Gas Target - Revision history

Ben Reed: /* Changing Gas Supply and Flushing the Lines */ Small change

2025-06-30T21:53:32Z

Changing Gas Supply and Flushing the Lines: Small change

← Older revision		Revision as of 14:53, 30 June 2025
Line 252:		Line 252:

	=== Changing Gas Supply and Flushing the Lines ===		=== Changing Gas Supply and Flushing the Lines ===
	In most cases, Rick Maharaj should be contacted to setup the gas supply for the target and to flush the lines. However, DRAGON personnel can do this themselves if the need arises and they feel comfortable doing so.		In most cases, the Detector Group (current contact - Rick Maharaj) should be contacted to setup the gas supply for the target and to flush the lines. However, DRAGON personnel can do this themselves if the need arises and they feel comfortable that they know what they doing.

	# On the east side of the DRAGON gas target to the right of the platform, close the gas supply line valve, labelled as valve 10 [[File:Screenshot 2025-06-27 164318.png\|center\|thumb\|Gas supply line valve and bypass valve]]		# On the east side of the DRAGON gas target to the right of the platform, close the gas supply line valve, labelled as valve 10 [[File:Screenshot 2025-06-27 164318.png\|center\|thumb\|Gas supply line valve and bypass valve]]

Ben Reed: Update Changing gas supply and flushing line instructions and added photos

2025-06-27T23:59:28Z

Update Changing gas supply and flushing line instructions and added photos

Ben Reed: Added instructions on how change gas supply and flush lines

2025-06-27T23:20:53Z

Added instructions on how change gas supply and flush lines

@@ Line 30: / Line 30: @@
 |Transferred to wiki
 |June 25th, 2025
 |}
@@ Line 245: / Line 250: @@
 * Turn off the leak detector.
 * If RV2 interlock was bypassed, restore the bypass and replace the Privileged User EPICS login by one for a General User.
 ==Emergency procedures, response to pump trips==

Lennarz: /* Pump trips */

2025-06-25T22:03:42Z

Pump trips

← Older revision		Revision as of 15:03, 25 June 2025
Line 259:		Line 259:

	===Pump trips===		===Pump trips===
			If the Roots blowers are tripped off because of an operator error that caused CMTRIN to momentarily exceed 60 Torr, prompt action may enable resumption of target use with minimal delay.

			* close HEBT2:IV8 and DRA:IV11
			* isolate the trap: close IVTR1 and OVTR1
			* look at the RB1B status page, reset interlocks and turn on the pump
			* clear interlocks and turn on the other Roots blowers
			* clear interlocks and restart turbo pumps if they tripped off

			If RB1B cannot be turned on because CMTRIN is > 60 Torr, the gas must be pumped away through the roughing pump RP1.

Lennarz: /* Loss of compressed air to valves */

2025-06-25T22:03:28Z

Loss of compressed air to valves

← Older revision		Revision as of 15:03, 25 June 2025
Line 254:		Line 254:

	===Loss of compressed air to valves===		===Loss of compressed air to valves===
			Valves will fail to the Closed state, except for VNT2 the vent valve for the roughing pump RP1. RP1 must be turned off if VNT2 fails to an Open state due to loss of compressed air (while power remains available to pumps).

			If general closure of gas target valves results in pressure > 60 Torr at CMTRIN, this will trip Roots blower RB1B and cause a cascade of shutdown of pumps and ion gauges. Otherwise, pumps may be left running if the loss of compressed air is expected to be of short duration.

	===Pump trips===		===Pump trips===

Lennarz: /* Power outage */

2025-06-25T22:03:15Z

Power outage

← Older revision		Revision as of 15:03, 25 June 2025
Line 249:		Line 249:

	===Power outage===		===Power outage===
			The EPICS control system is on no-break power, and will continue functioning if line power fails. The exhaust-line fans are on diesel backup power and should come back on within 10 seconds. The large mechanical vacuum pumps are not on back-up power, however. It should be possible to monitor what is happening to the target, but most devices will be unable to go "On". The valves (except for VNT2) fail to Closed, isolating the various volumes of the gas target system from each other and from HEBT2 and the Separator.

			If the cleaning trap was in use and loaded with hydrogen, it is important that the trap is kept cold while power is off. The LN2 consumption rate is low, so that power outages of several hours should be no problem. The trap pressure CG4 should be monitored. If it goes above 1 atm, gas will be blown from the trap, through the relief line, to the Hydrogen Exhaust pipe. Should this occur, it will be necessary to verify the correct seating of the relief valve "puck") before attempting to rough out the the trap again (after power has been restored).

	===Loss of compressed air to valves===		===Loss of compressed air to valves===

	===Pump trips===		===Pump trips===

Lennarz: /* Leak checking */

2025-06-25T22:03:01Z

Leak checking

← Older revision		Revision as of 15:03, 25 June 2025
Line 228:		Line 228:

	===Leak checking===		===Leak checking===
			The DRAGON group's Varian 979 automated leak checker may be connected to the gas target system to confirm that no leaks are present or to locate the source of a known leak. It should be connected by flexible line to a valve marked "Leak Chk." at the upstream east side of the gas target platform. Testing procedure, assuming the target has been pumped down to sub-Torr pressure at CMTRIN, with RP1 on and RV5,RV2 open:

			* Check availability a He cylinder, flexible tubing and "wand" to allow controlled delivery of small flows of He to specific locations.
			* Turn on leak detector. Switch is on the back of the unit.
			* Wait about 5 minutes for the system to test and stabilize.
			* When 'system ready' is displayed on the LCD, push the green button. (This button toggles between Test and Hold.)
			* The leak detector will rough out the flexible line. Wait until 1X10-3 is reached.
			* Open the manual valve ("Leak Chk").
			* If a Privileged User is present, the interlock on valve RV2 can be bypassed, allowing RV5 to be closed so that all the roughing is being done by the leak detector. In the absence of a Privileged User, valves GOT1V and GOT2V can be opened, to bypass RV2 (which will close close when RV5 is closed).
			* Adjust the He nozzle for tickle-the-tongue flow rate. Spray He at the highest suspect joint first, then pause to wait for a reaction from the leak checker. There is a volume control on its front panel to allow a single person to spray and listen for response.
			* Test all suspect joints, working downwards and pausing between joints to allow time for response.
			* If the concern is air leaking into a target which is circulating hydrogen gas, an allowable leak rate should be less than would allow 10 atm-cc of air to in-leak during the time hydrogen is in the target or in the cleaning trap.
			* Open RV5 and close the manual valve "Leak Chk".
			* Toggle the green button to Hold mode.
			* Push the Vent button.
			* Turn off the leak detector.
			* If RV2 interlock was bypassed, restore the bypass and replace the Privileged User EPICS login by one for a General User.

	==Emergency procedures, response to pump trips==		==Emergency procedures, response to pump trips==

Lennarz: /* Hidden valves */

2025-06-25T22:02:44Z

Hidden valves

← Older revision		Revision as of 15:02, 25 June 2025
Line 213:		Line 213:

	===Hidden valves===		===Hidden valves===
			The gas target system has three "hidden" valves -- that is, valves which are not controlled via the EPICS system and are not shown on the EPICS pages. They are manually adjusted, so as to give continuously variable flow rates in certain rarely-encountered situations.



			The '''inlet buffer''' fine control valve is located immediately below the Inlet Buffer Tank on the north-east side of the gas target platform. It is marked '''MV-IN'''. For experiments in which hydrogen gas is recirculated through the cleaning trap, initial loading of the trap is done by a series of "gulps" through the Inlet Buffer Tank: the tank is filled to about 50 Torr each "gulp". The fine control valve should be adjusted so that the time taken to reach 50 Torr is of order 15 to 20 seconds: short enough that the operator doesn't get distracted, long enough that hair-trigger operation of valve FILLV isn't needed. This flow rate would be too high in cases where the cleaning trap is not in use, or the gas is He, and fragile structures such as ultra-thin SiN windows are in the target. In such cases, the manual valve would be closed down to achieve a slower flow of gas into the system.


			The '''vent line''' fine control valve is located under the gas target platform, near the centre at the downstream edge. It has a pink ribbon to identify it. The least difficult access is from the south-west side, over the Roots blowers. For normal operation the valve will be open, so as not to limit flow of vent gas. The special cases typically concern thin solid targets or charge-boosting SiN foils: here the manual valve will be closed down and carefully opened to achieve a slow, safe rate of venting.


			The '''outlet buffer''' valve allows slow pump-down after venting to 1 atmosphere. It is between valve GOT2V and the Outlet Buffer Tank. If valve RV2 is kept closed and valves GOT1V and GOT2V are open, the rate of pump-down may be controlled by this manual valve. It is a Varian valve, marked '''MV-sloR''', located under the Inlet Buffer Tank.

			Because these valves are not displayed in EPICS, it is easy to forget that they may be the cause of "abnormal" behaviour when they are closed down to limit flow. Therefore, whenever any of these valves is adjusted, the fact should be noted in the Equipment Status e-log.

	===Leak checking===		===Leak checking===

Lennarz: /* Venting the target to 1 atmosphere */

2025-06-25T22:02:15Z

Venting the target to 1 atmosphere

← Older revision		Revision as of 15:02, 25 June 2025
Line 202:		Line 202:

	===Venting the target to 1 atmosphere===		===Venting the target to 1 atmosphere===

			* Empty the target (see above)
			* Secure the side plate of the gas target so that it stays in place after the target is vented.
			* If the turbo pumps are on, turn them off and wait 5 minutes. Begin braking of spinning turbos by admitting dry N<sub>2</sub> or air through vent valve VNT1: this valve should be opened and closed as rapidly as can be done by EPICS mouse-clicking.
			* Observe pressure at CMGC. If it is higher than 2-3 Torr, pump away the gas through RV2, then close RV2 and repeat the micro-vent through VNT1.
			* Allow 5 minutes for gas braking, then admit gas through VNT1 until CMTRIM registers 20 Torr. Wait 5 minutes.
			* Start the main venting (same as for a slit box): at the compressed Nitrogen cylinder beside MD2, verify that the manual valve "LN2 dewar pressure" is closed and "Separator vent" is open. Set the "dead-man switch" timer to 15 minutes. (In case you get distracted midway through the venting process, this prevents venting the whole cylinder of nitrogen by mistake.) Locate the vent line pressure relief valve (downstream of MD2, knee height, by valve VV21A. Adjust the pressure regulator (clockwise increases pressure!) until gas can be felt escaping the pressure relief valve.
			* Open VNT1. When pressure reaches reaches 760 Torr (gas escapes pressure relief valve), close the nitrogen cylinder and "separator vent" valves.
			* Close VNT1.

	===Hidden valves===		===Hidden valves===

Lennarz: /* Emptying target and trap at end of running */

2025-06-25T22:02:01Z

Emptying target and trap at end of running

← Older revision		Revision as of 15:02, 25 June 2025
Line 192:		Line 192:

	===Emptying target and trap at end of running===		===Emptying target and trap at end of running===

			* If the trap is in use, isolate it by closing OVTR1 then IVTR1.
			* Pump out the recirculating hydrogen gas via RV2 and RV5 using the roughing pump RP1. Make sure isolation valves IV8 and IV11 are closed!
			* Turn off the ion gauges and turn off power to the turbo pumps and then to the Roots blowers.
			* If the trap is in use, pump it out. Close RV2. Open RVTR1 and open RVTR1B when the pressure is low enough to satisfy the interlock. (This is a slow/fast system to avoid sucking zeolite dust up into the rest of the recirculation system.)
			* Close the manual valve of the LN2 supply dewar.
			* Lower the trap dewar using the hand-cranked hoist. Cover the top of the dewar to minimize condensation inside it.
			* Allow the zeolite to warm up, continuing to pump on it, for at least 4 hours. Verify that no more hydrogen is being desorbed from the zeolite by isolating the trap and watching for pressure rise on CG4. Continue pumping if required.

	===Venting the target to 1 atmosphere===		===Venting the target to 1 atmosphere===

← Older revision		Revision as of 16:59, 27 June 2025
Line 254:		Line 254:
	In most cases, Rick Maharaj should be contacted to setup the gas supply for the target and to flush the lines. However, DRAGON personnel can do this themselves if the need arises and they feel comfortable doing so.		In most cases, Rick Maharaj should be contacted to setup the gas supply for the target and to flush the lines. However, DRAGON personnel can do this themselves if the need arises and they feel comfortable doing so.

	# On the east side of the DRAGON gas target to the right of the platform, close the gas supply line valve, labelled as valve 10		# On the east side of the DRAGON gas target to the right of the platform, close the gas supply line valve, labelled as valve 10 [[File:Screenshot 2025-06-27 164318.png\|center\|thumb\|Gas supply line valve and bypass valve]]
	# In the gas supply shack, find the supply line for the DRAGON target. Tracing this backwards there will be two valves close to the ceiling. Open the valve for the required gas and close the other valve. (e.g. if changing from H2 to He, close the H2 valve and then open the He valve)		# In the gas supply shack, find the supply line for the DRAGON target. It is labelled number 10, the same as the gas supply valve at the target. Tracing this backwards there will be two valves close to the ceiling. Open the valve for the required gas and close the other valve. (e.g. if changing from H2 to He, close the H2 valve and then open the He valve)[[File:Media (15).jpg\|center\|thumb\|Gas supply for the target inside the gas supply shack]][[File:Media (16).jpg\|center\|thumb\|Helium and hydrogen supply valves, located near the ceiling above the flow meter for the target gas supply]]
	# Ensure the valve underneath the flow meter is pointing at the correct gas.		# Ensure the valve underneath the flow meter is pointing at the correct gas.[[File:Media (17).jpg\|center\|thumb\|Valve for selecting target gas]]
	# Go back to the DRAGON target and open the bypass valve located next to valve 10.		# Go back to the DRAGON target and open the bypass valve located next to valve 10.
	# Go back to the gas supply shack and read the flow rate on the flow meter. There are two balls in the flow meter, take the reading using the steal ball. Adjust the flow if needed using the valve on the flow meter (this shouldn't need adjusting).		# Go back to the gas supply shack and read the flow rate on the flow meter. There are two balls in the flow meter, take the reading using the steal ball. Adjust the flow if needed using the valve on the flow meter (this shouldn't need adjusting).
	#* For H2, the flow should be 85s (s = steal ball). This corresponds to 1 L/min.		#* For H2, the flow should be 85s (s = steal ball). This corresponds to 1 L/min.
	#* For He, the flow should be 100 s. This corresponds to 600 cc/min.		#* For He, the flow should be 100 s. This corresponds to 600 cc/min.[[File:Media (18).jpg\|center\|thumb\|Flow meter]]
	# Update the log book with the date, time, location, flow, user, experiment and a comment stating which gas was flushed and at what rate (follow the previous entries for DRAGON as a template)		# Update the log book with the date, time, location, flow, user, experiment and a comment stating which gas was flushed and at what rate (follow the previous entries for DRAGON as a template)[[File:Media (19).jpg\|center\|thumb\|Example logbook entries]]
	# The aim is to flush the supply line with 5x its volume in gas. ~~To ensure~~ this ~~has been done~~, the ~~supply~~ line ~~should~~ be flushed for ~~~1 hour~~.		# The aim is to flush the supply line with 5x its volume in gas. The total volume of the supply line is 3.7 L. So you need to allow sufficient time to flush 5x this volume.
	# After ~~an hour~~, close the bypass valve and then, if you are ready to supply the gas to the target, open supply line valve 10.		#* For hydrogen, with a flow of 1 L/min, the line needs to be flushed for a minimum of 19 mins.
			#* For helium, with a flow of 600 cc/min, the line needs to be flushed for a minimum of 31 mins.
			#* It is recommended to allow 40-60 minutes to ensure that the lines have been properly flushed.
			# After the required time, close the bypass valve and then, if you are ready to supply the gas to the target, open supply line valve 10.

	==Emergency procedures, response to pump trips==		==Emergency procedures, response to pump trips==