Systems are controlled by a control box that can either be placed within the ECU cabinet or used remotely by means of an extension cable. One toggle switch is used to power the system by means of a low voltage circuit. Another toggle switch is use to select between three modes of operation (Vent Mode, Cooling Mode or Heating Mode).
Conditioned Air Thermostat
Indoor temperature is controlled by a Johnson Controls System 350 Electronic Temperature Controller.
High Pressure cut out
The systems are protected by a Texas Instruments manual reset high pressure switch which is set to actuate at 425 psig.
Low Pressure cut out
The systems are protected by a Texas Instruments auto reset low pressure switch which is set to open at 10 psig and reset at 25 psig.
Heater high limit cutout
Each individual resistance heat element is controlled primarily by a Therm-O-Disc auto reset temperature limit switch, which will open the low voltage control circuit if extreme temperatures are present. Secondary limits are also incorporated in the event that the primary limits fail to actuate. The secondary limits are a non-resetable thermal cut-offs that open the primary line voltage to the element.
Refrigeration System
Systems are of the Vapor Compression type and use R134a refrigerant for high ambient operation. An ASME-UV/NB certified pressure relief valve is supplied, located within the condenser section, to safely expel refrigerant prior to the rupture of any system components (applied in accordance with the American Standard Safety Code for Mechanical Refrigeration ANSI/ASHRAE 15). Systems are supplied with a full charge of refrigerant conforming to ARI 700. The refrigerant systems can be serviced through 1/2" standard flare type fittings.
Transportation and Vibration
ECUs are certified to withstand MIL-STD-810-F. System cabinets are constructed of rugged and light weight aluminum (AL 5052-H32). Refrigerant piping contains vibration absorption loops for relief and are protected where abrasion is a factor. Motors are of the direct drive type to eliminate alignment issues and are mounted to withstand field abuse.
Electromagnetic Environmental Effects
Air Rover ECUs are certified to be in compliance with the requirements of MIL-STD-461E (Ground). Air Rover ECUs and control cables do not radiate electric field emissions in excess of those shown in MIL-STD-461E, method RE102, radiated emissions, electric field, 2 MHz to 1 GHz. Air Rover ECUs do not conduct emissions from power leads in excess of the applicable values shown in MIL-STD-461E, Method CE102, conducted emissions, power leads, 10 kHz to 10 MHz. Air Rover ECUs are not susceptible to conducted or radiated noise in accordance with the following: a. MIL-STD-461E, Method CS101, conducted susceptibility, power leads, second harmonic to 50 kHz b. Mil-STD-461E Method RS103, radiated susceptibility (Table VII), electric field, 2 MHz to 40 GHz.
Noise
All Four models run well under the required dB ratings specified. None of the models provided by Air Rover exceed: 60 dB (A) at 1 meter from any point on the perimeter of the evaporator side of the ECU housing. 72 dB (A) at 1 meter from any point on the perimeter of the condenser side of the ECU housing.
Reliability and Maintainability
ECUs are equipped with washable filters, protecting both indoor and outdoor coils. All access panels are fastened with Fast-lead Thread Screws to facilitate quick removal during system servicing. Pressure taps are located in a recessed panel to be accessed without the removal of service panels.
Mean-Time between Failures
The minimum mean-time-between-failure of the Air Rover ECUs meets or exceeds the USMC requirement of 2100 hours @ 80% reliability.
Maintenance ratio
The Air Rover family of ECUs has a maintenance ratio of 0.017 Maintenance man-hours per Operating Hour.
Scheduled Maintenance
The Air Rover family of ECUs requires scheduled maintenance once every 250 hours of operation. Scheduled maintenance includes checking and cleaning the evaporative and condenser filters.
Evaporator Compartment Sealing
The evaporator compartment door panels are sealed using a cross-linked Polyethylene weather stripping. Air leakage in the Evaporator compartment is certified not to exceed 20 standard cubic feet per minute (SCFM) when the evaporator compartment is subjected to an internal static pressure of 1.0 in. Evaporator sections are sealed with a closed-cell insulation material.
Electrical System
Electrical systems are designed to be in compliance with National Electric Code (NFPA), UL1950 and UL1995. All wiring is bundled and tied. Isolators are used to insulate between metal components to prevent abrasive action to the wire insulation. All wiring is color coded and well documented within an easy to follow wiring schematic that is supplied within the electrical enclosure. Wires are numbered and to correspond to the electrical schematics supplied with the units.
Safety
ECUs are designed in accordance with UL1995 Heating and Cooling Equipment. A great effort has been taken to assure that these ECUs can be safely installed, operated, and maintained. Electrical Operators are not exposed to any live uninsulated components while operating or servicing the ECU. Filters are easily removed for cleaning from access panels that are opened without exposing any electrical components of the system. Remote control boxes, where used, utilize low voltage current (24V AC) and are grounded back to the ECU through the extension cable. A circuit breaker is installed on the ECU that, when activated, cuts off all power to the ECU.
Mechanical Safety Provided During Service
All filters are accessed without exposing USMC service personnel to live or rotating components. Refrigerant pressures are checked without removing any service panels. All service panels can be quickly removed, with the use of fast-lead screws, if needed to gain access to components within the system from all four sides of the cabinet.
Insulating of high temperature components
All high temperature components are safely enclosed and protected to avoid exposure to operators.
Guarding of rotating parts
All guards of rotating parts will be capable of withstanding a 200 lb load within a 6" diameter area located in the most vulnerable position (UL 1995 section 54 Loading Test).
Venting of pressurized components
An ASME-UV/NB certified pressure relief valve is supplied, located within the condenser section, to safely expel refrigerant prior to the rupture of any system components (applied in accordance with the American Standard Safety Code for Mechanical Refrigeration (ANSI/ASHRAE 15).
Lift Provisions
These ECUs are supplied with a permanently mounted skid base. This base is manufactured with welded 14 Gage G90 steel which is then powder coat paint finished to match the ECU and to provide added corrosion protection. The skid base is forklift accessible from all sides with forklift pockets provided on two sides. Forklift pockets are 8 in. in width by 3 in. high spaced 13 in. to 18 in. apart depending on the model. The skid assembly has lifting and tie down rings in accordance with MIL-STD-209.
Fresh Air Inlet
Fresh air inlet dampers are available as an option on any of the four ECUs. These dampers will facilitate the introduction of outdoor air into the evaporator compartment.
Evaporator and Condenser Compartment Airflow
Evaporator air - Horizontally returned discharged A blow (push) through configuration is utilized to put a positive pressure on all condensate drain taps. This is done to reduce the ECU?s susceptibility to drain pan overflow.
Condenser air - The UL ECU models employ a vertical discharge configuration. All models are equipped with a washable condenser inlet air filter to protect the condenser coil and simplify cleaning.
Material Protection
ECUs are coated with a Polyester thermosetting, powder-coated finish.
Color: Desert Tan, Olive Drab, Storm Grey, or White
Film Thickness: ASTM# D1186 2.0 - 2.5 Mils
Pencil Hardness: ASTM# D3363 H - 2H
Impact: ASTM# DE2794
Direct: 160/lbs
Reverse: 160/lbs
Salt Spray: ASTM#B117 Pass 1000 hours salt spray, less than 1/8" creepage, no blistering.
Marking and Labeling
Identification Plates
Air Rover uses permanent 4 x 6" aluminum plate with stamped data fields containing the following information. The plate is attached by rivets in all four corners.
Air Rover (manufacturer) corporate information
Address
Phone Number
Support Web site
Date of Manufacture
Contract Number
NSN
Model Number
Serial Number
BTU/h
Unit Rating
VAC
Hertz
Phase
Compressor
VAC
RLA
LRA
FLA
Evap. Motor Type
RPM
HP
FLA
Cond. Motor Type
RPM
HP
Operating Voltage Range
Min. VAC
Max. VAC
Minimum Circuit Ampacity
HACR Type Circuit Breaker
Refrigerant Charge
Weight
Technical Manual ID
Labels
Bar Code Labels
Air Rover provides bar code labels on each ECU unit to identify NSN number and unit serial number.
Warning Labels
Warning labels are located on the unit at each serviceable location to identify dangers of electrical shock or hazardous materials.
Diagnostic Labels
Diagnostic labels are included to check refrigerant levels.
Quality Assurance Labels
All units are equipped with a quality assurance "passed" label before leaving Air Rover's manufacturing facility.
Schematics
Schematics are provided on the unit and in all technical documentation.
Wire Diagrams
Wire diagrams are provided on the unit and in all technical documentation.
Safety Markings and Labels
Safety markings and labels are provided on the unit where applicable.
Human Performance and Human Factors Engineering (HFE)
Air Rover's ECUs comply with all of the following human performance and HFE criteria in accordance with MIL- HDBK-1472.
Human Performance
The ECU is operable and maintainable by 5th through 95th percentile marines dressed in the Battle Dress Uniform (BDU), cold-wet weather protective clothing, and protective ensembles for Mission Oriented Protective Posture (MOPP) Levels I through IV. The ECU also minimizes personnel and training requirements within the limits of time, cost and performance trade-offs.
Simplicity of Design
Air Rover's ECUs represent the simplest design consistent with functional requirements and expected service conditions. The ECUs are capable of being operated, maintained and repaired in its operational environment by personnel with a minimum of training.
Hot Surfaces
Any surfaces, which, in normal operation, expose personnel to temperatures in excess of 140°F as a result of inadvertent contact or 120°F during handling, are appropriately guarded.
Design for Maintainer
Air Rover's ECUs are designed for ease of maintenance. All units are built from COTS. Mission critical items, which require rapid maintenance, are accessible through easy-access panels on the outside of the unit. Trained USMC personnel can perform replacement of high-failure items without endangering other components. Safety hazards such as heat, moving parts, and other dangerous components are clearly marked and easily avoidable.
Special Tools
Air Rover's ECU is maintainable using only the tools specified in SL-3-02536A, SL-3-00456A, SL-3-03341A, SL-3-03007C, SL-3-022964B. No special tools shall be used to perform maintenance or installation/removal of the Air Rover ECU.
Error-Proof Design
Provision to assist assembly and installation, and preclude improper assembly or installation, include the following:
Physical measures to preclude interchange of items of a same or similar form that are not in fact functionally interchangeable.
Physical measures to preclude improper mounting of units or components.
Measures (e.g., coding) to facilitate identification and interchange of interchangeable items. Measures (e.g., alignment pins) to facilitate proper mounting of items.
Measures to ensure that identification, orientation, and alignment provisions include cables and connectors. All parts having the same part number are functionally and dimensionally interchangeable.
Workmanship
Metal fabrication
Metal used in fabrication is free from kinks and sharp bends. The straightening of material is done by methods that will not cause injury to the material. Corners are square and true. All bends are made by controlled means to ensure uniformity of size and shape. Precaution is taken to avoid overheating materials. Heated steel is allowed to cool slowly. All surfaces are free of burrs. Air Rover has added two Strippit Global 20 Series Punch Presses to its manufacturing facility that ensure sheet metal is fabricated to strict tolerance levels in accordance with USMC requirements.
