AADCO 737 Series User manual

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OPERATING INSTRUCTIONS
AADCO 737-SERIES
PURE AIR GENERATORS
737-5 737-10
(5-lpm) (10-lpm)
AADCO INSTRUMENTS, INC.
145 South Miami Ave.
Village of Cleves, OH 45002
Telephone: [phone]
Fax: [phone]

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AADCO 737-5 AND 737-10 PURE AIR GENERATORS
TABLE OF CONTENTS
Section Page
LIST OF ILLUSTRATIONS.......................................................................... iii
0.0 DAMAGED AND/OR LOSS IN SHIPMENT PROCEDURE ..........................1
1.0 INSTALLATION ............................................................................................2
2.0 REAR PANEL CONNECTIONS....................................................................4
3.0 OPERATIONAL TEST..................................................................................5
4.0 OPERATIONAL PROCEDURES..................................................................7
5.0 PRINCIPLE OF OPERATION.....................................................................10
6.0 BALLAST TANK AND BALLAST BLEED SYSTEM....................................12
7.0 COMPRESSOR UNIT.................................................................................13
8.0 COMPRESSOR CONTROL SYSTEM........................................................14
9.0 PURIFICATION REACTORS......................................................................16
10.0 METHANE REACTORS .............................................................................18
11.0 PERFORMANCE SPECIFICATIONS.........................................................20
12.0 PREVENTIVE MAINTENANCE..................................................................22
13.0 TROUBLE SHOOTING...............................................................................23
14.0 PRESSURE SWITCH ADJUSTMENT........................................................32
15.0 COMPONENT REPLACEMENT.................................................................34
16.0 737-104 AUTO PURE AIR MANIFOLD ......................................................36
17.0 737-105 AUTO SOURCE SELECTOR.......................................................37
18.0 PARTS LIST ...............................................................................................38
ILLUSTRATIONS......................................................................40 through 62
WARRANTY...............................................................................................63

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AADCO 737-5 AND 737-10 PURE AIR GENERATORS
LIST OF ILLUSTRATIONS
Figure Page
1 GENERATOR & SILENCER HOUSING, REAR VIEW..........................................40
2 GENERATOR & SILENCER HOUSING, FRONT VIEW.......................................41
3 GENERATOR WITH “HOUSE” AIR ADAPTER ....................................................42
4 GENERATOR, FRONT PANEL............................................................................43
5 GENERATOR, INTERNAL VIEW, RIGHT SIDE...................................................44
6 GENERATOR, INTERNAL VIEW, LEFT SIDE......................................................45
7 GENERATOR WITH METHANE REACTOR & MIXER-RECEIVERS
OPERATING FROM EXTERNAL SOURCE, NO COMPRESSOR.....................46
7a GENERATOR, AS FIGURE 7, OPPOSITE VIEW.................................................47
8 COMPRESSOR SILENCER HOUSING, INTERNAL VIEW..................................48
9 BALLAST TANK WITH MANUAL BLEED.............................................................49
10 FREE STANDING METHANE REACTOR............................................................50
11 GENERATOR WITH AUTO SOURCE MANIFOLD...............................................51
11b GENERATOR WITH PURE AIR MANIFOLD........................................................52
11c AUTO PURE AIR MANIFOLD & AUTO SOURCE SELECTOR............................53
12 GC ANALYSIS FOR CO2, “C” PURIFICATION REACTOR ..................................54
13 CO2 OUTPUT FROM “A” VS “C” PURIFICATION REACTOR..............................55
14 MOISTURE VS TIME NOMOGRAPHS ................................................................56
15 FID RESPONSE CYLINDER AIR VS “B” PURIFICATION REACTOR..................57
16 EFFICIENCY OF THE METHANE REACTOR......................................................58
17 PNEUMATIC DIAGRAM.......................................................................................59
18 WIRING DIAGRAM ..............................................................................................60
19 737-5 ROTAMETER FLOW NOMOGRAPH.........................................................61

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20 737-10 ROTAMETER FLOW NOMOGRAPH.......................................................62

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0.0 DAMAGED AND/OR LOST IN SHIPMENT PROCEDURE
0.1 SHIPMENTS FOB FACTORY. This shipment was thoroughly inspected before it
was delivered to the carrier. Our responsibility for this shipment has now ended.
Therefore, a thorough inspection of the contents should be made upon its arrival.
0.2 In the event any portion of the shipment is damaged or missing, do not sign the
bill of lading or express receipt until the freight or express agent makes
appropriate notation on the receipt.
0.3 Concealed damage means damage which may not be apparent until after the
items are unpacked and tested. In case of concealed damage, a written request
for inspection should be filed with the carrier within 15 days of the delivery date.
Delay in making this request may provide grounds for refusal of your claim. Be
certain to retain the carbon, packing materials, wrappings, etc., until the carrier
has made his inspection. Keep in mind that concealed damage can occur from
rough handling even though the cartons show no evidence of external damage.
0.4 The carrier may request return of the damaged item to us for inspection and
repair. In this event, we will repair or replace the item and invoice you for the
costs involved. This invoice then becomes part of your claim upon the carrier.
0.5 SHIPMENTS FOB DESTINATION. In the case of damage in transit on
shipments made FOB Destination, we will gladly handle filing of the claim,
provided an acceptable inspection report from the carrier is furnished to us. In
the event that our claim is disallowed because of your negligence in obtaining the
report, it will be necessary to bill you for the repair or replacement charges.
0.6 RETURN TO ADDCO INSTRUMENTS, INC. If your property, while being
returned to AADCO Instruments, Inc., is damaged in transit, it will be your
responsibility to file a claim with the carrier. To assist you we will secure an
inspection report from the carrier and forward it to you.
0.7 Prior to shipment to AADCO Instruments, Inc. You should call or write notifying
us of your intent. You must include some identifying note or letter with the item.
This note should include the name of your factory contact and the nature of the
damage.

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1.0 INSTALLATION.
1.1 Before attempting installation, it should be borne in mind that the performance of
the pure air generator hinges upon the availability of a large volume of
pressurized air in close proximity to the instrument. THIS IS MANDATORY. If
the air source is unable to satisfy the sudden demands for pressurized air, the
pure air generator will NOT perform to specifications.
1.2 AADCO Instruments, Inc. supplies pure air generators with or without air
compressor, depending upon availability of compressed air at the user’s site. If
“plant” air is available, follow the procedure outlined for installation WITHOUT
COMPRESSOR (Sections 1.6 through 1.8), otherwise use the WITH
COMPRESSOR procedure (Sections 1.9 through 1.12).
1.3 If initial visual inspection reveals no damage after unpacking, remove all shipping
plugs from the bulkhead fittings on the rear of the instrument. Should there be
any indications of damage, see Section 0.0 for instructions. If further information
is required, consult the factory.
1.4 Locate the unit in an area which will permit a free flow of air, avoiding confined
spaces. This is especially important if the unit houses a methane reactor system.
The heat generated during operation of the methane reactor must be dissipated
away from the instrument. If the unit does not contain a methane reactor,
location is not critical. However, it should be kept away from the wall.
1.5 It is not unusual to situate these instruments on specially constructed shelves
above head level, in out of the way places outside the area of use; e.g., in
hallways, electrical rooms, etc.
1.6 For INSTALLATION WITHOUT COMPRESSOR, using a “plant” or “house” air
source, locate the unit as in Section 1.4. Install the “house” air adapter, Figure 3
(54), being certain that the connection to the EXTERNAL SOURCE fitting,
Figure 3 (57), is tight. Connect the air supply to the inlet fitting of the “house” air
adapter, Figure 3 (56). Close the water drain valve, Figure 3 (55), finger tight.
NOTE: Inlet air pressure cannot exceed 100-psig nor be less than 70-psig.
1.7 Install the power cord into a suitable electrical outlet.
1.8 Admit the source air into the “house” air adapter. The INPUT PRESSURE
gauge, Figure 4 (3), should indicate the pressure of the air source. Leak check
all incoming air connections with soap solution and remedy as needed. The unit
is now ready for operation.

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1.9 For INSTALLATION WITH COMPRESSOR, place the compressor assembly,
Figures 1 and 2 (50), between two level surfaces so that the underside of the
assembly is exposed. DO NOT INVERT. Remove the two red shipping bolts
located on the underside and retain for future use.
1.10 Place the generator unit and compressor unit side by side as shown in Figures 1
and 2, with the compressor unit, Figures 1 and 2 (50), left of the generator unit as
shown. Place the ballast tank Figures 1 and 9 (16), on top of the compressor
unit and install the curved metal tubing which is supplied and labeled, Figure 2
(53), between the compressor outlet fitting and the check valve on the ballast
tank, Figures 1, 2 and 9 (24).
1.11 Install the ¼-inch o.d. plastic tubing, Figure 1 (51), supplied between the outlet
fitting on top of the ballast tank and the PUMP fitting, Figure 1 (58), on the rear of
the generator unit. Lastly, install the dump muffler in the DUMP fitting Figure 1
(60) and direct downward.
1.12 Connect the compressor power cord into the AUX POWER outlet on the lower
rear of the generator unit, as shown in Figure 1. Once the six-foot power cord
has been inserted into the proper electrical outlet, the unit is ready for operation.

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2.0 REAR PANEL CONNECTIONS.
2.1 The DUMP bulkhead connection, Figure 1 (60), is the outlet for air containing
those impurities removed from the unclean feed air. It is vented outside the
instrument cabinet to prevent deposition of water and other materials within the
instrument. The DUMP connection also provides a suitable connection for
sample collection of the impurity concentrate which elutes from this port.
2.2 The DUMP port must NOT be closed or impeded by any restriction which would
produce back pressure at this point.
2.3 The PUMP bulkhead fitting, Figure 1 (58), is a standard ¼-inch swage
connection. Care should be taken that the air supply tubing is kink-free as in
Figure 1.
2.4 The PURE AIR bulkhead connector, Figure 1 (59), is the pure air outlet from the
pure air generator. It will accept ¼-inch swage type connectors.
NOTE: Particulate filters are neither required nor recommended.
2.5 The AUXILIARY POWER outlet, Figure 1, provides power to the compressor
through the PUMP switch, Figure 4 (1).
2.6 Those units supplied for connection to “house” air, as in Figure 3, are shipped
without PUMP switch, fuseholder, and AUXILIARY POWER outlet.

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3.0 OPERATIONAL TEST.
3.1 DO NOT CONNECT ANY EQUIPMENT TO THE PURE AIR GENERATOR
SYSTEM AT THIS TIME.
3.2 After making all electrical and pneumatic connections to both generator and
compressor units according to instructions attached to each unit and as
shown in the appropriate figures, the system is ready for operation.
3.3 IF INSTALLATION HAS BEEN COMPLETED AS SHOWN IN FIGURES 1 and
2 WHEREBY THE PURE AIR GENERATOR USES AN AADCO
COMPRESSOR, REFERENCE FIGURE 4 FOR THE FOLLOWING
OPERATIONS.
3.4 Depress the PUMP switch (1) on the generator unit by depressing the lamp
itself. The compressor should start and the indicator lamp within the PUMP
switch should light. Within a short time there should be indication of increasing
input pressure as noted on the INPUT PRESSURE gauge (3).
NOTE: The compressor will not start at this time if any pressure greater than
60-psig appears on the INPUT PRESSURE gauge.
3.5 At this time, the tubing leading from the compressor unit to the ballast tank and
to the generator unit should be checked for leaks by applying a soap solution to
all of the connections and tightening as required.
3.6 When the input pressure reaches 80-psig as evidenced on the INPUT
PRESSURE gauge, the compressor will cease to operate. The input pressure
at this time will remain constant at 80-psig.
NOTE: Checking for leaks when the compressor is not operating will be
pointless since the connecting hoses between the compressor and
generator will not be pressurized. This check can be made only
when the compressor is running.
3.7 Depress the power switch (2) by depressing the lamp itself. The indicator lamp
within the switch will light. The METHANE HEAT lamp (4) will light if there is a
methane reactor within the unit. There should be an audible “click” of the
solenoid valve on the purification reactor followed immediately by a momentary
decrease of the input pressure. This is the initial pressurization of one side of
the purification reactor. There may also be a rise in the output pressure, as
evidenced on the OUTPUT PRESSURE gauge (6), if the OUTPUT PRESSURE
REGULATOR (5) had been set previously to some pressure. In addition, the
cooling fan on the inside rear wall of the generator should operate, Figures 5

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and 6 (28).
3.8 Wait at least one minute to allow both sides of the purification reactor to
pressure up and then adjust the output pressure to any desired pressure up to
50-psig with the OUTPUT PRESSURE REGULATOR. This output pressure
will be observed on the OUTPUT PRESSURE gauge (6).
3.9 Output flow should be adjusted via the OUTPUT FLOW ADJUST valve (13) to
some value between zero and 10.0 on the rotameter (10).
3.10 After about one-half hour of operation the METHANE HEAT lamp (4), if
present, should cycle, indicating that a maximum temperature has been
reached and is being maintained. During this half-hour “burn-in”, copious
amounts of water will exit from the PURE AIR FITTING, Figure 1 (59), on the
rear of the generator unit. It is advantageous to attach temporarily a short (six
to twelve-inch by ¼-inch o.d.) length of plastic tubing to that fitting to permit the
exiting water to clear the hoses and power cords of the unit.
3.11 The METHANE HEAT pyrometer (7) should indicate 290C ± 10C. If a
temperature other than this is observed, refer to Section 13.22, Methane
Reactor, for remedial action.
3.12 During the entire interval, from start up to full maximum temperature of the
methane reactor, the input pressure should be cycling between 60 and 80-psig
indicating that the pressure switch is operating properly. If not, consult Section
14.0, Pressure Switch Adjustment.
3.13 If all operations have been followed according to Sections 3.4 through 3.11,
allow the system to operate for several hours to permit maximum elimination of
the “burn-in” water. See Figure 14 for moisture versus time for both purification
and methane reactors.
3.14 IF INSTALLATION HAS BEEN COMPLETED AS SHOWN IN FIGURE 3
WHEREBY THE PURE AIR GENERATOR USES “HOUSE” AIR FOR ITS AIR
SOURCE, OBSERVE THE FOLLOWING OPERATIONS.
3.15 Admit the source air into the pure air generator. The INPUT PRESSURE
gauge, Figure 4 (3), should indicate the pressure of the source air.
NOTE: This pressure must not be less than 60-psig nor greater than 100-
psig. If the input pressure is less than 60-psig the quality of the air
produced by the pure air generator will be jeopardized. If the
pressure is greater than 100-psig the unit may malfunction since the
components are not rated greater than 100-psig.

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3.16 Follow the procedures as outlined in Section 3.7 through Section 3.13.

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4.0 OPERATIONAL PROCEDURES.
4.1 Once all connections and checkouts have been completed as in Sections 3.0
through 3.13, the pure air generator system is ready for connection to the
equipment that is to receive the zero air. Connections must be made with ¼-
inch o.d. thin-walled tubing with the using equipment located as close to the
pure air generator as possible. One-eighth inch o.d. tubing or small bore ¼-
inch tubing should be avoided because of the back pressure exerted on the
system by the restrictive tubing.
4.2 If connection fittings at the using equipment are _-inch swage type, use ¼-inch
large bore tubing from the pure air generator to the using equipment and then
reduce to _-inch tubing, keeping the _-inch length as short as possible. All
“tee’s” should be ¼-inch also.
4.3 After completing all plumbing connections, close all needle valves and flow
control devices at the using equipment and open the OUTPUT FLOW ADJUST
valve, Figure 4 (13), completely counter clockwise so that there is NO flow at
the using equipment. The rotameter ball on the pure air generator should drop
to zero indicating that the system is leak tight. If not, check for leaks at all
connections with soap solution and tighten all loose connections until the
rotameter ball does drop to zero. It is imperative that all leaks are detected and
remedied before putting the system into full operation.
4.4 To determine the proper output pressure from the pure air generator,
ascertaining the greatest pressure required by any or all of the instruments is
necessary. For example, if there are five instruments and the highest pressure
required for any one or all of the instruments is 30-psig, then the output
pressure of the pure air generator can be set no lower than 40-psig. This 10-
psig pressure differential is mandatory for proper operation of any differential
pressure regulator. The 40-psig accommodates not only that instrument with
the 30-psig requirement but all of the others as well.
4.5 If the instruments connected to the pure air generator do NOT have their own
pressure regulators but, instead, have a mandated input pressure at which the
instruments are to function optimally, then it is the responsibility of the operator
to install separate pressure regulators after the generator, in the line, for each
instrument. AADCO Instruments offers in-line pressure regulators for this
purpose (part no. 20033).
4.6 There are two pressure conditions for operating the pure air generator.

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4.7 The first pressure condition is when the output is permitted to enter an ambient
pressure environment; i.e., wherein the effluent enters and purges an
environmental chamber; or passes into a sampling manifold which itself vents
to the atmosphere, etc. In each case there will be no back pressure exerted
upon the pure air generator.
4.8 In this “no back pressure” situation, the output flow is controlled by the
OUTPUT FLOW ADJUST knob, Figure 4 (13), and the flow reading is taken
from the rotameter, Figure 4 (10), in millimeters and compared with the
applicable nomograph, Figure 19 or 20, for actual flow in liters per minute.
4.9 The second pressure condition is when the pure air generator is connected to
external equipment and the OUTPUT FLOW ADJUST valve is opened counter
clockwise, permitting full flow through the valve. Flow control in this situation is
performed at the external equipment through is flow control system. In this
instance, the pure air generator is operating in a “back pressure” mode, placing
the rotameter under pressure and no longer allowing the rotameter to be direct
reading.
4.10 The pressure under which the rotameter is operating is determined by the
operator when setting the output pressure with the OUTPUT PRESSURE
REGULATOR, Figure 4 (5). This pressure setting will greatly influence the
relationship between the observed flow on the rotameter and the actual flow.
4.11 The formula for determining actual flow is N+1 x R.
N = Output pressure in atmospheres (14.7 psi = 1 atmosphere).
R = Rotameter reading in LPM (NOT millimeters).
4.12 You can readily see that at 45-psig output pressure the indicated flow at the
rotameter will be exactly one-half the actual flow and you must multiply the
rotameter readings at this pressure (45-psig) by TWO to determine the actual
flow.
4.13 For the operator’s convenience, listed in Section 4.14 are the multiplier for each
output pressure setting. Simply multiply the rotameter reading in LPM
(determined by the proper nomograph, Figure 19 or 20) using the multiplier
from the listing for that operating pressure.

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4.14 OUTPUT PRESSURE MULTIPLIER
60 2.24
55 2.16
50 2.08
45 2.00
40 1.91
35 1.82
30 1.73
25 1.63
20 1.53
15 1.415
10 1.29
5 1.155
4.15 The purpose of this exercise is to allow the operator to know his flow conditions
but, more importantly, TO AVOID EXCEEDING THE OUTPUT CAPACITY OF
THE PURE AIR GENERATOR AND JEOPARDIZING THE OUTPUT PURITY.
Each pure air generator has a maximum output rating and the operator should
know this before setting flows.
4.16 Any instrument that is sensitive to even slight variations in oxygen
concentration; i.e., flame ionization detectors used with total hydrocarbon
analyzers, gas chromatographs, flame photometric detectors, etc., all require
incorporation of mixer-receivers, Figure 7 (49), in the pure air generator system
for homogenization of the air mixture before use by the above-mentioned
detectors. NDIR, chemiluminescent, photoionization, and electrochemical
sensors are unaffected by slight variations in oxygen concentration and,
therefore, do not require mixer-receivers. See Section 18, Parts List, for
appropriate models.
4.17 SHUTDOWN PROCEDURE.
4.18 If the unit is not to be used for one week or more, depress the PUMP switch,
Figure 4 (1), depress the POWER switch, Figure 4 (2), and immediately cap
both the PURE AIR outlet, Figures 1 and 3 (59), and the DUMP fitting, Figures
1 and 3 (60), to avoid contaminants from entering the system.

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5.0 PRINCIPLE OF OPERATION (REFERENCE FIGURE 17).
5.1 The 737-series pure air generators produce absolutely clean air from
pressurized unclean air by chromatographic techniques. Pressurized air from a
compressor or other source enters the number one or number two column
system, depending upon the status of the solenoid valve located at the inlet of
the column. These valves (S-1 and S-2) are normally closed so that when the
POWER switch is off the inlets to the columns are closed, sealing the system
against possible contamination.
5.2 The pressurized air passes through the column where selective adsorption
takes place, with a subsequent separation of the various components present
in the air. Only the desired components, which elute first, are permitted to
reach the end of the column system and elute, whereupon the solenoid valve at
the head of the separation column closes and the solenoid valve at the inlet to
the alternate column systems opens.
5.3 Pressurized unclean air now enters the alternate column system where
separation again takes place. The alternation of the two column systems
produces a steady flow of purified air.
5.4 During the interval that pressurized unclean air is being separated in one
column, a portion of the clean air passes through the purge valve and
backflushes the alternate column of impurities. This purge valve, Figures 5 and
6 (19), has been set at the factory for optimum flow and MUST NOT BE
ALTERED.
5.5 The backflush flow of air with impurities exits from the instrument through the
swage bulkhead connector labeled DUMP at the rear of the instrument, Figure
1 (60). THIS EXIT MUST NOT BE RESTRICTED. A back pressure situation
must be avoided at this fitting.
5.6 The timer, which provides alternate power to the solenoid valves, has been set
to effect the proper residence time of the unclean air in the columns and also
the purge time for each size reactor.
5.7 To prolong the life of the support media within the columns, it is mandatory that
the operational directions for the instrument be followed as closely as possible.
Selection of this separation media, residence time in the column, proper input
pressures, purge flows, and column volumes have been determined to meet
the requirements of the particular 737-series pure air generator being used.
These components are NOT interchangeable except among units of the same
rated output.

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5.8 Damage to the purification reactor can occur if: (a) improperly filtered air is
admitted to the columns as with oil compressors, (b) water is admitted to
columns due to oversight on the operator’s part in failing to drain the ballast
tank and allowing water to carry over, (c) the unit is operated above its rated
capacity, or (d) the input pressure requirements are not met. See Section 3.15.

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6.0 BALLAST TANK AND BALLAST BLEED SYSTEM
6.1 The ballast tank, Figures 1, 2 and 9 (16), is placed in the system after the
compressor, prior to and in close proximity to the purification reactor, to serve
as a reservoir for the pressurized input air. Each tank has been carefully sized
for the rated capacity of its pure air generator.
6.2 When the solenoid valve at the inlet to the column opens, a requirement for a
rapid supply of pressurized air develops. The compressor alone would be
unable to satisfy this requirement within a reasonable amount of time and
would cause great variations in the input pressure and improper separations
within the purification reactor, resulting in variations in output pressure and flow
as well as a deterioration in purity. The pressurized volume within the ballast
tank, located immediately adjacent to the columns, provides an instant
response to this need.
6.3 Because the ballast tank is so critical to the operation of the system, care must
be taken to ensure there will be no decrease in its volume. Volume loss occurs
only when water from the input compressed air is permitted to collect in the
tank.
6.4 AADCO Instruments, Inc. supplies an internally-coated, rust-proof ballast tank
with each system which is equipped with a manual toggle valve, Figures 1, 2
and 9 (12), for bleeding the coalesced water from the tank.
6.5 The manual toggle valve system is a simple toggle valve located on the ballast
tank. This valve should be opened at least once every three days while the
system is operating and the ballast tank is pressurized. The air pressure within
the tank forces the accumulated water to the toggle BALLAST BLEED valve.
During periods of high humidity, a once per day bleed would be required.
6.6 The operator is manually able to determine the condition of the ballast tank by
opening the toggle valve at any time. There should be a sharp flow of
pressurized air with water from the tubing. If not, there is blockage which
should be cleared.

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7.0 COMPRESSOR UNIT.
7.1 A compressor, Figure 8 (43), contained is a separate sound-proofed assembly,
provides compressed air to the pure air generator. Each compressor is sized
for a particular generator system. When replacement is necessary, it should be
replaced with the same size compressor with the same voltage requirements.
7.2 The compressor is shock-isolated from the cabinet proper by four springs and a
special mounting plate, Figure 8 (46).
7.3 Operating air and cooling air are both admitted at the front bottom of the unit,
passing through a sound baffle system, and into the compressor chamber.
Care must be taken to avoid obstructing both the incoming air and the hot air
exiting from the cabinet. See Section 1.4.
7.4 Hot air is removed from the cabinet by a high volume fan, Figure 8 (45),
mounted on a vertical duct within the compressor cabinet. Failure of the fan will
cause the compressor to stop operating, even though power is applied,
because of increased temperature within the compressor chamber. A thermal
switch, located within the compressor motor, performs this operation. This
switch is both non-adjustable and inaccessible.
7.5 In addition to the duct-mounted cooling fan, a second fan is attached to the
drive shaft of the compressor itself. This fan is located directly beneath the
louvered shroud on the front end of the compressor and is press-fit on the drive
shaft.
7.6 Compressor replacement is dictated by its inability to supply compressed air at
the desired rate and/or pressure. See Section 12.5 for diagnostic procedures
and Section 13.1 for service.

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8.0 COMPRESSOR CONTROL SYSTEM
(SEE FIGURE 17 FOR PNEUMATIC REFERENCE
AND FIGURE 18 FOR ELECTRICAL REFERENCE.)
8.1 A combination pressure switch/pressure relief valve system is installed in all
AADCO pure air generators with output volumes greater than 1-LPM but less
than 50-LPM.
8.2 The purpose of this system is to permit the compressor to operate intermittently
rather than continuously. The compressor will turn on at 60-psig or less and off
at 80-psig. Operating the compressor in this manner greatly reduces
compressor wear and promotes cooler operation, both of which extend its
lifespan.
8.3 During operation the ballast tank, Figures 1, 2 and 9 (16), serves as the
pressure reference for the system. The pressure switch, Figures 5 and 6 (17),
serves as the sensor and the check valve, Figures 1, 2 and 9 (24), confines the
pressurized air within the ballast tank once the compressor has turned off.
8.4 The pressure switch is a normally closed switch, closing at 60-psig or less and
opening at 80-psig. This switch controls the coil of the solid state relay, Figures
5 and 6 (21), which in turn supplies power to the compressor through the AUX
POWER outlet, Figure 1.
8.5 Any low pressure condition (60-psig or less) within the ballast tank produces a
closed switch condition at the pressure switch. This in turn causes power to be
supplied to the compressor via the solid state relay, Figures 5, 6 and 11 (21),
and the AUX POWER outlet.
8.6 At 80-psig the pressure switch opens, removing power from the coil of the solid
state relay, which in turn removes power from the compressor.
8.7 The compressor pressure relief valve, Figure 8 (23), (a normally closed three-
way valve) is wired in parallel with the power to the compressor at the AUX
POWER outlet. When power is removed from the compressor it is also
removed from the compressor pressure relief valve. This causes the valve to
vent all tubing from the compressor to the valve to atmospheric pressure.
8.8 The compressor pressure relief valve is an important part of the compressor
control system. Its function is to vent to atmospheric pressure all tubing leading
from the compressor to the check valve inlet on the rear of the ballast tank
when the compressor is off.
8.9 If the compressor is permitted to start against pressure, its starting current
begins to rise dramatically, causing the compressor to run hotter, increasing

16
wear. The compressor relief valve eliminates this problem.
8.10 The AUX POWER outlet, Figure 1, is a four-conductor connector, one lead (the
red lead) carries power to the cooling fan located within the compressor
silencer housing. Power is applied to the cooling fan continuously, whether the
compressor in on or off, thus maintaining a favorable temperature within the
compressor silencer housing.
8.11 The compressor supplies air via the ballast tank to the pure air generator
through the PUMP fitting, Figure 1 (58), on the rear of the generator unit. This
air passes through the compressor pressure relief valve, Figure 8 (23), through
the check valve, Figures 1, 2 and 9 (24), and into the ballast tank, Figures 1, 2
and 9 (16), where its pressure is monitored by the pressure switch, Figures 5
and 6 (17), and the INPUT PRESSURE gauge, Figure 4 (3).
8.12 At 80-psig the pressure within the ballast tank causes the pressure switch to
open, removing power from the coil of the solid state relay, which in turn
removes power from the compressor and the compressor relief valve.
8.13 When power is removed from the compressor, the compressor pressure relief
valve vents the connecting tubing to atmospheric pressure and causes the
check valve, Figures 1, 2 and 9 (24), to close, confining the pressurized air
within the ballast tank.
8.14 This pressurized air enters the purification reactor, Figures 5, 6, 7 and 7a (18).
During the purification process, the air within the ballast tank is consumed,
decreasing the pressure within the tank again to 60-psig. At this point the
entire procedure is repeated, producing the on and off operation of the
compressor.
8.15 This system will operate efficiently only if some preventive maintenance is
performed every three or four weeks of sustained operation. These procedures
are covered in Section 12.0