Items

• Flow Meter Reading
During previous operation of SPARO, the flow meter marked "11 lpm" is used. During the summer this flow meter read 26 in the lab and 20 on the telescope. It will likely change during winter operation.
• ⁴He level
• 14.5" is a full level(using a thumper). If the eletronic level sensor is used, it is likely to read between 14.5" and 15". Try to keep the level above two inches. If the telescope is to change actuator positions, it is a good idea to have SPARO's level around 7-8". More full than this could result in a lot of helium dumping out of the fill tube. Less full than this risks allowing the pumped pot scintered plug to become unsubmerged.
• Hold time of 5-7 days on Viper during Austral winter 2000.
• Pumped Pot pressure
In the equilibrium state, a pressue of ~1 Torr indicates a cooling power capable of cycling in 5 hours. At ~0.075 Torr, the cycle should take about 24 hours. Note during a cycle, the pumped pot is involved in draining and filling modes of operation where the pressure does not indicate the pumped pot cooling power.
• Detector stage temperature
• When the dewar is cycled, this temperature should be between 290 and 310mK and should drift to about 370mK when the outer stage runs out of ³He.
• Hold time of 4 days on Viper during Austral winter 2000.
• Heaters on the Masterman System
• Snout Heat- Temp: -20 C to -5 C
• Relief Valve Heat- Temp: -20 C to -5 C
• Motor Heat- Temp: -20 C to -5 C
• Data System Enclosure Heat #1- Temp: +5 C to +20 C
• Data System Enclosure Heat #2- Temp: +5 C to +20 C
• Other Temperatures
• 2 Preamp temp(heated by blue power supplies-Check w/AD590's): +5 C to +25 C
• Pump on Viper Platform(Check w/AD590): -15 C to +50 C
During the summer operation, it is not necessary to have the access panel installed, as the pump is capable of heating with the panel out. During the winter, it may be necessary to install the panel, but when doing so, keep a close watch on the temperature so the pump does not overheat. If the temperature runs too high, it may be possible to open this panel slightly or to drill holes in it(or perhaps cut it into pieces.)

Maintenance Procedures

• Maintain ⁴He level- a fill must be done every three days or so. Running out of ⁴He will result in a capillary plug, which may require removing SPARO from Viper. Photos
• Cycling the dewar: The hold time for the ³He is between 3 and 4 days. The cycle needs to be performed before observing.
• Check and periodically replace the batteries in the 10 microamp current source box, which is used for the Silicon Diode Thermometers.
• Change preamp and data system batteries. Charge the run down ones. When charging the preamp batteries, replace the operational fuses with the "satellite" fuses. When these batteries are charged, reinstall the operational fuses. This operation should be done about every 3 days. This seems to be the maximum amount of time these batteries last.