NIRAD Data Package for the NASA WB-57

1
NIRAD Data Package for the NASA WB-57
Non-dispersed InfraRed Airborne CO2 Detector
(NIRAD)
Prepared by Darin Toohey University of Colorado,
Boulder April 2004 Updated March 2005
2

• This package has been updated to account for a
  change in mounting of NIRAD into the rack of the
  right wing pod in order to make room for the new
  fast ozone instrument during PUMA (April/May
  2005). The individual components of NIRAD are the
  same. However, they are now packaged into a
  single box that will be mounted to the left rear
  of the wing pod rack.
• Major changes to NIRAD, reflected in the revised
  slides below, are
• Weight has been reduced 4 kg (9 lb). New weight
  66.5 lb
• The instrument is contained in a single box
  rather than three separate components as
  previously. New dimensions 10(w) x 24(l) x 14
  (h)
• The box is mounted with six 10-32 cadmium plated
  stainless steel screws that are easily accessed
  for quicker installation and removal. New,
  simpler, structural calculation
• There is now a single gas line connection (as
  opposed to the original three) to make/break
  during installation and removal. New, simpler,
  operating procedures
• Minco heaters have been added to the
  gas-handling system to reduce changes in pressure
  regulator settings. New power diagram and
  specifications
• No changes to pressure system

3
1. Payload Description
Measurement Carbon Dioxide (CO2) Method
Non-dispersed infrared absorption spectroscopy
relative to a reference gas with known
CO2 Instrument Details Right wing pod, 66.5 lb,
10x24x14 (lwh), lt250 W (28V aircraft power at
lt10 A) Sampling frequency 10 Hz Accuracy lt
0.1 Precision lt0.03 at 10 Hz, lt0.01 at 1 Hz,
lt 0.003 at 10 seconds NIRAD consists of three
systems (1) CO2 detector, (2) power and data
acquisition, and (3) gas-handling. All three
systems have flown previously. The CO2 detector
was first flown in 1999 as part of CORE
instrument during RISO and ACCENT and again in
2004 during PUMA-A. There have been no changes to
the detector, other than inspection and routine
maintenance. The power and data acquisition
system were new for PUMA-A, and are flown here
without change, other than to software. The
gas-handling system is the same as that flown in
May 2004, except that it is now packaged into a
single box that contains the detector and
power/data system. The detector is packaged in
a vacuum housing to facilitate management of
temperature and pressure. At power-up the housing
is pumped down to 300 hPa by one stage of a
diaphragm pump and held at this pressure
throughout the flight. Thus, at pressure
altitudes lt 300 hPa the pressure within the
housing is above ambient. By design, if the
pressure differential is significantly greater
than about 5 psi, the O-ring seals leak. A
redundant additional mechanical safety relief
valve (set for 15 psi or less) is placed on the
housing. Two 1.2 L epoxy-coated, fiber-wrapped
aluminum bottles (DOT rated and certified) are
filled to 1600 psi before flight with zero air
doped with CO2. These standards are sampled
repeatedly during flight to provide an accurate
standard for reference to the NOAA/CMDL CO2
scale. Two-stage regulators provide a service
pressure of 25-30 psig throughout flight. The
bottles and regulators are backed with safety
relief valves. The diaphragm pump is
current-limited for a soft start (that is,
there is no electrical surge on startup, allowing
for use of compact, highly efficient Vicor VI-100
DC/DC converters.
4
Instrument Schematic
Electrical Outline

LiCor electronics and pressure controllers
Astec DC/DC
100 W rating
20 W
24V
Vicor VI-100
Pressure gauges and controllers
2 W
7805 7812
CO2 analyzer
10 W
28Vin
5V
PC-104 DC/DC
100 W rating
Computer A/D System
15 W
Vicor VI-100
Diaphragm pump
50 W
Heaters
75 W
5
2. Structural Analysis
(a) Itemized weight Component Weight,
kg Weight, lb CO2 analyzer 7.00 15.4 diaphragm
pump 4.10 9.0 MKS 248 Control
valve 0.54 1.2 solenoid deck 0.58 1.3 gas
standard 1w/relief valve 1.60 3.5 gas standard 2
w/relief valve 1.60 3.5 PC-104 computer
stack 0.60 1.3 dc/dc converter 1 0.10 0.2 dc/dc
converter 2 0.10 0.2 gas regulator 1w/relief
valve 1.00 2.2 gas regulator2 w/relief
valve 1.00 2.2 cables, gas lines,
fittings 2.16 4.4 frame, structure,
covers 9.55 21.0 inlet 0.50 1.0
Total 30.23 kg 66.5 lb
6
2. Structural Analysis (click on Excel
spreadsheet for supporting calculations)
(b) Issues There are two structural issues to
consider for integration of NIRAD into the wing
pod of the WB-57. The first issue involves the
mounting of the individual components listed on
the previous page into the box, the second
involves mounting the box to the rack. These will
be dealt with separately below. 1 - Mounting of
individual components into the instrument box Due
to small masses, nearly all components are
mounted within the respective housings with high
safety margins (factor of 10 or larger). The
component with the lowest safety factor is the
diaphragm pump, which weighs 10 lbs and is
mounted with four 10 stainless steel bolts to a
1/8 thick aluminum plate that forms the bottom
of the box. Viton rubber sheets are used between
the lugs of the pump and the plate to dampen
vibration, although the Vacubrand pump used here
was selected for its extraordinarily low
vibration. The bolts are secured into locking
captive washers (cinch nuts). Structural
analysis shows that all loads have safety margins
of x5 or larger, the lowest being the vertical
(up) load plus horizontal (forward/aft and
left/right) overturning moments (margin 10).
Thus, it is determined that the pump is safely
mounted to the box, and that all other
components, which are smaller and lighter, do not
represent safety issues.
2 Mounting of box and frame to rack The
instrument box is mounted to the rack with six
10 cadmium coated, stainless steel bolts.
Structural analysis shown in the accompanying
excel file indicates that the lowest safety
margin (380-480, or a factor of nearly 5 over
nominal ratings) is for the flange bending
(vertical load plus horizontal overturning
moments). Flange shearout has a safety margin of
over 700, and all other margins are at least a
factor of ten over nominal ratings.
7
(No Transcript)
8
3. Electrical Load Analysis
Maximum value will occur on ascent, immediately
following power-up, where the pressure is largest
and temperatures are lowest. This is due to
loading of diaphragm pump and heaters. Nominal
current draw will depend on cruise altitude
lower values pertaining to highest
altitudes Momentary (lt 0.1s) surges of 0.3 A
may occur due to valve switching at 120 second
intervals
9
4. Pressure/vacuum systems

• NIRAD has three systems that fall under the
  category of pressure/vacuum (P/V) systems flow
  system (P and V), gas handling system (P), and
  detector housing (P and V). These will be
  discussed separately below.
• The flow system consists of a Vacuubrand MD
  VarioSP 4-stage diaphragm pump, two stages of
  which compress air to 1000 hPa (15 psi)
  absolute pressure from ambient pressure under all
  flight conditions, and two stages that serve to
  pull air through the flow system ultimately
  venting to ambient air. A safety relief valve set
  to 5 psig serves to limit potential
  over-pressure situations (see C below). All
  materials are capable of withstanding an
  overpressure of 45 psig without damage.
• The gas-handling system consists of two
  Structural Composites Industries (SCI) 1.2 L
  epoxy-coated fiber-wrapped Al bottles (ALT
  296C-32449 and ALT296C-32479) both DOT-E
  7277-3000). Bottles were recertified in April
  2004. The bottles are filled with CO2-doped air
  to a service pressure of 1600 psi before each
  flight, thus serving as standards for in-flight
  calibration. The bottles are backed with Nupro
  series R3A (177-R3A-K1-E) stainless steel safety
  relief valves that can be set at Ellington Field
  prior to use.
• The detector vacuum housing is custom built from
  six 2024-T3 aluminum plates machined for reduced
  weight. Only the bottom plate is structural. The
  four side plates are welded together to provide
  an adequate vacuum seal. This weld is not
  structural. Viton O-rings seal the top and bottom
  plates to the rectangular sides of the housing.
  Vacuum is maintained by actively pumping on the
  sealed box, and any small leaks are compensated
  for by venting the flow through the LiCor
  analyzer into the box. At low altitudes, the
  housing is at a lower pressure than ambient.
  Above 35,000 feet, the housing is maintained
  several psi above ambient pressure. At these low
  pressure differentials, the box remains sealed.
  However, laboratory tests in a bell jar (photos
  available upon request) show that the housing can
  withstand 10-12 psig positive differential.
  However, under larger positive differentials the
  O-ring seal on the top lid distorts sufficiently
  (0.015-0.020) to allow release of pressure.
  Thus, the housing is best characterized as a
  leaky vessel whose primary function is to
  provide a ballast volume to aide in pressure
  control of the LiCor 6251 CO2 analyzer. The
  pressure within the housing is maintained
  electronically using an MKS-1250 pressure
  controller. As outlined in the figure on the
  following page, should the electronics fail, the
  valves will normally close, and the pressure
  within the housing will come to the same as that
  of the compressor stage of the diaphragm pump.
  Therefore, the safety relief valve described in A
  is best placed at the immediate outlet of the
  diaphragm pump.

10
5 psig safety relief valve
Normally closed valves

Vent to box
Housing pressure determined by this feedback loop
Housing
11
5. Laser systems - none 6. Hazard Source
Checklist

• Enumerate or mark N/A
•  
• N/A - Flammable/combustible material, fluid
  (liquid, vapor, or gas)
• N/A - Toxic/corrosive/hot/cold material, fluid
  (liquid, vapor, or gas)
•  
• X - High pressure system (static or dynamic)
• We fly two CO2-in-air standards for in-flight
  calibration. These cylinders (Structural
  Composites Industries Model 374, DOT-E 7277-3000
  spec) are 1.25 l in volume and filled to a
  pressure of 1600 psi 109 bar) and are fitted
  with Nupro series R3A (177-R3A-K1-E) pressure
  relief valves preset to 2200 psi. Pressure is
  reduced by a Scott 51-14D two-stage regulator
  equipped with a safety relief valve or a Veriflo
  HIR100 single-stage regulator equipped with a
  Swagelok CA Series (SS-4CPA2-EP-50) pressure
  relief valve.
•  
• X - Evacuated container (implosion)
• The Licor detector housing (see photo) is
  designed to maintain the detector at a near
  ambient pressure and room temperature so that
  the system remains stable over short (100-1000
  seconds) timescales. The preferred operating
  pressure and temperature of the instrument is
  250 hPa and 30 oC, such that the housing
  pressure is electronically controlled to be 250
  hPa. Therefore, under nominal operation, the
  pressure in the housing is below ambient to
  pressure altitudes of 250 hPa (11-12 km),
  altitudes above which the pressure differential
  reverses and the housing is slightly above (2-3
  psig) ambient. The housing contains static O-ring
  seals between the sidewalls and the cover and
  bottom plates. These seals tighten under negative
  pressure but are designed intentionally to leak
  under positive pressure differentials in excess
  of 7-10 psig.
•  
• Under passive conditions (e.g. instrument power
  failure), the pressure within the housing relaxes
  to ambient. In the case of failure of electronic
  pressure control, but continuous operation of the
  compressor pump, the pressure within the housing
  can increase to the pressure of the compressed
  air or the O-ring cracking pressure, whichever is
  lower (e.g. 7-10 psig). The housing is tested by
  sealing to 1 atm and pumping in a bell jar to an
  ambient pressure of 0.5 psi. Photos of the test
  will be supplied prior to flight.
• N/A - Frangible material
• N/A - Stress corrosion susceptible material
• N/A - Inadequate structural design (i.e., low
  safety factor)
• N/A - High intensity light source (including
  laser)

12
X - Rotating device The diaphragm pump consists
of a rotating armature driven by brushless 24
VDC, and small flywheel to reduce vibration.
Friction in the diaphragms is sufficient to stop
rotation within a few seconds of power loss.
 N/A - Extendible/deployable/articulating
experiment element (collision) N/A - Stowage
restraint failure N/A - Stored energy device
(i.e., mechanical spring under compression)
Vacuum vent failure (i.e., loss of
pressure/atmosphere) N/A - Heat transfer
(habitable area over-temperature) N/A -
Over-temperature explosive rupture (including
electrical battery) N/A - High/Low touch
temperature N/A - Hardware cooling/heating loss
(i.e., loss of thermal control) N/A -
Pyrotechnic/explosive device X - Propulsion
system (pressurized gas or liquid/solid
propellant) Gas bottles and regulators, as
described above. The bottles are clamped to a ½
thick 2024-Al machined plate surrounded by a
1/16 thick aluminum housing and bolted to the
rack within the wingpod via the Al plate. The
largest diameter tubing maintained at high
pressure is ¼ stainless steel contained within
the bottle housing. The force of any inadvertent
release of pressure is smaller than the safety
margins for structural components in this same
housing (e.g. bottle and regulator). N/A - High
acoustic noise level N/A - Toxic off-gassing
material N/A - Mercury/mercury compound N/A -
Organic/microbiological (pathogenic)
contamination source N/A - Sharp
corner/edge/protrusion/protuberance N/A -
Flammable/combustible material, fluid ignition
source (i.e., short circuit under-sized
wiring/fuse/circuit breaker) N/A - High voltage
(electrical shock) N/A - High static electrical
discharge producer N/A - Software error or
computer fault N/A - Carcinogenic
material Other
13

• 7. Ground support requirements
• Power 15 A, 120 VAC, for AC/DC converter to
  test instrument and for a laptop computer to
  reduce data
• We will have two investigator-provided size A
  cylinders of compressed air doped with CO2 for
  use as standards for NIRAD.
• We have no chemicals
• Typical working hours 8 am to 7 pm, 7 days, but
  access to aircraft after normal hours will not be
  necessary
• No special equipment is needed for handling
  equipment
• Storage for 3 shipping boxes 36x20x20 and two
  gas cylinders.

8. Hazardous materials none 9. MSDS n/a
14
10. Mission procedures

• Preflight checkout
• Connect monitor and keyboard to instrument
• Turn on 28 V power to right wing
• Turn instrument on (position 2)
• Condition - fail light should turn on with
  instrument on and go off within 60 seconds
• D. Watch GSE screen for several minutes to verify
  proper operation
• E. Turn instrument off
• F. Can power down 28 V to wing at any time
• G. 20 minutes before take off, open valves to
  gas bottles 3 turns
• 2. Preflight procedure
• A. G. 20 minutes before take off, open valves to
  gas bottles 3 turns
• 3. Flight
• Instrument on - as soon as convenient after take
  off
• Condition - fail light should turn on with
  instrument on and go off within 60 seconds

15

• NIRAD Installation Instructions
• Install Box to Wing Pod Rack (install before
  ozone)
• Remove front and rear skins (if applicable)
• Place box on left rear of rack about 1inch from
  left rear corner pressure gauges should be
  visible from back of rack
• From above, insert three 10 socket cap bolts
  with flat washers to left rail of rack tighten
  with allen wrench
• From below, Insert three 10 bolts socket cap
  bolts with flat washers to inner angle bracket,
  tighten with allen wrench
• 2. Attach Tubing
• Connect ¼ black tubing from inlet to feedthrough
  port on rear panel of instrument - 1 to Cal 1
  and 2 to Cal 2
• Tighten swagelok nuts finger tight plus ¼ turn
  with 9/16 box wrench
• 4. Attach Power Cable
• Connect power connector to the circular connector
  on the front of the pump/computer box

16

• Removal Instructions
• 1. Remove Power Cable
• A. Disconnect circular power cable at front of
  pump/computer box (black box)
• 2. Disconnect Tubing
• Disconnect sample line from ¼ swagelok union at
  inlet and from bulkhead feedthrough on back panel
  of instrument
• 3. Remove ozone instrument
• 4. Remove Instrument Box from Rack
• Use allen wrench to loosen and remove three 10
  bolts and flat washers from below angle bracket
  on starboard side of instrument.
• Use allen wrench to loosen and remove three 10
  bolts and flat washers from above on port side of
  instrument
• Lift and remove instrument

17

• NIRAD CO2 On-board bottle filling procedures
• May 12, 2004
• Prepared by Darin Toohey
• University of Colorado
• Note all procedures carried out with bottle out
  of the rack and on a lab bench
• 1. Prepare ground bottle
• Attach high pressure regulator to ground bottle,
  calibration gas 1.
• Set regulator pressure to zero by turning
  regulator handle counterclockwise to stop.
• Open bottle valve record bottle pressure on
  checklist
• Turn regulator handle clockwise to raise pressure
  to 200 psi, close bottle valve
• Open regulator valve to empty regulator
• Repeat steps C through R three times to purge gas
  from regulator
• 2. Connect ground bottle to flight bottle system
• Attach 1/8 swagelok nut to flight bottle fill
  line, tighten finger tight
• Open ground bottle cylinder valve, record
  pressure on checklist

18

• 3. Fill flight bottle
• Raise ground bottle regulator pressure to 500
  psi
• Open regulator valve
• Open transfer/fill valve slowly, bleeding air
  into flight cylinder
• When flight bottle pressure matches regulator
  pressure, raise regulator pressure in 100 psi
  increments until the pressure in the flight
  bottle is within 100 psi of the ground bottle
  pressure to a maximum of 1600 psi
• Record flight and ground bottle pressures in
  checklist
• Close transfer/fill valve
• Close regulator valve and ground bottle main
  valve
• With 7/16 open end wrench, break 1/8 swagelok
  nut at transfer line to slowly release pressure
  in transfer line
• Disconnect transfer line
• Open regulator valve to release pressure in
  regulator
• Remove regulator and transfer to second ground
  bottle
• Repeat steps 1-3 to fill second bottle