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IFR Gas Mixer Information

Contact: Doug Wright,

Gas Analysis Results
Trip point settings
Hardware Specifications
Isobutane release limit
Isobutane bottle change procedure html pdf ppt

GasRegulator settings Typical usage rates Cost Grade (Supplier is Air Gas)
Argon 32-40 psig One six-pack per 3 days
(40.3 lbs per day)
Isobutane 30-34 psig One bottle per 28 days
(4.2 lbs per day)
$450/bottle 99.5% by weight in liquid phase
Freon 32-40 psig One 1000lb tank per 14 days
(72 lbs/day)
$3500/tank (no purity spec)
Backup = three full and one partial 120lb bottles

Pager lists:

Pressure Units
1 atmosphere = 1 bar
1 bar = 14.5 psi
      = 750.06mm Hg = 750.06 torr  (1mm Hg =1torr)
      = 29.53 " Hg
      = 401.47 " H20
      = .01 kPa
Cole Parmer Unit Pressure Conversions

Flow Units
sccm = cc/minute at 0° C and 1 atmosphere


  • Get adjustable power supply and recalibrate flow meters
  • Change flow controller gain factor to match meters (once calibrated)
  • Removed flow controllers from panel to reset decimal point (do spare as a test)
  • Replace pneumatic relay that leaks (last one on south side, controls fill valve)
  • Calibrate EPICs panels for flow (after calibrating hardware)
  • Argon. Check the gauges on the output-side of the regulators to determine which gauge is correct (there is a 4psi difference between the two gauges). Replace the bad gauge(s).
  • Fix house air connection to spare line (running through regulator backwards)
  • Tighten/replace compressed air actuator (south-most)

Log Book

9-25-03. 6:10am. Input flow fault and fill operation fault. Reseting the system solved the prolbem.
7:30am. Happened again. Shifter reset.
8:15am. Happened again (input flow fault), shifter paged me. Reset and ok. No indications of problem.

Manifold pressure 40psi
Primary 42psi 46psi bottle
Second. 44    56
Cyl #1 temp 88 F
     2      88

9-23-03. 5:30am. Output flow fault. Shifter pushed reset button, but did not do SIAMs. It appeared that the system completed a fill cycle even though the isobutane was shutoff. Talked shifter through reset process. Fill proceded normally. 9:00pm. Input flow fault. Happened while cryotech in gas shack (according to shifter). No apparent cause, shifter reset and ok. Both argon sixpacks were full, perhaps this was caused by argon six-pack change?

9-12-03. 10pm. All faults tripped when IR2 switched back from emergency to site power (part of recovery from site power failure earlier in the day). Many other systems were tripped. Siam crate power was off. Isobutane shutoff valves could not be reset because DCH isobutane had a problem. DCH experts had to clear DCH problem first.

9-12-3. 8am. New problem. Isobutane flow controller extremely erratic. Caused fault when isobutane flow monitor exceeded upper limit (monitor was no longer dead). Suspected liquid in flow controller. Fix was to put on infinite vent and reduce regulator pressure in gas shack to 30 psi. After about 30 minutes, both the flow controller and flow monitor recovered. Had to completely close the regulator to get the pressure to drop. Then reopened the regulator.

9-11-03. 8pm. More input flow faults, but not due to isobutane pressure. Ultimately traced it to sudden and spurious drop in isobutane flow monitor. Eventually the meter died completely! Set lower trip limit to -9 to avoid trips until gauge/meter can be replaced.

Input flow fault at 2am. Due to low isobutane pressure. Primary bottle ran out, but secondary bottle was only 24 psi (contrary to test during the day where it was 30 psi). Switching this bottle to the primary regulator (set at 40psi) was still insufficient to complete a fill. The pressure dropped below 12psi. Note, at 12 psi the flow controller began to lose flow. Solution, set interior regulator to maximum and raise primary regulator to 43 psi (measured during fill), which reads 42 psi on manifold gauge.

Also replaced isobutane cylinder#1 old=75lbs, new=191 lbs. Restored rubber pad under cylinder #1. Cylinder temperature was 59 Fahrenheit at 5am. Took gas sample (bottle #1).

9-3-03. Tested effect of removing control cable on the output flow monitor. It indeed causes a trip, but only mixed gas output flow fault. It does not cause any other faults, even if the system is filling. Note that engaging the output fault override prevents the fault from happening.

Calibrated output gas monitor. Signal is pin#2, signal ground pin #11. Set full scale (5V) using external power supply. Set gas calibration constation of 0.652. The output flow reads 12.6 l/min actual.

Isobutane cylinder gas lines were swapped! Probably done by techs when they disconnected/reconnected us for work on the DCH gas system.

Weighed both cylinders. Cylinder #1 was 113 lbs, #2 was 114 lbs, tare weight is 68 lbs. Replaced cylinder #2 with new bottle (189lbs). Raised primary regulator pressure to 36 psi, raised secondary to 29 lbs. Set regulator on gas mixer to 26 psi.

9-1-03. Steve Faulkes noted that control cable to new output flow meter (mixed flow monitor gas 5) was loose. Tightened connector.

8-28-03. 7pm. Input flow fault. Reset and ok. No obvious reason for fault.

8-21-03. Gas system mods completed. System restarted. Switch to mixed gas in IR2. Flow controller settings:

     argon  isobutane  freon 
old   715      273      902
new   715      546      902
Also changed vent duration from 15 to 20 seconds. Changed input flow (high and low) limits on flow meters to match expected flows. Expect new flow rate to be 11 l/min actual. With gas flowing, fill time (1500->1600 torr) is 14 minutes. Drain time (1600->1500) is 6 minutes.

8-20-03. Matt Neibel & Steve Foulkes started on replacing gas system parts to increase flow rate. New 20 slm on freon line. Old 10 slm moved from freon to argon line. Old 5 slm removed from argone line. New 100 slm meter on mixed gas output. Old 10 slm meter removed. Still waiting for pneumatic valve for mixed flow output line.

7-25-03. Gas inventory. Isobutane both tanks installed 6-19-03. Two full tanks in rack. Freon. Two full tanks, online noticably light, standby probably full. Argon, Three sixpacks installed 7-25-03 (tanks 1,2,3 = 1500,1500, 1700 psi). One full six-pack in reserve.

7-22-03. Tightened last two units of pneumatic valve block in gas mixer. This stopped the loud hissing, leak. Removed Sierra Flo-box from mixer rack. Put in bottom drawer of black filing cabinet in gas shack.

6-27-03 Took gas sample. Adjusted isobutane regulators. Freon tank arrived.

                  cyl.1  cyl.2
bottle temp         110    100 degree Fahrenheit
bottle press.        60     83 psi
reg. press. set      30     26 psi, set using vent
reg. press. flowing  28     2? psi

manifold  press.   27   psi
inside regulator   24   psi
mixer press.       23.0 psi

6-19-03 Paged at 4:30 am for gas alarm. Low isobutane pressure, but secondary regulator showed 32 psi on cylinder #2. Came to SLAC. Gauge is bad, it reads 12.5 psi too high. Both isobutane bottles were empty. Replaced isobutane cylinders #1 and #2. New bottles were temp=55F which gives on 22 psi. Could not start mixer because of low pressure fault. Lowered trip point on pressure monitor 3 from 15 to 12. With both bottles online, this allowed system to mix gas. At the beginning of the cycle the isobutane flow controller set the gas to 7.00 before settling down to 1.33 (the proper setting). This caused the input pressure line to drop below the old trip point of 15 psi. Other strange behavior is that the large manifold pressure gauge on the isobutane supply outside, did not indicate the pressure drop during the mix cycle. Asked Mike Racine to two bottles of isobutane and check why freon tank has not been replaced. Racine replies that bottle ordred yesterday, should arrive 6-23-03.

5-29-03 Freon tank empty, ordered new one according to Mike Racine.

5-21-03 Requested order new isobutane cylinder to Mike Racine.

5-12-03 Isobutane cylinder#2 replaced.

5-9-03 Freon tank arrived (ordered 5-2-03).

5-2-03 M. Racine reports that freon tank ordered 4-14-03 arrived by 4-18-03 and he has retrained the tech on duty (with regard to the freon tank). A new tank should have been ordered today.

5-01-03 D. Wright noticed freon tank #1 (online) was empty. Emailed Mike Racine.

4-14-03 Freon tank empty, swapped out. Mike Racine ordered new freon tank.

4-3-03 ~3pm. Premix bottle 16 psi.

4-2-03 3:15pm Premix online bottle 27 psi, regulator set 5 psi. (Simani) Standby bottle is off.

3-29-03 Input fault. Reset and now ok. No reason for fault.

3-24-03 Isobutane arrived.

3-20-03 Requests to Mike Racine:

  • Order two isobutane bottles
  • Repair/replace kinked braided flex line on freon tank #2
  • Replace input gauges on premix regulators so we can read 100psi. Current gauges have too large of a range.
Lester the cryotech came by and said the flex line and new guages will be installed tomorrow (Friday).

Luca measured the fill rate using online monitor of Epics. Fills for 5.5 hours, coasts for 0.5 hours. So ~10% remaining capacity.


  • Mike Racine reports premix gas panel finished and installed.
  • Freon tank arrived (ordered 3-13-03!).

3-13-03 Mike Racine reports ordering new freon tank.

3-12-03 Input fault trip alarms due to freon pressure being low. Online bottle ran out, but the standby bottles was valved off at the tank. Cryotechs did not follow procedures! Called Mike Racine and requested techs fix the situation. Wes came down and corrected valve settings, but did not order freon or move tanks or belly band (end of the shift).

3-5-03 Pigtail for spare 120lb freon tank installed.

3-3-03 Put new isobutane bottle online. Cylinder #2 old 78lbs, new 195 lbs. New freon tank arrived.

2-24-03 Mike Racine new freon tank ordered.

2-19-03 Met with Mike Racine and Matt for premix plumbing design:

  • Install unistrut for two premix bottles on outside of gas shack wall
  • Install gas line from outside to extra spare line in gas shack. Existing spare line to remain intact (connected to gas mixer spare/argon line)
  • Order two regulators and build panel for switching primary/secondary regulators between cylinders
  • Also requested new pigtail for 120lb freon cylinder.

1-28-03 Called Mike Racine. Asked for two new isobutane bottles (only one was delivered on 1-21-03), and informed him of strange checklist entry for 1-26-03. Mike later reported that the vender will deliver the remaining bottle by Feb 7, and Mike's request for 2 more bottles should go into the system tomorrow.

Henry Sent PO request to Judy Meo for premix with 1% SF6, 4.6% isobutane, 35% Halocarbon 134a, balance argon.

1-27-03 Changed isobutane cylinder#1 to secondary (was primary) cylinder#2 to primary (was secondary). Ray Rodriguez attempting to debug SIAM5, did not fix. Problem is that gas shack alarms are getting through, but not being identified as RPC problem. Tightened set screw on purge valve on manifold of tank #2, was not working.

1-25-03 11pm. Freon input faults. Freon pressure is too low (after resetting the faults pressure was 15psi and slowly falling, causing eventual trip). Both freon tanks contain liquid. Regulator outside showing 50psi (should be 40). Raised pressure on regulator inside gas shack (3/4 turn) from 18psi to 30 psi. Also the cryotech log sheet is already filled out for 5:50am tomorrow! The online argone six-pack is currently 1200 psi.

                  freon pressure
date     time     epics led   regulator
1-25-03  11:30pm  612   27.4  30
1-26-03   8:20am  765

1-20-03 Isobutane cylinder #3 replaced by cryotech MCS. Old was 94lbs, new not weighted, nominal is 193lbs.

1-9-03 Spoke to Mike Racine. He will order a freon tank today and another tank tomorrow. His purchase authority limit ($3500) prevents ordering more than one at a time. Also he put in the isobutane order on 12-20-02 but SLAC didn't enter it into the system in 1-2-03.
Called Mike Racine (2pm). Ordered another freon tank today. Will put in additional order tomorrow. Isobutane bottles come from Houston. Looking at delivery on Monday or Tuesday (DCH uses Matheson. Their bottles go from Houston to East coast and then to SLAC, and cost $200 more than Air Gas).
Asked Robert to put full 120lb bottles on each freon regulator. He must get new pigtale for one of the regulators. He will also remove the two partial bottles and relabel the old bottle that is neearly full. Scales check out ok. Note that the Matheson scales (red/green dial) subtract the tare weight (set to 48lbs) while the other (white dial) reads the total weight.

1-8-03 Robert reports that Jim McDonald does not permit us to use one of their untested isobutane bottles and that purchasing says there is a "good chance" for an isobutane bottle to arrive Friday.


  • New freon tank connected. Mike Racine ordered another tank yesterday.
  • Isobutane low (request was 12-20-02) vendor estimates delivery on Jan 17! Not soon enough, so request one bottle by 1-10-03. Can use one of existing DCH spare bottles if necessary. Cryotech (Robert Moore) will get permission from Jim McDonald to use DCH bottle in emergency. Robert also called purchasing to pursue delivery of original bottles by Friday. Robert will follow up every day this week until solved.

1-6-03 New tank still not connected. Simani called cryotechs and left message to put online.

1-3-03 New freon tank arrived, but not connected to system. Left message for cryotechs to connect and put tank on "standby."

1-2-03 Called cryotechs to check on freon tank order. Bob Hall had SLAC purchasing call company. Will deliver tomorrow (tank coming from Vacaville).


  • 10:30am 1000lb freon tank (#3, South) installed and online. Next tank expected Jan 2. Wes will move full 120lb to rack with freon regulators.
  • Freon on-line regulator is all the way open. During fill regulator pressure is 36 psi while tank pressure is 45 psi.
  • Requested (Wes and Mike Racine) order of two isobutane bottles placed today.


  • 9pm Trip caused by low freon pressure. 91 lbs. Reset mixer, freon pressure failing (slowly) to 18 psi. Shut off bottle and open 120lb bottle on tank#1 line (online).
  • 1:52pm Gas sample (bottle #3) taken.
  • 10:30am Old 120lb bottle 105 lb => 35 hours remaining

12-16-02 3pm Two new 120lb freon bottles arrive and are connected to freon tank#1 and #3 input lines.

12-15-02 2am Power failure at IR2 caused IFR and DCH gas to trip. Howard reset circuit breakers in gas shack and reset all faults. PTI pressure 1016 Torr


  • 12:08 pm Filling, Pressure (epics) Ar, Iso, Freon: 621, 596, 573
  • 12:20 pm Freon bottle weight 145 lbs => 37 lbs/day => 2.5 days left
  • 8:30pm Gas shutoff because accelerator is down


  • Trips caused by empty freon tanks. Tank requested on 10-30-02 was never ordered! Put small freon bottle online (~120 lbs) should last at least three days. Cryotech Matt Neibal on duty, contacted Mike Racine. Mike Will place emergency order Saturday or Monday for new 1000 lb tank, should be available on Monday.
  • At 9pm the small freon bottle weighted 168 lbs (TW=48lbs).
  • Isobutane cylinder #2 replaced. Emtpy 86 lbs, new 198 lbs.

11-15-02 Measured flow rate on each endcap door:

    Epics                     Relative
    Flow  Press.   Flow-161   Flow
WB  1429  349        1268     1.00
EB  1537  348        1376     1.09
WF  2080  341        1919     1.51
EF  1952  343        1791     1.41
All 2667  317

11-13-02 Wednesday, 3pm. Output pressure fault, no problems with argon or isobutane. Reset and everything ok.

Tested output flow meter #5 (MKS Type 660 mod 120). Total IFR flow exceeds meter max value. Barrel flow also exceeds max value, endcap door is approx. half max value. Flow was shut off via the valves on the main manifold on the outside of the barrel steel in IR2.

               Epics          In Gas Shack 
               Flow  Press.   Flow  Press.
Flow off        161   372      272   9.8
EB door on     1529   348     3999   7.9
All            2667   318     7113   5.8

11-10-02 Sunday, 12:30pm. Argon ran out causing input fault. Six packs #1 (east, online) and #2 (middle, standby) were empty. Put #3 (west) on online and shut off other two. Paged cryotechs to swap empties and check for leaks.

10-30-02 Called cryotechs, requested new freon tank (#2). Asked techs again to rotate tank #1 so we can connect it to the system.

10-28-02 Raised isobutane regulator on side of mixer from 24 to 26 psi.

10-27-02 11:30pm: Called shift leader to reset gas mixer from last night. Input flow fault would not reset. Used maintence key to reset. During fill noticed that isobutane pressure dipped close to 22psi, outside pressure was 35pis. Next time at SLAC raise regulator pressure on mixer in gas shack.

10-26-02 9pm: Gas system trip. Argon pressure is too low, but EPICs panel shows isobutane pressure fault. Isobutane pressure is fine. Davide says the online and standby argon six-packs are empty. Turns on third six-pack and says there is a leak at the three-way valve. Cryotech (Gary) paged. Third six-pack is ok. Gary says there was a brief leak on the second six-pack. Also says the first six-pack shows 1600 psi! Six-packs 1 and 3 are connected. Giants lose game six to Angels, World Series tied at 3-3.

10-1-02 Ordered two new isobutane bottles (Cryotech: Dennis)

9-27-02 Replaced isobutane bottle #2. Old bottle 74lbs, new bottle 199 lbs.


  • Cleaned out clog in vent on freon tank #3 (sample of sandy material that clogged the vent is taped to page in logbook in the gas shack).
  • Gas sample bottle #1
  • Primary isobutane tank pressure 33psi, regulator pressure 33.5 psi

9-24-02 Ordered new freon tank (Cryotech: Wes)

9-23-02 Freon tank #1 empty, #2 online, #3 standby

8-21-02 Ordered new freon tank (Cryotech: Bob Hall)

8-19-02 Freon tank #3 empty, #1 online, #2 standby

7-19-02 Gas flow restored to RPCs in IR2. Spare supply line not in use because it appears that someone else disconnected the distribution panel from the spare supply inside IR2.

7-17-02 Repaced isobutane bottle secondary. Old bottle 85lbs. New bottle (cylinder #1) 195lbs. Note new naming convention. Primary regulator set to 40psi, secondary 30psi. Gas is not flowing because there will be work on compressed air lines at IR2.

7-15-02 Isobutane manifold changes completed.

7-11-02 Ordered new freon tank (Cryotech: Dennis).

7-9-02 Cryotech Gary removed outside isobutane panel, noted extra relief valve on one line, proposes additional modifications. Contacted HEEC for approval.

7-8-02 Freon tank #2 empty, #3 online, #1 standby. Took gas sample bottle #2. Shut off gas mixer and opened supply lines to air in IR2 in preparation for isobutane modifications.

6-18-02 Switched spare supply line from argon to mixed gas.

6-11-02 Freon tank #3 on standby, #2 is online.

Reviewed isobutane manifold modifications with Mike Racine. Need 1 week installation. New parts will cost $1k (includes new regulators and gauges). Nando/Bill/Henry choose July 8-14 for installation.


  • To Mike Racine: Requested new braid on freon tank #3 and tank rotation. Requested new manifold (a la argon/freon) for easy bottle replacement and mods to isobutane supply so that regulator gauges can be replaced.
  • From Mike Racine. Compressed air leak on 5-28-02 was due to operator error and affected the entire site. Not caused by BaBar, nor was there anything that BaBar could do. Installed check valve on supply to BaBar to prevent backup bottles from being depleted. Dessicator o-ring should not need maintenance.
  • Replaced empty primary isobutane bottle: Old bottle 72lbs, new bottle 188lbs.
  • Took gas sample bottle #3.

6-3-02 Ordered new freon tank (Cryotech: Lester).

5-31-02 Freon tank #1 (North) empty. Tank #3 has kink in braid and should be rotated.

5-28-02 Owl Shift. Site compressed air supply failed due to leak. Eventually repaired. The leak was caused by (SLAC) operator error and was not found for quite some time. Elogbook:5-28-02:Owl Elogbook:5-28-02:Day

5-2-02 Requested new freon tank and two isobutante bottles from Cryotech: Dennis.

5-1-02 Freon Tank #3 (South) is empty, put #2 on standby, #1 online. Isobutane secondary is empty. Old bottle 74lbs. New bottle 197lbs. Order more freon and isobutane.

4-10-02 Called Chris Harvey (LLNL Chemist running Mass-Spec. analysis). Latest gas analysis on sample taken 3-11-02 was run three times (on three different days). Results are consistent, and include 0.25% N2. I asked him to recalculate if ignoring N2 and the fractions changed only by delta of 0.1%, so this is not a significant systematic effect.

3-12-02 Called cryotechs (Mike). Asked to order two freon tanks and complain to Airgas about half filled isobutane bottle


3-8-02 From Swetha Reddy (for Butch Byers)

Isobutane usage Calendar 2001
IFR 1020 lbs
DCH 1416
Tot 2436 (limit is 2600)

Calendar 2000
IFR 746lbs

3-4-02 Switched extra output flow supply to mixed gas (was argon for remediation test). Bill Wisnewski in the gas shack and Doug Wright was on the phone. Note that we first relieved the argon pressure through the IFR vent.

3-1-02 Freon tank empty (#1 North)

2-21-02 Timed gas cycler: 32 minutes cycler on, 15 minutes cycler off with output flow of 7113.

R  = r(1+t/T)   R = input flow; r=output flow
                T = time duration of cycler on
                t = time duration of cycler off

1-30-02 Rotameters on each corner of detector: Gilmont Instruments Model 65 mm (glass length is 65mm) GF-5321-2000 Scale is non-linear from 0-120 catalog According to part #, endblocks are aluminum, and scale is "Direct Reading" as opposed to calibrated.

1-29-02 Adjusted isobutane regulator (takes time for bottle to warm up)


  • Requested cryotech (Wes) to order and install new freon tank #3
  • Replaced empty isobutane bottle
  • Take gas sample bottle #3

1-22-02 Freon #3 (South) ran out


  • Installed 9-flow test-gas manifold in IR2 to spare gas line to gas shack.
  • Found and fixed three leaks on stainless connections on spare line in gas shack.
  • Tested switchover from argon to mixed gas. Should disable IFR cycler when opening valves to put argon in spare supply line. Don't forget to renable the cycler when after the valve is fully open.
  • 5:25pm Set flow to 3cc/min (nominal) of pure argon to test-gas manifold at 6psi

12-7-01 Requested cryotech support from Mike Racine for the following:

  • Replace gauges on test-stand regulator, bottle 200psi max output 20-50psi max
  • Connect shunt on extra gas line

12-7-01 Requested cryotech (Matt) to

  • order new isobutane, two empties
  • Order new freon tank (#1 North), cryotechs should disconnect and connect bottle when it arrives

12-5-01 Gas sample taken bottle #1, Isobutane primary empty, Freon #1 (North) empty

11-19-01 Requested cryo-tech (Robert) to rotate new freon bottle, so valve faces the manifold

11-02-01 Requested new freon bottle from cryo-tech (Gary)

Mike Racine: Normally order Standard Grade argon (99.995% 60$ per six-pack), but in Aug 01 cryo ordered Ultra High Purity (UHP 99.9995% 400$ per six-pack) by mistake. Requested approval to order standard. Approved.

10-30-01 Connected new freon tank (#3), disconnected empy (#2), replaced empty isobutane bottle

10-16-01 Requested labels on freon manifolds (to Mike Starek, completed by Gary 10-30-01)

10-12-01 Replaced empty isobutane bottle, connected new freon tank

9-18-01 Gas sample taken

8-?-01 Freon manifolds installed, similar to new argon manifolds

8-14-01 House compressed air line has leak, causing valves to close. Flow stopped and caused fault. Cyrotech (Mike Starek) repaired leak (o-ring in dessicator had disintegrated). He also replaced the backup air cylinder since it had run empty during the leak.

6-01-01 Adjusted argon regulators

  • Took gas sample
  • Moved belly band on freon tanks

    5-25-01 Adjusted argon regulators

  • Met with Mike Racine and Art Candia about cryotech tasks and gas system modifications

    5-15-01 Adjusted argon regulators

  • Changed isobutane primary (old=83lbs, new=188lbs)
  • Swept morning dove out of argon gas tent

    5-12-01 System trip when isobutane primary ran out (raised pressure on secondary)

    4-4-01 Changed argon six-pack

    3-28-01 System trip when isobutane secondary ran out (raised pressure on primary)
    Changed isobutane secondary (old=80 lbs, new=198)

    3-7-01 ordered 50 gaskets for sample bottle Cajon NI-4-VCR-2

    3-7-01 2pm Output Gas Fault. Everything was fine. Reset and ok. PEPII had just started injection.

    2-9-01 Gas sample taken (bottle 3)

    2-1-01 Changed isobutane primary (old=90 lbs, new=201)

    1-25-01 Gas sample taken

    1-18-01 3:30pm Mix changed, hypernews posting

    1-10-01 Gas sample taken

    11-17-00 Gas sample taken

    11-10-00 Mix changed

               flow controller        target
               reading  dial-setting  fraction
    argon      4.49        9.02        65.5%
    isobutane  1.55        3.17         4.5
    freon 134a 9.00        9.02        30.0

    7-31-00 Mix changed (3:20pm)

               flow controller        target
               reading  dial-setting  fraction
    argon      3.56                    60.5%
    isobutane  1.33                     4.5
    freon 134a 9.00                    35.0