Transcript messner

LST Gas System
R. Messner
May 2004
Readiness Review
1
Will cover a few of the items
below
•
Gas Mix – the issue of what gas mixtures will be allowed in the
LST system has been resolved
–
–
•
Gas Mixing System
–
–
–
•
Finished with checkout
Had found problems with firmware; fixed
IR-2 Distribution Panels
–
•
In leak test
Want to test output flows ASAP
Integrate with the GIB
Gas Interrupt Box (GIB)
–
–
•
FHA: O’Neill, Budnick
HEEC review
Flow restrictor in hand, checked out
Gas Supply Manifolds
–
Next to be assembled
•
Gas Shack Safety System Expansion underway
•
Electrical
•
External Monitor System
2
Gas Mix
Instead of getting a specific mix approved,
we want approval for a region of mixes
Representation of a three component gas
100
%CO2=100-%Ar-%Isobutane
80
Not 'Physical'
60
Possible Mixes
40
CERN T
Bureau of Mines T
20
ci
ci
0
0
20
40
60
80
100
Per Cent Argon
3
Gas Mix
The operating region takes into account the
stability we have seen in the RPC system
Per Cent Argon (proposed limit, 9.7% isobutane at 0% argon)
Runnable Region (9.41 % isobutane at 0% argon)
Runnable Region +- 1.0% drift
Compare_errors_vs_flammable_region_II
Example Point (8.65% isobutane, 3% argon)
10
%CO2=100-%Ar-%Isobutane
9.5
9
8.5
8
All Operational Settings Are To Be Below the Blue Line
7.5
0
2
4
6
8
10
Per Cent Argon
4
Mixing System Functionality
Mass Flow Meters
Pressure Sensors
CO2
Mass Flow Controllers
CO2
Ar
Ar
Iso
Iso
Flow Control Box
Gas Interrupt Box
(homemade)
Monitors gas flows;
will shut off inputs if
flows or ratios are
not correct
Mass Flow Meter Readings
Shut-off
solenoids
will close if
the gas mix
drifts out of
the allowed
region
Vent
Sample
Port
One master flow;
slaves set by a
ratio to actual flow
of master
Status
A fourth mass
flow meter
can provide a
tie-breaking
vote in case
of MFM/MFC
disagreement
Can also pick
up small drifts
in mixed gas
flows
5
Gas Rack - in leak test
6
Gas Rack
7
Gas Interrupt Box
Functionality
Reading In
From Flowmeters
Simpson
0-5 Volts
CO2
Simpson
2
S
%
S
Mix
2
%
Reading In Range?
Simpson
Iso
2
%
S
S
2
%
Reading Out
To Monitor
Trip?
Reading In Range?
To Monitor
Solenoid
Power
To Solenoids
Argon
Simpson
Shut Off Power
Reading In Range?
To Monitor
8
GIB in checkout
9
Overview of the IR-2
Distribution
Sextant Distribution Manifold
with safety bubblers and rotameters
Layer Distribution Manifold with Resistors
Left Half
Right Half
PSI
“ H2O
Left Half
Right Half
Output Collection Manifold with Bubblers
Left Side Modules
Right Side Modules
10
Silica tubing flow
resistor
11
Check of silica tubing
flow resistance
Delta P (inches H20) for 5.22 liters per hour thru one inch of tube
y = 2.0575e-07 * x^(-3.9842) R= 1
Measurement
Delta_P_thru_one_inch_of_tube
5
4
3
Measured at 50 cc/min:
Delta P = 1.8-2.0 inches H2O
for a 1.875 inch long piece
of 0.53 mm ID silicon tubing
2
1
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
Inner Diameter (inch)
12
Gas Shack Layout
North
12 Feet
10 Feet
Covered
22 feet
19 Feet
He
CO2
Terminal
N2
Light
3.88 in
Fan
RPC
inert
gas
MH-6
VME
crate
Argon
DCH
gas
DCH
gas
Air
Electrical
Panel
Light
Cabinet
15.5 Feet
DCH
elec
DCH and RPC Manifold Panels
Two new inert gas supplies;
Each will have a shutoff valve, orifice,
overpressure releases
Construct a new isobutane supply rack and manifold;
Will have two isobutane shutoff valves, orifice
13
Summary
• The loose ends involved in determining a
permissible gas mix have been resolved
• Very close to having a functional mixing system
with its monitor system to ensure a nonflammable and a runnable mix
– Use air or nitrogen, check the self consistency
and stability of system
• It is important to keep moving ahead; sufficient
and timely technical support is critical
– Want the gas rack in the gas shack before the end
of May
– Delayed a bit because we want to get the manifolds
done first; then we can do more things in parallel
• Expansion of Gas Shack safety system in
progress
• EPICs monitor system will be the next item to
attack
14
Spare Slides
15
Looked at the recent performance of
the RPC system
Snapshots taken a week apart, a half day at a time
This is a measure of the stability
of the gas mixture
Fraction of Isobutane
gasreadings_output_oct_dec_2003_cleaned
0.046
11/20
11/27
12/04
12/11
12/18
0.0455
+- 0.0005 out of 0.045
0.045
Or ~ 1.0 % of the
reading
0.0445
0.044
0
2000
4000
6000
8000
10000
12000
Index
16
Recent performance of the RPC
system
Isobutane
Fraction in Gas Mixture
Percentage Isobutane
2000
1500
-1 % of nominal
+1 % of nominal
1000
500
0
Range
17