This guide is intended as an overview of the operation of the SRM compressor and includes instructions for use of the main and backup Haskris Chill Water systems. For in depth operational instructions, see the Cryomech Compressor vendor manual and the Haskris Water Chiller vendor manuals.
The Superconducting Rock Magnetometer (SRM) uses a cyro-compressor to keep a small amount of Helium compressed in order to reach superconducting temperatures. The compressor is water cooled.
The complete Cryomech 2800 He compressor manual can be found here >>> PT405-RM CP2850 Installation_ Operation_ and Maintenance Manual.pdf
The SRM Cryomech 2800 (Figure 1a) chilled input line and warm water return line are directly plumbed the water cooled Haskris (Figure 1b- the white unit at the forward end of the paleomagnetics lab) through a set of three way valves. This unit is in turn cooled by the ship's chill-water. In the event that the ship’s chill water fails or is shut down for maintenance or for repair, a backup water cooling system is in place. The backup system is a Haskris Air Cooled Water Chiller system (Figure 1c). This Haskris is also plumbed to the compressor via the set of three way valves. Switching between these systems requires that the user turn the three way valves (explained below in detail).
Figure 1a: Cryomech 2800 Series Compressor for SRM. The compressor is located at the aft end of the paleomagnetics lab just behind the load end of the SRM track. | Figure 1b: Main Haskris Water Chiller (water cooled). This unit is located at the forward end of the paleomagnetics lab and requires ship chill-water. | Figure 1c: Backup Haskris Water Chiller (air cooled). This unit is located at the forward end of the Core lab under the Forward Description Table. Since the unit is air cooled, it will generate heat in the lab space. |
To monitor the status of the compressor, use the CryoWATCH program (Figure 2a) which is available on the SRM computer. The compressor is connected to the SRM PC via an RS232 cable. The application displays the status of the compressor and logs these values to a text file (Figure 2b). The communications setup should be the default baud rate of 115200 and a slave address of 16, and the com port may need to be adjusted. As of Expedition 397P Tie-up in Cape Town (August 2022), the com port is 7.
When first logging in or restarting the computer, open IMS before opening Cryowatch, otherwise IMS will have trouble with some of its COMs (this problem can be fixed by updating the "CRYOMECH" VISA-Alias in the Cryowatch program).
Figure 2a: CryoWATCH Panel Desktop Icon | Figure 2b: CryoWATCH window. User may monitor water temperatures and oil temperatures after changing the chill water supply. |
The user may set the Logging File Path and the log period (in seconds) as they see fit. The right hand side of the virtual panel with logging displays the temperatures for the water in, water out, Helium gas, and the oil temperature. The arrow at the boundary between the red and blue bars indicates the current temperature. The upper-most black bar indicates the maximum temperature seen and the lower-most black blue bar marks the minimum temperature seen. This panel also displays the amps that the motor is using and the current high and low pressure of the helium lines. Acceptable temperature and pressure ranges are given in Table 1 and alarm settings used during Expedition 397 (Oct-Dec 2022) after repetitive rises in temperature are given in Table 2. The additional tabs available allow the user to view graphs of the temperatures, pressures, and other parameters over time. This is useful when adjusting the water flow rate. Caution: The Panel tab will allow the user to turn the compressor on and off.
Table 1: Acceptable temperature and pressure ranges for Cryomech 2800 Series Compressor | |||||||||||||||
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*Since the Cryomech water temperature is now set by Haskris units for both the main and backup system, these temperature windows are much tighter and the new limits need to be determined and set in the Cryowatch program. |
Table 2: Alarm settings used during Exp 397 |
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Alternatively: If CryoWATCH is unavailable, the Cryomech Virtual Panel with Logging panel is available. This can be found on the SRM desktop at C:\Users\daq\Desktop\cryomech\Cryomech\virt_panel. Set the com port number correctly, designate a file path, and the compressor data will be logged.
If you notice the SRM area is unusually quiet and/or an audible beep is coming from the compressor, check the front panel of the compressor (Figure 3). It will display the fault that has caused the compressor to shut down. Check the Cryomech Compressor user guide for error messages and how to handle each.
Figure 3: SRM Cryomech Compressor. The red box indicates the display which shows the error messages. |
Switching between the main system (ship's chill-water cooled) and backup system is straight forward and should only take a minute. Figure 4a,b show the basic plumbing circuit and the correct valve orientations for each system. The backup system should be ready to put in to service at anytime. In order to ensure this, both systems should be cleaned and purged at the end of every expedition as described below.
Figure 4a: Diagram of the main Haskris and plumbing with its valves set correctly. | Figure 4b: Diagram of the backup Haskris and plumbing with its valves set correctly. |
The ship’s chill water may be shut down for routine maintenance or repair. In this situation, the crew should notify the technical staff prior to the shutdown. This will allow a technician to switch to the backup Haskris system before the chill water is shut down, preventing the compressor from shutting down and allowing the SRM system to continue working uninterrupted.
If the ship’s chill water system shuts down unexpectedly, the cooling water delivered to the Haskris will begin to warm up. Cryowatch's alarms trigger when the "water in" exceeds 73°F. The Haskris will continue to pump until its water reaches 125°F, but the Cryomech will shut down before that when the oil temperature reaches 120°F. This takes around 10 minutes and as long as the temperature as it is noticed is plenty of time to switch to the back up system. Once this happens the compressor will not start again until the oil is below 100°F and the field will need to be re-trapped. An audible alarm, called Buzzbox, was installed above the SRM to prevent such incidents and triggers when the "water in" temperature exceeds 73°F. Techs around the core lab can then quickly react and switch to the backup system without consequences on the compressor. See SRM Alarm (BuzzBox) for water temperature for further details on the alarm.
This protocol assumes that the backup Haskris is clean, full of ship tap water, and plugged in. It also assumes that the Purge Valve is closed and the Backup Shutoff Valve is open (Figure 5 - details in Purging the Systems below) and Cryowatch is running and logging.
Figure 5: Purge Valve is closed and the Backup Shutoff Valve is open. | Figure 6: The two selector valves shown in the Backup position. |
This protocol assumes that the main Haskris is clean, full of ship tap water, and plugged in and the ship's chill-water is functioning and both valves are open (Figure 7). It also assumes that the Purge Valve is closed and the Backup Shutoff Valve is open (Figure 5 - details in Purging the Systems below ) and Cryowatch is running and logging.
Figure 7: Ship's chill-water valves shown open. | Figure 8: The two selector valves shown in the main position. |
Purging the systems not only helps to keep the reservoirs and lines clean, but also tests the backup system ensuring that it is ready to put into service on a moments notice. It should be done at the end of every expedition in the same way that the reservoirs were a regular EOX maintenance task.
While the process is not difficult, it is best to prep for the job and maybe even do a mental run through if is the the first time.
Figure 9: The purge valve open and the backup shutoff valve closed. |
Figure 10: The "from cryomech" line switched to the backup system by turning its black selector valve down 180°. |
A reusable stainless-steel "wye" filter was installed on the ship's chill water supply before the main Haskris on X397T. It should be inspected regularly (TIME TO BE DETERMINED DEPENDING ON HOW QUICKLY IT GETS DIRTY) and cleaned or replaced.
To remove the filter: