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The MV1 VM1 valve which is a red box in the back of HR3 will start blinking and close the main recovery path and then it forces helium gas through REG4 (making the horn sound).  Closing this valve increases the pressure in the recovery manifold so that PC1 with a spike (usually just to 2 psi or so but less than 4 psi).  Building pressure in this space pushes helium to the buffer tank through REG4 and REG3.

Functionality of the cycles in HR3

1.  VM1 (red-box valve):
     * Controls inlet gHe to the Kaeser Compressor
     * Closes if there is no pressure rise of '1 psi' (can be changed on the HR3 PLC Screen) in the buffer tank between the sample time period (there are two parameters: sample time period (mins), sample spacing (mins))
     * Has a switch to change its mode to "MANUAL" mode which

2. SV7:
    * There are two threshold values: closing-threshold and opening-threshold that can be set via the HR3 PLC Screen
    * Operating closing-threshold is 70 psi
    * Operating opening-threshold is 90 psi
    * There is a check-valve of 50psig bypassing this SV7 (i.e. if the Buffer Tank pressure (PSW4) > 50 psig, then it stays open to the outside tank regardless of the SV7 state until Buffer tank pressure (PSW4) < 50sig)
    * There is a setting called "SV7 stays closed when compressor idle" which couples to the Kaeser cycles (IDLE → LOAD → STANDSTILL ).
       If it is "YES" (which seems to be the default): then SV7 is OPEN when the Kaeser Compressor is in the "LOAD" state (is shown as a dark arrow (left-to-right))
       If it is "NO": then SV7 is OPEN when the Kaeser Compressor is in the "IDLE" state (is shown as a hollow arrow (left-to-right).

3. Kaeser Compressor (reference Kaeser 9_5869_33 USE SM Operating Manual.pdf):
    * Has two control modes "DUAL" and "QUADRO" (see Section 4.4.2 page 26 on the Kaeser 9_5869_33 USE SM Operating Manual.pdf)
    * DUAL: Switch between LOAD (when it reaches preset-minimum), and IDLE (when it reaches preset-maximum). When the preset Idling time has elapsed, the machine switches to READY/STANDSTILL mode.
    * QUADRO: Switch between LOAD and READY/STANDSTILL after short periods of being IDLE.
                        Following extended times in various operating modes, the machine switches from LOAD to READY/STANDSTILL. The time in LOAD and IDLE operating modes are taken as minimum runtime.

How to Run the Kaeser Compressor continuously on the LOAD mode? (Configuration 1)

This is based on the test we performed on 11/17/2023  (see http://twist.phys.virginia.edu:8081/General/789)

Configuration 1: Kaeser continuously runs with "LOAD" mode (indicated by a sold arrow on the Kaeser screen)
Configuration 2: Kaesuer starts with "IDLE" mode (indicated by a hollow arrow on the Kaeser screen), and only goes to the "LOAD" mode for a second (with simultaneously opening the SV7 only while the LOAD mode is present). This switching happens every ~ 2 mins

Therefore we performed two types of trials to reproduce configuration 1 and configuration 2 and we found that those are consistent in each trial regardless of the "SV7 stays closed when compressor idle" state (either "YES" or "NO").

If the compressor is running, then press the 'emergency stop' button (Red button) of the Kaeser compressor.

Configuration 1: (i) Close the gHe valves so that the PC1 is ~0.6. If this is higher, we have to vent by changing VM1 to manual and rotating that valve.
                           (ii) Start the Kaeser compressor by rotating the red knob, pressing red button, then green button, and in this case you will have to press the "green button on top part of HR3".
                          (iii) Count for 10 seconds, then open the gHe circulation hand valves
                           * You can observe that SV7 is open and Kaeser on the "LOAD" mode continuously.

Configuration 2: (i) Have a higher pressure on PC1, let's say ~5psig (I think any value above 0.75psig would work [ need to test that]), or open the valves to circulation before starting the HR3.
                           (ii) Start the Kaeser
                           * You can observe that PC1 quickly drops down to ~0.6 psig, SV7 stays closed, and Kaeser stays with "IDLE" mode for ~2mins; then SV7 will open and Kaeser changes its mode to "LOAD" only for a second.

Note: After some time, if PC1 stays below 0.6 psig for a longer time, HR3 will go to some kind of an Idle state. In that case, you just have to press the "Green" button on the top part of the HR3 and it should start immediately, then check the Kaeser screen to ensure the "arrow" is bold (not hollow). If the arrow is "hollow" then follow the steps above mentioned under "Configuration 1"
    HR3 top part (see the "Manual Start Button")                              Kaeser Screen (check the arrow in the bottom of that screen)
          Image Added                                             Image Added

The minimum flow required by HR3 to run continuously (Based on an observation on 17 Dec 2023 )

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The inlet flow indicated a drop from ~5slm (avg) to ~4slm (avg), and at that time HR3 stopped. That may indicate we need at least 5slm to keep HR3 running.
Around that time when HR3 stopped PC1 is averaging around ~0.3-0.4psig.. (basically no observed changes in PC1)
Then, notice that the inlet pressure built up to ~0.75psig (slowly), and then the HR3 immediately started.
Thus, the condition to be in the "Configuration 1" (continuously LOAD mode), is to have the inlet pressure below ~0.7 psig.
If there is a higher pressure then it will go to the "configuration 2" (mostly IDLE, but LOAD for a few seconds mode).

So, the summary is,
1)  we need to have at least ~5slm inlet flow for HR3 to continuously be in the "Configuration 1" mode.
2) (A confirmation of what we have seen before): When it turns back ON, if PC1 is ~0.75 or below, then it will go to the "Configuration 1", otherwise "Configuration 2"

Recursive cycles in fault mode:

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When we actually started trying to liquefy HR3 started running normally on its own.  There may or may not be a correlation.

Information about some 'key' (or major) valves on the top part of HR3

VM1

VM1 has two operational configurations:
  1. Manual: Adjust the hand valve in the bottom to open/close
  2. Auto: Automatic control with the inputs from PC1 and PSW4.
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REG4

According to the P&ID this REG4 regulates 8psig. On 14 Nov 2023 we found that its outlet was ~20psig (as shown in the following picture) indicated by the P9 pressure indicator. The RV4 relief valve is relieving at 12 psig. So, on 14 Nov 2023 we adjusted this REG4 down to 11 psig.

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Kaeser Compressor

Kaeser Compressor Display (Click this link to see images)
Kaeser Compressor Maintenance

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