Aerotech BT 400-46 Owner's manual

Installation – Operation
Maintenance Instructions
And Parts List

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: [email protected]
www.hermannelson.com
06.19.09REVISION 1.03
WARNING!
EXPLOSION HAZARD
Do not operate heater in explosive vapor area.
EXHAUST FUMES
Do not operate heater in enclosed spaces. Adequate ventilation is required to prevent
buildup of exhaust fumes which can be toxic in concentrated amounts.
DIESEL
Diesel used in operating this heater is explosive.
• Do not refuel during operation.
• Avoid open flame near fuel tank fuller neck.
• Make sure fire extinguisher is in easy reach.
HIGH TEMPERATURE
Heat exchanger casing, muffler, exhaust hose, and exhaust stack may become
Dangerously hot.
• Do not touch heater parts during or immediately after operation.
• Perform maintenance only after heater has cooled.
I

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: [email protected]
www.hermannelson.com
06.19.09REVISION 1.0
WARNING!
CARBON MONOXIDE
Exhaust gases from the combustion chamber and diesel engine contain poisonous carbon
Monoxide gas. Exhaust stack must always be properly installed during operation of
Heater to prevent exhaust gases from entering intake.
ELECTRICITY
Shock or injury may result from working on electrical components. Disconnect battery before performing
any repairs.
ROTATING PARTS
Serious injury may result from contact with rotating parts. Stand free of moving parts and possible
pinch points prior to start-up and during operation.
NOISE HAZARD
Wear approved ear protection equipment within 10 feet (3.05 meters) of operating heater.
Failure to do so may result in impairment or loss of hearing.
COMPRESSES AIR
Death or severe injury might result when compressed air is used to blow dirt from skin or
clothing.
Air entering body openings is extremely dangerous. Compresses air used for cleaning shall not
exceed 30 psi (210 KPA). Use goggles or face shield for eye protection.
II

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: [email protected]
www.hermannelson.com
06.19.09REVISION 1.03
Table of Contents
• • • • • • • • • • • • • • • • • •
SECTION 1 _______________________________________________PAGE 1
INTRODUCTION
1.1 General
1.2 Scope
1.4 Safety Precautions
SECTION 2 _______________________________________________PAGE 2
2.1 General
2.2 Scope
2.3 Power Unit
2.5 Fuel System
2.7 Heat Exchanger
2.9 Cabinet
2.11 Trailer
2.13 Specifications
SECTION 3 _______________________________________________PAGE 6
PREPARATION FOR USE AND STORAGE
3.1 General
3.2 Scope
3.4 Preparation for use
3.6 Preparation for storage
SECTION 4 _______________________________________________PAGE 8
OPERATING INSTRUCTIONS
4.1 General
4.2 Scope
4.4 Theory of Operation
4.6 General Theory
4.11 Detailed Theory
4.12 Fuel System
4.13 Fuel System
4.15 Burner Control Valve
4.18 Fuel Atomizing Head
4.20 Temperature Selector Valve
4.23 Temperature Selector Indicator Knob
4.26 Electrical System
4.28 Operating Instructions
4.31 Operating Under Normal Circumstances
4.34 Operating Under Extreme Cold Conditions
III

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: [email protected]
www.hermannelson.com
06.19.09REVISION 1.03
Table of Contents
• • • • • • • • • • • • • • • • • •
SECTION 5 _______________________________________________PAGE 22
MAINTENANCE INSTRUCTIONS
5.1 General
5.2 Scope
5.4 Cleaning
5.6 Flexible Ducts
5.8 Lubricating
5.10 Inspection and Preventive Maintenance
5.12 Battery
5.18 Fuel Filter
5.20 V-Belt
5.24 Heat Exchanger Assembly
5.29 Fan and Mounting Ring Assembly
5.36 Heat Exchanger
5.41 Carbon Monoxide Test
5.42 Heater Ignition System
5.44 Coil
5.46 Igniter Cable and Igniter Plug
5.51 Fuel Pump
5.67 Troubleshooting
SECTION 6 PAGE 39
SECTION 7 PAGE 83
ALPHAMERIC INDEX
IV

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: [email protected]
www.hermannelson.com
06.19.09REVISION 1.03
Table of Contents
• • • • • • • • • • • • • • • • • •
PARTS LIST
LIST OF ILLUSTRATIONS:
FIGURE NO. TITLE PAGE
2-1 Heater Fuel System 2
2-2 Sectional View of Nozzle and Combustor 4
4-1 Control Panel Components 9
4-2 Schematic Diagram of Fuel Pump 10
4-3 Burner Control Valve 12
4-4 Fuel Atomizing Head 13
4-5 Temperature Selector Valve 15
4-6 Heater Electrical System Circuit 16
4-7 Duct Attachments 19
4-8 Fuel Gauge and Flame Window Location 20
5-1 Fuel Pump Mounting Bracket 27
5-2 Nozzle and Combustor 30
5-3 Igniter Plug Adjustment Points 31
5-4 Valve and Block Assembly 32
5-5 Pump Pressure Testing Assembly 33
5-6 Fuel System Air Leak Testing 35
LIST OF TABLES:
TABLE NO. TITLE PAGE
2-1 Specifications 3
2-2 Fuel Specifications and Requirements 3
4-1 Control and Indicator Locations and Use 9
5-1 Lubrication Instructions 23
5-2 Inspection, Checks and Services 24
5-3 Troubleshooting Chart 37
V

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: [email protected]
www.hermannelson.com
06.19.09REVISION 1.03
Section 1 • Introduction
• • • • • • • • • • • • • • • •
1.1 General
1.2 Scope
1.3 These instructions are for use by personnel to whom the BT400-46 heater manufactured
by AEROTECH HERMAN NELSON INC. has been issued. They contain the information on
the operation and maintenance of the heater as well as the description of the major units and their
functions in relation to other components of the heater. In addition, a list of parts which may be
required for maintaining the heater, is provided in Section 6.
1.4 Safety Precautions
1.5 Precautionary measures to be taken during operation and maintenance of the heater are
contained in the appropriate paragraphs of the manual. In addition, all safety precautions
are listed in the front of this manual.
1.6 Below is a list of definitions to terms commonly used in this book.
DANGER: You will be subject to serious injury or death if you fail to follow instructions!
WARNING: You could be subject to serious injury or death if you fail to follow instructions!
CAUTION: You can be hurt if you fail to follow instructions!
NOTICE: Your heater or other property could be damaged if you fail to follow instructions!
1

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: [email protected]
www.hermannelson.com
06.19.09REVISION 1.03
Section 2 • Description
• • • • • • • • • • • • • • • •
2.1 General
2.2 The model BT400-46 heater is a fully enclosed, portable, two wheel, trailer mounted unit,
intended for use in ground heating maintenance shelters, portable hangers, aircraft engines and
fuselages, and other similar enclosures.
2.3 Power Unit
2.4 The model BT400-46 heater is supplied with a variety of diesel engines. A drive coupling is
attached to the drive shaft of the engine and is attached to a driven coupling by way of a flexible
rubber sleeve. The driven coupling drives the heater fan through a pulley, a V-belt drives the fuel
pump.
2.5 Fuel System
2.6 The fuel system supplies a variety of fuel to the heater and the engine. Fuel is drawn from a
removable 35 gallon fuel tank through an automotive type fuel filter (see figure 2-1) by a belt-
driven fuel pump. Fuel flows through the nozzle contained in a holder with Inlet and bypass fuel
lines. As the fuel leaves the nozzle it is atomized and ignited by the igniter plug. Fuel is also
bypassed from nozzle, through a check valve, to the temperature selector valve on the control
panel. The check valve prevents a reverse flow.
Figure 2-1 • Heater Fuel System
• • • • • • • • • • • • • • • •
2

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: [email protected]
www.hermannelson.com
06.19.09REVISION 1.03
Table 2-1 • Specifications
• • • • • • • • • • • • • • • •
LENGTH 74” inches
HEIGHT 44” inches
WIDTH 54” inches
SHIPPING WEIGHT 800 lbs
ENGINE See supplement
HEATED AIR OUTLET 12” inches diameter
EXHAUST OUTLET 5” inches diameter
RATING 400,000 BTUH @ -65°F (-54°C) ambient
AIR OUTLET RANGE 150 TO 280°F (66 to 138°C) maximum
AIR DELIVERY RATE 1500 CFM @ 280°F (138°C) maximum
FUEL TANK CAPACITY 35 gallons (132.5 liters)
ELECTRICAL 12 volts, negative ground
BATTERY Group 12H
FUEL See Table 2-2
ENGINE LUBRICANT 0W-30
Table 2-2 • Fuel Specifications &
Requirements
• • • • • • • • • • • • • • • •
AMBIENT
TEMPERATURE
-65°F (-54°C) & ABOVE
-50°F (-46°C) & ABOVE
-40°F (-40°C) & ABOVE
+20°F (-7°C) & ABOVE
-25°F (-32°C) & ABOVE
-60°F (-51°C) & ABOVE
SPECIFICATION
MIL-T-5624
MIL-T-5624
MIL-T-83133
W-F-800
W-F-800
W-F-800
SYMBOL/
NOMENCLATURE
JP-4-AIRCRAFT TURBINE FUEL
JP-5-AIRCRAFT TURBINE FUEL
JP-8-AIRCRAFT TURBINE FUEL
DF-2-DIESEL FUEL
DF-2-DIESEL FUEL
DF-2-DIESEL FUEL
REMARKS
PRIMARY FUEL
ALTERNATE FUEL
ALTERNATE FUEL
ALTERNATE FUEL
ALTERNATE FUEL
ALTERNATE FUEL
3

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: Air4ce[email protected]
Check Out Our Web site www.hermannelson.com New Items Added Weekly
12.18.07 REVISION 1.02
Figure 2-2 • Sectional View of
Nozzle & Combustor
• • • • • • • • • • • • • • • •
2.7 Heat Exchanger
2.8 Fuel flowing from the nozzle is ignited in the combustor (see figure 2-2). The burning fuel
strikes a plate or target in the combustor and is diffused into the heat exchanger. Air from
the fan enters holes in the side of the combustor in a manner that will ensure proper fuel-air
mixture. The burning fuel flows through the heat exchanger in a spiral path between the
surfaces of the ventilating air tubes and is expelled through the exhaust opening at the top
of casing. Ventilating or heating air is forced through the parallel tubes and the space
between the heat exchanger shell and the casing. A damper control, which is locked by a
handwheel mounted in a slot above the discharge end of the heater, is used to reduce heat
output, by reducing the air volume without reducing the temperature. Volume can be set
between full and one-half or full volume.
4

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: Air4ce[email protected]
Check Out Our Web site www.hermannelson.com New Items Added Weekly
12.18.07 REVISION 1.02
Section 2
• • • • • • • • • • • • • • • •
2.9 Cabinet
2.10 The power unit is enclosed in a cabinet which provides protection against the elements
and prevents damage during storage or transit. The cabinet is hinged to provide access to
the power unit and all other controls for easy maintenance.
2.11 Trailer
2.12 Atwo-wheeled trailer is provided to transport the heater from worksite to worksite. Duct
holders hold the ducts when not in use. An adjustable tow bar serves as a support when the
trailer is at rest. Do not exceed 20 mph when towing.
2.13 Specifications
2.14 The BT400-46 heater specifications are listed in Table 2-1.
5

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: Air4ce[email protected]
Check Out Our Web site www.hermannelson.com New Items Added Weekly
12.18.07 REVISION 1.02
Section 3 • Preparation for Use & Storage
• • • • • • • • • • • • • • • •
3.1 General
3.2 Scope
3.3 The heater unit is shipped as a pre-tested, completely assembled unit. There are, however,
certain steps which shall be taken prior to putting the unit into operation or storage.
3.4 Preparation for use
3.5 To prepare the heater for use proceed as follows:
(a) Remove all crafting, blocking, and protective material from heater.
! CAUTION !
Do not use forklift to move heater.
This could cause damage to unit.
(b) Check action of parking brake and set brake to prevent heater from rolling.
(c) Inspect unit for any damaged gauges, meters, valves, loose connections or
mountings, loose or missing hardware, frayed insulation on wiring, or any
other damage.
(d) Check drive V-belt for proper tension and condition.
(e) Using a hydrometer, check each battery cell for a specific gravity of 1.250
or higher. Ensure electrolyte level is 1/4 inch to 1/2 inch above the top of the
battery plates.
! WARNING !
Use protective clothing, face shield, rubber gloves and apron when servicing battery.
! WARNING !
Do not smoke or use an open flame in heater vicinity while servicing the fuel tank.
Failure to comply may result in serious injury or death.
(g) Remove fuel tank filler cap and fill tank to capacity with recommended fuel.
Replace filler cap.
(h) Check engine oil level.
(i) Ensure tire pressure is 20 psi max. 6

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: Air4ce[email protected]
Check Out Our Web site www.hermannelson.com New Items Added Weekly
12.18.07 REVISION 1.02
Section 3 • Preparation for Use & Storage
• • • • • • • • • • • • • • • •
3.6 Preparation for Storage
3.7 To prepare heater for storage proceed as follow:
(a) Drain fuel from tank
(b) Replace fuel filter with a new filter.
(c) Disconnect and remove battery from heater.
! WARNING !
Use protective clothing, face shield, rubber gloves and apron
when removing battery from heater.
(d) Replace fuel nozzle.
7

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: Air4ce[email protected]
Check Out Our Web site www.hermannelson.com New Items Added Weekly
12.18.07 REVISION 1.02
Section 4 • Operation instructions
• • • • • • • • • • • • • • • •
4.1 General
4.2 Scope
4.3 This section describes the theory of operation, operating controls and indicators and the operative
procedures for the heater.
4.4 Theory of Operation
4.5 The description will be presented in two parts; (1) General Description and (2) Detailed Description. The
general description explains the interrelationship of functional components at an operation level. Functions
of individual components and unique assemblies are given in the detailed description.
4.6 General Theory
4.7 Fuel is drawn from the fuel tank through the fuel filter and delivered under constant pressure to the variable
discharge combustion nozzle (see figure 2-1). Fuel pressure causes the temperature selector valve to open
and bypass a metered amount of fuel back to the fuel tank. The ignition system produces a high voltage
spark at the igniter plug to ignite the fuel and air mixture. The resultant flame heats the heat exchanger.
Ambient air is forced through the heat exchanger by the fan assembly. As the ambient air passes through
the heat exchanger it is directed through the heat deflector to the heat exchanger outlet.
4.8 As the heated air leaves the heat exchanger outlet, it passes over the temperature selector valve and burner
control valve sensing elements. The air temperature detected by the temperature selector valve’s sensing
elements determines the amount of fuel that is bypassed to the fuel tank thus maintaining the desired output
air temperature. In the event of a high output temperature, the burner control valve sensing elements detects
this condition and turns off the burner.
4.9 Electrical System
4.10 A battery supplies power for the heater control circuits. A toggle switch on the control panel turns on the
panel light for night time illumination. To start the diesel engine a momentary switch is moved to and held
in the closed position providing a circuit to energize the starter solenoid. The starter solenoid closes making
a circuit from the battery to the starter motor. For cold-weather starting a momentary switch is moved to and
held in the closed position providing a circuit for the preheater relay. The preheater relay closes providing a
circuit for the preheater which warms the air entering the diesel engine. An oil pressure switch closes and
remains closed during engine operation unless oil pressure is lost. Power for the hourmeter is provided
through the oil pressure switch, thus being energized during engine operation to record the total operating
time. During engine operation a flywheel altemator produces a voltage which is maintained by the voltage
regulator at a suitable potential for recharging of the battery.
8

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: Air4ce[email protected]
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12.18.07 REVISION 1.02
Table 4-1 • Control & Indicator
Location and Use
• • • • • • • • • • • • • • • •
FIGURE AND
ITEM CONTROL OR INDICATOR DESCRIPTION AND USE
FIG 4-1-1 PANEL LAMP Night time illumination of control panel
FIG 4-1-2 LAMP SWITCH Turns panel lamp on and of
FIG 4-1-3 STARTER SWITCH Momentary switch when in “on” position energizes
starter motor
FIG 4-1-4 PREHEATER SWITCH Momentary switch when in “on” position energizes
starter preheater
FIG 4-1-5 HOURMETER Indicates total hours of engine operation
FIG 4-1-6 BURNER CONTROL VALVE Depressive valve engages burner
FIG 4-1-7 TEMPERATURE SELECTOR
VALVE Rotating knob clockwise increases discharge temp. Rotating knob counterclockwise decreases temp.
FIG 4-1-8 DISCHARGE TEMPERATURE
INDICATOR Indicates discharge temperature in degrees F
FIG 4-1-9 TEMPERATURE INDICATOR
KNOB Indicates approximate temperature range
Figure 4-1 • Control Panel Components
• • • • • • • • • • • • • • • •
9

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: Air4ce[email protected]
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12.18.07 REVISION 1.02
Section 4
• • • • • • • • • • • • • • • •
4.11 Detailed Theory
4.12 Fuel System
4.13 Fuel Pump
4.14 The fuel pump is mounted on a bracket to the left of the engine. The pump is belt driven by the diesel
engine. The pump has three outlets (see figure 4-2). A primary by-pass will handle all the flow if the
balanced valve is closed. If the primary by-pass line is closed, the fuel will flow into the balanced valve
and hence out through both the nozzle fuel line and the secondary by-pass line. The secondary by-pass
supplies fuel to the diesel engine and returns surplus back to the fuel tank. The burner control valve, which
is in the primary by-pass line, is closed to obtained fuel flow to the nozzle. When this valve is open the
pump can not build up sufficient pressure to open the balanced valve and effect flow through the nozzle
fuel line. Closing the burner control valve allows the pump to build up pressure to the point where the
valve opens allowing fuel flow in the nozzle fuel line. The pressure at which the balanced valve opens is
determined by the compression of the piston spring, normally the spring is adjusted to 150 psi. This
pressure can be checked at the burner control valve. Since the pump delivers fuel in excess of the
maximum nozzle capacity there will always be flow through the secondary by-pass line when burner
control valve is on. Fuel from the secondary by-pass flows back into the tank through a check valve which
opens under a pressure of about 5 psi, which is sufficient to divert adequate fuel to the engine.
Figure 4-2 • Schematic Diagram of
Fuel Pump
• • • • • • • • • • • • • • • •
10

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: Air4ce[email protected]
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12.18.07 REVISION 1.02
Section 4
• • • • • • • • • • • • • • • •
4.15 Burner Control Valve
4.16 The burner control valve (see figure 4-3) is not intended for manual heat regulation, the manual
control knob serving only to either full close (burner on) or fully open (burner off) the primary by-pass
line which returns fuel back to the tank. Pressing the knob downward seats a ball which seals the inner
axial passage leading to the fuel outlet. At the same time, fuel under pump pressure flows into the area
over the diaphragm, forcing the diaphragm downward against the loading spring. This allows the push
pins to drop so that the pressure balancing spring may force the movable sleeve downward to hold the ball
firmly in its seat, closing the outlet passage. Thus the fuel pressure acts to keep the valve closed. Lifting
the knob raises the movable sleeve, permitting the lower plunger to be in turn raised by the plunger spring,
freeing the ball from its seat. Fuel then flows through the inner valve body to the outlet. This relieves the
fuel pressure on the diaphragm and the valve returns to the open position.
4.17 The burner control valve also serves as an overheat protection safety valve. This isachieved through the
action of a sensing element in the discharge air system. When the discharge air temperature exceeds safe
limits (about 350°F), the thermostatic medium in the sensing element will expend sufficient pressure to
assist the loading spring so that together they force the diaphragm upward, opening the valve. This turns
off the burner. The valve will not close again to permit subsequent burner operation until operated
manually.
11

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
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12.18.07 REVISION 1.02
Figure 4-3 • Burner Control Valve
• • • • • • • • • • • • • • • •
12

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
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Section 4
• • • • • • • • • • • • • • • •
! CAUTION !
Beware of chips – Pipe, tubing and valve ends must be clean. System contaminants in
any valve can foul valve seats and cause leakage. Back flush systems before putting in
service whenever possible. Install screen or filters where required to protect valves.
Pipe Dope – Goes on male thread carefully so nothing gets in valve and system. Strings
of tape type sealants can foul valve seats.
4.18 Fuel Atomizing Head
4.19 The fuel nozzle screws into a nozzle holder, the combination being known as the fuel atomizing head. Fuel
from the inlet line enters the nozzle supply chamber through a strainer screen (see figure 4-4), then flows
through slots in the inner had through which impacts a whirling motion to the fuel so that it partially
atomizes as it enters the swirl chamber. Atomization is completed as the fuel sprays through the discharge
orifice into the combustor. A portion of the fuel is also forced into a by-pass chamber which leads to the
by-pass outlet passage in the nozzle holder. A check valve connected between the outlet and by-pass fuel
line prevents a reverse fuel flow to the nozzle from the by-pass line. Fuel is discharged from the nozzle at
a fixed continuous rate and a continuous fixed flame is obtained. Changes in heat output is obtained by
varying the volume of fuel discharged from the nozzle. This is accomplished indirectly by controlling the
amount of fuel flowing through the by-pass fuel line through the action of the temperature selector valve.
Figure 4-4 • Fuel Atomizing Head
• • • • • • • • • • • • • • • •
13

AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: [phone] (24 Hours) Fax: [phone] Email: Air4ce[email protected]
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12.18.07 REVISION 1.02
Section 4
• • • • • • • • • • • • • • • •
4.20 Temperature Selector Valve
4.21 Manual adjustment of the temperature selector valves within the operating range (150°F to 280°F)
applies motion through a pressure cone (see figure 4-4) to an inverted spring cup which forms the holder
for the needle assembly. The resulting movement of the needle seat orifice gives a smooth, continuous
regulation of fuel flow throughout the normal operating temperatures. A similar control of fuel is obtained
by upward and downward movement of the diaphragm. The diaphragm is spring loaded to the point
where a very slight additional upward pressure will result in further opening of the valve and increase the
flow of fuel in the by-pass line. This additional pressure is supplied by the expansion of the thermostatic
medium in the heat sensing element located in the discharge air stream. This pressure applied to the heat
sensing element located in the discharge air stream. This pressure applied to the diaphragm balances the
fuel flow to the selected temperature.
4.22 Adjustment of the valve for any discharge temperature results in an initial fuel discharge greater than
needed to maintain the selected temperature. The resulting increased heat output of the combustor brings
the heater up to the selected temperature rapidly. As the discharge temperature rises, the action of the
temperature sensing element opens the valve further, increasing the fuel flow in the by-pass line, thereby
decreasing the nozzle fuel discharge, consequently reducing the combustor heat output. The discharge air
temperature overshoots the selected temperature, then cycles about this temperature until a stable
condition is reached. Selecting a new temperature results in the same type of hunting action until
stabilizing at the new temperature.
4.23 Temperature Selector Indicator Knob
4.24 The temperature selector indicator knob is mounted on the control panel next to the temperature selector
knob. The approximate temperature is indicated by the pointer. When the temperature selector knob is
rotated, a pinion on the shaft engages a pinion on the temperature selector indicator knob shaft and rotates
the knob in direct relationship to the temperature selector valve.
14